Effect of long-term rumen-protected methionine supplementation on performance of Shami goats and growth performance of their kids

Abstract

An experiment was conducted to study the effect of supplementing the diets of Shami goats with rumen-protected methionine (RPM) in late pregnancy (last 60 days) and early lactation on milk production, composition, fatty acid profile in the first 60 days of lactation, and on growth performance of their kids. Three groups were used (25 goats/group) in a completely randomised design. Groups were a control with no supplements (0RPM) or supplemented with either 2.5 (2.5RPM), or 5.0 g/head.day RPM (5RPM). Birth and weaning weights for kids were recorded and analysed. Milk production was measured and sampled biweekly from each dam and analysed for milk composition. Results showed that RPM had no effect on birth and weaning weights, or average daily gain of Shami kids. However, milk to gain ratio of kids was significantly (P < 0.05) improved. Milk production increased significantly (P < 0.05) in 5RPM group compared with 0RPM and 2.5RPM groups. Milk protein content was the highest (P < 0.05) in the 2.5RPM group, followed by the 5RPM and 0RPM groups, whereas milk fat content was not different among the groups. Meanwhile, yields of both components were significantly (P < 0.05) higher in milk of treated groups. Casein and energy-corrected milk were increased (P < 0.05) with treatment. No effect on dry-matter intake was recorded, while feed to milk ratio was better (P < 0.05) for RPM groups than for 0RPM group. Milk fatty acids composition did not show significant changes after RPM treatment. In conclusion, results showed that supplementing RPM to Shami goats in late pregnancy did not affect birthweight or growth of suckling kids but improved milk production and milk protein, although no clear dose response to RPM was detected.