Does coping style affect behavioral responses and growth performance of lambs weaned at different ages

Abstract The objective of this study was to determine the relationships between coping style (CS), and physiological, behavioral characteristics and growth performance of lambs weaned at different ages. Male Karakas lambs (n = 75, mean age = 30 d) obtained from a breeder farm were subjected to a 3-minute open field test. Of the 75 lambs classified by hierarchical clustering on principal components’ scores on open field test behaviors, 40 were assigned to one of two groups as proactive (Pro, n=20) or reactive (Rea, n=20). Pro (n=10) and Rea (n=10) lambs were selected randomly and weaned at 45 d (D45). The remaining 20 lambs (10 Pro, 10 Rea) were weaned at 75 d (D75). Lambs from Pro and Rea groups (Pro n=5, Rea n=5) were randomly assigned to each pen (n=10). Blood samples were taken from lambs just before and 20 minutes after the start of open field test and at weaning (on 0, 1, 3, 5, and 7 d after weaning) to measure serum cortisol (Cort), glucose (GluC), lactate dehydrogenase (LDH), creatine kinase (CK), total protein (TP), and triglyceride (TRG) concentrations. There was no significant effect of CS on blood parameters measured both in open field test and that measured at weaning (P> 0.05). Coping style had significant effect on live weight (LW) and average daily weight gain (ADWG) (P 0.05). There was a significant positive partial correlation between aggressive behaviors (AGG) and GluC (P