Comparing Body Weight, Body Biometrical Parameters, Blood Metabolites, and Progesterone Concentration of Ewe Lambs and Yearling Ewes

Regardless of reasonable reproductive performance of ewe lambs of many breeds, Ghezel ewe lambs have a very poor fertility rate, but Ghezel yearling ewes have a high fertility rate. So, comparing ewe lambs with yearling ewes can help us to understand the reason of this difference. Accordingly, this study was designed to evaluate body weight, body biometrical parameters, serum metabolites, progesterone concentration, and trait correlations of Ghezel ewe lambs and yearling ewes. During the breeding season, Ghezel ewe lambs (n=36, 7 months old) and yearling ewes (n=39, 18 months old) were weighed, their body biometrical parameters were measured, blood samples were collected, and serum metabolites and progesterone concentrations were measured. Then, all data were analyzed by the general linear model procedure of SAS software. The results of this study indicated higher relative body weight, all body biometrical parameters (except head length), and progesterone concentration in yearling ewes in comparison with ewe lambs (p 0.01). However, serum urea and glucose concentrations were lower in yearling ewes in comparison with ewe lambs (p 0.05). Also, results indicated a positive correlation of relative body weight and age with progesterone concentration of yearling ewes (p 0.01). On the other hand, results indicated a negative correlation of serum progesterone, relative body weight and age with urea concentration of yearling ewes (p 0.05). The overall results of this study indicated that Ghezel ewe lambs had lower relative body weight, body parameters, and progesterone concentration, but higher blood glucose and urea concentrations in comparison with yearling ewes.