不同粒度猫尾草对羔羊体外发酵特性和微生物数量的影响

通过Rusitec-s体外发酵系统研究不同粒度猫尾草对羔羊体外发酵参数与微生物数量的影响，选取6种不同粒度(1.00、2.36、3.35、4.75、8.00和12.50 mm)的猫尾草作为试验饲粮的纤维来源，按照猫尾草的粒度将试验分为6个处理组，每个处理4个重复，利用Rusitec-s型人工瘤胃模拟装置进行48 h体外发酵，测定养分降解率、发酵参数及发酵液中6种微生物菌群的拷贝数。结果表明：与其他处理组相比，2.36 mm组显著提高了体外中性洗涤纤维降解率(IVNDFD)、丁酸、异丁酸、戊酸、异戊酸摩尔比和溶纤维丁酸弧菌(B. f)数量(P<0.05)，且显著降低总产甲烷菌(TMe)数量(P<0.05)。总菌(TB)与氨态氮(NH3-N)浓度、乙酸摩尔比呈正相关(R²=0.84,P=0.038;R²=0.88,P=0.021);B. f数量与丙酸摩尔比呈正相关(R²=0.82,P=0.045)，且与pH呈负相关(R²=-0.98,P=0.001);TMe数量与体外粗蛋白质降解率(IVCP...

Effects of particle size on Uraria crinita rumen in-vitro fermentation characteristics and microbial population in lambs

This study investigated the effect of difference in particle size on in vitro rumen fermentation and microbial population when Uraria crinita was used as the dietary fiber source for lambs. Six treatments were set up with differing U. crinita particle size （1.00， 2.36， 3.35， 4.75， 8.00 and 12.50 mm） as rumen fermentation substrates incubated 48 hours in vitro using Rusitec-s artificial rumen simulation. There were four replicates per treatment. The results showed that degradation rate of in vitro neutral detergent fiber degradability （IVNDFD）， the molar ratios of butyrate， isobutyrate， valerate， isovaleric， and the copy number of Butyrivibrio fibrisolvens （B.f）in the 2.36 mm particle size treatment were significantly increased （P<0.05）， while the number of total Methanogens （TMe） （P<0.05） was significantly decreased. Total bacteria number was positively correlated with ammonia nitrogen concentration and acetic acid molar ratio （R² =0.84， P=0.038； R² =0.88， P=0.021）. B.f was positively correlated with propionate molar ratio （R² =0.82， P=0.045）， and negatively correlated with pH （R² =-0.98， P=0.001）. TMe were positively correlated with in vitro crude protein degradability （IVCPD） （R² =0.91， P=0.012）， and negatively correlated with in vitro dry matter degradability and IVNDFD （R² =-0.86， P=0.027； R² =-0.83， P=0.043）. Methanobacteriaceae（Mba） was negatively correlated with pH （R² =-0.90， P=0.015）. These results describe how different particle sizes of U. crinita fermentation substrate affect the rumen microbial community structure and population numbers in lamb fermentation broth in vitro， resulting in changes in fermentation outcomes. Under the experimental conditions， the 2.36 mm particle size provided the best fermentation outcome for 3-month-old lambs.