Effects of feeding garlic stem and leaf silage on rates of plasma leucine turnover, whole body protein synthesis and degradation in sheep

An experiment was conducted to assess the feeding effects of garlic stem and leaf silage on nitrogen (N) balance, ruminal fermentation patterns, rates of plasma leucine turnover (LeuTR), whole body protein synthesis (WBPS) and degradation (WBPD) in sheep using combined experiments of isotope dilution method of [1-13C]leucine and N balance test. The experimental diets fed in this trial consisted of mixed hay (Hay-diet, as control) and hay plus garlic stem and leaf silage diet (GS-diet, at ratio of 9:1) in a crossover design for each 21 days period. The isotope dilution method using [1-13C]leucine was performed on the 21th day of each dietary treatment for measuring plasma LeuTR. The use of garlic stem and leaf silage as a feed under current study did not show any metabolic and physiological disorders of animals. Nitrogen digestibility, N absorption and N retention were numerically higher in GS-diet than Hay-diet. Ruminal total volatile fatty acids concentration did not differ between the diets but molar proportion of acetate was significantly lower (P = 0.03), proportion of propionate was numerically higher and butyrate was tended to be higher (P = 0.07) in GS-diet than Hay-diet. Plasma non-esterified fatty acids (NEFA) concentration was significantly lower (P < 0.01) and glucose concentration was greater (P = 0.03) for GSdiet compared with Hay-diet. Feeding garlic silage numerically increased plasma LeuTR and WBPS in sheep. Although N retention, plasma LeuTR and WBPS did not differ significantly between the diets but numerically higher values imply that garlic stem and leaf silage may have positive impacts in N utilization without resulting in overall inhibition of ruminal fermentation and could be supplemented with basal diet in rearing sheep owing to its plenty of bioactive components.