Effects of Increasing the Energy Density of a Lactating Ewe Diet by Replacing Grass Hay with Soybean Hulls and Dried Distillers Grains with Solubles

The objective of this experiment was to determine the effects of increasing the energy density of a lactating ewe diet by replacing grass hay (GH) with soybean hulls (SH) and replacing soybean meal (SBM) with dried distillers grains with solubles (DDGS) on ewe body condition, milk production and nutrient composition, and lamb performance. Sixteen 2-year-old ewes were selected based on a common lambing date. All diets contained 60% roughage and 40% concentrate. Dietary roughage source, however varied from completely GH to completely SH, and SBM was replaced by DDGS. Diets were formulated to contain 13.9% CP and an increasing amount of dietary energy as SH and DDGS replaced GH and SBM. The control diet for this experiment was composed of 60% GH and 11.6% SBM (GH-SBM). Treatment diets were 60% GH and 25.4% DDGS (GH-DDGS); 20% GH, 40% SH, 15.3% DDGS (SH40-DDGS); and no GH, 60% SH, 10% DDGS (SH60-DDGS). The SH, protein concentrate, and mineral portion of the diet was pelleted and mixed with the chopped GH, when GH was included in the diet. The SH60-DDGS diet was a completely pelleted diet. Ewes were offered feed twice daily, and a weigh-suckle-weigh technique was performed weekly throughout the 8-week lactation to quantify production and characterize nutrient composition milk in the ewe. Ewe BW and BCS was recorded at the beginning and end of the trial and lamb growth performance was monitored weekly. Replacing GH and SBM with SH and DDGS increased milk production without decreasing ewe BW and BCS during lactation. Although, total milk solids, protein, and fat were decreased when SH and DDGS replaced GH and SBM, lamb growth performance was improved. Increased milk production that resulted with the inclusion of SH and DDGS in the diet was sufficient to overcome the lesser nutrient composition of the milk to result in differences in lamb growth. These data are consistent with the hypothesis that replacing GH and SBM with SH and DDGS increases dietary energy density and results in increased milk production and lamb growth without compromising ewe BW and BCS