Promotie

Laura Webb - Food for Rumination. Developing novel feeding strategies to improve the welfare of veal calves

Veal calves are typically fed high quantities of milk replacer supplemented with solid feed, which tends to contain a relatively small portion of roughage. 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 abnormal oral behaviours and gastrointestinal health disorders. Novel feeding strategies aimed at improving the welfare of veal calves should comprise sufficient roughage to meet every individual's needs in terms of chewing activity, and this throughout their lifetime, whilst stimulating good gastrointestinal health.

Promovendus dr. LE (Laura) Webb
Promotor prof.dr.ir. IJM (Imke) de Boer
Copromotor dr.ir. EAM (Eddy) Bokkers
dr.ir. CG (Kees) van Reenen
Organisatie Wageningen University, Animal Production Systems
Datum

vr 31 oktober 2014 13:30 tot 15:00

Locatie Auditorium, building number 362
Generaal Foulkesweg 1
362
6703 BG Wageningen
0317-483592

Veal calves are typically fed high quantities of milk replacer supplemented with solid feed, which tends to contain a relatively small portion of roughage. 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 mainly include tongue playing and excessive oral manipulation of the environment, and are thought to develop in calves when chewing activity (i.e. eating and rumination) is not adequately stimulated. 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.

Increasing solid feed provision stimulated chewing activity and reduced AOB frequency, although this was less true for solid feed mixtures comprising a large proportion of concentrate (i.e. 80%). The relationship between the amount of solid feed provided and AOB, however, was not straightforward. If calves experience a decrease in chewing activity as they grow older, their welfare may be compromised. Solid feed provision should be increased throughout the fattening period to meet the growing need of calves for structure in their feed. Moreover, ad libitum provision of hay, a roughage source with both high levels of structure and fermentable fibre, seemed to meet all three objectives of encouraging rumination and rumen development without exacerbating abomasal damage. If hay is omitted in veal production due to its high iron content, then multiple roughage sources should be provided to calves that together provide sufficient structure and fermentable fibre. The simple addition of ad libitum long straw to a typical veal diet (with a high concentrate proportion) seemed to improve behaviour, and therefore, welfare, significantly.

Calves preferred milk replacer, concentrate and hay over straw and maize silage, although preferences varied across age and depended on the variable considered to assess preference (i.e. intake, time spent eating or frequency of visits). Calves were willing to work for hay and straw, despite being fed a high-energy diet of milk replacer and concentrate. In addition, they showed a preference for long over chopped hay, but not long over chopped straw. Calves voluntarily selected an average of 1000 g DM roughage and 2000 g DM concentrate on top of milk replacer (provided ad libitum), and seemed to select a diet that enabled them to meet their needs in terms of chewing activity.

Novel feeding strategies aimed at improving the welfare of veal calves should comprise sufficient roughage to meet every individual's needs in terms of chewing activity, and this throughout their lifetime, whilst stimulating good gastrointestinal health.