Effects of roughage source, amount, and particle size on behavior and gastrointestinal health of veal calves

Abstract

The European Union 1997 Directive, stipulating that veal calves should be fed a minimum of 50 to 250 g of fibrous feed from 8 to 20 wk of age, is vague. A fibrous feed ration maximum of 250 g has been implicated in welfare issues, namely the occurrence of abnormal oral behaviors and poor gastrointestinal health. Past research suggests that this amount is insufficient to prevent the development of abnormal oral behaviors and enabling good rumen development. Different sources and particle sizes of roughage could lead to very different welfare outcomes. In a 3×2 × 2 factorial design, 240 group-housed calves (10±1 d; 46.1±0.1 kg) were fed different roughage sources (straw, maize silage, or maize cob silage; the latter 2 were dried and provided no extra moisture compared with straw) in 2 amounts (250 or 500 g of dry matter per day), and 2 particle sizes (chopped or ground). Roughage was supplemented to milk replacer (MR) from 2 wk after arrival. In addition, 60 calves were fed 1 of 3 additional control treatments: MR only (n=20), MR plus an iron supplement (n=20), or MR plus ad libitum hay (n=20). Oral behaviors were recorded using instantaneous scan sampling at 2-min intervals for 2 h in 3 periods per day, at 12 and 22 wk of age. Calves were slaughtered at 24 wk of age and rumen and abomasal health parameters were recorded. Limited provision of straw resulted in behavior comparable with that from unlimited provision of hay, with reduced tongue playing and oral manipulation of the environment, as well as increased chewing compared with diets with no roughage supplement. Straw prevented ruminal hairballs, but impaired rumen development and increased abomasal damage. A higher ration of roughage increased chewing (12 wk), decreased oral manipulation of the trough (12 and 22 wk) and the pen (22 wk), and increased rumen weight. However, more roughage led to increased abomasal damage for certain parameters. Longer feed particles had no obvious benefits for behavior, but decreased hairball prevalence. Overall, unlimited hay had the highest benefit for both behavior and gastrointestinal health. Adding iron to the MR did not alter behavior or gastrointestinal health compared with MR without iron supplement. This study demonstrated that different roughage sources, amounts, and particle sizes have different effects on veal calf behavior and gastrointestinal health, and hence on veal calf welfare.

The role of solid feed amount and composition and of milk replacer supply in veal calf welfare

“…This is also the diet that resulted in a high level of rumination (i.e., approximately 20%). A rumination frequency of 20% was also reported in previous work with similar behavioral observation methods (Webb et al, 2013) and in a study where calves were given ad libitum access to MR and 5 SF components (Webb et al, 2014). Providing SF with R:C 50:50 instead of 20:80 increased the frequency of rumination and subsequently decreased the frequency of abnormal oral behaviors.…”

“…Previous work on veal calves revealed an average voluntary intake of hay of 1.2 kg of DM/d at 27 wk of age (Webb et al, 2013). Moreover, Figure 2.…”

“…Veal calves develop abnormal oral behaviors such as excessive oral manipulation of the pen and abnormal rolling of the tongue, that is, tongue playing (Leruste et al, 2014), most likely due to an inadequate provision of solid feed (SF) and, in particular, insufficient structure in the SF (Mattiello et al, 2002;Webb et al, 2013;Leruste et al, 2014). It has been suggested that little structure limits natural rumination, which in turn leads to frustration and stress in the calves and ultimately to the development of abnormal oral behaviors (Mattiello et al, 2002;Webb et al, 2013;Webb, 2014).…”

“…Veal calves develop abnormal oral behaviors such as excessive oral manipulation of the pen and abnormal rolling of the tongue, that is, tongue playing (Leruste et al, 2014), most likely due to an inadequate provision of solid feed (SF) and, in particular, insufficient structure in the SF (Mattiello et al, 2002;Webb et al, 2013;Leruste et al, 2014). It has been suggested that little structure limits natural rumination, which in turn leads to frustration and stress in the calves and ultimately to the development of abnormal oral behaviors (Mattiello et al, 2002;Webb et al, 2013;Webb, 2014). Increased rumination can occur through increasing the provision of SF (Webb et al, 2012(Webb et al, , 2013, increasing the proportion of roughage or the presence of longer particles in the SF (Balch, 1971;Mertens, 1997;Kahyani et al, 2013), or providing coarser roughage sources (Mattiello et al, 2002;Webb et al, 2013).…”

“…It has been suggested that little structure limits natural rumination, which in turn leads to frustration and stress in the calves and ultimately to the development of abnormal oral behaviors (Mattiello et al, 2002;Webb et al, 2013;Webb, 2014). Increased rumination can occur through increasing the provision of SF (Webb et al, 2012(Webb et al, , 2013, increasing the proportion of roughage or the presence of longer particles in the SF (Balch, 1971;Mertens, 1997;Kahyani et al, 2013), or providing coarser roughage sources (Mattiello et al, 2002;Webb et al, 2013). However, most studies ignore potential differences in satiety, by providing…”