Effect of dietary supplementation with rumen-protected amino acids, lysine and methionine, on the performance of Comisana ewes and on the growth of their lambs

The purpose of the study was to evaluate the effect of supplementing the diets ofComisana ewes with rumen protected methionine and lysine (RP-ML) for a durationof 60 days on quantitative–qualitative production of milk, antioxidant parametersof milk and blood, biochemical parameters of blood, and lambs’ growth perfor-mance. Two groups of 15 ewes with equal average body weight were consideredfor the trial. The control group was administered a standard diet (Control, C) andthe experimental group the standard diet supplemented with 1.5% lysine and 1.0%methionine (Treated, T). Results showed that RP-ML supplementation positivelyinfluenced milk yield, fat and protein content, and casein ( p < 0.01). Furthermore,lambs of the T group, compared with those of the C group, showed a 15% highergrowth rate during the suckling period of 42 days. Finally, the total antioxidantcapacity of milk, measured by ferric reducing antioxidant power and 2,20-azino-bis(3-ethylbenzotiazolin-6-sulfonic acid assay, was significantly lower in T groups( p < 0.05). In conclusion, the results showed that the integration of RP-ML in ewescould be a valid strategy in order to improve their performances but further investi-gations are necessary to define the right concentration to be administered to theanimals.