Protein Supplementation Improves Performance of Lambs Fed Low-Quality Forage

The objective was to investigate the effect of supplementing Awassi lambs fed low-quality forage with soybean meal. Twenty-one lambs (initial body weight (BW) of 26.1 ± 2.57 kg) were randomly assigned to the study diets, 1) the basal diet (forage mix; CON; n = 7); 2) the basal diet supplemented with either 125 (SBM125; n = 7); or 3) with 250 (SBM250; n = 7) SBM g/head/day. The forage mix was composed of 65% wheat straw and 35% alfalfa hay. The experimental diet was offered to the animals for 54 days. On day 40, four animals from each group were chosen to assess N balance and nutrient digestibility. The intake of crude protein (CP) and dry matter (DM) was the highest (p < 0.016) in the SBM250 group, followed by the SBM125 group and the CON diet. Digestibility of DM and CP was higher (p <0.05) for the SBM-containing diets than the CON diet. Final BW and average daily gain were greater (p < 0.008) for lambs that consumed SBM-containing diets than for those that consumed the CON diet. In summary, the growth performance, forage utilization, and nutrient digestibility improved for lambs fed low-quality forage when supplemented with soybean meal.