PSI-13 In vitro digestibility and gas production of diets containing different levels of soybean molasses for feedlot sheep.

Abstract

The objective of this study was to evaluate the effects of different levels of soybean molasses (SM) on in vitro digestibility and greenhouse gas production in feedlot sheep. Nine crossbred ruminally-cannulated male sheep (71.1 ± 12.8 kg BW) were distributed in a triple 3 × 3 Latin square design. Treatments consisted of diets containing 0, 10 or 20% SM (DM basis). After 14-d adaptation period, in vitro gas production (mL/g and mL/g disappeared [mL/gd]) were evaluated after 24-h incubation at 39°C. Total gas production was estimated using a digital pressure meter equipped with a pressure transducer, while CH4 and CO2 concentrations were obtained using gas chromatography. In vitro digestibility of DM (IVDMD), NDF (IVNDFD), and CP (IVCPD) were performed using the Ankom DaisyII incubator. Data were analysed using the MIXED procedure of SAS. Contrasts were used to determine the linear and quadratic effects of SM, and Control × SM treatments. The inclusion of SM promoted a quadratic effect in CO2 production (mL/g and mL/gd, P < 0.05), with greater values for treatments with 10% SM. The SM addition linearly decreased total gas and CH4production (mL/gd, P < 0.05). The inclusion of the by-product linearly increased the IVDMD and decreased the IVNDFD of the diets (P < 0.0001), while quadratically effected the IVCPD with the lowest value observed for treatments with 10% SM (P < 0.0001). When all treatments with SM were evaluated against the Control, a significant effect was observed for total gas, IVDMD, IVNDFD and IVCPD, with averages of 368.9 × 444.0 ml/gd, 82.1 × 76.9%, 35.2 × 50.6% and 83.2 × 84.8%, respectively. The results indicate that increasing levels of SM at up to 20% (DM basis) in the diets for feedlot sheep can reduce the greenhouse gas emissions and promote a better use of the diets.