The effect of four fibrous feed supplementations on different welfare traits in veal calves

The aim of the present study was to evaluate the optimum starch-fibre content of manufactured dry feed for veal calves. In three identical barns (B1, B2, B3), 126 calves were assigned to seven groups fed the same milk replacer. In each barn there was a control group (C1, C2, and C3), fed only the all-liquid diet, and one (or two in B3) group(s) receiving additional pellets (P1, P2, P3, and P4). Pellets differed by their composition; their starch and NDF characteristics were as follows: 48.0–26.2% (P1); 32.6–43.4% (P2); 25.0–52.2% (P3); and 1.8–78.2% (P4), respectively (in % of dry matter). Health, characteristics of the rumen, performance, and ruminating behaviour were compared between treatments. In calves having access to solid feed, the weight of reticulo-rumen increased by 23–46% compared to controls (p<0.05). The ruminal mucosa became covered with small size papillae (non-existent in controls) and stomach hairballs were consistently reduced. In P1, P2 and P3, rumen fermentation was assumed because of the darkening of the mucosa and the carcass weight increased by 6.5, 7.5 and 5.6%, respectively, when compared to their respective controls (p<0.05). Abomasal ulcerations occurred in two barns but they were unrelated to solid feed. Rumination was more frequently observed in P3 and in P4, but in this latter group some digestive troubles occurred and the growth was slightly lower than in control (C3). It is suggested that, within the range of investigated diets, the best dietary compromise could be starch 25% and NDF fibre 50% of feed dry matter.