Protein Supplementation Improves Performance of Lambs Fed Low-Quality Forage

SIMPLE SUMMARY: In Jordan and in the Middle East, both quantity and quality of forage have declined in recent decades. Livestock producers have thus tended to use plant protein supplements such as soybean meal to correct for protein deficiencies. In this study, soybean meal supplementation improved the performance of lambs fed low-quality forage. ABSTRACT: 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.