Effects of betaine and rumen-protected fat onfinishing production performance and regulation of digestion and metabolismin Hu sheep

This study was conducted to investigate the effects of different levels of betaine and rumen-protected fat on production performance, blood parameters, and rumen fermentation in Hu sheep. We used a 2×3 dual-factor experiment, consisting of three levels of betaine(0,4, and 8 g·d-1) and two rumen-protected fat concentrations (0, and 2.4%). In the experiment,48 3 month-old Hu sheep lambs were randomly arranged into six groups with eight duplicates of one sheep. The experiment included three periods: an acclimation period of 10 days, a pre-trial period of 7 days, and a trial period of 50 days. Dietary 2.4% rumen-protected fat significantly reduced the production performance, final weight, and carcass weight (P<0.05), whereas it remarkably improved plasma triglycerides and cholesterol content of Hu sheep fat-tail weight (P<0.05). Dietary betaine had no effect on blood parameters, production performance, slaughter performance, and blood parameters of Hu sheep (P>0.05). Betaine and rumen-protected fat had no interaction effect on production performance or blood parameters of Hu sheep. Dietary 2.4% rumen-protected fat could significantly reduce the digestibility of NDF and ADF (P<0.05), with no obvious impact on DM, OM, or CP digestibility, rumen fermentation, or different types of fatty acids of Hu sheep (P>0.05), whereas dietary betaine had no significant effect on nutrient digestibility, rumen fermentation, or different types of fatty acids (P>0.05). There was no interaction effect on rumen fermentation or nutrient digestibility (P>0.05). The results suggest that under the conditions in this study, betaine had no regulatory effect on fattening production of Hu sheep, whereas rumen-protected fat played a role through ingestion, fat metabolism, and decomposition of fibre. Dietary 2.4% rumen-protected fat reduced fattening production of Hu sheep. In actual production, rumen-protected fat is inadvisable as a dietary additive to influence high meat production.