Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Smullen van beschimmeld stro
Hendriks, Wouter ; Cone, John - \ 2018
biobased economy - animal nutrition - biomass - fibres - enzymes - digestibility - straw
Delicious mouldy straw : animal nutrition
Hendriks, Wouter ; Cone, John - \ 2018
biobased economy - animal nutrition - biomass - fibres - enzymes - digestibility - straw
Kuiken kan maximaal 36 uur zonder eten
Jong, Ingrid de - \ 2018
animal welfare - animal production - poultry - animal nutrition - animal health
Code of Practice for the Care and Handling of Rabbits: Review of Scientific Research on Priority Issues
Turner, Patricia ; Buijs, Stephanie ; Rommers, J.M. ; Tessier, Maxime - \ 2017
National Farm Animal Care Council - 69 p.
animal welfare - animal production - rabbits - animal housing - animal nutrition - animal health - animal behaviour
It is widely accepted that animal welfare codes, guidelines, standards or legislation should take advantage of the best available knowledge. This knowledge is often generated from the scientific literature. In re-establishing a Code of Practice development process, NFACC recognized the need for a more formal means of integrating scientific input into the Code of Practice process. A Scientific Committee review of priority animal welfare issues for the species being addressed will provide valuable information to the Code Development Committee in developing or revising a Code of Practice. As the Scientific Committee report is publicly available, the transparency and credibility of the Code is enhanced. For each Code of Practice being developed or revised, NFACC will identify a Scientific Committee. This committee will consist of a target number of 6 scientists familiar with research on the care and management of the animals under consideration. NFACC will request nominations from 1) Canadian Veterinary Medical Association, 2) Canadian Society of Animal Science, and 3) Canadian Chapter of the International Society for Applied Ethology. At least one representative from each of these professional scientific bodies will be named to the Scientific Committee. Other professional scientific organizations as appropriate may also serve on the Scientific Committee. Purpose & Goals The Scientific Committee will develop a report synthesizing the results of research relating to key animal welfare issues, as identified by the Scientific Committee and the Code Development Committee. The report will be used by the Code Development Committee in drafting a Code of Practice for the species in question. The Scientific Committee report will not contain recommendations following from any research results. Its purpose is to present a compilation of the scientific findings without bias. The full Terms of Reference for the Scientific Committee can be found within the NFACC Development Process for Codes of Practice for the Care and Handling of Farm Animals, available at www.nfacc.ca/code-development-process#appendixc.
Project Insecten in pluimvee
Ruis, Markus - \ 2017
animal welfare - poultry - animal nutrition - animal behaviour - animal production
Valorisation of waste streams from by-product to worm biomass
Laarhoven, Bob - \ 2017
University. Promotor(en): Cees Buisman, co-promotor(en): Hardy Temmink; Hellen Elissen. - Wageningen : Wageningen University - ISBN 9789463438117 - 141
biomass - residual streams - animal nutrition - fisheries - organic wastes - helminths - biomassa - reststromen - diervoeding - visserij - organisch afval - wormen

There is a global demand for more feed resources to keep up with the increasing production of livestock. The hunger for resources is most urgent in the aquaculture sector, which to a large degree depends on the non-sustainable use of fish oil/ meal from wild fish. Aquatic macro invertebrates such as the freshwater worm Lumbriculus variegatus (Oligochaeta, Lumbriculidae, common name blackworms, further abbreviated as Lv) are rich in proteins, lipids, vitamins and minerals. When cultivated on safe and low-grade organic wastes they can provide a sustainable fishmeal alternative for most freshwater and marine fish.

Chapter 1 introduces the concept of aquatic worm production on waste streams. Worm biomass composition and relevant research lines are explained. Organic waste sludges from food industries are a rich source of bio-molecules and can be upgraded to (fish) feed when fed to aquatic worms. For valorisation of waste streams by aquatic worms, as proposed in this thesis, these streams preferably are free from contaminants such as organic micro pollutants, heavy metals and pathogens. For example, this would not be the case when sewage (municipal) sludge is used as a substrate for the worms. However, such contaminated sludges may still be applied for non-food applications. Thus, the quality of the waste stream that is used as a substrate for the worms determines the application potential of the worm biomass as well as the options for downstream processing and refinery.

Previous research showed that Lv can be used for reduction and compaction of sewage sludge. The consumption of (suspended) sludge particles results in a dry matter reduction of 25 - 50 % and in worm faeces that are 60 % more compact than the original waste sludge. This contributes to a significant reduction in sludge processing costs. Sludge reduction by aquatic worms is mainly studied by research groups in The Netherlands and in China. Unfortunately, it is generally accepted free swimming worms in full-scale wastewater treatment plants is extremely difficult, mainly because of large (seasonal) population fluctuations. A controlled reactor concept applying the sessile (crawling, sediment dwelling) species Lv already was developed in earlier research. The key characteristic of this reactor is a carrier material for the worms, which also functions as a separation layer between the waste stream (worm food) and a water phase used for aeration, worm harvesting and worm faeces collection. This concept also was the starting point for the development of the improved reactor concept that is described in this thesis.

The two main objectives of this thesis were: (1) to assess the potential of organic waste streams and by-products for Lv production for fish feed and (2) to develop a (cost and resource) effective bioreactor for this purpose.

In Chapter 2 a new, standardized method is described and tested that can be used for a quantitative and qualitative assessment of the effect of different substrates on worm growth. This method not only can be used to select waste streams suitable for worm production, but also is proposed as a tool is ecotoxicology studies.

The test method consists of beaker experiments with a combination of agar and sand to optimize food uptake by and growth of the worms. The effects of agar gel, sand, and food quantity were studied and evaluated for different food sources. Agar gel addition ameliorated growth conditions by reducing microbial food hydrolysis and by improving the sediment structure. This guaranteed that substrate ingestion and worm growth in the first place were the result of the food quality and the effect of other (environmental) factors was reduced. A final test with secondary potato starch sludge demonstrated the test method is appropriate for the evaluation of solid and suspended organic feedstuffs/waste streams.

In Chapter 3 the standardized method of chapter 2 was used for worm growth studies, focussing on the effect of carbon to nitrogen (C/N) ratios of diets on worm growth and reproduction. Growth and reproduction of Lv on different combinations of wheat based derivatives like gluten and gray starch was studied at fixed isoenergetic levels (expressed as chemical oxygen demand (COD) of the food), but at different C/N ratios. Growth and reproduction rates were compared to those on Tetramin, a substrate known to result in excellent worm growth. Growth was mainly controlled by the C/N ratio of the single and mixed wheat fraction diets. Lower C/N ratios of around 6-7 gave a much better performance than high C/N ratios of around 20. This probably was caused by Lv relying on the presence of proteins as carbon and energy source. Although growth and reproduction rates were not as high as on the control diet, the results were promising for development of a worm biomass production reactor, operating on by-products from wheat processing industries.

In Chapter 4 a new reactor concept for Lv cultivation on waste streams was developed and tested. In a vertical tubular reactor a centralized food compartment was surrounded by a gravel layer that mimicked the natural habitat of Lv. Secondary (biological) sludge from a potato starch processing industry was used as a clean and low value food source. The results with respect to worm growth rate, density and production and nutrient recovery were compared to the previous reactor design. Much higher worm densities were achieved (6.0 compared to 1.1 kg ww m-2 carrier material) as well as much faster Lv growth rates (4.4 - 12 compared to 1.2 % d-1). As a result the areal worm production rate was no less than 40 times higher (560 compared to 14 g ww m-2 d-1). The higher worm density, which was found to be independent of gravel size in a range of 2.4 to 8.0 mm, allowed for a significantly shorter food retention time in the reactor (~ 2.2 days compared to > 10 days for the previous reactor design). This restricted microbial mineralization of the food, making high nutrient recoveries from waste to worm biomass possible: 16-30 % COD, 19-22 % N and 9-11 % P. The high biomass density also limited the release of ammonium, which at large concentrations is toxic for the worms. However, even shorter food retention times (e.g. higher loading rates) are not recommended as a minimum microbial activity is needed for conversion of the original substrate into compounds that can be taken up by the worms.

In Chapter 5 worm growth, reproduction and biomass quality were evaluated on several waste streams and by-products of bacterial, animal and plant origin. The effect of 26 different diets, all applied at high food levels, on Lv growth, reproduction and fatty acid (FA) content and profile were investigated. For this purpose the standardized test method of Chapter 2 was used. In addition, it was discussed which diet composition and food sources would be most suitable for large scale production of Lv.

Diets consisting of single cell biomass from bacterial or plant origin with a high protein content (C/N ratio < 8.8), high P content (C/P < 50) and low in total ammonia nitrogen (TAN) (< 20 g N/kg) gave the highest growth rates and vital worms without signs of mortality. Besides the C/P ratio of the diet, worm conditions related with the difference between test and pre-culture conditions. The starting weight of the worms seemed to have an effect on the total fatty acid content of the worms. The growth potential of a diet rich in proteins and P depends on how much TAN is associated with the diet. By blending different food sources these factors to a certain extent can be manipulated. Lv seemed to have a distinct and very stable FA composition, irrespective of the diet’s FA composition. The worms were rich in poly unsaturated FAs (PUFAs), including several w3 and w6 FAs, and contained relatively high levels of C18 and C20 PUFAs. This makes them suitable as fish feed, in particular for freshwater fish.

In order to serve aquaculture feed markets with an attractive alternative to fish meal, such as aquatic worm biomass, a continuous and secure bulk production needs to be realized. In Chapter 6 the performance parameters established in chapter 4 (worm growth rate, density and biomass production rate) were used as the input for a feasibility assessment of large scale worm production on secondary sludge from the potato industry. In addition, in chapter 6 future value chains and lines of research were discussed.

A hypothetical worm production system treating the surplus secondary sludge from a potato processing factory can reduce excess sludge production by 50 % in solids and 62 % in volume. This is accompanied by a daily production of 1.6 metric ton of fresh worm biomass. With a very conservative estimation of the worm density of 1.6 kg ww/m2 carrier material a footprint of the system of 217 m2 can be realized, which is at least two times smaller than with a previous reactor design without a gravel layer. With reduced sludge processing costs and a conservative market price of 1.4 €/kg dry worm biomass, worm production can already be realized at an annual rate of return of 3 years. However, the costs are highly sensitive for worm biomass stocking, reactor construction and operation. A more accurate economic assessment should be based on the results of pilot-scale research.

Two general product types, whole biomass (as fish feed) and refined products can be distinguished and applied in two application areas (feed and non-food), depending on the quality of the organic (waste) sludge that the worms have been produced from. Valorisation for potential bulk markets needs further refinery of crude worm biomass into a lipid (worm oil) and a protein fraction (protein isolate). This can result in several new and unique business models in aquaculture, feed, chemical and agriculture sectors. Obviously, an assessment of economical and legislative boundary conditions needs to be part of such business models.

Worm biomass is a potential high quality fishmeal replacer, with a similar or even better potential than other waste based alternatives such as single cell biomass and insects. A comparison between Lv and fishmeal with respect to crude composition, essential amino acids and FAs learns that Lv is a highly suitable fish feed source. It can provide essential amino acids at sufficiently high levels. Based on its FA composition and (relatively low) fat content, Lv can best be considered a protein source. Still, worm biomass is rich in PUFA, which could be a potential high value product for feed applications. Compared to black soldier fly and bacterial production systems, Lv shows intermediate production efficiencies, while biomass harvesting and processing probably is more easy.

Additional advantages of Lv worm biomass to replace fishmeal are: 1) Lv acts as a strong natural fish attractant, 2) the growth efficiency of fish on worms is high in comparison to regular feeds, 3) the nutritional profile of worms matches that of fishmeal, 4) the worms are a natural feed source for freshwater fish and 5) the worms allow a secure and stable feed production that is independent of natural resources.

Further recommendations for future research as outlined and discussed in chapter 6 are mostly related to the technical upscaling of the reactor technology and obtaining more detailed insight in controlled worm growth in response to food characteristics, reactor design and operational conditions.

Predicting methane emission of dairy cows using milk composition
Gastelen, Sanne van - \ 2017
University. Promotor(en): Wouter Hendriks, co-promotor(en): Jan Dijkstra; Kasper Hettinga. - Wageningen : Wageningen University - ISBN 9789463437097 - 266
dairy cows - dairy cattle - methane production - emission - milk composition - fatty acids - cattle feeding - fermentation - nutrition physiology - animal nutrition - pollution - melkkoeien - melkvee - methaanproductie - emissie - melksamenstelling - vetzuren - rundveevoeding - fermentatie - voedingsfysiologie - diervoeding - verontreiniging

Enteric methane (CH4) is produced as a result of microbial fermentation of feed components in the gastrointestinal tract of ruminant livestock. Methane has no nutritional value for the animal and is predominately released into the environment through eructation and breath. Therefore, CH4 not only represents a greenhouse gas contributing to global warming, but also an energy loss, making enteric CH4 production one of the main targets of greenhouse gas mitigation practices for the dairy industry. Obviously, reduction of CH4 emission could be achieved by simply reducing livestock numbers. However, the global demand for dairy products has been growing rapidly and is expected to further grow in the future. Therefore, it is critical to minimize environmental impact to produce high-quality dairy products. The overall aim of this PhD research was, therefore, to develop a proxy for CH4 emission that can be measured in milk of dairy cows.

There are currently a number of potentially effective dietary CH4 mitigation practices available for the livestock sector. The results of Chapter 3 show that replacing fiber-rich grass silage with starch-rich corn silage in a common forage-based diet for dairy cattle offers an effective strategy to decrease enteric CH4 production without negatively affecting dairy cow performance, although a critical level of starch in the diet seems to be needed. Little is known whether host genetics may influence the CH4 emission response to changes in diet. Therefore, the interaction between host DGAT1 K232A polymorphism with dietary linseed oil supplementation was evaluated in Chapter 7. The results of Chapter 7 indicate that DGAT1 K232A polymorphism is associated with changes in milk composition, milk N efficiency, and diet metabolizability, but does not affect digestibility and enteric CH4 emission, whereas linseed oil reduces CH4 emission independent of the DGAT1 K232A polymorphism.

Accurate and repeatable measurements of CH4 emission from individual dairy cows are required to assess the efficacy of possible mitigation strategies. There are several techniques to estimate or measure enteric CH4 production of dairy cows, including climate respiration chambers, but none of these techniques are suitable for large scale precise and accurate measurements. Therefore, the potential of various metabolites in milk, including milk fatty acids (MFA), as a proxy (i.e., indicators or animal traits that are correlated with enteric CH4 production) for CH4 emission of dairy cows gained interest. Until recently, gas chromatography was the principal method used to determine the MFA profile, but this technique is unsuitable for routine analysis. This has led to the application of Fourier-transform infrared spectroscopy (FTIR) for determination of the MFA profile. Chapter 2 provides an overview of the recent research that relates MFA with CH4 emission, and discusses the opportunities and limitations of using FTIR to estimate, indirectly via MFA or directly, CH4 emission of dairy cattle. The recent literature on the relationship between MFA and CH4 emission gives inconsistent results. Where some studies found a clear and strong relation, other studies consider MFA to be unreliable predictors for CH4 emitted by dairy cows. Even the studies that do find a clear relation between MFA and CH4 emissions do not describe similar prediction models using the same MFA. These discrepancies can be the result of many factors, including dietary composition and lactation stage. Additionally, literature showed that the major advantages of using FTIR to predict CH4 emission include its simplicity and potential practical application on a large scale. Disadvantages include the inability to predict important MFA for the prediction of CH4 emission, and the moderate power of FTIR to directly predict CH4 emission. The latter was also demonstrated in Chapter 9, in which the CH4 prediction potential of MFA was compared with that of FTIR using data from 9 experiments (n = 218 individual cow observations) covering a broad range of roughage-based diets. The results indicate that MFA have a greater potential than FTIR spectra to estimate CH4 emissions, and that both techniques have potential to predict CH4 emission of dairy cows, but also limited current applicability in practice. Much focus has been placed on the relationship between MFA and CH4 emission, but milk also contains other metabolites, such as volatile and non-volatile metabolites. Currently, milk volatile metabolites have been used for tracing animal feeding systems and milk non-volatile metabolites were shown to be related to the health status of cows. In Chapter 4, the relationship between CH4 emission and both volatile and non-volatile metabolites was investigated, using data and milk samples obtained in the study described in Chapter 3. In general, the non-volatile metabolites were more closely related to CH4 emissions than the volatile metabolites. More specifically, the results indicate that CH4 intensity (g/kg fat- and protein-corrected milk; FPCM) may be related to lactose synthesis and energy metabolism in the mammary gland, as reflected by the milk non-volatile metabolites uridine diphosphate-hexose B and citrate. Methane yield (g/kg dry matter intake) on the other hand, may be related to glucogenic nutrient supply, as reflected by the milk non-volatile acetone. Based on the metabolic interpretations of these relationships, it was hypothesized that the addition of both volatile and non-volatile metabolites in a prediction model with only MFA would enhance its predictive power and, thus, leads to a better proxy in milk for enteric CH4 production of dairy cows. This was investigated in Chapter 5, again using data and milk samples described in Chapter 3. The results indicate that MFA alone have moderate to good potential to estimate CH4 emission. Furthermore, including volatile metabolites (CH4 intensity only) and non-volatile metabolites increases the CH4 emission prediction potential.

The work presented in Chapters 3, 4 and 5, was based upon a small range of diets (i.e., four roughage-based diets in which grass silage was replaced partly or fully by corn silage) of one experiment. Therefore, in Chapter 6, the relationship between CH4 emission and the milk metabolome in dairy cattle was further quantified. Data (n = 123 individual cow observations) were used encompassing a large of roughage-based diets, with different qualities and proportions of grass, grass silage and corn silage. The results show that changes in individual milk metabolite concentrations can be related to the ruminal CH4 production pathways. These relationships are most likely the result from changes in dietary composition that affect not only enteric CH4 production, but also the profile of volatile and non-volatile metabolites in milk. Overall, the results indicate that both volatile and non-volatile metabolites in milk might provide useful information and increase our understanding of CH4 emission of dairy cows. However, the development of CH4 prediction models revealed that both volatile and non-volatile metabolites in milk hold little potential to predict CH4 emissions despite the significant relationships found between individual non-volatile metabolites and CH4 emissions. Additionally, combining MFA with milk volatile metabolites and non-volatile metabolites does not improve the CH4 prediction potential relative to MFA alone. Hence, it is concluded that it is not worthwhile to determine the volatile and non-volatile metabolites in milk in order to estimate CH4 emission of dairy cows.

Overall, in comparison with FTIR, volatile and non-volatile metabolites, the MFA are the most accurate and precise proxy in milk for CH4 emission of dairy cows. However, most of MFA-based models to predict CH4 emission tend to be accurate only for the production system and the environmental conditions under which they were developed. In Chapter 8 it was demonstrated that previously developed MFA-based prediction equations did not predict CH4 emission satisfactory of dairy cows with different DGAT1 genotypes or fed diets with or without linseed oil. Therefore, the greatest shortcoming today of MFA-based CH4 prediction models is their lack of robustness. Additionally, MFA have restricted practical application, meaning that most MFA retained in the current CH4 prediction models cannot be determined routinely because of the use of gas chromatography. The MFA that can be determined with the use of infrared spectroscopy are however no promising predictors for CH4 emission. Furthermore, MFA have only a moderate CH4 prediction potential. This together suggests that it might not be the best option to focus in the future on MFA alone as a proxy for CH4 emission of dairy cows.

The FTIR technique has a low to moderate CH4 prediction potential. However, FTIR has a great potential for practical high throughput application, facilitating repeated measurements of the same cow potentially reducing random noise. Results of this thesis also demonstrated that FTIR spectra do not have the potential to detect differences in CH4 emission between diets which are, in terms of forage level and quality, commonly fed in practice. Moreover, the robustness of FTIR spectra is currently unknown. Hence, it remains to be investigated whether FTIR spectra can predict CH4 emissions from dairy cows housed under different conditions from those under which the FTIR-based prediction equations were developed. It is therefore concluded that the accuracy and precision to predict CH4 emission using FTIR needs to increase, and the capacity of FTIR to evaluate the differences in CH4 emission between dairy cows and different types of diets needs to improve, in order to actually be a valuable proxy for CH4 emission of dairy cows.

Effects of β-Glucans and resistant starch on fermentation of recalcitrant fibers in growing pigs
Vries, S. de; Gerrits, W.J.J. ; Kabel, M.A. ; Zijlstra, Ruurd ; Vasanthan, Thava - \ 2017
animal nutrition - carbohydrate structures - digestibility measurements - fermentable fibers - food chemistry - growing pigs - in vivo digestion - nutritional modelling - rapeseed meal
Effects of the presence of β-glucans and resistant starch in diets on nutrient and fiber degradability of rapeseed meal [RSM] (Brassica napus) and Distillers Dried Grain with Solubles (DDGS) were tested in a 2 × 3 factorial arrangement. Two basal diets, containing either 500 g/kg RSM or DDGS and ~400 g/kg corn starch were formulated to meet or exceed nutrient requirements of growing pigs. Corn starch was partly replaced with the β-glucan-extract (β-GLUC; 60 g/kg w/w) or completely replaced with retrograded tapioca (RG; 400 g/kg w/w), resulting in 6 dietary treatments. A total of 10 crossbred barrows (initial body weight, 28 ± 1.4 kg (SD); Duroc × Large White/Landrace; Hypor, Inc., Regina, SK, Canada) were fed the 6 experimental diets. In total, 46 observations were obtained in 10 pigs over 7 periods in an incomplete 10 × 7 Youden square. Each of 7 sequential 14 days experimental periods consisted of a 9 days adaption to the diets followed by 2 days collection of feces, 2 days collection of ileal digesta for digestibility measurements, and 1 day collection of ileal digesta for the measurement of retention time. Pigs were weighed weekly during the experiment after consuming their morning meal. Feces were collected from 08.00 to 17.00 h using bags attached to rings glued around the anus. Bags were collected within 1 h after defecation and immediately frozen (-20 °C). Ileal digesta for digestibility measurements were collected from 08.00 to 17.00 h into plastic bags (10 cm in length and 4 cm in diameter). The bags were removed when filled approximately 70 % with digesta, or after a maximum of 1 h, and immediately frozen (-20 °C). For retention time measurements, on day 14 of each experimental collection, 3.4 g Cr as Cr2O3 (solid phase marker) and 3.4 g Co as Co (II)-EDTA (soluble phase marker) were mixed into the morning meal. Digesta were collected at 45, 90, 180, 270, 360, 540, and 720 min after feed consumption.
'Meer reststromen benutten in veevoer'
Gerrits, Walter - \ 2017
residual streams - animal nutrition - sustainability - food - food production - livestock farming
Stalboekje Varkens 2016: handboek voor natuurlijke diergezondheidzorg met kruiden en andere natuurproducten : Natuurlijk gezond met kruiden en andere natuurproducten
Groot, Maria ; Asseldonk, Tedje van - \ 2017
IJmuiden : RIKILT Wageningen UR (RIKILT-uitgave 2016.701) - 168
varkens - veehouderij - biologische landbouw - geneeskrachtige kruiden - diervoeding - diergezondheid - dierenwelzijn - dierlijke productie - pigs - livestock farming - organic farming - herbal drugs - animal nutrition - animal health - animal welfare - animal production
Stalboekje Vleeskalveren 2016 : handboek voor natuurlijke diergezondheidzorg met kruiden en andere natuurproducten
Groot, Maria ; Asseldonk, Tedje van - \ 2017
IJmuiden : RIKILT Wageningen UR (RIKILT-uitgave 2016.702) - 128
rundvee - dierenwelzijn - diergezondheid - diervoeding - geneeskrachtige kruiden - dierlijke productie - biologische landbouw - cattle - animal welfare - animal health - animal nutrition - herbal drugs - animal production - organic farming
Deze uitgave van ‘Stalboekje vleeskalveren’ is bedoeld om kalverhouders te helpen bij het vinden van de juiste toepassing van kruiden en andere natuurproducten. Kruiden en andere natuurproducten kunnen ter ondersteuning van gezonde dieren bij stress en ter ondersteuning van therapeutische maatregelen worden ingezet. Grootste meerwaarde is dat problemen voorkomen worden en dieren weerbaar gemaakt worden. Deze gids geeft een leidraad welke kruiden en natuurproducten op basis van beschikbare kennis een effect kunnen hebben bij verschillende gezondheidsproblemen. De ontwikkelingen op dit gebied gaan snel en daarom zal dit boekje regelmatig herzien en aangevuld moeten worden.
Nutrition of pigs kept under low and high sanitary conditions : effects on animo acid and energy metabolism and damaging behaviour
Meer, Yvonne van der - \ 2017
University. Promotor(en): Walter Gerrits, co-promotor(en): Alfons Jansman; Aart Lammers. - Wageningen : Wageningen University - ISBN 9789463431972 - 181
pigs - feeds - pig feeding - animal nutrition - amino acid metabolism - animal health - energy metabolism - abnormal behaviour - behaviour disorders - immune system - nutrition physiology - varkens - voer - varkensvoeding - diervoeding - aminozuurmetabolisme - diergezondheid - energiemetabolisme - abnormaal gedrag - gedragsstoornissen - immuunsysteem - voedingsfysiologie

It is economically and environmentally important to match the nutrient supply to the nutrient requirements in pig production. Until now, the effects of different sanitary conditions on energy and nutrient requirements are not implemented in recommendations for nutrient composition of pig diets. The current nutrient requirement data are based on studies with pigs in experimental settings, which can be regarded as rather optimal. Changes in nutrient requirements caused by differences in sanitary conditions are poorly documented. As in the pig production sector farm conditions are variable it is of major importance to determine the effects of low sanitary conditions (LSC) on requirements for amino acids and energy in growing pigs. Pigs under LSC have an increased risk of clinical and subclinical infections, resulting in a chronic stimulation of their immune system. Immune system stimulation is known to influence energy and amino acid metabolism. However, most studies in pigs evaluating the relationship between immune system stimulation and nutrient requirements often use specific experimental challenge models. Whereas such models have the obvious advantage of reproducibility and allow mechanistic insight in the effects of stimulating specific parts of the immune system, these models often induce clinical illness, rather than subclinical infections. Results obtained with such models may therefore be difficult to translate to practical situations. Therefore the objective of the present thesis was to study the effect of low and high sanitary conditions (HSC) on amino acids and energy metabolism in pigs. Also interactions between the immune system, nutrient metabolism and damaging behaviour of pigs were considered in this thesis.

The experiment described in Chapter 2 was designed to study the effect of different dietary crude protein levels and extra amino acid supplementation on the growth performance of pigs kept under different sanitary conditions. In a 2×2×2 factorial arrangement, 68 groups of 9 pigs were allocated to either LSC or HSC, and were offered ad libitum access to two different diets, a normal crude protein concentration diet or a low crude protein concentration diet, each having either a basal dietary amino acid profile or supplemented dietary amino acid profile containing 20% more methionine, threonine, and tryptophan compared with the basal profile. The pigs were followed from 10 weeks of age until slaughter. Haptoglobin concentrations in serum and IgG antibody titers against keyhole limpet heamocyanin, collected in the starter, grower, and finisher phases, and pleuritis scores at slaughter were greater for LSC pigs compared with HSC pigs, illustrating that sanitary conditions affected health conditions. The average daily gain and gain to feed ratio were greater for HSC pigs compared with LSC pigs. A 20% increase in dietary supplementation of methionine, threonine, and tryptophan relative to lysine increased gain to feed ratio more in LSC than in HSC pigs. The results therefore illustrated that dietary requirements for methionine. threonine, and tryptophan were greater for LSC compared with HSC pigs.

In Chapter 3 the damaging behaviour of 576 pigs from the experiment in Chapter 2 was evaluated. At 15, 18, and 24 weeks of age, prevalence of tail and ear damage, and of tail and ear wounds was scored. At 20 and 23 weeks of age, frequencies of biting behaviour and aggression were scored by behaviour sampling. The prevalence of ear damage during the finisher phase and the frequency of ear biting were increased in LSC compared with HSC pigs. The frequency of ear biting was increased in low protein fed pigs compared with normal protein fed pigs. The supplemented AA profile reduced ear biting only in LSC pigs. The prevalence of tail wounds was lower for pigs in LSC than for pigs in HSC in the grower phase. Regardless of dietary amino acid profile or sanitary status, pigs fed low protein diets showed more ear biting, tail biting, belly nosing, other oral manipulation directed at pen mates, and aggression than pigs fed normal protein diets, with no effect on ear or tail damage. In conclusion, both LSC and a reduction of dietary protein increased the occurrence of damaging behaviours in pigs and therefore may negatively impact pig welfare.

The experiment of Chapter 4 was designed to quantify the difference in energy requirements for maintenance, and in incremental efficiencies for deposition of dietary energy and protein in the body of clinically healthy pigs kept under LSC or HSC, fed a basal diet either or not supplemented with additional methionine, threonine and tryptophan.

In a 2 × 2 factorial arrangement, 24 groups of 6 pigs each were allocated to either a LSC or HSC, and were offered two different diets having either a basal or a dietary amino acid profile supplemented with methionine, threonine, and tryptophan. For each group of pigs, complete energy and nitrogen balances were determined during two consecutive weeks, during which feed was available ad libitum or at 70% of ad libitum. Fasting heat production was determined over a 25 h period of fasting after a period of restricted feeding. Low sanitary conditions increased fasting heat production from 696 to 750 kJ/(kg BW0.6 . d), regardless of the dietary amino acid supplementation. The incremental efficiency of ingested nitrogen for retention in the body was reduced in LSC pigs from 73 to 53%, but incremental efficiencies of digestible energy intake for fat deposition in the body were unaffected by the experimental treatments. These findings showed that the effects of continuous immune stimulation by introducing LSC, was affecting energy and nutrient efficiencies of pigs both at maintenance level and at a feeding level close to ad libitum intake.

In Chapter 5 diurnal patterns for heat production, respiratory quotient, and carbohydrate and fat oxidation of the pigs studied in the experiment of Chapter 4 were evaluated to get more insight in the mechanisms behind the effects found in Chapter 4. The LSC pigs had reduced activity compared with HSC and a higher resting metabolic rate during the period of restricted feeding, especially during the light parts of the day. Therefore the diurnal energy expenditure pattern of LSC and HSC pigs can be considered as different. Fat and carbohydrate oxidation patterns were not different for LSC and HSC pigs, indicating that protein and fat deposition during the day was similar for LSC and HSC pigs.

Overall, the results of this thesis indicate that both energy and AA requirements are greater in LSC pigs compared with HSC pigs. It is questionable, however, whether it is nutrient and cost effective and biologically possible to satisfy these increased nutrient requirements in LSC pigs, as the incremental efficiency of N for retained protein is low, and ADFI is reduced for LSC pigs compared with HSC pigs. The present thesis demonstrates that care should be taken in reducing dietary protein concentrations to improve protein efficiency in pigs, as it incurs a risk to increased damaging behaviours, particularly when pigs are kept under LSC.

Interactions and functionalities of the gut revealed by computational approaches
Benis, Nirupama - \ 2017
University. Promotor(en): Mari Smits; Vitor Martins dos Santos, co-promotor(en): Dirkjan Schokker; Maria Suarez Diez. - Wageningen : Wageningen University - ISBN 9789463434546 - 247
pigs - mice - digestive tract - digestive system - intestinal microorganisms - intestinal mucosa - computational science - immune system - feeds - animal nutrition - nutrition physiology - animal health - varkens - muizen - spijsverteringskanaal - spijsverteringsstelsel - darmmicro-organismen - darmslijmvlies - immuunsysteem - voer - diervoeding - voedingsfysiologie - diergezondheid

The gastrointestinal tract is subject of much research for its role in an organism’s health owing to its role as gatekeeper. The tissue acts as a barrier to keep out harmful substances like pathogens and toxins while absorbing nutrients that arise from the digestion of dietary components in in the lumen. There is a large population of microbiota that plays an important role in the functioning of the gut. All these sub-systems of the gastrointestinal tract contribute to the normal functioning of the gut. Due to its various functionalities, the gut is able to respond to different types of stimuli and bring the system back to homeostasis after perturbations.

The work done in this thesis uses several bioinformatic tools to improve our understanding of the functioning of the gut. This was achieved with data from model animals, mice and pigs which were subjected to changing environments before their gastrointestinal response was measured. Different types of stimuli were studied (eg, antibiotic exposure, changing diets and infection with pathogens) in order to understand the response of the gut to varying environments. This data was analysed using different data integration techniques that provide a holistic view of the gut response.

Vertical data integration techniques look for associations between different types of ~omics data to highlight possible interactions between the measured variables. Lateral integration techniques allow the study of one type of ~omics data over several time points or several experimental conditions. Using these techniques, we show proof of interactions between different sub-systems of the gut and the functional plasticity of the gut. Of the several hypotheses generated in this thesis we have validated several using existing literature and one using an in-vitro system. Further validation of these hypotheses will increase understanding of the responses of the gut and the interactions involved.

FeedOmics, an approach to evaluate the functional properties of protein containing feed ingredients
Kar, Soumya K. - \ 2017
University. Promotor(en): Mari Smits; Jerry Wells, co-promotor(en): Alfons Jansman; Dirkjan Schokker. - Wageningen : Wageningen University - ISBN 9789463434461 - 254
compound feeds - ingredients - protein sources - proteins - functional properties - metabolism - feed formulation - protein digestion - proteomics - digestive tract - nutrition physiology - animal nutrition - livestock feeding - mengvoer - ingrediënten - eiwitbronnen - eiwitten - functionele eigenschappen - metabolisme - voersamenstelling - eiwitvertering - eiwitexpressieanalyse - spijsverteringskanaal - voedingsfysiologie - diervoeding - veevoeding

This thesis presents FeedOmics approach as a toolkit, to evaluate (novel) protein containing feed ingredients of different origin considering both their nutritional and functional value in terms of their capacity to support or modify nutrient supply, the animal’s physiology, tissue development and functioning. Such knowledge may contribute to introduce novel and/or alternative protein containing feed ingredients in the diet of livestock, thus creating a sustainable food supply for growing human population.

Assessing methane emission from dairy cows : modeling and experimental approaches on rumen microbial metabolism
Lingen, Henk J. - \ 2017
University. Promotor(en): Wouter Hendriks, co-promotor(en): Jan Dijkstra; Andre Bannink; Caroline Plugge. - Wageningen : Wageningen University - ISBN 9789463431590 - 207
dairy cows - methane - emission - microbial degradation - rumen metabolism - rumen fermentation - models - fatty acids - biochemical pathways - animal nutrition - nutrition physiology - melkkoeien - methaan - emissie - microbiële afbraak - pensmetabolisme - pensfermentatie - modellen - vetzuren - biochemische omzettingen - diervoeding - voedingsfysiologie

Methane (CH4) is a greenhouse gas (GHG) with a global warming potential of 28 CO2 equivalents. The livestock sector was estimated to emit 7.1 gigatonnes of CO2 equivalents, which is approximately 14.5% of total global anthropogenic GHG emissions. Enteric CH4 production is the main source of GHG emissions from dairy cattle, representing 46% of the global GHG emissions in dairy supply chains. Dairy production has great value in view of the ability of ruminants to effectively turn human inedible biomass into human edible food and to produce food from non-arable land. Consequently, there is an urgent need to develop strategies to decrease dairy cattle enteric CH4 emission. Evaluation of these strategies requires meticulous quantification and increased understanding of anaerobic fermentation and methanogenesis in the rumen ecosystem. The overall aim of this PhD research was, therefore, to quantitatively evaluate enteric CH4 emission from dairy cows as affected by feeding and rumen microbial metabolism.

A meta-analysis was performed to quantify relationships between enteric CH4 yield (per unit of feed and unit of milk) and milk FA profile in dairy cattle and to develop equations to predict CH4 yield based on milk FA profile of cows fed a wide variety of diets. Various milk FA concentrations were significantly or tended to be positively or negatively related to CH4 yield per unit of feed or milk. Mixed model multiple regression resulted in various milk FA included in optimal equations to predict CH4 yield per unit of feed and per unit of milk. These regression equations indicated a moderate potential for using milk FA profile to predict CH4 yield.

For the development of a mechanistic model of CH4 production in the rumen, the thermodynamic control of pH2 on reaction rates of specific fermentation pathways, NADH oxidation and methanogenesis was theoretically explored. This control was determined using the thermodynamic potential factor (FT), which is a dimensionless factor that corrects a predicted kinetic reaction rate for the thermodynamic control exerted. The thermodynamic feasibility of these microbial conversions showed that the control of pH2 on individual VFA produced and associated yield of H2 and CH4 cannot be explained without considering NADH oxidation, with a considerable effect of pH.

For obtaining experimental support of the conclusions drawn from the theoretical exploration, diurnal patterns of gaseous and dissolved metabolite concentrations in the bovine rumen, H2 and CH4 emitted, and the rumen microbiota were monitored. In addition, the effect of dietary inclusion of linseed oil on these patterns was assessed. An in vivo experiment with rumen cannulated dairy cows was performed to study the anaerobic metabolism and the microbiota composition in the rumen. A 100-fold increase in pH2 in the rumen headspace was observed at 0.5 h after feeding, followed by a decline. Qualitatively similar patterns after feeding were observed for H2 and CH4 emission, ethanol and lactate concentrations, and propionate molar proportion, whereas an opposite pattern was seen for acetate molar proportion. Associated with these patterns, a temporal biphasic change in the microbial composition was observed as based on 16S ribosomal RNA with certain taxa specifically associated with each phase. Bacterial concentrations were affected by time and increased by linseed oil supplementation. Archaeal concentrations tended to be affected by time and were not affected by diet, despite linseed oil supplementation tending to decrease the partial pressure and emission of CH4 and tending to increase propionate molar proportion. The various diurnal profiles that were monitored support the key role of the NAD+ to NADH ratio in rumen fermentation and the importance of diurnal dynamics when understanding VFA, H2 and CH4 production.

A dynamic mechanistic model was developed, in which the thermodynamic control of pH2 on VFA fermentation pathways, and methanogenesis in the bovine rumen are incorporated. The model represents substrate degradation, microbial fermentation and methanogenesis in the rumen, with the type of VFA formed to be controlled by the NAD+ to NADH ratio, which in turn is controlled by pH2. Feed composition and feed intake rate representing a twice daily feeding regime were used as model input. The model predicted a marked peak in pH2 after feeding that rapidly declined in time. This peak in pH2 caused a decrease in NAD+ to NADH ratio followed by an increased propionate molar proportion at the expense of acetate molar proportion. In response to feeding, the model predicted a sudden increase and a steady decrease in CH4 production in time. The pattern of CH4 emission rate followed the patterns of pH2 and H2 emission rate, but its magnitude of increase in response to feeding was less pronounced. A global sensitivity analysis indicated the parameter that determines the NADH oxidation rate to explain the most substantial part of the variation of predicted daily CH4 emission. The modeling effort provides the integration of more detailed knowledge than accomplished in previous rumen fermentation models and enables assessment of diurnal dynamics of rumen metabolic pathways yielding VFA, H2 and CH4.

For assessing the general value of the research reported in this thesis, the potential for predicting enteric CH4 emission from dairy cattle based on milk FA profile was discussed in the light of published studies and compared with empirical modeling of enteric CH4 based on feed input. Moreover, the concept of NAD-controlled fermentation was considered in a more general perspective by comparing the rumen ecosystem with bioreactor systems. Furthermore, the feasibility of the developed models as an alternative for IPCC tiered approaches was explored. In conclusion, the research reported in this thesis contributes to an increased understanding of rumen fermentation and microbial metabolism, and has provides a basis to further improve prediction models of enteric CH4 emissions from dairy cattle.

KringloopToets: sluiten van de nutriëntenkringloop op het niveau van Noordwest-Europa : inhoudelijke en procesmatige rapportage
Leenstra, Ferry ; Vellinga, Theun ; Bremmer, Bart - \ 2017
Wageningen : Wageningen Livestock Research (Wageningen Livestock Research rapport 1019) - 47
nutriëntenstromen - voer - diervoedering - diervoeding - recycling - noordwest-europa - nutrient flows - feeds - animal feeding - animal nutrition - northwestern europe
The Nutrient Cycle Assessment aims at visualizing nutrient flows. In policy documents closing of nutrient cycles at the level of North Western Europe is often mentioned. Province North Brabant, farmers organisation ZLTO and NGO BMF examined together with Wageningen University & Research the effects of closing the borders of North West Europe (Benelux, France, Germany, UK) for feed ingredients and animal products. The results of this exercise were discussed in a separate session with representatives of the feed industry. This report describes the conclusions of the analysis and the lessons that can be learned from this exercise for future work with the Nutrient Cycle Assessment.
First week nutrition for broiler chickens : effects on growth, metabolic status, organ development, and carcass composition
Lamot, David - \ 2017
University. Promotor(en): Bas Kemp, co-promotor(en): Henry van den Brand; Peter Wijtten. - Wageningen : Wageningen University - ISBN 9789463430777 - 187
broilers - animal nutrition - poultry feeding - feeds - growth - metabolism - carcass composition - nutrition physiology - vleeskuikens - diervoeding - pluimveevoeding - voer - groei - metabolisme - karkassamenstelling - voedingsfysiologie

During the first week of life, broiler chickens undergo various developmental changes that are already initiated during incubation. Ongoing development of organs such as the gastro- intestinal tract and the immune system may affect the nutritional requirements during this age period. Despite the residual yolk that is available at hatch and that may provide nutritional support during the first days after hatch, the growth performance may be affected by the time in between hatch and first feed intake. Furthermore, it remains largely unknown to what extend nutritional composition of a pre-starter diet, as well as feed availability directly after hatch have an effect on physiological development directly after hatch, but also at later age. The aim of this thesis was to determine the impact of feed availability and feed composition provided during the first week of life on short-term physiological development, as well as potential long-term effects on growth performance of broiler chickens. Especially early hatched chickens were suggested to benefit more from direct feed access compared to midterm and late hatched chickens, as they tended to have a higher body weight gain during the first week after hatch. A delay in feed access for 48 h resulted in lowered body weight gain and feed intake when compared to direct feed access, but so did a short (13 to 26 h) delay in feed access after hatch. In the latter case, delayed feed access resulted in a lower weight to length ratio of the jejunum and ileum at 4 d of age compared with chickens with direct feed access. Although delayed feed access after hatch resulted in lower body weight gain during the first week after hatch and thereafter, it can be discussed whether this is truly an impairment of long-term growth or just a delayed onset of growth. With respect to feed composition, the inclusion of fish oil and medium chain fatty acids in a pre-starter diet had minor effects on humoral immune function. Inclusion of medium chain fatty acids did result in higher body weight gain and lowered feed efficiency during the first week of life, but only during the period it was provided. Feeding increased diet densities during the first week of life, obtained by formulating diets with different dietary fat levels, resulted in an increased gain to feed ratio, whereas body weight gain and feed intake decreased. Despite the shift in dietary energy supply from carbohydrates to fat and the perceived lower fat digestibility in young broiler chickens, nitrogen metabolizability and fat digestibility were not affected in the current study by feeding increased diet densities. The relative crop, liver and pancreas weights decreased when feeding increased diet densities, whereas the length of the entire intestinal tract increased. This suggests that broiler chickens repartition visceral organ development in response to feeding more concentrated diets during the first week of life. Interestingly, protein and fat accretion were not affected. Continued feeding of increased diet densities after 7 d of age resulted in increased BW gain, G:F ratio and metabolizable energy intake, but mainly during the periods that these diets were provided. In summary, even short durations of delayed feed access already impact intestinal development of young broiler chickens. However, a delayed feed access up to 48 h after hatch does not result in impaired growth, but only a delayed onset of growth. Even though digestibility of fats and oils may be suboptimal in young broiler chickens, feeding of these diets does not have to result in lowered performance per se. Young broiler chickens appear to adapt themselves towards high density diets with high fat inclusion levels in the first week of life, enabling them to digest and metabolize these diet types despite a suboptimal capacity for fat digestion. High density diets result in higher growth performance, but only for the period these diets are provided and thus carry-over effects at later age appear to be limited.

Aspects of rumen adaptation in dairy cattle : morphological, functional, and gene expression changes of the rumen papillae and changes of the rumen microbiota during the transition period
Dieho, Kasper - \ 2017
University. Promotor(en): Wouter Hendriks, co-promotor(en): Jan Dijkstra; Andre Bannink; J.Th. Schonewille. - Wageningen : Wageningen University - ISBN 9789463430258 - 248
dairy cattle - rumen - rumen microorganisms - morphology - gene expression - animal nutrition - dry period - lactation - melkvee - pens - pensmicro-organismen - morfologie - genexpressie - diervoeding - gustperiode - lactatie

In dairy cattle the nutrient requirements change rapidly around calving. During the dry period nutrients are required for maintenance, recovery from the previous lactation, and fetal growth. After calving, milk production commences and the energy requirements can increase by a factor 3 to ~184 MJ net energy for lactation during the first weeks of lactation, compared with the dry period, whereas feed intake doubles to ~24 kg dry matter (DM)/d compared with the dry period. In addition, high quality lactation rations are fed, usually containing a sizable portion of concentrate, thereby increasing fermentable organic matter (FOM) intake to ~14 kg/d. As a result, daily volatile fatty acid (VFA) production by the rumen microbiota increases from ~60 mol/d during the dry period to ~132 mol/d during early lactation. To maintain rumen pH at levels favorable for microbial fermentation, and prevent a negative impact on production and health, clearance of the produced VFA is essential. This mainly occurs through absorption over the rumen wall. The increase in capacity of the rumen for absorption of VFA is associated with morphological and functional changes of the rumen papillae which cover the rumen wall. However, current knowledge of these changes as they occur around calving is scarce (Chapter 1). Increasing our understanding of the adaptation of the rumen can provide new insights to optimize dairy cattle nutrition and thereby health, welfare, and production.

The objective of this thesis was to study the adaptation of the rumen to ration changes during the dry period and early lactation. Changes in rumen papillae morphology, fractional absorption rate of VFA (kaVFA), and changes in the composition of the rumen microbiota were the primary targets for study. In addition, the expression of genes and proteins associated with absorption and metabolism of VFA by the rumen epithelium were studied to better understand the relationship between functional changes and morphological changes of the papillae. Uniquely, all these aspects were studied in parallel in the same dairy cows during the dry period and early lactation using a repeated measurement setup. Two experiments were conducted. In the lactation experiment, the effect of transition from the dry period to the subsequent lactation, and the effect of early lactation concentrate build-up strategy on the adaptation of the rumen were studied. In the dry period experiment, the effect of feeding supplemental concentrate during the late dry period in order to ‘prepare’ the rumen for the lactation was studied. Treatments of both experiments were aimed at creating a difference in FOM intake (kg/d) and thereby VFA production (mol/d), as VFA production was hypothesized to affect rumen papillae development and thereby the capacity for VFA absorption.

During the lactation experiment, intake of FOM did not change during the dry period (5.7 kg/d), but increased during the subsequent lactation to 15.0 kg/d at 80 d postpartum (pp). In addition, the rapid increase in concentrate allowance resulted in a temporarily 22% greater FOM intake compared with a gradual increase at 16 d pp (Chapter 2). The total production rate of VFA, measured using an isotope dilution technique (Chapter 3), was affected by these changes in FOM intake and increased 2.3 fold to 123 mol/d after calving, compared with the dry period (53 mol/d). The temporarily greater FOM intake with the rapid increase in concentrate allowance at 16 d pp coincided with a 54% greater propionate production (34 mol/d) compared with a gradual increase in concentrate allowance, whereas acetate (66 mol/d) and butyrate (10 mol/d) production were not affected. Papillae surface area (Chapter 2) decreased by 19% between 50 d antepartum (ap) and 3 d pp to 28.0 mm2, but increased during early lactation to 63.0 mm2. Papillae surface area increased faster with the rapid increase in concentrate allowance and surface area was 38, 34 and 22% larger at 16, 30, and 44 d postpartum respectively, than with a gradual rate of increase of concentrate allowance. Histology (Chapter 2) revealed that rumen papillae and epithelium thickness decreased slightly after calving, but were not affected by the concentrate treatment. Feeding concentrate during the dry period did not affect daily FOM intake (6.0 kg/d) but did increase VFA concentration in the rumen fluid by 21 mM to 121 mM, and increased papillae surface by 29% (Chapter 4). However, the increased papillae surface area in the dry period was not maintained to the subsequent lactation period. After calving, papillae surface area increased by 50% to 58.0 mm2 at 45 d pp. The postpartum development of the rumen papillae was not affected by the treatment during the dry period. These results indicate that rumen papillae respond to changes in FOM and VFA production intake during the dry period and early lactation, and that the magnitude of this response depends on the rate of change in FOM intake.

During both experiments, kaVFA was measured using a buffer incubation technique in an empty washed rumen. During the lactation experiment (Chapter 3), in accordance with the developments in papillae surface area, the kaVFA decreased during the dry period from 0.48/h at 50 d ap to 0.34/h at 3 d pp. During the subsequent lactation, it increased rapidly to 0.56/h at 16 d pp and further to 0.72/h at 80 d pp. However, the greater papillae surface area due to the rapid increase in concentrate did not coincide with a greater kaVFA. During the dry period experiment (Chapter 4), kaVFA increased after calving by 50% to 0.48/h at 45 d pp, but the increase in papillae surface area due to supplemental concentrate during the dry period did not affect the kaVFA during the dry period (0.36/h) or the subsequent lactation. These results indicate that papillae surface area is not the limiting factor for kaVFA.

Changes in the expression of genes were studied at the mRNA level in papillae tissue from both experiments (Chapter 5). The expression of apoptosis related genes was not affected by sampling day or its interaction with treatment for both experiments, suggesting papillae proliferation during the transition period was mainly the result of an increased mitosis rate. The limited changes in the expression of genes associated with rumen epithelial transport and metabolism of VFA in dairy cows during the transition period do not suggest that these capacities of the epithelium increased per unit of surface area. Thus the major response to the increase in daily VFA production after calving was tissue proliferation. In addition, papillae from the lactation experiment were used to study expression at the protein level using immunoblotting. Results showed that expression of several proteins changed during early lactation indicating modulation of intracellular pH regulation and sodium homeostasis, and VFA metabolism. Only for one gene, a significant but weak correlation between the examined mRNA and protein expression levels was observed, indicating that care must be taken when interpreting results obtained at either level.

Ration changes associated with the transition from the dry period to lactation affected the rumen microbiota during the lactation experiment (Chapter 6). The rapid increase in concentrate allowance postpartum temporarily decreased bacterial community richness by as much as 30% compared with a gradual increase in concentrate. This transient depression in bacterial community richness with a rapid, but not a gradual, rate of increase of concentrate allowance pp indicates that the rate of change in ration composition and feed intake has a greater effect than the change in ration composition and feed intake level as such. The relative abundances of most major bacterial taxa were affected by the transition to lactation, but few were affected by the rate of increase of the concentrate allowance. The relative abundances of rumen protozoal taxa changed after calving, and were affected by the concentrate treatment. However, differences between treatments groups disappeared again when concentrate intake became similar. The archaeal community was likewise affected by both the transition to lactation and the treatment. The observed changes in rumen microbiota composition, including changes in bacterial community richness, did not appear to affect the fractional degradation rate of NDF, starch, CP, and OM measured in situ using a nylon bag technique.

The results in the present thesis show that morphologically and functionally the rumen papillae can adapt rapidly to the changes in FOM intake and daily VFA production associated with the transition from the dry period into the subsequent lactation. However, the contrast in response of rumen papillae surface area development and the fractional absorption rate of VFA to the concentrate treatments indicates that papillae surface area is not the limiting factor for VFA absorption. This proposition is further supported by the limited histological changes of the rumen epithelium and limited changes in gene expression. Considering that the capacity for absorption and metabolism of VFA per unit of papillae surface area remains similar, an extra-epithelial factor, likely visceral blood flow, limits VFA absorption. The capacity of the rumen to adapt after calving and the limited beneficial effect of supplementing concentrate during the dry period indicate that dry period feeding strategies can best be optimized for the prevention of periparturient diseases.

Positiefljst
Wageningen Livestock Research, ; Groen Kennisnet, - \ 2017
Wageningen UR Livestock Research
dierenwelzijn - gezelschapsdieren - huisdieren - huisvesting, dieren - diergedrag - diervoeding - diergezondheid - zoönosen - wetgeving - animal welfare - pets - domestic animals - animal housing - animal behaviour - animal nutrition - animal health - zoonoses - legislation
Per 1 juli 2017 is de Positieflijst van kracht. Op de Positieflijst zijn alle diersoorten opgenomen die zijn beoordeeld in het kader van artikel 2.2 eerste en tweede lid van de Wet dieren. Deze website geeft informatie over de Positieflijst.
Of proteins and processing: mechanisms of protein damage upon rapeseed processing and their effects on nutritional value
Salazar Villanea, Sergio - \ 2017
University. Promotor(en): Wouter Hendriks; Harry Gruppen, co-promotor(en): Thomas van der Poel; E.M.A.M. Bruininx. - Wageningen : Wageningen University - ISBN 9789462579873 - 182
animal nutrition - rapeseed - rapeseed protein - feed processing - proteins - digestion - pigs - diervoeding - raapzaad - raapzaadeiwit - voedermiddelbewerking - eiwitten - spijsvertering - varkens

Hydrothermal processing is a common practice during the manufacture of protein-rich feed ingredients, such as rapeseed meal (RSM), and feeds. This processing step can induce physical and chemical changes to the proteins, thereby reducing the digestibility and utilization of crude protein (CP) and amino acids (AA). Whilst most literature has linked the chemical changes to the proteins with negative effects on protein digestibility, the effects of the physical changes of the protein conformation have not been considered simultaneously. Hence, the aim of this thesis was to provide further insight into the mechanisms of protein damage during ingredient/feed processing and their effects on protein hydrolysis/digestibility. In Chapter 2, the available literature on the physical changes that occur to vegetable proteins used in swine diets after processing was reviewed. Overall, hydrothermal processing increases the contents of intermolecular/intramolecular β-sheets and disulfide bonds, which were negatively correlated to protein digestibility. The correlations, however, were dependent on the type of protein analysed. When the physico-chemical changes in the proteins occur during processing of the ingredients, proteins usually become less responsive to further processing treatments. Rapeseed proteins were used as model, as this oilseed is hydrothermally processed during the oil extraction process and is further processed when incorporated in animal diets.

Protein damage during production of rapeseed meal

There is high variability in the nutritional value of commercial RSM. The variation is mainly due to the conditions used during the desolventization/toasting step. Therefore, the aim of the experiment in Chapter 3 was to characterize the secondary structure and chemical changes that occur during toasting of RSM and their effects on in vitro protein digestibility. A cold defatted RSM was toasted for 120 min with samples obtained every 20 min. Increasing the toasting time from 0 to 120 min increased protein denaturation by 3-fold and decreased protein solubility by 4-fold, lysine content by 23% and the reactive lysine content by 37%. The proportion of intermolecular β-sheets increased after the initial 20 min of toasting, but steadily decreased thereafter. The contrary was observed for the proportion of α-helices. The changes in the secondary structure of proteins were not correlated to the rest of the physical and chemical changes. Therefore, changes in the secondary structure of proteins cannot be considered good indicators of damage to proteins due to hydrothermal processing. The rate of protein hydrolysis decreased by 2-fold when toasting time was increased from 0 min to 120 min. The changes in protein solubility and lysine/reactive lysine contents were positively correlated to the rate of protein hydrolysis. Changes to the physical conformation of rapeseed proteins occur at faster rates during toasting compared to chemical changes.

In Chapter 4, it was hypothesized that the decrease in the rate of protein hydrolysis with increasing toasting time was due to the reduction in protein solubility. In order to test this hypothesis, the soluble and insoluble protein fractions from each of the RSM studied in Chapter 3 were separated and hydrolysed. Hydrolysis kinetics and the molecular size distribution of the peptides resulting after hydrolysis were analysed. The extent of hydrolysis of the insoluble protein fraction was 44% higher than that of the soluble protein fraction. The rate of hydrolysis of the soluble protein fraction separated from the hydrothermally treated RSM was 3-9 fold higher than that of the insoluble protein fraction. In the insoluble fraction, formation of both disulfide bonds and Maillard reaction products (MRP) (fructosyl-lysine [FL], carboxymethyl-lysine [CML] and carboxyethyl-lysine [CEL]) was noticed, which explains the decrease in the rate of protein hydrolysis with longer toasting times. Overall, increasing the toasting time of the whole RSM and the insoluble protein fraction increased the size of the peptides resulting after enzymatic hydrolysis. A shift in the mechanism of protein hydrolysis from a more one-by-one type to a more zipper-type likely explained the correlations between the rate of hydrolysis and the molecular size distribution after hydrolysis. Protein solubility seems to be a key parameter for understanding the decrease in the rate of protein hydrolysis with increasing toasting time.

The correlations between two in vitro protein digestibility methods and the standardised ileal digestibility in growing pigs of severe thermally-treated soybean and rapeseed meals were studied in Chapter 5. Soybean meal and RSM were toasted in the presence of lignosulfonate in order to induce severe thermal damage to the proteins. In vitro protein digestibility was analysed using the two-step enzymatic method (pepsin at pH 2.0 and pancreatin at pH 6.8) and the pH-STAT method. The standardised ileal digestibility values were obtained from a previous experiment, in which ileal-cannulated growing pigs were used. The degree of hydrolysis after 10 min was positively correlated (r = 0.95, P = 0.046) to the standardised ileal CP digestibility. The in vitro rate of protein hydrolysis using the pH-STAT method and CP digestibility using the two-step enzymatic method tended to be positively correlated to the standardised ileal digestibility of CP (r = 0.91, P = 0.09, for both in vitro methods). In conclusion, both in vitro methods might be used for the in vivo digestibility of severe thermally-treated ingredients.

Effects of diet processing on protein digestibility of RSM with different extents of damage

The processed ingredients (e.g. rapeseed meal) are mixed with other ingredients and processed further during the compound feed manufacturing process. The effects of the diet processing methods (e.g. pelleting and extrusion) on protein digestibility could depend on the extent of the damage of the ingredients used. The aim of Chapter 6 was to test the effects of toasting time of rapeseed meal, diet processing method and the interaction between both on protein digestion along the gastrointestinal tract and apparent/standardised ileal digestibility of CP and AA. Mash, pelleted and extruded diets were manufactured using either 0, 60 or 120 min toasted RSM as the only protein source, for a total of 9 different experimental diets. Whilst increasing the toasting time decreased the contents of lysine and reactive lysine in the diets, no effects were noticed after pelleting or extrusion of the diets compared to the mash. The mean particle size of the diets was reduced from 479 μm in the mash diets to 309 and 211 μm after pelleting and extrusion, respectively. A total of 81 growing boars were individually fed with one of the experimental diets. Following euthanasia, the small intestine was divided in 3 sections of equal length and the contents of the final 1.5 m of each small intestine section were sampled. The apparent CP digestibility for each section of the gastrointestinal tract was used to calculate the rate of CP digestion based on a second order equation. The rate of digestion was higher in the diets containing 0 min toasted RSM compared to the diets that contained 60 or 120 min toasted RSM. The diet processing method tended to affect the rate of protein digestion, with higher rates for the extruded > pelleted > mash diets. Significant effects of the interaction between toasting time and diet processing method were found on the apparent ileal CP digestibility. Whilst a lower apparent ileal CP digestibility was found in the 120 min toasted RSM mash diet compared to the 0 and 60 min toasted RSM mash diets, no differences were observed between the different toasting times in the pelleted and extruded diets. Similar significant interactions were noticed for the apparent ileal digestibility of some dispensable and indispensable AA (e.g. arginine, isoleucine, leucine, methionine, threonine, alanine, glycine, proline, serine). Pelleting of the 60 and 120 min toasted RSM diets increased the standardized ileal digestible CP content by 6 and 15%, respectively, compared to the 60 and 120 min toasted mash diets. Extrusion of the 0, 60 and 120 min toasted RSM diets increased the standardized ileal digestible CP content by 5, 9 and 12%, respectively, compared to the 0, 60 and 120 min toasted mash diets. Similar positive effects of pelleting and extrusion were obtained for the apparent ileal digestible contents of lysine and reactive lysine, especially for the diets that contained RSM toasted for longer times. In conclusion, the severe effects of protein damage during the production of RSM on protein digestibility can be (partially) ameliorated by processing of the diets.

Processing of ingredients and diets can lead to the formation of early (e.g. FL) and advanced (e.g. CML and CEL) MRP. These MRP have been associated with common metabolic disorders, for example atherosclerosis. Absorption of dietary MRP has been previously estimated based on indirect measurements, such as concentrations in blood, urine and faeces, which could be biased by endogenous formation of MRP and deposition in tissues. Hence, the aim of Chapter 7 was to measure the apparent ileal digestibility of early (FL, determined as furosine after acid hydrolysis) and advanced (CML and CEL) MRP. The same diets and ileal digesta samples as in Chapter 6 were used in this study. The 0 min toasted RSM diets (mash, pelleted and extruded) were excluded from this study. Sucrose was added to these diets immediately before feeding in order to increase their feed intake, which could confound the determination of the apparent ileal digestibility of the MRP for these treatments. The content of FL was higher in the 120 min compared to the 60 min toasted RSM diets, whereas it was lower in the extruded diets compared to the pelleted and mash diets. The decrease in FL content after extrusion of the diets can probably be related to conversion of the early into advanced MRP, as the content of CML was higher in the extruded diets compared to the pelleted and mash diets. The contents of FL, CML and CEL were positively correlated to the contents of these compounds in the ileal chyme. The apparent ileal digestibility of FL, CML and CEL for the different diets ranged from -8.5 to 19.1%, -0.2 to 18.3% and 3.6 to 30%, respectively. In conclusion, the apparent ileal digestibility of the early and advanced MRP from thermally-treated RSM diets in growing pigs were overall low and did not seem to be related to the contents of these compounds in the diets.

The results of this thesis indicate that the changes to the physical conformation of proteins during toasting of RSM occur at a faster rate than chemical changes. Both types of changes affect protein solubility, which is important in determining the rate of protein hydrolysis. It is suggested in this thesis that the rate of protein hydrolysis of hydrothermally-processed ingredients is probably the main contributing factor for the in vivo protein digestibility. This was demonstrated, as increasing the toasting time of RSM decreased the rate of CP digestion in growing pigs. The negative effects of longer toasting times on CP and AA digestibility, however, could be ameliorated by pelleting and extrusion of the diets. The positive effects of diet processing methods (pelleting and extrusion) on the digestibility of damaged proteins from thermally-treated ingredients should be taken into account in feed evaluation studies and formulation of practical diets.

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