BackgroundGarlic and its constituents are reported to have been effective in reducing methane emission and also influence glucose metabolism in body; however, studies in ruminants using garlic leaves are scarce. Garlic leaves contain similar compounds as garlic bulbs, but are discarded in field after garlic bulb harvest. We speculate that feeding garlic leaves might show similar effect as garlic constituents in sheep and could be potential animal feed supplement. Thus, we examined the effect of freeze dried garlic leaves (FDGL) on rumen fermentation, methane emission, plasma glucose kinetics and nitrogen utilization in sheep.MethodsSix sheep were fed Control diet (mixed hay and concentrate (60:40)) or FDGL diet (Control diet supplemented with FDGL at 2.5 g/kg BW0.75 of sheep) using a crossover design. Methane gas emission was measured using open-circuit respiratory chamber. Plasma glucose turnover rate was measured using isotope dilution technique of [U-13C]glucose. Rumen fluid, feces and urine were collected to measure rumen fermentation characteristics and nitrogen utilization.ResultNo significant difference in rumen fermentation parameters was noticed except for rumen ammonia tended to be higher (0.05 < P < 0.1) in FDGL diet. Methane emission per kg dry matter ingested and methane emission per kg dry matter digested were lower (P < 0.05) in FDGL diet. Plasma glucose concentration was similar between diets and plasma glucose turnover rate tended to be higher in FDGL diet (0.05 < P < 0.1). Nitrogen retention was higher (P < 0.05) and microbial nitrogen supply tended to be higher (0.05 < P < 0.1) in FDGL diet.ConclusionFDGL diet did not impair rumen fermentation, improved nitrogen retention; while absence of significant results in reduction of methane emission, glucose turnover rate and microbial nitrogen supply, further studies at higher dose would be necessary to conclude the merit of FDGL as supplement in ruminant feedstuff.

BackgroundThe use of antibiotics in animal diets is facing negative feedback due to the hidden danger of drug residues to human health. Traditional Chinese herbal medicine has been used to replace antibiotics in the past two decades and played an increasingly important role in livestock production. The present study was carried out to assess the feeding effects of a traditional nourishing Chinese herbal medicine mixture on kinetics of plasma glucose, protein and energy metabolism in sheep. Ruminal fermentation characteristics were also determined.MethodsFour sheep were fed on either mixed hay (MH-diet) or MH-diet supplemented with 2% of Chinese herbal medicine (mixture of Astragalus root, Angelica root and Atractylodes rhizome; CHM-diet) over two 35-day periods using a crossover design. The turnover rate of plasma glucose was measured with an isotope dilution method using [U-13C]glucose. The rates of plasma leucine turnover and leucine oxidation, whole body protein synthesis (WBPS) and metabolic heat production were measured using the [1-13C]leucine dilution and open circuit calorimetry.ResultsBody weight gain of sheep was higher (P = 0.03) for CHM-diet than for MH-diet. Rumen pH was lower (P = 0.02), concentration of rumen total volatile fatty acid tended to be higher (P = 0.05) and acetate was higher (P = 0.04) for CHM-diet than for MH-diet. Turnover rates of plasma glucose and leucine did not differ between diets. Oxidation rate of leucine tended to be higher (P = 0.06) for CHM-diet than for MH-diet, but the WBPS did not differ between diets. Metabolic heat production tended to be greater (P = 0.05) for CHM-diet than for MH-diet.ConclusionsThe sheep fed on CHM-diet had a higher body weight gain and showed positive impacts on rumen fermentation and energy metabolism without resulting in any adverse response. Therefore, these results suggested that the Chinese herbal medicine mixture should be considered as a potential feed additive for sheep.

The present study was conducted to investigate the effect of feeding whole-crop corn silage (WCS) compared with mixed hay (MH) or grass silage (GS) on physiological and digestive responses of sheep at thermoneutral temperature (20°C) or exposed to heat (30°C). Six sheep were fed ad libitum with one of three diets in a replicated 3 × 3 Latin square design for 24 days. After 14 days’ adaptation, they were exposed to thermoneutral (20°C) and then heat exposure (30°C) for 5 days each. Rumen sample was collected on Day 4, whereas physiological response and nitrogen (N) balance were carried-out for three successive days in each exposure period. Respiration rate and rectal temperature of WCS-fed sheep were lower (P < 0.05) than of MH and GS fed sheep and both were higher (P < 0.01) during heat exposure. The intakes of dry matter (DM) and N and the digestibilities of N and neutral detergent fibre were lower (P < 0.05) for the WCS diet than for MH and GS diets and they did not differ between two temperature exposures. However, WCS-fed sheep had higher (P < 0.05) digestibilities of DM and organic matter, as well as metabolisable energy intake (M/D) than the sheep fed MH or GS diet, and there was no temperature effect on them. As DM and N intakes were lower for the WCS diet, the variables of rumen fermentation were also lower (P < 0.05) than the other two diets except propionate and butyrate concentrations, and they did not differ between temperature exposures except NH3 concentration. In conclusion, physiological responses were improved in the WCS diet and this approach thus shows promise for feeding heat-exposed animals. However, as results were inconsistent in terms of nutrient intake and digestibility, further work is needed and we suggest investigating the effect of feeding WCS with supplemented N.