The effect of rearing system on behavioural and immune responses of buffalo heifers

From November 2005 to October 2006 thirty-two buffalo heifers from the same commercial farm were used to evaluate the effect of rearing system on a range of behavioural and immune variables. Sixteen heifers were group-housed in indoor slatted floor pen (3.0 m2/animal) with an outdoor paddock (3.0 m2/animal) at ~5m above sea level (group IR). Sixteen others were kept at ~600m above sea level. They grazed a fenced Mediterranean maquis of ~40ha (group ER). 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 6x6-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. Phytohaemagglutinin (PHA, 1mg/animal) was used to perform a skin test based on specific delayed type hypersensitivity. During the novel object test, IR animals touched more and devoted more time to the traffic cone than ER animals (P =0.003 and P=0.008, respectively). Avoidance distance at manger was lower in ER animals than IR (P=0.004). Skin thickness after PHA injection was higher in ER heifers than in IR (P=0.003). 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.