Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

    Records 1 - 20 / 77

    • help
    • print

      Print search results

    • export

      Export search results

    Check title to add to marked list
    Kruiden voor landbouwhuisdieren
    Groot, M.J. - \ 2019
    Wageningen : Groen Kennisnet
    animal welfare - animal production - goats - turkeys - rabbits - dairy cattle - poultry - sheep - pigs - veal calves - animal nutrition - animal health
    Ontstaan ‘haanburger’ is vergelijkbaar met kalfsvlees
    Heeres-van der Tol, J.J. - \ 2017
    Wageningen : Livestock Stories blog, Wageningen University & Research
    animal welfare - animal production - dairy cattle - veal calves - animal housing - animal behaviour - animal health - animal nutrition
    Van kalf tot koe, maar hoe? Wat komt daar allemaal bij kijken?
    Heeres-van der Tol, J.J. - \ 2017
    Wageningen : Livestock Stories blog, Wageningen University & Research
    animal welfare - animal production - dairy cattle - veal calves - animal housing - animal behaviour - animal health - animal nutrition
    Alternatieve vloeren voor vleeskalveren
    Heeres-van der Tol, Jetta ; Wolthuis, Maaike ; Bokma, Sjoerd ; Smits, Dolf ; Stockhofe, Norbert ; Vermeij, Izak ; Reenen, Kees van - \ 2017
    Wageningen : Wageningen Livestock Research (Wageningen Livestock Research rapport 1056) - 103
    dierenwelzijn - dierlijke productie - vleeskalveren - huisvesting - diergedrag - diergezondheid - animal welfare - animal production - veal calves - housing - animal behaviour - animal health
    Gezonde Vleeskalveren: Het belang van een goede start : Lesmateriaal & informatie voor docenten
    Kluivers-Poodt, M. - \ 2016
    Wageningen : Wageningen Livestock Research - 4
    vleeskalveren - dierenwelzijn - diergezondheid - lesmaterialen - veal calves - animal welfare - animal health - teaching materials
    Gezonde vleeskalveren : Het belang van een goede start
    Kluivers-Poodt, M. - \ 2016
    Wageningen : Wageningen Livestock Research - 2
    vleeskalveren - dierenwelzijn - diergezondheid - lesmaterialen - veal calves - animal welfare - animal health - teaching materials
    Vleeskalveren komen van melkveebedrijven. Vanaf een leeftijd van twee
    weken gaan ze naar het vleeskalverbedrijf, waar ze in ongeveer 6 tot 7
    maanden worden opgefokt voor de kalfsvleesproductie. Stierkalveren die
    op het melkveebedrijf al goed groeien en op gewicht komen, presteren ook
    in de mestperiode beter en hebben minder medicijnen en antibiotica nodig.
    Gezonde vleeskalveren - Een sterk kalf: belang van een goede opfok op het melkveebedrijf : Kennisclip
    Ruis, M.A.W. - \ 2016
    Dierenwelzijnsweb
    dierenwelzijn - dierlijke productie - diergezondheid - antibiotica - vleeskalveren - rundvee - animal welfare - animal production - animal health - antibiotics - veal calves - cattle
    Stierkalveren die op het melkveebedrijf al goed groeien en op gewicht komen presteren ook in de mestperiode beter en hebben minder medicijnen en antibiotica nodig. Bij opzet van minder vitale nuchtere kalveren op het vleeskalverbedrijf is de uitval circa 2 procent hoger, en het kost €20 tot €30 per kalf extra aan arbeid en medicijnen.

    Factoren in de kalveropfok die bijdragen aan de weerstand en gezondheid van vleeskalveren zijn: een hygiënische, tochtvrije huisvesting, voldoende biest van goede kwaliteit, goede kwaliteit melk en het vrij zijn van ziektes. Deze factoren geven een sterker vleeskalf, waardoor de kans op problemen in de mestfase vermindert.

    In opdracht van Wageningen UR Livestock Research en het Ontwikkelcentrum, project 'Naar gezonde kalveren en kippen' (BO-20-011-032). Meer informatie over diergezondheid en dierenwelzijn: www.dierenwelzijnsweb.nl
    Gezonde vleeskalveren : een warm welkom: belang van een goede opvang : Kennisclip
    Ruis, M.A.W. - \ 2016
    Dierenwelzijnsweb
    dierenwelzijn - dierlijke productie - diergezondheid - antibiotica - vleeskalveren - rundvee - animal welfare - animal production - animal health - antibiotics - veal calves - cattle
    Vleeskalveren komen van melkveebedrijven, vanaf een leeftijd van twee weken. Ze komen vaak eerst bij elkaar op een verzamelplaats en gaan van daar naar het vleeskalverbedrijf. Ongeveer de helft van de kalveren komt van Nederlandse melkveebedrijven, de rest komt uit het buitenland, vooral Duitsland en Oost-Europa.

    Een optimale opvang bevordert een goede start op het vleeskalverbedrijf. Hiervoor is het van belang de kalveren rustig op te vangen in een verwarmde stal, individuele aandacht en zorg te bieden, en lauw water met elektrolytenmix te verstrekken om een tekort aan vocht en lichaamszouten aan te vullen.

    In opdracht van Wageningen UR Livestock Research en het Ontwikkelcentrum, project 'Naar gezonde kalveren en kippen' (BO- 20-011-032). Meer informatie over diergezondheid en dierenwelzijn: www.dierenwelzijnsweb.nl
    Gezonde vleeskalveren - Goede opstart: infectiedruk en weerstand in balans : Kennisclip
    Ruis, M.A.W. - \ 2016
    Dierenwelzijnsweb
    dierenwelzijn - dierlijke productie - diergezondheid - antibiotica - vleeskalveren - rundvee - animal welfare - animal production - animal health - antibiotics - veal calves - cattle
    In de vleeskalverhouderij komen gezondheidsproblemen - met name luchtwegproblemen - vooral in de eerste 3 weken voor. In deze periode zijn de dieren individueel gehuisvest om ze goed te kunnen controleren. Er is regelmatig contact met de dierenarts.

    De gezondheid van vleeskalveren wordt bepaald door de balans tussen infectiedruk en weerstand tegen ziektes. Infectiedruk in de vleeskalverhouderij wordt voor een groot deel bepaald door ziekteverwekkers die de kalveren meenemen van het melkveebedrijf. Verminderen van stress en optimaliseren van voeding en klimaat hebben een positieve invloed op de weerstand van de dieren.

    In opdracht van Wageningen UR Livestock Research en het Ontwikkelcentrum, project 'Naar gezonde kalveren en kippen' (BO 20-011-032). Meer informatie over diergezondheid en dierenwelzijn: www.dierenwelzijnsweb.nl
    Gezonde vleeskalveren : optimale groei: verbeteringen in voer : Kennisclip
    Ruis, M.A.W. - \ 2016
    Dierenwelzijnsweb
    dierenwelzijn - dierlijke productie - diergezondheid - antibiotica - vleeskalveren - rundvee - animal welfare - animal production - animal health - antibiotics - veal calves - cattle
    Traditioneel werd aan vleeskalveren alleen kalvermelk gevoerd. Nu wordt vanaf opzet op het vleeskalverbedrijf naast kalvermelk ook ruw- en krachtvoer verstrekt. Rosé kalveren gaan na een week of 6-7 melkvoeding volledig over op ruw- en krachtvoer.

    Voldoende ruwvoer komt tegemoet aan de natuurlijke kauwbehoefte van kalveren. Hoe vezelrijker het rantsoen, hoe meer ‘pensprik’, en hoe beter de vertering. Een blankvleeskalf van 6 maanden beschikt bij voorkeur dagelijks over 2 kg krachtvoer, 1 kg ruwvoer en 2 kg droge stof kalvermelk. Nieuw onderzoek richt zich op het verbeteren van weerstand en vitaliteit van kalveren via de voeding.
    In opdracht van Wageningen UR Livestock Research en het Ontwikkelcentrum, project 'Naar gezonde kalveren en kippen' (BO-20-011-032). Meer informatie over diergezondheid en dierenwelzijn: www.dierenwelzijnsweb.nl
    Critical ethical issues in USA animal production : executive summary
    Hoste, R. ; Oosterkamp, E.B. - \ 2016
    LEI Wageningen UR (Factsheet / LEI Wageningen UR VR2015-137) - 2
    animal welfare - animal ethics - animal husbandry - legislation - european union - usa - eu regulations - animal production - animal housing - dairy cattle - pigs - veal calves - beef cattle - broilers - dierenwelzijn - dierethiek - dierhouderij - wetgeving - europese unie - vs - eu regelingen - dierlijke productie - huisvesting, dieren - melkvee - varkens - vleeskalveren - vleesvee - vleeskuikens
    In 2014, the non-governmental organisation Wakker Dier in the Netherlands criticised ING for financing animal farms outside the European Union (EU). The NGO expressed its concern that local regulation would not sufficiently guarantee animal welfare standards up to the level guaranteed under EU regulations. Early 2015, LEI Wageningen UR was requested to identify potential detrimental activities in the United States of America (USA) animal husbandry sector due to gaps between EU and USA legislation and local animal welfare standards applied in the USA. Activities covered by ING clients in the USA and thus in scope of this research involve pigs, layers, broilers, veal calves, dairy cows and beef cows. The aim of this report is to provide a qualified comparison of animal welfare standards in the USA and the EU and to identify animal welfare and other potential ethical issues within animal farming in the USA and to identify critical issues on which ING is advised to take a strategic position.
    A field trial on the effects of algae addition to calf feed. Project T2014
    Elissen, H.J.H. ; Berg, W. van den; Kootstra, A.M.J. - \ 2015
    Lelystad : Wageningen UR, PPO/Acrres (Rapport / PPO-AGV 662) - 41
    calves - calf feeding - feed formulation - feeds - veal calves - liveweight - animal health - feed conversion - algae - kalveren - kalvervoeding - voersamenstelling - voer - vleeskalveren - levend gewicht - diergezondheid - voederconversie - algen
    This report describes a field trial that took place between 1 July and 2 October 2015 at a Dutch rose veal farm in which a group of 30 calves was fed with formula milk of which 2% of the dry matter was substituted with concentrated freshwater algae. The control group consisted of 25 calves. The farm owners collected the data, which were statistically analyzed and reported at ACRRES. During the trial the following parameters were monitored: calf weight, amounts of formula milk, water, solid feeds, feed additions and medication, deviations in manure structure, and disease incidence. Individual calf weights were determined at arrival and four weighing dates. The main conclusion of this field trial is that the addition of algae to the formula milk of rose veal calves during a period of 44 to 51 days did not have a statistically significant effect on calf weight increase up to 13 weeks after the start of the trial.
    Progress report validation of parameters to determine unconsciousness during slaughter of veal calves
    Gerritzen, M.A. ; Verhoeven, H.A. ; Hindle, V.A. - \ 2015
    Wageningen UR Livestock Research (Livestock Research rwport 405) - 28
    animal welfare - animal production - veal calves - animal health - slaughter - dierenwelzijn - dierlijke productie - vleeskalveren - diergezondheid - slacht
    Replacing lactose from calf milk replacers : effects on digestion and post-absorptive metabolism
    Gilbert, M.S. - \ 2015
    Wageningen University. Promotor(en): Wouter Hendriks, co-promotor(en): Walter Gerrits; Henk Schols. - Wageningen : Wageningen University - ISBN 9789462576032 - 171
    vleeskalveren - lactose - kunstmelk - polysacchariden - glucose - fructose - glycerol - zetmeelvertering - metabolisme - fermentatie - kalvervoeding - diervoeding - voedingsfysiologie - veal calves - lactose - filled milk - polysaccharides - glucose - fructose - glycerol - starch digestion - metabolism - fermentation - calf feeding - animal nutrition - nutrition physiology

    Summary PhD thesis Myrthe S. Gilbert

    Replacing lactose from calf milk replacers – Effects on digestion and post-absorptive metabolism

    Veal calves are fed milk replacer (MR) and solid feed. The largest part of the energy provided to veal calves originates from the MR. Calf MR contains 40 to 50% lactose, originating from whey, a by-product from cheese production. High and strongly fluctuating dairy prices are a major economic incentive to replace lactose from the calf MR by alternative energy sources. The objective of this thesis was to study the effects of replacing lactose from calf MR on nutrient digestion and fermentation and post-absorptive metabolism.

    In Chapter 2 and 3, four starch products (SP) were evaluated for replacing lactose. The four SP differed in size and branching, and consequently required different ratios of starch-degrading enzymes for their complete hydrolysis to glucose. Gelatinized starch required α-amylase and (iso)maltase; maltodextrin required (iso)maltase and α-amylase; maltodextrin with α-1,6-branching required isomaltase, maltase and α-amylase and maltose required maltase. In Chapter 2, adaptation to these SP was assessed during 14 weeks, using a within-animal titration study. Forty male Holstein-Friesian calves (n = 8 per treatment) were assigned to either a lactose control MR or one of four titration strategies, each testing the stepwise exchange of lactose for one of the SP. For control calves, fecal dry matter (DM) content and fecal pH did not change over time. The response in fecal DM content and fecal pH in time did not differ between SP treatments and decreased linearly with 0.57% and 0.32 per week, respectively, where one week corresponded to an increase in SP inclusion of 3%. This indicates that the capacity for starch digestion was already exceeded at low inclusion levels, resulting in SP fermentation. All SP required maltase to achieve complete hydrolysis to glucose and it was, therefore, suggested that maltase is the rate-limiting enzyme in starch digestion in milk-fed calves.

    Following the titration, a fixed inclusion level of 18% of the SP in the MR was applied. Effects on starch-degrading enzyme activity, nutrient disappearance, SP fermentation and jugular glucose appearance were measured (Chapter 3). Lactase activity in the brush border was high in the proximal small intestine of all calves, resulting in a high apparent ileal disappearance of lactose (≥ 99% of intake). Maltase and isomaltase activities in the brush border were not increased for any of the SP treatments. Luminal α-amylase activity was lower in the proximal small intestine but greater in the distal small intestine of SP-fed calves compared to control calves. This amylase activity in the distal small intestine of SP-fed calves might have been of microbial origin. Apparent SP disappearance did not differ between SP treatments. The difference between apparent ileal (62%) and total tract (99%) SP disappearance indicated substantial SP fermentation in the large intestine (37% of intake). In addition, total tract SP fermentation was quantified using fecal 13C excretion which originated from the naturally 13C-enriched corn SP. Total tract SP fermentation averaged 89% of intake, regardless of SP treatment. MR leaking into the reticulorumen was measured as the recovery of Cr in the reticulorumen at slaughter after feeding MR pulse-dosed with Cr 4h prior to slaughter. MR leaking into the reticulorumen averaged 11% for SP-fed calves. By difference, this leaves 41% of the SP intake fermented in the small intestine. This coincided with increased fecal nitrogen (N) and DM losses for SP-fed calves. However, apparent total tract crude fat disappearance tended to increase when replacing lactose with SP. The substantial SP fermentation indicates that only 10% of the SP intake was enzymatically hydrolyzed and absorbed as glucose. This was in agreement with the marginal increase in 13C enrichment in peripheral plasma glucose after feeding naturally 13C-enriched gelatinized starch and maltose, compared to a clear increase after feeding naturally 13C-enriched lactose to control calves. It was concluded that fermentation, rather than enzymatic digestion, is the main reason for small intestinal starch disappearance in milk-fed calves. The expected decrease in growth performance with such extensive SP fermentation is partially compensated by the greater crude fat digestion and possibly by a reduced urinary glucose excretion when replacing lactose with SP.

    Glucose, fructose and glycerol do not require enzymatic hydrolysis and can be absorbed directly from the small intestine. However, these lactose replacers might differentially affect glucose and insulin metabolism and with that energy partitioning. The effects of partly replacing lactose with glucose, fructose or glycerol on energy and N partitioning and glucose homeostasis and insulin sensitivity were, therefore, studied in Chapter 4 and 5. Forty male Holstein-Friesian calves either received a lactose control MR or a MR in which one third of the lactose was replaced with glucose, fructose or glycerol (n = 10 per treatment). Energy and N retention were not affected by MR composition. Fructose absorption from the small intestine was incomplete resulting in fructose fermentation. This resulted in fecal losses of DM, energy and N and the lowest numerical energy and N retention for fructose-fed calves. Postprandial plasma concentrations of glucose exceeded the renal threshold for glucose in glucose-fed calves and control calves, which resulted in urinary glucose excretion. Glycerol was likely excreted with the urine of glycerol-fed calves. Oxidation of glucose, fructose and glycerol was quantified by feeding a single dose of [U-13C]glucose, [U-13C]fructose or [U-13C]glycerol with the MR and subsequently measuring 13CO2 production. Oxidation of lactose replacers did not differ between lactose replacers and averaged 72% of intake. However, the time at which the maximum rate of oxidation was reached was delayed for fructose-fed compared to glucose-fed and glycerol-fed calves, indicating that fructose was converted into other substrates before being oxidized. Conversion of fructose and glycerol into glucose was confirmed by an increase in 13C enrichment of peripheral plasma glucose after feeding [U-13C]fructose and [U-13C]glycerol, respectively. Insulin sensitivity did not differ between MR treatments, but was already low at the start of the experiment at 15 weeks of age and remained low throughout the experiment. It was concluded that glucose and glycerol can replace one third of the lactose from the calf MR, but that inclusion of fructose should be lower to prevent incomplete absorption from the small intestine.

    In literature and the studies in this thesis, high inter-individual variation in growth performance was found in veal calves. The experiment described in Chapter 6 was, therefore, designed to assess the predictability of later life growth performance by charactering calves in early life. In addition, it was examined whether the ability of calves to cope with MR in which lactose is partially replaced by alternative energy sources can be predicted. From 2 to 11 weeks of age, male Holstein-Friesian calves were fed a lactose control MR and solid feed according to a practical feeding scheme and were characterized individually using targeted challenges related to feeding motivation, digestion, post-absorptive metabolism, immunology, behavior and stress. Based on the results in Chapter 4, a combination of glucose, fructose and glycerol in a 2:1:2 ratio was used to replace half of the lactose from the MR (GFG). From 11 to 27 weeks of age, calves received a lactose control MR or the GFG MR (n = 65 per treatment). Growth performance from 11 to 27 weeks of age tended to be lower for GFG-fed than for control calves (-25 g/d). Measurements in early life explained 12% of the variation in growth performance in later life. However, this was mainly related to variation in solid feed refusals. When growth performance was adjusted to equal solid feed intake, only 4% of the variation in standardized growth performance in later life, reflecting feed efficiency, could be explained by early life measurements. This indicates that > 95% of the variation in feed efficiency in later life could not be explained by early life characterization. It is hypothesized that variation in health status explains substantial variation in feed efficiency in veal calves. Significant relations between fasting plasma glucose concentrations, fecal dry matter and fecal pH in early life and feed efficiency in later life depended on MR composition. These measurements are, therefore, potential tools for screening calves in early life on their ability to cope with a MR in which half of the lactose is replaced by glucose, fructose and glycerol (in a 2:1:2 ratio).

    The studies reported in this thesis demonstrate that glycerol, glucose and a combination of glucose, fructose and glycerol in a 2:1:2 ratio are promising lactose replacers. The effects of replacing lactose by other carbohydrate or energy sources described in this thesis are required to evaluate the potential of lactose replacers for inclusion in calf milk replacers and provide input for feed evaluation for calves and ruminants.

    Methaanproductie bij witvleeskalveren
    Gerrits, W.J.J. ; Dijkstra, J. ; Bannink, A. - \ 2014
    Wageningen : Wageningen UR Livestock Research (Rapport 813) - 15
    vleeskalveren - methaan - emissie - kunstmelk - diervoedering - nederland - veal calves - methane - emission - filled milk - animal feeding - netherlands
    De methaanemissie uit (deels) met kunstmelk gevoerde Nederlandse witvleeskalveren is veel lager dan de door IPCC gehanteerde defaultwaarden aangeven. Aanbevolen wordt om de methaanconversiefactor, Ym (de fractie van de bruto energieopname met voer die emitteert als methaanenergie) meer dan te halveren. Tevens wordt aanbevolen om de jaarlijkse methaanemissie door witvleeskalveren vast te stellen met een aparte waarde van 0,003 voor de gevoerde kunstmelk en een waarde van 0,055 voor gevoerde ruw- en krachtvoeders, uitgaande van de jaarlijkse rantsoenberekeningen volgens gestandaardiseerde methode door het CBS.
    Knelpunten bestrijding mond- en klauwzeer en klassieke varkenspest
    Bergevoet, R.H.M. ; Bondt, N. ; Asseldonk, Marcel van - \ 2014
    Den Haag : LEI Wageningen UR (LEI report 2014-022) - ISBN 9789086156818 - 37
    mond- en klauwzeer - klassieke varkenspest - huisvesting, dieren - biggen - overschotten - dierenwelzijn - varkens - vleeskalveren - melkvee - schapen - geiten - ziektebestrijding - diergezondheid - dierlijke productie - dierziekten - foot and mouth disease - classical swine fever - animal housing - piglets - surpluses - animal welfare - pigs - veal calves - dairy cattle - sheep - goats - disease control - animal health - animal production - animal diseases
    Dit onderzoek inventariseert de belangrijkste knelpunten tijdens de uitbraakfase van Mond- en klauwzeer en Klassieke Varkenspest die voortkomen uit de geldende regelgeving en/of uit de structuur van veehouderijsectoren, en beschrijft de mogelijke oplossingsrichtingen.
    Stalboekje vleeskalveren : handboek voor natuurlijke diergezondheidzorg met kruiden en andere natuurproducten
    Groot, M.J. ; Asseldonk, T. van - \ 2014
    Wageningen : RIKILT Wageningen UR - 128
    vleeskalveren - diergezondheid - dierziektepreventie - rundveehouderij - geneeskrachtige kruiden - medicinale planten - biologische landbouw - dierenwelzijn - veal calves - animal health - animal disease prevention - cattle husbandry - herbal drugs - medicinal plants - organic farming - animal welfare
    In dit boekje worden handvaten gegeven om met natuurlijke middelen de gezondheid en de weerstand van de dieren te bevorderen en zo ziektes te voorkomen. Tevens kunnen middelen worden ingezet om de ernst van de ziekte te reduceren. Doel is tevens om de dierenartsen te informeren over de mogelijkheden van natuurproducten en de wetenschappelijke onderbouwing hiervan inzichtelijk te maken.
    Hazards and adverse effects for the assessment of animal welfare on farm and during transport: A preliminary table for bulls, veal calves and slaughter pigs
    Visser, E.K. ; Ouweltjes, W. ; Spoolder, H.A.M. - \ 2014
    Wageningen : WUR Livestock Research - 50
    animal welfare - animal production - beef cattle - veal calves - pigs - animal housing - transport - dierenwelzijn - dierlijke productie - vleesvee - vleeskalveren - varkens - huisvesting, dieren - transport
    Kruiscontaminatie van antibiotica : onderzoek naar de aanwezigheid van antibioticaresiduen in mest van vleesvarkens en vleeskalveren en op pluimveebedrijven
    Zuidema, T. ; Stolker, A.A.M. ; Ginkel, L.A. van - \ 2014
    Wageningen : RIKILT Wageningen UR (RIKILT rapport 2014.015) - 47
    antibioticumresiduen - plattelandsomgeving - mest - drinkwater - blootstelling - besmetting - varkens - vleeskuikens - vleeskalveren - pluimvee - rundvee - antibiotic residues - rural environment - manures - drinking water - exposure - contamination - pigs - broilers - veal calves - poultry - cattle
    Dit onderzoek heeft tot doel een eerste indicatie te krijgen over het voorkomen van antibioticaresiduen in dieren en hun directe omgeving. Het gaat daarbij met name om de onbedoelde blootstelling als gevolg van kruiscontaminatie. Hiertoe is een onderzoek gedaan naar de aanwezigheid van antibioticaresiduen in mestmonsters van vleesvarkens, vleeskalveren en vleeskuikens. Bij vleeskuikens is ook onderzoek gedaan in omgevingsmonsters (blootstelling vanuit de omgeving) en in watermonsters (blootstelling van dieren via water).
    Food for rumination : developing novel feeding strategies to improve the welfare of veal calves
    Webb, L.E. - \ 2014
    Wageningen University. Promotor(en): Imke de Boer, co-promotor(en): Eddy Bokkers; Kees van Reenen. - Wageningen : Wageningen University - ISBN 9789462570955 - 250
    vleeskalveren - kalvervoeding - voer - kunstmelk - concentraten - ruwvoer (roughage) - abnormaal gedrag - herkauwen - voedingsvoorkeuren - dierenwelzijn - diergezondheid - veal calves - calf feeding - feeds - filled milk - concentrates - roughage - abnormal behaviour - rumination - feeding preferences - animal welfare - animal health

    Summary of thesis entitled: “Food for Rumination – Developing novel feeding strategies to improve the welfare of veal calves”, Laura Webb

    Veal calves are typically fed high levels of milk replacer supplemented with solid feed, which tends to contain a relatively small roughage component. Feeding strategies used in veal production have been associated with welfare issues, including the development of abnormal oral behaviours (AOB) and poor gastrointestinal health. AOB include tongue playing, excessive oral manipulation of the environment, grazing of the coat of other calves, and sham chewing, and are thought to develop in calves when chewing activity (i.e. eating and rumination) is not adequately stimulated. Common gastrointestinal health issues include poor rumen development and lesions in the abomasum.

    The aim of this thesis was to develop novel feeding strategies to improve the welfare of veal calves, i.e. to minimise the development of AOB and gastrointestinal health disorders as well as maximise chewing activity.

    The EU legislation stipulates a minimum of 250 g of `fibrous feed' for 20 week-old calves, but this amount does not seem supported by previous research in terms of it optimising calf welfare. In addition, it does not specify what fibrous feed refers to in terms of source and particle length of roughage. Developing novel feeding strategies for calves necessitates a better understanding of how different roughage characteristics might affect behaviour and gastrointestinal health, and this is what was investigated in Chapter 2. Because none of the single roughage sources investigated were able to improve both behaviour and health, it is likely that a combination of roughage sources would be optimal. For example, an appropriate diet choice may include a combination of roughage sources that facilitate good ruminal papillae development (e.g. maize silage), minimise plaque formation, and encourage both rumen muscularisation and rumination (e.g. straw). This chapter also suggested that hay, as a roughage source with both high levels of structure and high levels of fermentable fibre, could achieve both objectives of encouraging rumination and rumen development. Hay, however, is not used in veal production due to its high iron content that would lead to darker meat colour, which is less preferred by consumers.

    In Chapter 3, different amounts of a solid feed mixture were fed to calves and behaviour was monitored. The results showed that calves fed no solid feed on top of their milk replacer still displayed a rumination-like behaviour, which was in previous literature referred to as `sham chewing'. This result gives an indication as to the importance of rumination in calves. Moreover, this chapter failed to find a straightforward linear relationship between amount of solid feed provided and level of AOB displayed. Certain amounts of solid feed were found to initially stimulate chewing activity to a high level, but later, as calves grew older and more experienced with roughage, failed to stimulate chewing above the level displayed by calves fed no solid feed. Providing such an amount of roughage seemed to be more detrimental in terms of behaviour than providing an amount that results in a constant level of chewing activity throughout the fattening period.

    In order to develop animal-friendly feeding strategies, it is important to know what the animals would choose when given free choice. Therefore, in Chapter 4, the feed preferences of calves for milk replacer, concentrate, hay, straw and maize silage were investigated. This study showed that at 6 months, calves selected on average approximately 1250 g dry matter (DM) milk replacer, 1000 g DM roughage and 2000 g DM concentrate. Although all calves with free choice showed high levels of chewing activity and subsequently low levels of AOB, large individual differences existed in intake levels and feed preferences. Moreover, outcomes were dependent on the variable used to assess preferences: i.e. intake (in g DM relative to metabolic body weight), duration of feeding, or number of visits to each diet component. On average, however, calves showed a preference for milk replacer, concentrate and hay, over straw and maize silage.

    In contrast to free choice testing, as was used in Chapter 4, double demand operant conditioning gives an indication as to the strength of a preference. In Chapter 5, different methods to analyse data collected from double demand operant conditioning studies were investigated. Due to the dependence level between the two resources presented simultaneously, i.e. at any given time the test animal can only work for one resource, it would seem that proportions of rewards achieved for one resource over the total number of rewards achieved for both resources would be an adequate dependent variable in this type of analysis.

    In Chapter 6 the statistical method developed in Chapter 5 was used to assess the preference of calves for long and chopped hay and straw, and their preference for hay versus straw. Two to five month-old calves learned the double demand operant task and were motivated to work for roughage on top of a high energy diet of milk replacer and concentrate. They showed a preference for long over chopped hay, but not for long over chopped straw, and showed a strong preference for hay over straw.
    In Chapter 7 it was investigated whether temperament might affect learning of a double demand operant task in calves. Studies in horses and voles previously found that certain individuals seemed unable to learn certain tasks. If one could find out why, individual training programs could be designed and non-learners would not be removed from studies, potentially avoiding biases in data due to only certain temperament profiles making it through the learning criteria. Chapter 7 gave some indication that temperament may affect learning in calves, and it is the first study in calves to do so. However, due to the low number of animals used, further research is necessary to confirm which temperamental traits affect learning ability in calves.

    Relationships between tongue playing and: 1) hypothesised measures of chronic stress, and 2) hypothesised temperamental traits were investigated in Chapter 8. Large individual differences in the performance of tongue playing in calves subjected to similar husbandry conditions were found. This suggests that although tongue playing might well be a warning sign for chronic stress, and hence poor welfare, individual variation in the propensity to tongue play in response to stressful conditions exists. This could be due to differences in temperament. In contrast to what theoretical papers suggest, calves that showed more tongue playing showed characteristics of a reactive coping style. This result is, however, consistent with previous experimental papers on calves and other species.

    Results from Chapters 2 to 8 were combined into the design of the experiment described in Chapter 9. In this chapter, various feeding strategies (i.e. different amounts of solid feed combined with different concentrate to roughage ratios, different types of ad libitum choice diets, and feeding milk replacer via an open bucket or automated milk dispenser[AMD]) were applied and the effect on behaviour was recorded. Rumination was mainly affected by roughage provision, regardless of concentrate provision. Therefore, increasing solid feed provision without increasing the roughage content would most likely have little effect on rumination, although it would probably increase eating time to a certain extent. Because of the timing of tongue playing and oral manipulation of the environment (found in both Chapters 3 and 9), we suggest that the first of these two AOB is related to chewing activity in general, whereas the second may be more related to anticipation of an upcoming meal and positive reinforcement of feeding behaviours following an unsatisfactory meal. Calves provided ad libitum access to long straw in racks showed high levels of chewing activity and low levels of AOB relative to calves that did not have access to a straw rack but otherwise received the same diet. Six-month-old calves with ad libitum access to straw, maize silage and concentrate (but a restricted milk replacer allowance of 1050 g DM/d) consumed on average approximately 900 g DM/d roughage and 2300 g DM concentrate at 6 months of age. Feeding milk replacer via an AMD seemed to have little impact on behaviour, although it led to lower levels of tongue playing at 15 wk relative to bucket-fed calves.

    In Chapter 10, I first reflect on possible underlying mechanisms of AOB and on the best methods to assess animal preferences. AOB seem to develop in veal calves due to a number of factors, starting with the thwarting of chewing activity, of which rumination at least is most likely a behavioural need. Other factors involved in the development of AOB include chronic stress resulting from the thwarting of chewing activity, anticipation of an upcoming meal, and positive reinforcement of feeding behaviours following a meal that was unsatisfactory. Of great importance is the understanding of individual variation in the propensity to develop AOB, because stereotypic behaviours in sub-optimal environments have been linked to improvements in welfare (relative to non-stereotyping animals). Ruminants seem to be able to select a diet that maximises their comfort. Developing feeding strategies to improve veal calf welfare, therefore, requires the assessment of calf feed preferences. Choice tests and cross point analysis of double demand functions are two possible methods for the assessment of animal preferences, and both these methods include drawbacks and benefits. In contrast to choice tests, double demand offers a setting that closer mimics the complexity of natural environments by imposing a cost on access to resources and enables quantification of the strength of preferences. However, this procedure requires appropriate statistical methods, which take into account the dependence structure between the two simultaneously available resources. Finally, practical implications of the research presented in this thesis are described in Chapter 10. The development of novel feeding strategies to improve the welfare of veal calves is challenged by individual differences in feed preferences, chewing efficiency, and behavioural response to chronic stress caused by inadequate feeding. The latter is demonstrated by only certain calves developing AOB when chewing activity is not stimulated enough by the feeding strategy, whilst others do not develop such behaviours. This complicates the evaluation of the effects of feeding strategy on veal calf behaviour. However, based on the results of this thesis and previous research it seems that young calves should first receive a diet that optimises rumen development, before receiving coarser roughages that stimulate chewing activity, rumen muscularisation, and minimise plaque and hairball prevalence in the rumen. Adequate amounts of roughage and concentrate at 6 months of age seem to be 1000 and 2000-3000 g DM, based on voluntary intake.

    Check title to add to marked list
    << previous | next >>

    Show 20 50 100 records per page

     
    Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.