Thirty-six Holstein Friesian heifers (dairy herd replacements) were assigned to one of three regrouping treatments during the post-calving period. In Treatment 1, heifers were introduced individually to an established group of cows and heifers within 24 h of calving ('Single - day 1'). In Treatment 2, heifers were housed individually in a straw pen for 1 week after calving before being added individually to the group ('Single - day 7'). In Treatment 3, two heifers were housed together in a straw pen for 1 week after calving before being added as a pair to the group ('Pair - day 7'). The size of the resident group remained constant at 16 animals (10 mature cows and 6 first-lactation heifers). The behaviour of the heifers was assessed during their first 8 h and first month in the resident group, and milk yield parameters, body condition loss and live weight loss were assessed during the first month post-calving. Reproductive performance was assessed during the post-calving period, and hoof health parameters were measured 1 month prior to calving, and at 1 and 3 months post-calving. Heifers in the 'Pair - day 7' treatment appeared to associate closely during their first month in the group by spending more time than expected in the same pen area and in adjacent cubicles (P<0.001). During the first 8 h in the group, heifers in the 'Pair - day 7' treatment tended to lie down more (when more than half of the resident group was lying) than heifers in other treatments (P<0.06). However, during the first month in the group heifers in the 'Pair - day 7' treatment appeared more active than heifers in other treatments (P<0.05), and it is suggested that this reflected reduced fearfulness. Heifers in the 'Pair - day 7' treatment also tended to show greater milk protein yields and milk fat+protein yields during the first month post-calving than heifers in other treatments (P<0.1). Heifers in the 'Pair - day 7' treatment showed greater hoof lesion scores at 3 months post-calving than heifers in other treatments (P<0.01), and it is suggested that this reflects greater levels of behavioural activity during the first month post-calving. There were no significant differences in behavioural and performance parameters between heifers in the 'Single - day 1' and 'Single - day 7' treatments. Reproductive performance, and post-calving live weight and body condition losses were not affected by any of the treatments in this study.
|Publication Title||Applied Animal Behaviour Science|
|Author Address||Agri-Food and Biosciences Institute, Hillsborough, Co. Down BT26 6DR, UK. Niamh.OConnell@afbini.gov.uk|
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