干玉米纤维饲料与羊草组合替代苜蓿干草对体外瘤胃发酵的影响

摘要

本试验旨在研究干玉米纤维饲料(DCFF)与羊草组合替代饲粮中的部分苜蓿干草对奶牛体外瘤胃发酵的影响.以奶牛饲粮为发酵底物,采用DCFF与羊草组合后分别等比替代底物中0、5.00％、10.50％、17.50％、22.90％的苜蓿干草,其中DCFF在底物中比例分别为0、3.00％、7.00％、11.00％和15.00％,分别命名为0DCFF、3DCFF、7DCFF、11DCFF、15DCFF组.测定体外发酵24 h的发酵参数、微生物区系及48 h的产气参数.结果表明:1)DCFF与羊草组合替代苜蓿干草对体外发酵产气量、潜在产气量和产气速率影响显著(P＜0.05),均随着替代比例的增加而先升高后下降,其中11D CFF组最高;DCFF与羊草组合替代苜蓿于草对体外发酵于物质消失率的影响显著(P＜0.05),11D CFF和15DCFF组显著高于其他各组(P＜0.05).2)DCFF与羊草组合替代苜蓿干草对发酵液微生物蛋白、氨态氮、乙酸、丙酸、丁酸和总挥发性脂肪酸浓度影响显著(P＜0.05),均随着替代比例的增加而呈先升高后平缓的趋势;DCFF与羊草组合替代苜蓿干草对发酵液pH影响显著(P＜0.05),随着替代比例的增加而呈先下降后平缓的趋势.3)DCFF与羊草组合替代苜蓿干草对发酵液黄色瘤胃球菌、产琥珀酸丝状杆菌、溶纤维丁酸弧菌的相对数量影响显著(P＜0.05),均随着替代比例的增加呈先升高后平缓的趋势;发酵液牛链球菌、溶淀粉琥珀酸单胞菌、嗜淀粉瘤胃杆菌、白色瘤胃球菌的相对数量各组间无显著差异(P＞0.05).综上所述,利用DCFF与羊草组合替代奶牛饲粮中部分苜蓿干草有利于体外瘤胃发酵,其中替代17.50％和22.90％苜蓿干草的体外发酵效果较好,此时饲粮中DCFF的比例分别为11.00％和15.00％.%The aim of this study was to investigate the effects of replacing alfalfa hay with dry corn fiber feed (DCFF) and Chinese leymus on in vitro rumen fermentation of dairy cows.A diet for dairy cows was used as a fermentation substrate.Different proportions (0,5.00％,10.50％,17.50％ and 22.90％) of alfalfa hay in the substrate were replaced with combinations of DCFF and Chinese leymus (DCFF proportion in the fermentation substrate was 0,3.00％,7.00％,11.00％ and 15.00％,respectively),which were named 0DCFF,3DCFF,7DCFF,11DCFF,15DCFF groups,respectively.Fermentation parameters and microflora after fermented for 24 h,and gas production parameters after fermented for 48 h were determined.The results showed as follows:1) replacing alfalfa hay with DCFF and Chinese leymus had significant effects on gas production (GP),potential gas production and gas production rate of in vitro fermentation (P＜0.05),which showed firstly increased and then decreased tendency with the increase of replacing proportion,and 11 DCFF group had the highest values;replacing alfalfa hay with DCFF and Chinese leymus had significant effects on dry matter disappearance rate of in vitro fermentation (P＜0.05),11DCFF and 15DCFF groups were significantly higher than the other groups (P ＜ 0.05).2) Replacing alfalfa hay with DCFF and Chinese leymus had significant effects on the concentrations of microbial protein (MCP),ammonia nitrogen,acetic acid,propionic acid,butyric acid and total volatile fatty acids (TVFA) in fermentation fluid (P ＜ 0.05),which showed firstly increased and then gentle tendency;replacing alfalfa hay with DCFF and Chinese leymus had significant effectson pH in fermentation fluid (P＜0.05),which showed firstly decreased and then gentle tendency.3) Replacing alfalfa hay with DCFF and Chinese leymus had significant effects on the relative counts of R.flavefaciens,F.succinogenes and B.fibrisolvens in fermentation fluid (P＜0.05),which showed firstly increased and then gentle tendency;there were no significant difference of the relative counts of S.bovis,S.amylolytica,R.amylophilus,R.albus in fermentation fluid among groups (P＞0.05).It is concluded that replacing alfalfa hay in diet for dairy cows with DCFF and Chinese leymus can improve in vitro rumen fermentation,when the replacing proportions are 17％ and 23％,the effects are better,and the proportions of DCFF are 11.00％ and 15.00％ at this time,respectively.