Influence of ad libitum feeding of urea-treated wheat straw with or without corn steep liquor on intake, in situ digestion kinetics, nitrogen metabolism, and nutrient digestion in Nili-Ravi buffalo bulls

Abstract

Influence of different levels of corn steep liquor (CSL) on chemical composition of urea-treated wheat straw (UTWS), feed intake, ruminal characteristics, digestion kinetics, nitrogen (N) metabolism, and nutrient digestibility by ruminally cannulated buffalo bulls was studied using 4 × 4 Latin square design. Wheat straw was treated with 5% urea and ensiled with 0, 3, 6, and 9% CSL on a dry matter (DM) basis and was ensiled in laboratory silos for 5, 10, and 15 days. Neutral detergent fibre (NDF) contents of UTWS ensiled with 0, 3, 6, and 9% CSL were 74.01, 76.16, 77.34, and 78.93%, respectively. Acid detergent fibre (ADF), cellulose, and lignin were similar across treatments. The increase in NDF content was due to increased neutral detergent insoluble nitrogen (NDIN), as when NDF was calculated on crude protein (CP)-free basis (NDF – NDIN × 6.25), its concentration was same for UTWS ensiled with or without CSL. Four diets were formulated to contain 20% concentrate and 80% UTWS ensiled with or without CSL. Dry matter, digestible DM, organic matter (OM), CP, ADF, and NDF intakes were higher in bulls fed UTWS ensiled with CSL. Significant increases in both DM disappearance and rate of disappearance and a reduction in lag time of UTWS ensiled with CSL was noticed. There were significant differences in ruminal ammonia concentrations between diets containing UTWS ensiled with or without CSL at 3, 6, and 12 h postprandial. Higher digestibilities for DM, OM, CP, ADF, and NDF were noted with UTWS ensiled with CSL. Nitrogen balance was positive for all animals; however, the animals fed UTWS ensiled with CSL retained higher amount of N. These results indicated that CSL was very effective in enhancing the utilisation of ammoniated straw for buffaloes by minimising the nutrient loss at ruminal and cellular levels.