Supplementing Metabolizable Protein to Ewes during Late Gestation: Effects on Ewe and Offspring Performance
Abstract
We hypothesized that MP intake at or above requirements during late gestation would improve dam and offspring performance. In year 1, ewes received one of three isocaloric dietary treatments during late gestation: 60MP1: 60% of MP requirements; 80MP1: 80% of MP requirements; and 100MP1: 100% of the MP requirements on a DM basis during the last 4 weeks of gestation for a ewe bearing twins. Similarly, in year 2, ewes received one of three isocaloric dietary treatments during late gestation: 60MP2: 60% of MP requirements; 100MP2: 100% of the MP requirements; and 140MP2: 140% of MP requirements. Dam performance was positively impacted by supplementing MP at or above requirements by maintaining dam BW and BCS. However, milk production was not significantly altered by maternal MP intake during late gestation. In both years, maternal MP intake did not affect offspring performance from birth to weaning. Metabolizable protein intake in isocaloric diets during late gestation had little influence male offspring feedlot performance or carcass characteristics. A reduction in maternal MP intake during late gestation reduced wether lamb N retention, but maternal MP supplementation above requirements did not enhance N retention of wether offspring. The data from the current study suggests that feeding 100% of MP requirements during late gestation may have greatest positive impacts on female reproductive performance. This analysis was strictly to determine the profitability of wether offspring alone during the feedlot phase based on their BW entering the feedlot and their performance. The wethers born to ewes fed 60% of MP requirements were the most profitable in both years, due to reduced BW entering the feedlot and increased HCW at slaughter. Overall, increasing maternal MP intake above requirements during late gestation did not improve offspring performance compared with offspring from ewes consuming reduced MP during late gestation. Therefore, feeding ewes 100% of MP requirements during late gestation may be the most beneficial to ensure positive dam and offspring performance.