不同精粗比日粮中添加小肽对牦牛瘤胃体外发酵特性的影响  

An in vitro study of dietary concentrate∶forage ratio and small peptide supplementation effects on ruminal fermentation parameters of yaks

作　　者：涂瑞[1] 苗建军 彭忠利[1] 高彦华[1] 柏雪[1] 谢昕廷 TU Rui;MIAO Jian-jun;PENG Zhong-li;GAO Yan-hua;BAI Xue;XIE Xin-ting(Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization,Ministry of Education,College of Life Science and Technology,Southwest Minzu University,Chengdu 610041,China)

机构地区：[1]西南民族大学生命科学与技术学院,青藏高原动物遗传资源保护与利用教育部重点实验室,四川成都610041

出　　处：《草业学报》2020年第3期78-88,共11页Acta Prataculturae Sinica

基　　金：四川省重点研发项目(2017NZ0042);四川省肉牛创新团队藏区肉牛(牦牛)产业技术研发与集成应用专项资助。

摘　　要：为研究不同精粗比日粮中添加小肽对牦牛瘤胃体外发酵产气量、养分降解率以及发酵参数的影响,采用3×5交叉设计,以底物的精粗比(40∶60、50∶50、60∶40)和小肽的添加水平(0、0.75%、1.50%、2.25%、3.00%)作为两试验因素,试验共15个处理,每个处理3个重复,在发酵48 h后采集发酵样品进行测定。结果表明:1)日粮精粗比对中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的降解率无显著影响(P>0.05);随小肽添加水平的升高,NDF和ADF的降解率呈先升高后降低的二次曲线变化(P<0.01),以1.50%和2.25%水平效果较佳。日粮精粗比和小肽添加水平对产气量(GP)和干物质(DM)、粗蛋白(CP)的降解率存在极显著的互作效应(P<0.01)。2)随日粮精粗比的升高,pH逐渐降低(P<0.01),微生物蛋白(MCP)合成量逐渐升高(P>0.05),且50∶50和60∶40无显著差异。随小肽添加水平的升高,pH和MCP均呈二次曲线变化(P<0.01),以2.25%水平最高。日粮精粗比和小肽添加水平对氨态氮(NH3-N)浓度存在显著的互作效应(P<0.05)。3)日粮精粗比和小肽添加水平对挥发性脂肪酸(VFA)存在极显著的互作效应(P<0.01)。在3种精粗比条件下,随小肽添加水平的升高,乙酸与丙酸比(乙/丙)和乙酸、异丁酸、异戊酸比例呈二次曲线变化(P<0.05),以1.50%水平时乙/丙最小,乙酸比例最低,2.25%水平时异位酸比例最高。综上所述,日粮精粗比和小肽添加水平对体外产气量、养分降解率和发酵参数有着显著影响。本试验条件下,精粗比为50∶50和60∶40时效果较好,小肽的添加水平以1.50%和2.25%为宜。This study investigated the effects of different combinations of dietary concentrate∶forage ratio and small peptide supplementation on in vitro gas production,nutrient digestibility and ruminal fermentation parameters of yaks.The experiment comprised a factorial combination of three different concentrate∶forage ratios(40∶60,50∶50,60∶40;CFRs)and five different small peptide supplementation levels(0,0.75%,1.50%,2.25%,3.00%),making a total of 15 treatments,with 3 replicates per treatment.Fermentation samples were collected after 48 hours of fermentation.It was found that:1)CFR had no significant effect on the degradation rate of neutral detergent fibre and acid detergent fibre(P>0.05).Across the range of small peptide supplementation levels,the degradation rate of neutral detergent fibre and acid detergent fibre displayed a quadratic pattern(P<0.01).The optimal small peptide supplementation treatments were 1.50%and 2.25%.There were significant interactions between CFR and the level of small peptides for gas production and the degradation rates of dry matter and crude protein(P<0.01).2)With increase in CFR from 40∶60 to 60∶40,rumen pH decreased(P<0.01),while microbial protein increased(P>0.05).However,no significant changes in digestive parameters between CFR 50∶50 and 60∶40 were observed.A quadratic response pattern(P<0.01)was also observed for pH and microbial protein across the range of small peptide supplementation rates tested,with the optimal supplementation rate being 2.25%.A significant interaction was observed between CFR and the level of small peptide supplementation,for the concentration of ammonia nitrogen(P<0.05).3)There was a significant interaction between CFR and the level of small peptide supplementation for rumen volatile fatty acid concentrations(P<0.01).Across the three tested CFRs,acetate∶propionate and the proportion of acetate,isobutyrate and isovalerate presented quadratic variation(P<0.05).The lowest value of acetate∶propionate ratio and lowest proportion of acetate occu

关 键 词：小肽 精粗比 牦牛 体外发酵 

分 类 号：S82[农业科学—畜牧学]