Effect of Barley Supplementation on Both Pubertal Age and Metabolic Profile of D’man Lambs Living in a Hostile Environment
Nadia Taïbi, Nouria Boukenaoui, Aida Kahal, Zaina Amirat, Farida Khammar

Energy and protein adjustment of experimental ration allowed monitoring and recording the reproductive performance (androgen levels and testicular volume) and metabolic profile of D'man breed which is subjected to environmental stress and nutritional control. Lambs were separated in tow homogeneous groups and randomly assigned to two diets. In this experiment, each lamb received respectively 250 and 500 g of barley per day in addition to a basic nutrition. Age at puberty is determined by androgens assay and nutritional status is assessed by plasma concentrations of circulating metabolites (glucose, cholesterol, total protein and calcium). Our results indicate that barley supplementation had a good benefit on average daily gain (ADG) on Group B (77.53 versus 51.36 g per day). Puberty is more affected by diet (P < 0.021) and lesser extent by age (P < 0.045) suggesting that this physiological state would be well correlated with genetic factors that will be relegated to secondary position in opposition to alimentary factor: 66 versus 25 % of lambs of group B are pubescent; they reached 51% versus 68 % of their adult weight, with a rate of plasma androgens corresponding to 2.34 ± 1.20 versus 1.8 ± 0.14 ng/ml. The testicular volume is multiplied by a factor of 11 versus 9. In fact, lambs of Group B reached puberty 90 days rather than those of group A at 5 versus 8 months. The biochemical profiles means are globally identical between the two groups but always in favor of those who received the supplementation. One month after weaning, all biochemical parameters, except proteins of group B, were falling in both groups probably because of the transition to another nutritional state (milk versus concentrate).While, the protein content of group B is high, it remains nevertheless no statistically significant (P> 0.05). This increase is probably associated to bypass protein and also to the contribution of the microbial nitrogen at the duodenal flow. The gap between the two groups for reproductive and metabolic characters implies the effectiveness of the diet in terms of energy and protein digestibility. Thus, adjustment of nutrient intakes between the groups A and B supports the hypothesis that food is a major factor unwavering in reproductive events, especially when supplementation coincides with the breeding season.

Full Text: PDF     DOI: 10.15640/jaes.v4n1a8