玉米不同加工方式的开食料对羔羊早期断奶前和断奶后瘤胃发酵和微生物区系的影响

Effects of Starters with Different Processing Methods of Corn on Rumen Fermentation and Microflora of Pre-Weaning and Post-Weaning Lambs

本试验旨在评价玉米不同加工方式的开食料对羔羊早期断奶前和断奶后瘤胃发酵和微生物区系的影响。选择初生重相近的24只8日龄湖羊公羔[平均体重(5.04±0.75) kg],随机分为2组,每组12只,分别接受颗粒化开食料(PS组,玉米及其他原料全部粉碎后制粒)和蒸汽压片玉米开食料(SFS组,玉米进行蒸汽压片处理后破碎,其他原料粉碎后制粒,然后将破碎的蒸汽压片玉米与其他原料制成的颗粒料混合后饲喂)。羔羊1~7日龄随母羊哺乳,8日龄与母羊分开,单栏饲养,同时开始饲喂代乳粉和开食料,35日龄断代乳粉。分别于21(断奶前)和42日龄(断奶后),每组随机选择6只羔羊屠宰,采集瘤胃内容物,测定瘤胃发酵参数和微生物区系。结果显示:与PS组相比,SFS组羔羊断奶前和断奶后瘤胃液总挥发性脂肪酸、丙酸和丁酸含量均显著提高(P<0.05),断奶前分别提高了23.06%、35.58%、56.44%,断奶后分别提高了7.82%、28.87%、32.47%。SFS组拟杆菌门(Bacteroidetes)的相对丰度(61.96%)在断奶前就已超过厚壁菌门(Firmicutes,32.08%)和变形菌门(Proteobacteria,3.99%)成为第一优势菌门,且接近断奶后水平(65.36%);而PS组拟杆菌门的相对丰度(57.28%)在断奶后才超过厚壁菌门(31.21%)和变形菌门(1.15%),且仍低于断奶前和断奶后SFS组拟杆菌门的相对丰度(61.96%和65.36%)。与PS组相比,SFS组断奶前和断奶后夏普氏菌属(Sharpea)和原细菌属(Oribacterium)的相对丰度显著增加(P<0.05)。在瘤胃功能上,仅在KEGG水平3中断奶前与酶相关的氨基酸代谢的功能基因表达量SFS组显著高于PS组(P<0.05),而转运因子、脂肪酸降解代谢的功能基因表达量显著低于PS组(P<0.05)。以上结果说明,与颗粒化开食料相比,蒸汽压片玉米开食料更加有利于羔羊早期断奶前后阶段的瘤胃发酵、优势菌群的建立以及断奶前的氨基酸和脂肪酸代谢功能。

This study aimed to evaluate the effects of starters with different processing methods of corn on rumen fermentation and microflora of pre-weaning and post-weaning lambs. Twenty-four 8-day-old male Hu lambs[average body weight:(5. 04 0. 75)kg]with similar birth weight were randomly divided into two groups with 12 lambs in each group. Lambs were assigned to one of two dietary treatments:1)pelleted starter(PS group,corn and other feed ingredients were pelleted after grinding);2)steam-flaked corn starter(SFS group,the corn was crushed after steam-flaked processing,other feed ingredients were pelleted after grinding,and then the crushed steam-flaked corn was mixed with the pelleted feeds). Lambs before 7 days of age were breast feeding and separated from their dams at 8 days of age and moved into individual cages. From 8 to 35days of age,the lambs were fed milk replacer(MR)and their respective ad lib starter. Feeding of MR was stopped at 35 days of age. Six lambs for each group were euthanized at 21(pre-weaning)and 42 days of age(post-weaning)for sampling,respectively. The rumen contents were collected to measure rumen fermentation parameters and microflora. The results showed that the contents of total volatile fatty acids,propionate and butyrate of pre-weaning and post-weaning lambs in SFS were significantly higher than those in PS group(P <0.05),and they were improved 23.06%,35.58%,56.44%(pre-weaning)and 7.82%,28.87%,32.47%(post-weaning),respectively. The relative abundances of Bacteroidetes(61.96%)of lambs in SFS group had exceeded Firmicutes(32.08%)and Proteobacteria(3.99%),and became the first predominant phylum during pre-weaning,and closed to the relative abundance of Bacteroidetes(65.36%)for post-weaning lambs. While in PS group,the relative abundances of Bacteroidetes(57.28%)exceeded Firmicutes(31. 21%)and Proteobacteria(1. 15%)post-weaning,and still lower than them of Bacteroidetes in SFS lambs pre-weaning(61.96%)and post-weaning(65.36%). Compared with PS group,the relative abundances of Sharpea and Oribacterium of pre-weaning and post-weaning lambs in SFS group were significantly increased(P<0.05). In rumen function,only at KEGG level 3,the functional gene expression of enzyme related amino acid metabolism in SFS group was significantly higher than that in PS group pre-weaning(P<0.05),while the expression of functional genes of transport factors and fatty acid degradation and metabolism in SFS group was significantly lower than that in PS group(P<0.05). The results indicate that steam-flaked corn starter is benefit to the rumen fermentation,establishment of dominant microflora of lambs pre-weaning and post-weaning and the rumen amino acid and fatty acid metabolism functions pre-weaning compared with polleted starter.