Performance and Measures of Stress in Lambs Weaned at 45 and 90 Days

A study was conducted to evaluate effects of age at weaning on various growth characteristics and stress measures of Zandi lambs. The lambs were weaned at 45 and 90 days of age. The body weights and average daily gain (ADG) were monitored during the experimental period and 5 months of age. Cortisol, glucose, blood urea nitrogen (BUN) and lamb behavior (agitation, vocalization) were recorded before and after weaning. After separation, lambs weaned at 45 d of age had greater agitation scores and bleats. Furthermore, serum cortisol, glucose and BUN concentration were higher for lambs at a weaning age of 45 d. The ADG and weaning and 5-months weights were similar. The results of the present study indicated that there is no significant difference in the growth traits of Zandi lambs, weaned at 45 or 90 days of age, and suggested that lamb could be weaned at 45 days of age.