Influence of Dry Feed Supplements on Different Parameters of Welfare in Veal Calves
Abstract:The aim of the study was to compare different behavioural, physiological and performance traits in three groups of veal calves fed either a routine all-liquid diet with milk replacer (G0) or the same diet supplemented with a total of 10kg (G10) or 25kg (G25) of pelleted straw and cereals. Each of the three feeding programmes involved 21 male Friesian calves kept in individual crates for 20 weeks (from 1 to 21 weeks of age). Oral activities, haematological variables, ruminal characteristics, health and performance were all investigated. In calves supplied with dry feed, there was no evidence of ruminating behaviour; and chewing, regarded as a non-nutritive oral activity, was clearly reduced. The incidence of tongue playing and manipulating objects was not influenced by additional pellets.
Haemoglobin concentrations were higher in G25 than in other groups as a result of the extra iron supplied in the pellets. Other blood variables were unchanged. In G10 and G25 changes in rumen characteristics were clearly demonstrated by the following observations: i) the weight of reticulo-rumens increased by 11 and 35 per cent, respectively; ii) small papillae (virtually non-existent in calves fed an all-liquid diet) were present, and there was a darkening of the mucosa; and iii) there was a marked reduction in the number of hairballs, resulting from a continuous elimination of ingested hair by ruminal motility. In G25, carcase weight was significantly (P < 0.05) increased by 6.5 per cent compared with controls and no detrimental effects such as bloating or abomasal ulceration were observed when dry feed was added. Supplying calves with straw-cereal pellets was considered positive for the physiological aspects of welfare in veal calves. However, other diet compositions capable of inducing rumination behaviour should also be investigated.