| This article aimed to study the effect of Bacillus lichenformis, Candida tropicalis, and Lactobacillus plantarum on methane emission, nutrients metabolism and rumen fermentation. The research contents were divided into the following 3 tests.Experiment 1: Effect of Bacillus lichenformis on methane emission, nutrients metabolism and rumen fermentation in mutton sheepThis study was conducted to investigate the effect of dietary supplementation of different levels of Baclicus lincheniformis on methane emission, nutrient metabolism and rumen fermentation in mutton sheep, with an aim to provide reference of probiotics for reducing methane and improving energy efficiency. Twenty-four healthy Dorper（♂） × thin-tailed Han（♀） crossbred wether（F1） with an average body weight of 45.00±1.96 kg were divided into 4 groups, with 6 in each group and each wether as one replicate, and fed one of the following 4 diets: basal diets（ Control） or basal diets supplemented with 2.4×108（ Low）, 2.4×109（ Medium）, or 2.4×1010（ High） CFU Baclicus lincheniformis per day per sheep. The experiment lasted for 31 days, including a 18-day adaptation period. For the following 12 days, methane emission was measured using open-circuit respirometry system and the feces and urine were collected for measuring digestibility and metabolizability. At the last day of the period, ruminal digesta of each wether was collected through the oral cavity at 0 h（08:00）, 1 h（09:00）, 3 h（11:00）, 6 h（14:00）, 9 h（17:00） after feeding, using a tumor gastric juice collector, to investigate supplementary Baclicus lincheniformis on ruminal fermentation and the population of methanogen and protozoa using qPCR. The results showed that daily CH4 in Low group（P<0.05） and Medium group（P<0.05） were both reduced and that in High group（P>0.05） was unaffected significantly by supplementary Baclicus lincheniformis. Treatments of three levels from low to high all reduced the CH4 output scaled to digestible dry matter intake（P<0.05） by 11.52%, 13.12% and 6.87%, respectively. Three supplemental treatments improved the digestibility of dry matter（DM; P<0.05）, organic matter（OM; P<0.05）, neutral detergent fiber（NDF; P<0.05）, acid detergent fibre（ADF; P<0.05）, nitrogen（N; P<0.05）, N retention（P<0.05） and the ratio of retention/N intake（P<0.05）, whereas there was no significant among treatments. Ruminal pH（P>0.05）, total volatile fatty acia（TVFA）（P>0.05） and the ratio of acetate to propionate（A/P）（P>0.05） were unaffected by Baclicus lincheniformis. The ammonia were decreased both in Low group（P<0.05） and Medium group（P<0.05）, whereas increased in High group（P<0.05）. Supplementary Baclicus lincheniformis decreased ruminal population of methaogen and protozoa both in Low group（P<0.05） and Medium group（P<0.05）, whereas increase that in High group（P<0.05）. The total bacteria in three supplemental treatments were unaffected significantly. In conclusion, dietaty Baclicus lincheniformis could reduce the methane emission at the suitable dose of 2.4×109 CFU Baclicus lincheniformis per day per sheep, while increase the nutrient metabolism without adversely affecting rumen fermentation.Experiment 2: Effect of Candida tropicalis on methane emission, nutrients metabolism and rumen fermentation in mutton sheepThis study was conducted to investigate the effect of dietary supplementation of different levels of Candida tropicalis on methane emission, nutrient metabolism and rumen fermentation in mutton sheep, with an aim to provide reference of probiotics for reducing methane and improving energy efficiency. Twenty-four healthy Dorper（♂） × thin-tailed Han（♀） crossbred wether（F1） with an average body weight of 51.12±2.23 kg were divided into 4 groups, with 6 in each group and each wether as one replicate, and fed one of the following 4 diets: basal diets（ Control） or basal diets supplemented with 4×108（ Low）, 4×109（ Medium）, or 4×1010（ High） CFU Candida tropicalis per day per sheep. The experiment lasted for 31 days, including a 18-day adaptation period. For the following 12 days, methane emission was measured using open-circuit respirometry system and the feces and urine were collected for measuring digestibility and metabolizability. At the last day of the period, ruminal digesta of each wether was collected through the oral cavity at 0 h（08:00）, 1 h（09:00）, 3 h（11:00）, 6 h（14:00）, 9 h（17:00） after feeding, using a tumor gastric juice collector, to investigate supplementary Candida tropicalis on ruminal fermentation and the population of methanogen and protozoa using qPCR. The results showed that daily CH4 in Low group（P<0.05） was reduced and that in High group（P<0.05） was increase, and that in Medium group（P>0.05） was unaffected significantly by supplementary Candida tropicalis. Treatments of three levels from low to high all reduced the CH4 output scaled to digestible dry matter intake（P<0.05） by 17.5%, 5.34% and 9.62%, respectively. Three supplemental treatments improved the digestibility of dry matter（DM; P<0.05）, organic matter（OM; P<0.05）, neutral detergent fiber（NDF; P<0.05）, acid detergent fibre（ADF; P<0.05）, nitrogen（N; P<0.05）, N retention（P<0.05） and the ratio of retention/N intake（P<0.05）, whereas there was no significant among treatments. Total volatile fatty acia（VFA）（P<0.05） and the molar proportion of propionate（P<0.05） were increased, the molar proportion of acetate（P<0.05） and the ratio of acetate to propionate（A/P）（P<0.05） were decreased, whereas the ruminal pH（P>0.05） and ammonia（P>0.05） were unaffected significantly by Candida tropicalis. The total of ruminl bacteria were increased in three supplemental treatments（P<0.05）. The ruminal population of methaogen and protozoa in Medium group（P<0.05） and High group（P<0.05） were both increased and those in Low group（P>0.05） were unaffected significantly. In conclusion, dietaty Candida tropicalis could reduce the methane emission at the suitable dose of 4×108 CFU Candida tropicalis per day per sheep, while increase the nutrient metabolism with adversely affecting rumen fermentation. Experiment 3: Effect of Lactobacillus plantarum on methane emission, nutrients metabolism and rumen fermentation in mutton sheepThis study was conducted to investigate the effect of dietary supplementation of different levels of Lactobacillus plantarum on methane emission, nutrient metabolism and rumen fermentation in mutton sheep, with an aim to provide reference of probiotics for reducing methane and improving energy efficiency. Twenty-four healthy Dorper（♂） × thin-tailed Han（♀） crossbred wether（F1） with an average body weight of 51.75±1.48 kg were divided into 4 groups, with 6 in each group and each wether as one replicate, and fed one of the following 4 diets: basal diets（ Control） or basal diets supplemented with 5×109（ Low）, 5×1010（ Medium）, or 5×1011（ High） CFU Lactobacillus plantarum per day per sheep. The experiment lasted for 31 days, including a 18-day adaptation period. For the following 12 days, methane emission was measured using open-circuit respirometry system and the feces and urine were collected for measuring digestibility and metabolizability. At the last day of the period, ruminal digesta of each wether was collected through the oral cavity at 0 h（08:00）, 1 h（09:00）, 3 h（11:00）, 6 h（14:00）, 9 h（17:00） after feeding, using a tumor gastric juice collector, to investigate supplementary Lactobacillus plantarum on ruminal fermentation and the population of methanogen and protozoa using qPCR. The results showed that daily CH4 in Medium group（P<0.05） was reduced and that in High group（P<0.05） was increase, and that in Low group（P>0.05） was unaffected significantly by supplementary Lactobacillus plantarum. CH4 output scaled to digestible dry matter intake in Low group（P<0.05） and Medium group（P<0.05） were reduced by 5.84% and 15.28%, respectively, whereas there was no significant in High group（P>0.05）. Three supplemental treatments improved the digestibility of dry matter（DM; P<0.05）, organic matter（OM; P<0.05）, neutral detergent fiber（NDF; P<0.05）, acid detergent fibre（ADF; P<0.05）, nitrogen（N; P<0.05）, N retention（P<0.05） and the ratio of retention/N intake（P<0.05）, whereas the acid detergent fibre（ADF; P<0.05） were unaffect in those groups. Total volatile fatty acia（VFA） were increase in Low group（P<0.05） and Medium group（P<0.05）, and the molar proportion of propionate（P<0.05） were increased, and the molar proportion of acetate（P<0.05） and the ratio of acetate to propionate（A/P）（P<0.05） were decreased in three supplemental treaments. The ruminal pH（P>0.05） and were unaffected significantly by Lactobacillus plantarum. The ammonia were decreased in Low group（P<0.05） and High group（P<0.05） and was unaffect in Medium group（P>0.05）. The total of ruminl bacteria in Medium group（P<0.05） and High group（P<0.05） were both increased and those in Low group（P>0.05） were unaffected significantly. The ruminal population of methaogen and protozoa in Medium group（P<0.05） were both increased. The ruminal population of protozoa were decrease in Low group and High group, whereas the ruminal population of methaogen in those groups were unaffected significantly（P>0.05）. In conclusion, dietaty Lactobacillus plantarum could reduce the methane emission at the suitable dose of 5×1010 CFU Lactobacillus plantarum per day per sheep, while increase the nutrient metabolism with adversely affecting rumen fermentation. |
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