Oat hay as winter feed improves digestibility, nitrogen balance and energy utilization of Tibetan sheep (Ovis aries) in the Qinghai Tibetan Plateau

Abstract

The objective of this study was to detect the digestion and metabolism of Tibetan sheep (Ovis aries) fed on either natural pasture or cultivated oat, which can provide a theoretical basis for the seasonal supplementary feeding of livestock in alpine meadows. Twelve (18-month-old), Tibetan sheep with an average body weight of 40 ± 0.23 kg were used in a metabolism study. During the formal experimental period, a 100 g from each forages were collected and analysed to determine the Dry Matter (DM), Crude Protein (CP), Ether Extract (EE), Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), Water Soluble Carbohydrates (WSC) and Gross Energy (GE) contents. Oat OM, CP, EE, and WSC contents were higher (P < 0.001) than those of native herbage, while native forage contained higher (P < 0.001) DM, NDF, and ADF content. Throughout the experimental period, the daily Dry Matter Intake (DMI) and Organic Matter Intake (OMI) of sheep were not significantly different (P > 0.05). The oat fed group showed higher (P < 0.001) CP daily intake compared to native herbage fed group. The apparent digestibility of DM, OM, CP, and EE were higher (P < 0.001) in oat fed animals compared to sheep fed native herbage. Our data indicated that nitrogen retention (nitrogen balance) for Tibetan sheep was positive with nitrogen more than 8.1 g/d (R² = 0.860, P = 0.001) and the digestible nitrogen exceeding 3.6 g/d (R² = 0.874, P = 0.001). Energy utilization results indicated that oat herbage Digestible Energy (DE), DE/ Gross Energy (GE), Metabolizable Energy (ME), ME/DE and ME/GE were higher (P < 0.001) than that of native grass. It was concluded that the nutritional quality of oat forage was higher than of native herbage. Hence, it can be fed to animals as hay to expand the source of fodder in winter.