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.

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Both the rooster and incubation temperature affect embryonic metabolism and day-old chicken quality in laying hens
Brand, H. van den; Kraats, Sabrina van de; Sözcü, Arda ; Jöerissen, R. ; Heetkamp, M.J.W. ; Anker-Hensen, I. van den; Ooms, M. ; Kemp, B. - \ 2018
In: The XVth European Poultry Conference (EPC). - Zagreb, Croatia : - ISBN 9789082915709 - p. 128 - 128.
chicken quality - embryonic heat production - incubation temperature - laying hens - rooster
During incubation, the main factors driving embryonic metabolism and developmentare nutrient availability, oxygen availability and embryo temperature. Both nutrient andoxygen availability are expected to be particularly affected by the hen and thus the henis thought to majorly determining embryonic metabolism and day-old chicken quality.However, in wild birds it has been suggested that the rooster is of influence on offspringquality, directly or via affecting egg size and egg composition. In poultry, the role of therooster in embryonic development and metabolism is hardly investigated. In case therooster affects egg composition, this can mean that the incubation temperature needs to be adjusted to obtain optimal embryo temperature. The role of incubation temperatureon embryonic metabolism and development in the broiler chicken is extensivelyinvestigated, but much less information is available regarding laying hen chickens.The aim of the experiment was to investigate the role of the rooster and the incubationtemperature on laying hen embryonic development and chicken quality. Eggs of twogenetic crossbreds (AB and BB; 51 to 59 weeks of age) were used. Hens originated fromthe same breeder flock, were housed at the same farm, obtained the same managementand diet but were mated with a different rooster. In six consecutive batches, eggs ofboth crossbreds (59.0 to 61.0 gram) were incubated at an eggshell temperature (EST) of37.8oC during the first 14.5 days and at an EST of 36.7, 37.8 or 38.9oC from day 14.5 ofincubation onward. In all batches, eggs of both crossbreds were used, but EST differedamong batches. Egg composition was determined in fresh eggs, heat production wasdetermined between day 14.5 and 18.5 of incubation and day-old chicken quality wasdetermined at 6 hours after hatching or at pulling. Yolk weight tended to be higher(Δ=0.28 gram; P=0.08) in AB than in BB crossbreds, whereas other egg components didnot differ. Heat production between day 14.5 and 18.5 of incubation was higher in theAB than in the BB crossbred (Δ=2.61%; P<0.001). At pulling, AB chickens were lighter,had less red hocks, more red beaks and worse navel scores than BB chickens. An ESTof 36.7oC resulted in later hatching time, higher heart weight and higher intestineweight than an EST of 38.9oC. It can be concluded that both the rooster and incubationtemperature appears to affect embryonic metabolism and day-old chicken quality.
A Public Survey on Handling Male Chicks in the Dutch Egg Sector
Gremmen, H.G.J. ; Bruijnis, M.R.N. ; Blok, V. ; Stassen, E.N. - \ 2018
Journal of Agricultural and Environmental Ethics 31 (2018)1. - ISSN 1187-7863 - p. 93 - 107.
animal ethics - animal welfare - chicks - laying hens - public opinion
In 2035 global egg demand will have risen 50% from 1985. Because we are not able to tell in the egg whether it will become a male or female chick, billons of one day-old male chicks will be killed. International research initiatives are underway in this area, and governments encourage the development of an alternative with the goal of eliminating the culling of day-old male chicks. The Netherlands holds an exceptional position in the European egg trade, but is also the only country in the European Union where the downside of the egg sector, the practice of killing day-old male chicks, is a recurrent subject of societal debate. ‘Preventing the killing of young animals’ and ‘in ovo sex determination’ are the two alternative approaches available to solve this problem. It is clear that both approaches solve the problem of killing day-old male chicks, either by keeping them alive or by preventing them from living, but they also raise a lot of new animal welfare-related dilemmas. A thorough analysis was undertaken of these dilemmas and the results are presented in this article. The analysis resulted in an ethical framework based on the two main approaches in bioethics: a consequentialist approach and a deontological approach. This ethical framework was used to develop an online survey administered to ascertain Dutch public opinion about these alternative approaches. The results show that neither alternative will be fully accepted, or accepted by more than half of Dutch society. However, the survey does provide an insight into the motives that are important for people’s choice: food safety and a good treatment of animals. Irrespective of the approach chosen, these values should be safeguarded and communicated clearly.
Automatic ultra-wideband sensor detection shows selection on feather pecking increases activity in laying hens
Haas, E.N. de; Eijk, J.A.J. van der; Rodenburg, T.B. - \ 2017
In: Xth European Symposium on Poultry Welfare, 19-22 June 2017, Ploufragan - France. - World's Poultry Science Association (WPSA) - p. 101 - 101.
broiler breeders - nesting behaviour - genetics - nest design - housing - climate - laying hens - feather pecking - ultra-wideband tracking - activity - sensor technology
Broilers have been selected for growth related characteristics, which are negatively correlated to reproductive traits. This genetic background creates challenges in broiler breeders, as the hens do not make optimal use of the nests provided. This project aims to investigate what factors determine nesting behaviour, i.e. where a broiler breeder hen prefers to lay her eggs. Factors such as genetic background, social interactions, physical characteristics of the nest and climate might interfere with the natural nesting behaviour of the hen. Also fundamental trade-offs between different motivations, such as hunger, comfort and safety, might influence nesting behaviour. Behaviour and use of space will be measured in experimental set-ups in order to gain insight in the importance of different system components. This knowledge will be used to optimise housing conditions and develop strategies that stimulate the hen to lay her egg in the nest. The performance of this improved system will be tested in field experiments to investigate the transferability of results from experimental to field conditions.
Behavioural and physiological characterisation of laying hen lines divergently selected on feather pecking
Eijk, J.A.J. van der; Lammers, A. ; Rodenburg, T.B. - \ 2017
In: Xth European Symposium on Poultry Welfare, 19-22 June 2017, Ploufragan - France. - World's Poultry Science Association (WPSA) - p. 60 - 60.
broiler breeders - nesting behaviour - genetics - nest design - housing - climate - laying hens - feather pecking - fearfulness - coping style - stress - imune system
Broilers have been selected for growth related characteristics, which are negatively correlated to reproductive traits. This genetic background creates challenges in broiler breeders, as the hens do not make optimal use of the nests provided. This project aims to investigate what factors determine nesting behaviour, i.e. where a broiler breeder hen prefers to lay her eggs. Factors such as genetic background, social interactions, physical characteristics of the nest and climate might interfere with the natural nesting behaviour of the hen. Also fundamental trade-offs between different motivations, such as hunger, comfort and safety, might influence nesting behaviour. Behaviour and use of space will be measured in experimental set-ups in order to gain insight in the importance of different system components. This knowledge will be used to optimise housing conditions and develop strategies that stimulate the hen to lay her egg in the nest. The performance of this improved system will be tested in field experiments to investigate the transferability of results from experimental to field conditions.
Automatic ultra-wideband sensor detection shows selection on feather pecking increases activity in laying hens
Haas, Elske de - \ 2017
laying hens - feather pecking - ultra-wideband tracking - activity - sensor technology
Ramps and hybrid effects on keel bone and foot pad disorders in modified aviaries for laying hens
Heerkens, J.L.T. ; Delezie, E. ; Ampe, B. ; Rodenburg, T.B. ; Tuyttens, F.A.M. - \ 2016
Poultry Science 95 (2016)11. - ISSN 0032-5791 - p. 2479 - 2488.
aviary - foot health - keel bone - laying hens

Non-cage systems provide laying hens with considerable space allowance, perches and access to litter, thereby offering opportunities for natural species-specific behaviors. Conversely, these typical characteristics of non-cage systems also increase the risk of keel bone and foot pad disorders. The aim of this study was twofold: 1) to investigate if providing ramps between perches (housing factor) reduces keel bone and foot pad disorders and 2) to test for genetic predisposition by comparing 2 different layer hybrids. In a 2 × 2 design, 16 pens were equipped either with or without ramps between perches and nest boxes (8 pens/treatment), and housed with either 25 ISA Brown or Dekalb White birds per pen (in total 200 birds/hybrid). Keel bone injuries and foot health were repeatedly measured via palpation and visual assessment between 17 and 52 wk of age and daily egg production was recorded. The relationships between the dependent response variables (keel bone and footpad disorders, egg production) and independent factors (age, ramps, hybrid) were analyzed using generalized linear mixed models and corrected for repeated measures. Ramps reduced keel bone fractures (F1,950 = 45.80, P <0.001), foot pad hyperkeratosis (F1,889 = 10.40, P = 0.001), foot pad dermatitis (F1,792 = 20.48, P <0.001) and bumble foot (F1,395 = 8.52, P <0.001) compared to pens without ramps. ISA Brown birds sustained more keel bone fractures (F1,950 = 33.26, P <0.001), had more foot pad hyperkeratosis (F1,889 = 44.69, P <0.001) and laid more floor eggs (F1,1883 = 438.80, P <0.001), but had fewer keel bone deviations (F1,1473 = 6.73, P <0.001), fewer cases of foot pad dermatitis (F1,792 = 19.84, P <0.001) and no bumble foot as compared to Dekalb White birds. Age, housing and hybrid showed several interaction effects. Providing ramps proved to be very effective in both reducing keel bone and foot pad problems in non-cage systems. Keel bone and foot pad disorders are related to genetic predisposition. These results indicate that adaptation of the housing systems and hybrid selection may be effective measures in improving laying hen welfare.

Transfer of pyrrolizidine alkaloids from various herbs to eggs and meat in laying hens
Mulder, Patrick P.J. ; Witte, Susannah L. de; Stoopen, Geert M. ; Meulen, Jan van der; Wikselaar, Piet G. van; Gruys, Erik ; Groot, Maria J. ; Hoogenboom, Ron L.A.P. - \ 2016
Food Additives & Contaminants. Pt. A, Chemistry, Analysis, Control, Exposure & Risk Assessment 33 (2016)12. - ISSN 1944-0049 - p. 1826 - 1893.
eggs - laying hens - liver - meat - Pyrrolizidine alkaloids - transfer

To investigate the potential transfer of pyrrolizidine alkaloids (PAs), laying hens were fed for 14 days with diets containing 0.5% of dried common ragwort, common groundsel, narrow-leaved ragwort or viper’s bugloss, or 0.1% of common heliotrope. This resulted in total PA levels in feed of respectively 5.5, 11.1, 53.1, 5.9 and 21.7 mg kg 1, with varying composition. PAs were transferred to eggs, in particular yolk, with steady-state levels of respectively 12, 21, 216, 2 and 36 µg kg 1. Overall transfer rates for the sum of PAs were estimated between 0.02% and 0.23%, depending on the type of PAs in the feed. In animals slaughtered shortly after the last exposure, levels in meat were slightly lower than those in eggs, levels in livers somewhat higher. When switched to clean feed, levels in eggs gradually decreased, but after 14 days were still above detection limits in the hens exposed to higher PA levels. Similar was the case for meat and especially kidneys and livers. It is concluded that the intake of PA containing herbs by laying hens may result in levels in eggs and meat that could be of concern for consumers, and as such should be avoided.

Heritability of body surface temperature in hens estimated by infrared thermography at normal or hot temperatures and genetic correlations with egg and feather quality
Loyau, T. ; Zerjal, T. ; Rodenburg, T.B. ; Fablet, J. ; Tixier-Boichard, M. ; Pinard-van der Laan, M.H. ; Mignon-Grasteau, S. - \ 2016
Animal 10 (2016)10. - ISSN 1751-7311 - p. 1594 - 1601.
adaptation - egg quality - genotype–environment interaction - heat stress - laying hens

Exposure of laying hens to chronic heat stress results in loss of egg production. It should be possible to improve hen resilience to chronic heat stress by genetic selection but measuring their sensitivity through internal temperature is time consuming and is not very precise. In this study we used infrared thermography to measure the hen’s capacity to dissipate heat, in a commercial line of laying hens subjected to cycles of neutral (N, 19.6°C) or high (H, 28.4°C) ambient temperatures. Mean body temperatures (BT) were estimated from 9355 infrared images of wing, comb and shank taken from 1200 hens. Genetic parameters were estimated separately for N and H temperatures. Correlations between BT and plumage condition were also investigated. Wing temperature had low heritability (0.00 to 0.09), consistent with the fact that wing temperature mainly reflects the environmental temperature and is not a zone of heat dissipation. The heritability of comb temperature was higher, from 0.15 to 0.19 in N and H conditions, respectively. Finally, the shank temperature provided the highest heritability estimates, with values of 0.20 to 0.22 in H and N conditions, respectively. Taken together, these results show that heat dissipation is partly under genetic control. Interestingly, the genetic correlation between plumage condition and shank and comb temperatures indicated that birds with poor condition plumage also had the possibility to dissipate heat through featherless areas. Genetic correlations of temperature measurements with egg quality showed that temperatures were correlated with egg width and weight, yolk brightness and yellowness and Haugh units only under H conditions. In contrast, shell colour was correlated with leg temperature only at thermo-neutrality.

How to fulfill EU requirements to feed organic laying hens 100% organic ingredients
Krimpen, M.M. Van; Leenstra, F. ; Maurer, V. ; Bestman, M. - \ 2016
Journal of Applied Poultry Research 25 (2016)1. - ISSN 1056-6171 - p. 129 - 138.
EU requirements - laying hens - methionine - organic - protein

From December 2017 onward, including non-organic protein sources in diets for organic poultry will no longer be allowed in the EU. Moreover, in the EU the use of synthetic amino acids in organic diets is prohibited. The main dietary challenge in European organic egg production is to fulfill the protein requirement, especially the methionine (Met) requirement of the hens. Currently available Met-rich ingredients are discussed. In the group of ingredients of plant origin, expelled sunflower seed has a relatively high digestible Met content and is also commonly available. Met content of plant ingredients can be increased by selection of high Met varieties and by specifically breeding on high Met content, e.g. by crossing different breeds. Plant processing techniques might be helpful to concentrate the protein and digestible Met content of ingredients. Applying the dry fractionation technique on legumes and cereals might result in protein concentrates with CP content of at least 50%. A further development of simple separation techniques, which separate the hulls from the other plant fractions and reduce the fiber content after de-hulling, might be helpful to increase digestible Met content. Energy dilution of the diet, concomitant with a proportional reduction in other nutrients, is an option as well to fulfill the requirement of 100% organic diets. As a consequence, hens have to consume more feed to meet their nutrient requirements. There are options to fulfill the requirement of 100% ingredients of organic origin, but if the practical, economical, and footprint issues are taken into account, the list of options is very small.

Genetic and Non-Genetic Inheritance of Natural Antibodies Binding Keyhole Limpet Hemocyanin in a Purebred Layer Chicken Line
Berghof, T.V.L. ; Klein, S.A.S. van der; Arts, J.A.J. ; Parmentier, H.K. ; Poel, J.J. van der; Bovenhuis, H. - \ 2015
PLoS ONE 10 (2015)6. - ISSN 1932-6203 - 13 p.
laying hens - immune-responses - parameters - iga - survival - isotypes - associations - sensitivity - disease - cells
Natural antibodies (NAb) are defined as antibodies present in individuals without known antigenic challenge. Levels of NAb binding keyhole limpet hemocyanin (KLH) in chickens were earlier shown to be heritable, and to be associated with survival. Selective breeding may thus provide a strategy to improve natural disease resistance. We phenotyped 3,689 white purebred laying chickens for KLH binding NAb of different isotypes around 16 weeks of age. Heritabilities of 0.12 for the titers of total antibodies (IgT), 0.14 for IgM, 0.10 for IgA, and 0.07 for IgG were estimated. We also estimated high, positive genetic, and moderate to high, positive phenotypic correlations of IgT, IgM, IgA, and IgG, suggesting that selective breeding for NAb can be done on all antibody isotypes simultaneously. In addition, a relatively substantial non-genetic maternal environmental effect of 0.06 was detected for IgM, which may reflect a transgenerational effect. This suggests that not only the genes of the mother, but also the maternal environment affects the immune system of the offspring. Breaking strength and early eggshell whiteness of the mother’s eggs were predictive for IgM levels in the offspring, and partly explained the observed maternal environmental effects. The present results confirm that NAb are heritable, however maternal effects should be taken into account.
Early feeding and early life housing conditions influence the response towards a noninfectious lung challenge in broilers
Simon, K. ; Vries Reilingh, G. de; Bolhuis, J.E. ; Kemp, B. ; Lammers, A. - \ 2015
Poultry Science 94 (2015)9. - ISSN 0032-5791 - p. 2041 - 2048.
intestinal immune-responses - symbiotic bacteria - delayed access - laying hens - germ-free - system - colonization - performance - maturation - microbiota
Early life conditions such as feed and water availability immediately post hatch (p.h.) and housing conditions may influence immune development and therefore immune reactivity later in life. The current study addressed the consequences of a combination of these 2 early life conditions for immune reactivity, i.e., the specific antibody response towards a non-infectious lung challenge. Broiler chicks received feed and water either immediately p.h. or with a 72 h delay and were either reared in a floor or a cage system. At 4 weeks of age, chicks received either an intra-tracheally administered Escherichia coli lipopolysaccharide (LPS)/Human Serum Albumin (HuSA) challenge or a placebo, and antibody titers were measured up to day 14 after administration of the challenge. Chicks housed on the floor and which had a delayed access to feed p.h. showed the highest antibody titers against HuSA. These chicks also showed the strongest sickness response and poorest performance in response to the challenge, indicating that chicks with delayed access to feed might be more sensitive to an environment with higher antigenic pressure. In conclusion, results from the present study show that early life feeding strategy and housing conditions influence a chick's response to an immune challenge later in life. These 2 early life factors should therefore be taken into account when striving for a balance between disease resistance and performance in poultry.
High natural antibody titers of indigenous chickens are related with increased hazard in confinement
Wondmeneh, E. ; Arendonk, J.A.M. van; Waaij, E.H. van der; Ducro, B.J. ; Parmentier, H.K. - \ 2015
Poultry Science 94 (2015)7. - ISSN 0032-5791 - p. 1493 - 1498.
laying hens - responses - survival - immunity - corticosterone - population - strains - stress - innate - plasma
Natural antibody (NAb) levels and survival rates were evaluated in 4 breeds of laying hens in Ethiopia: indigenous, improved indigenous, exotic layer, and crossbred. Titers of NAb isotypes IgG and IgM binding keyhole limpet hemocyanin (KLH) in serum were measured at 20, 26, 35, and 45 wk age. Repeated-measure ANOVA showed that IgG and IgM levels vary with time within each breed (P <0.05). Indigenous chickens had significantly (P <0.05) higher NAb levels at all ages. The Cox proportional hazard analysis showed increased hazard with increased levels of NAbs in the exotic layers (P <0.05). However, the reduced hazards with increased levels of NAbs were not significant in the improved indigenous and crossbred chickens. Indigenous chickens showed increased hazard with increasing levels of NAb (P > 0.05). We concluded that not only the NAb levels but also the effect of Nabs on survival vary between indigenous and improved breeds. The results indicate that NAb levels are associated with survival in elite (improved) breeds, but are associated with increased hazard in indigenous chickens.
Genetic relations between natural antibodies binding keyhole limpet hemocyanin and production traits in a purebred layer chicken line
Klein, S.A.S. van der; Berghof, T.V.L. ; Arts, J.A.J. ; Parmentier, H.K. ; Poel, J.J. van der; Bovenhuis, H. - \ 2015
Poultry Science 94 (2015)5. - ISSN 0032-5791 - p. 875 - 882.
red-blood-cells - sheep erythrocytes - laying hens - immune-response - selection experiments - parameters - survival - isotypes - responsiveness - sensitivity
Natural antibodies (NAb) are an important component of the first line of immune defense. Selective breeding for enhanced NAb levels in chickens may improve general disease resistance. It is unknown what the consequences of selection for NAb will be on the productive performance of laying hens. In this paper we describe the genetic relations between NAb titers binding keyhole limpet hemocyanin at 19 wk age and production traits in a white purebred leghorn chicken line observed in several time periods. A linear animal model was used to estimate (co)variance components, heritabilities, and correlations. Negative genetic correlations were found between egg weight and NAb titers, and between egg breaking strength and NAb titers. Positive genetic correlations were found between the feed conversion ratio (consumed feed/egg mass produced) and NAb titers, and egg production and NAb titers. Negative phenotypic correlations were found between body weight and NAb titers, between egg weight and NAb titers, and between egg breaking strength and NAb titers. Positive phenotypic correlations were found between egg production and NAb titers, and feed conversion ratio and NAb titers. In general, phenotypic correlations were more often significant, but less pronounced than genetic correlations. Other production traits were not found to be significant related to NAb titers. These findings suggest that there is a genetic tradeoff between levels of immunity and some production traits, although the underlying mechanism(s) remain(s) unclear. The results suggest possible consequences for production efficiency as a result of selective breeding for improved general disease resistance by natural antibodies.
The role of genes, epigenetics and ontogeny in behavioural development
Rodenburg, T.B. - \ 2014
Applied Animal Behaviour Science 157 (2014). - ISSN 0168-1591 - p. 8 - 13.
gallus-gallus-domesticus - feather pecking behavior - laying hens - maternal-care - low mortality - offspring phenotype - zebra finches - stress - selection - cannibalism
This review focuses on the role of genes, epigenetics and ontogeny in behavioural devel-opment of animals. The behavioural characteristics of an individual are determined by itsgenes and by its physical and social environment. Not only the individual’s early life andcurrent environment are of importance, but also the environment of previous generations.Through epigenetic processes, stress in parents and even grandparents can translate intochanges in behavioural and physical characteristics of the offspring. Another influentialfactor for behavioural development is maternal hormones. Recent studies indicate thathormonal effects may also be closely related to epigenetic changes. Also, the environmentduring ontogeny has considerable impact on behavioural development: in both mice andlaying hens, high quality maternal care resulted in animals that were less fearful. In layinghens maternal care also led to a reduction in cannibalistic pecking. Genetic selection andselection experiments will also play a key role in breeding animals for the housing systemsof the future. To optimize behavioural development of farm animals and to minimize risksof damaging behaviour, integral approaches are needed that combine selection of the opti-mal genotype with provision of a favourable environment for parents and offspring, bothduring ontogeny and later life.
Tail Biting in Pigs: Blood Serotonin and Fearfulness as Pieces of the Puzzle?
Ursinus, W.W. ; Reenen, C.G. van; Reimert, I. ; Bolhuis, J.E. - \ 2014
PLoS ONE 9 (2014)9. - ISSN 1932-6203
obsessive-compulsive disorder - individual coping characteristics - environmental enrichment - laying hens - feather pecking - growing pigs - peripheral serotonin - behavioral-responses - platelet serotonin - growth-performance
Tail biting in pigs is a widespread problem in intensive pig farming. The tendency to develop this damaging behaviour has been suggested to relate to serotonergic functioning and personality characteristics of pigs. We investigated whether tail biting in pigs can be associated with blood serotonin and with their behavioural and physiological responses to novelty. Pigs (n = 480) were born in conventional farrowing pens and after weaning at four weeks of age they were either housed barren (B) or in straw-enriched (E) pens. Individual pigs were exposed to a back test and novel environment test before weaning, and after weaning to a novel object (i.e. bucket) test in an unfamiliar arena. A Principal Component Analysis on behaviours during the tests and salivary cortisol (novel object test only) revealed five factors for both housing systems, labeled ‘Early life exploration’, ‘Near bucket’, ‘Cortisol’, ‘Vocalizations & standing alert’, and ‘Back test activity’. Blood samples were taken at 8, 9 and 22 weeks of age to determine blood platelet serotonin. In different phases of life, pigs were classified as tail biter/non-tail biter based on tail biting behaviour, and as victim/non-victim based on tail wounds. A combination of both classifications resulted in four pig types: biters, victims, biter/victims, and neutrals. Generally, only in phases of life during which pigs were classified as tail biters, they seemed to have lower blood platelet serotonin storage and higher blood platelet uptake velocities. Victims also seemed to have lower blood serotonin storage. Additionally, in B housing, tail biters seemed to consistently have lower scores of the factor ‘Near bucket’, possibly indicating a higher fearfulness in tail biters. Further research is needed to elucidate the nature of the relationship between peripheral 5-HT, fearfulness and tail biting, and to develop successful strategies and interventions to prevent and reduce tail biting.
Effects of phytase supplementation on phosphorus retention in broilers and layers: A meta-analysis
Bougouin, A. ; Appuhamy, J.A.D.R.N. ; Kebreab, E. ; Dijkstra, J. ; Kwakkel, R.P. ; France, J. - \ 2014
Poultry Science 93 (2014)8. - ISSN 0032-5791 - p. 1981 - 1992.
coli-derived phytase - soybean meal diets - apparent metabolizable energy - different calcium levels - wheat-based diets - microbial phytase - laying hens - growth-performance - nonphytate phosphorus - nutrient utilization
Phytase, a widely used feed additive in poultry diets, increases P availability and subsequently reduces inorganic-P supplementation and P-excretion. Phytase supplementation effect on P-retention in poultry has been investigated, but the effect sizes were highly variable. The present study’s objective was to conduct several meta-analyses to quantitatively summarize the phytase effect on P-retention in broilers and layers. Data from 103 and 26 controlled experiments testing the phytase effect on P-retention were included in 2 separate meta-analyses for broilers and layers, respectively. The mean difference calculated by subtracting the means of P-retention for the control group from the phytase-supplemented group was chosen as an effect size estimate. Between-study variability (heterogeneity) of mean difference was estimated using random-effect models and had a significant effect (P <0.01) in both broilers and layers. Therefore, random-effect models were extended to mixed-effect models to explain heterogeneity and obtain final phytase effect size estimates. Available dietary and bird variables were included as fixed effects in the mixed-effect models. The final broiler mixed-effect model included phytase dose and Ca-to-total-P ratio (Ca:tP), explaining 15.6% of the heterogeneity. Other variables such as breed might further explain between-study variance. Broilers consuming control diets were associated with 48.4% P-retention. Exogenous phytase supplementation at 1,039 FTU/kg of diet increased P-retention by 8.6 percentage units on average. A unit increase of phytase dose and Ca:tP from their means further increased P-retention. For layers, the final mixed-effect models included dietary Ca, age, and experimental period length. The variables explained 65.9% of the heterogeneity. Layers receiving exogenous phytase at 371 FTU/kg were associated with a 5.02 percentage unit increase in P-retention. A unit increase in dietary Ca from its mean increased P-retention, whereas an increase in the experiment length and layer’s age decreased P-retention. Phytase supplementation had a significant positive effect on P-retention in both broilers and layers, but effect sizes across studies were significantly heterogeneous due to differences in Ca contents, experiment length, bird age, and phytase dose.
Path planning for autonomous collection of eggs on floors
Vroegindeweij, B.A. ; Willigenburg, L.G. van; Groot Koerkamp, P.W.G. ; Henten, E.J. van - \ 2014
Biosystems Engineering 121 (2014). - ISSN 1537-5110 - p. 186 - 199.
laying hens - prelaying behavior - layers
A problem in loose housing systems for laying hens is the laying of eggs on the floor; these eggs need manual collection. This job is heavy and time-consuming and automated collection is desired. For collection using a robot, a collection path is required. A novel path planning algorithm is introduced for non-uniform repetitive area coverage (NURAC) paths and evaluated based on information about floor egg distribution probability. Firstly, a spatial map was developed that describes the potential for floor eggs at each location in a poultry house. Next, paths for floor egg collection are planned with a dynamic programming approach that covers the house floor area and frequently revisits locations with a high potential on floor eggs. These paths are compared with the paths used for floor egg collection by a farmer and evaluated with help of a simulated set of floor eggs. With respect to the average time eggs are present on the floor, paths planned for a robot are compared to two collection rounds of a farmer. With respect to the structure of the path and the number of visits to locations with a high potential, the robot paths outperform the farmer. Although optimality of the path is not guaranteed, the presented results are promising for the use of a robot to collect floor eggs, and will result in a reduction of the demand for manual labour. Extending the floor egg model with feedback information could further improve the results.
Impact of nutrition on welfare aspects of broiler breeder flocks
Krimpen, M.M. van; Jong, I.C. de - \ 2014
Worlds Poultry Science Journal 70 (2014)1. - ISSN 0043-9339 - p. 139 - 150.
low-density diets - quantitative food restriction - ovarian follicular hierarchy - fed representative 1957 - feather-pecking line - laying hens - feed restriction - body-weight - growth-rate - gastrointestinal motility
To ensure health and reproductive performance, broiler breeders are feed restricted during the rearing period and, to a lesser extent, during the production period. Although restricted feeding improves health and bird welfare, on the other hand the birds are chronically hungry and suffer from frustration of feeding motivation, which has a negative effect on bird welfare. The aim of the current paper is to give an overview of the role of feed (nutritional aspects as well as feeding management) as a possible tool to improve broiler breeder welfare. Possible strategies discussed are 1) dietary dilution, by reducing the energy content and/or increasing the NSP content, by adding soluble or insoluble fibres to the diet; 2) adding appetite suppressants (e.g. calcium propionate) to the diet; 3) changing feeding management (e.g., scattering feed in the litter). Some of these strategies, i.e. dietary dilution or adding appetite suppressants, positively affect behavioural patterns of the birds, by reducing stereotypic pecking and eating motivation, and increasing the time spent sitting. Appetite suppressants have however been criticised for causing birds to feel ill. These behavioural changes, however, can only be considered as indirect parameters of improved bird welfare and there is still a need for a reliable indicator of hunger. It is clear that nutritional strategies can be helpful in reducing hunger stress in broiler breeders. Nutrition, however, cannot fully solve the broiler breeder paradox. The main reason for this paradox is related to breeding goals that are focussed on improving feed conversion and increasing breast meat percentage. Future genetic selection should aim at uncoupling the link between (re)production and welfare or reducing the conflict between these outcomes.
Responses to novel situations of female and castrated male pigs with divergent social breeding values and different backtest classifications in barren and straw-enriched housing
Reimert, I. ; Rodenburg, T.B. ; Ursinus, W.W. ; Kemp, B. ; Bolhuis, J.E. - \ 2014
Applied Animal Behaviour Science 151 (2014). - ISSN 0168-1591 - p. 24 - 35.
different coping characteristics - individual behavioral-characteristics - environmental enrichment - growing-pigs - physiological-responses - animal-welfare - fear reactions - laying hens - multilevel selection - surgical castration
The growth of a pig is not only affected by its own genes, but also by the genes of itspen mates. This indirect effect on a pig’s growth is represented as social breeding value(SBV) in a newly developed breeding model. It has been hypothesized that pigs could affecttheir pen mates’ growth through their behavior. We investigated whether pigs selectedfor a relatively positive (+SBV) or negative genetic effect (-SBV) on the growth of theirpen mates and kept in either barren or straw-enriched pens differ in fearfulness. Effectsof coping style, as assessed in a backtest, and gender were also investigated. Pigs (n = 480)were subjected to a group-wise novel rope test and human approach test and individuallyto a novel environment test in which after 5 min a bucket was lowered from the ceiling.In the novel rope test +SBV pigs were faster than -SBV pigs to touch a rope (P <0.01) andin the novel environment test +SBV pigs showed less locomotion than -SBV pigs afterintroduction of the bucket (P <0.05). Furthermore, straw-enriched pigs were faster thanbarren housed pigs to touch a rope in the novel rope test (P <0.10) and faster to approach(P <0.05) and touch a person (P <0.05) in the human approach test, suggesting that theyare less fearful or more curious than pigs in barren housing. Straw-enriched pigs also hadlower salivary cortisol concentrations than barren housed pigs (P <0.001). Pigs classifiedas high-resisting in the backtest spent more time near the person in the human approachtest (P <0.10) and showed more locomotion (P <0.10) and vocalizations (P <0.001) afterintroduction of the bucket in the novel environment test than low-resisting pigs. Giltsappeared less fearful than barrows, because they were faster to touch a rope in the novelrope test (P <0.05) and faster to approach (P <0.05) and touch a person (P <0.10) in thehuman approach test. In addition, in the novel environment test, gilts were more calm(P <0.05) in the period before the bucket was introduced, paid more attention to the bucketonce it was lowered (P <0.10) and were overall more active (P <0.01). Gilts also had lowerbasal cortisol concentrations than barrows (P <0.001). Overall, these results suggest that+SBV pigs might be less fearful than -SBV pigs. Furthermore, the response of pigs in noveltytests seems to depend also on their housing conditions, coping style, and gender.
Eggspectation: organic egg authentication method challenged with produce from ten different countries
Ruth, S.M. van; Koot, A.H. ; Brouwer, S.E. ; Boivin, N. ; Carcea, M. ; Zerva, C.N. ; Haugen, J.E. ; Hohl, A. ; Koroglu, D. ; Mafra, I. ; Rom, S. - \ 2013
Quality Assurance and Safety of Crops & Foods 5 (2013)1. - ISSN 1757-8361 - p. 7 - 14.
laying hens - carotenoids - quantification - identification - zeaxanthin - lutein - hplc - yolk
Many consumers are willing to pay a higher price for organic eggs. Since these eggs retail at a higher price than conventional eggs and their identity is difficult to verify, they are susceptible to fraud. For the authentication of Dutch eggs RIKILT developed an analytical test method based on carotenoid profiling. In the present study, the method was challenged with eggs from 10 countries. Eggs from 94 farms (65 organic, 29 conventional) were subjected to the carotenoid High Performance Liquid Chromatography Diode Array Detection profiling combined with k-nearest neighbour classification chemometrics to predict the farming management system category: organic or conventional. The eggs from 39 of the 40 EU organic farms and the eggs of 27 of the 29 EU conventional farms, as well as eggs from 17 of the 25 organic farms from outside the EU were classified correctly. The latter lower rate was mainly due to eggs from Turkey; 78% of which were misclassified. The methodology was successful in farming management prediction of the EU eggs, as well as for eggs from Canada, Israel and Norway. The identity of the eggs from Turkey was consistently incorrectly predicted and needs further research.
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