Abstract

It was hypothesized that the inclusion of wheat dry distillers' grains with solubles (WDDGS) up to 470 g/kg dry matter (DM), fed to lambs in iso-nitrogenous diets, would neither affect growth performance, nor subcutaneous adipose tissue fatty acid composition. Thus, this study aimed to assess the effects of increasing concentrations of WDDGS in iso-nitrogenous diets on in vitro fermentation, in sacco degradation, growth performance and fatty acid profiles of adipose tissue in lambs. Increasing concentrations of WDDGS (100, 300 and 470 g/kg dry matter (DM)) were achieved by replacing soybean meal, alfalfa hay and soybean hulls. In vitro fermentation of the diets was conducted to measure fermentation variables and CH4 production. In situ digestion kinetics of DM, crude protein (CP), and neutral detergent fiber (NDF) of the treatment diets were evaluated using three ruminally cannulated cows. Additionally, 60 lambs were used to determine the effect of WDDGS on growth performance and fatty acid profiles of subcutaneous tail fat. In the in sacco study, WDDGS increased (P = 0.03) DM, CP and NDF effective degradability and reduced (P < 0.01) rumen undegradable protein. In the in vitro incubations, CH4 production (mg/g DMD) increased (P = 0.05) in the 470 g/kg WDDGS group. In the growth trial, increasing WDDGS in the diet linearly reduced DMI (P = 0.02), ADG (P < 0.01) and hot carcass weight (P < 0.01). Linear increases in trans-10 octadecenoic acid (P = 0.02) and linear decrease in oleic acid (P < 0.01) resulted in a linear reduction of total monounsaturated fatty acids (MUFA; P = 0.02) yet, linoleic acid was linearly increased (P < 0.01). In summary, increasing concentrations of WDDGS in iso-nitrogenous diets fed to lambs decreased animal performance and negatively affected the fatty acid profile of adipose tissue. (c) 2013 Elsevier B.V. All rights reserved.