PSIV-5 - Effects of Soybean Meal Addition to Increase Crude Protein in Growing Easycare Lamb Diets

Abstract: A common industry practice is to substitute soybean meal (SBM) in place of corn for growing lambs in a feedlot setting, but there is limited data evaluating its impact, especially in hybrid hair sheep. The objective of this experiment was to evaluate the effect of increasing levels of crude protein (CP) by substituting SBM place of corn in growing Easycare lambs. A total of 77 Easycare (Dorper × Katahdin × Romanov) lambs were utilized in a completely randomized design with 7 replicate pens per treatment. Lambs (33 females; 26.3 ± 0.99 kg and 44 castrated males; 27.2 ± 0.95 kg) were fed for 28 days. The three dietary treatments included 1) Control (basal diet; 7.7% SBM and 11.0% CP); 2) SBM4 (4% SBM replacing corn in the basal diet; 11.7% SBM and 12.8% CP); and 3) SBM8 (8% SBM replacing corn in the basal diet; 15.7% SBM and 14.8% CP). Average daily gain (ADG), average daily feed intake (ADFI), gain to feed (G:F), and income over feed costs were determined. At the conclusion of the study, 15 castrated males were harvested to evaluate dietary impact on carcass characteristics. Data were analyzed using the GLIMMIX procedure of SAS v9.4 (SAS Inst., Cary, NC). Castrated males fed the control diet had reduced (P < 0.05; 0.20 kg/d) ADG compared to those fed SBM4 or SBM8 (0.29 and 0.32 kg/d, respectively) or ewes consuming any diet (0.29 kg/d for all treatments). However, there was no evidence (P > 0.05) that dietary treatment impacted final body weight, ADFI, G:F, income over feed cost, or measured carcass characteristics. These results suggest that growing Easycare castrated males benefit from 4% added SBM in place of corn to increase dietary CP, and that additional research is warranted to evaluate longer-term impacts on cost and carcass impacts.