Influence of housing system on behavioural and immune responses of buffalo heifers

From November 2005 to October 2006 thirty-two buffalo heifers were used to evaluate the effect of rearing system on behavioural and immune responses. Sixteen heifers (group IR) were group-housed in indoor slatted floor pen (3.0 m2/animal) with an outdoor paddock (3.0 m2/animal). Sixteen others (group ER) grazed a fenced Mediterranean maquis of ~ 40 ha (~ 600 m a.s.l.). The animals at beginning of experiment were aged 8-9 months and weighted 190 kg. Phytohaemagglutinin (PHA, 1 mg/animal) was used to perform a skin test based on non-specific delayed type hypersensitivity, whereas 5 mg of keyhole limpet hemocyanin (KLH) were injected subcutaneously to evaluate humoral immune response. At the end of the experimental period the animals were subjected to a novel object test. Each animal was exposed to a novel environment (a 6 x 6 m paddock), where in the middle a traffic cone was present. Avoidance distance at manger was evaluated by an assessor who walked slowly (1 step per second) toward each animal with one hand slightly forward until signs of withdrawal. Daily weight gain was higher in IR (0.56±0.02 kg/d) than ER (0.50±0.02 kg/d) animals, although puberty was reached at similar age (667 vs 675±11 d, for IR and ER respectively).During the novel object test, IR animals touched more and devoted more time to the traffic cone than ER animals. Avoidance distance at manger was lower in ER animals than IR. Skin thickness after PHA injection was higher in ER heifers than in IR, whereas the two groups showed a similar humoral immune response. The results indicated that an extensive rearing system based on pasture seems to be a valid method to promote welfare and sustainability of buffalo heifer.