Effects of replacing barley grain with triticale-based dried distillers’ grains with solubles on nutrient digestibility, lamb growth performance and carcass traits
The objective of this research was to determine the effects of increasing proportions of triticale-based dried distillers’ grains with solubles (TDDGS) in the diet on nutrient digestibility, growth and carcass traits of lambs. The control diet contained 72.5% barley grain, 10.0% beet pulp, 9.0% sunflower hulls, 3.0% alfalfa meal and 5.5% mixed supplement, which contained molasses, calcium carbonate, minerals and vitamins. Treatment diets contained TDDGS in place of barley grain at 20, 40 or 60% of diet dry matter (DM). In a growth study, 60 weaned lambs stratified by live weight (26.6 ± 3.6 kg) were fed one of the four diets to slaughter weight. Additionally, a digestibility study using these diets in a replicated 4 × 4 Latin square design was conducted using 12 ram lambs. Increasing dietary allocation of TDDGS in the diet did not affect (P > 0.12) DM intake, average daily gain or feed efficiency (feed:gain). At slaughter, cold carcass weight and grade rule scores responded quadratically (P = 0.04) to increasing TDDGS in the diets. Feeding TDDGS did not affect other carcass traits (P > 0.22). Total saturated fatty acids and monounsaturated fatty acids in subcutaneous fat were unaffected by TDDGS, whereas polyunsaturated fatty acids increased linearly (P = 0.03). Concentration of t10, c12-conjugated linoleic acid (CLA) in carcass fat increased linearly (P = 0.02) with increasing TDDGS, but there was no effect (P ≥ 0.20) on concentrations of c9, t11-CLA or t11-18:1. In the digestibility study, DM intake increased linearly (P < 0.01) with increasing TDDGS in the diet, whereas digestibility of DM, crude protein and fat responded quadratically (P < 0.01). Starch digestibility decreased and ADF digestibility increased linearly (P < 0.01), but there was no treatment effect on NDF digestibility (P > 0.29). Total nitrogen, total phosphorus and soluble phosphorus excretion increased (P < 0.01) with increasing TDDGS. In conclusion, TDDGS can be fed in place of barley grain at levels up to 60% in diets for lambs without adverse affects on growth performance or carcass traits, but this practice will lead to an increase in N and P excretion into the environment.Key words: Lamb, digestibility, triticale distillers grains, performance, carcass characteristics