甲酸对全株饲料桑青贮营养和发酵品质、有氧稳定性及体外瘤胃发酵特性的影响

Effects of Formic Acid on Nutrition and Fermentation Quality,Aerobic Stability and in Vitro Rumen Fermentation Characteristics of Whole Plant Forage Mulberry Silage

本研究旨在探究甲酸对全株饲料桑青贮营养和发酵品质、有氧稳定性及体外瘤胃发酵特性的影响,为全株饲料桑的开发利用提供科学有效的理论支撑。试验分为5组,各组分别在饲料桑中添加0(对照组,CK组)、2(FA2组)、4(FA4组)、6(FA6组)、8 mL/kg(FA8组)甲酸,每组4个重复,青贮90 d。分别在有氧暴露第0(当天)、3、6、9、12天采集样品,测定其青贮品质和有氧稳定性,以选出适宜甲酸添加水平。随后,进一步探究饲料桑添加甲酸后对奶牛瘤胃发酵的影响,将饲料桑分为3组:饲料桑青贮原料组(M组)、未添加甲酸青贮饲料桑组(CK组)和经筛选出最优甲酸添加水平青贮饲料桑组(FA2组),每组3个重复,进行48 h体内降解试验和体外发酵试验。结果表明:1)有氧暴露期间,FA4组干物质(DM)含量始终最高,有氧暴露第0、3、6、12天显著高于CK和FA6组(P<0.05);FA2、FA4组有氧暴露第9天中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量显著低于CK和FA8组(P<0.05)。2)有氧暴露第0天,FA2、FA4、FA6、FA8组pH及氨态氮(NH_(3)-N)、乙酸(AA)含量均显著低于CK组(P<0.05)。随有氧暴露时间延长,FA2组pH稳定且始终最低。3)有氧暴露期间,FA2组饲料温度始终低于CK组和环境温度。因此,适宜的甲酸添加水平为2 mL/kg。4)FA2组干物质消化率(DMD)显著高于CK组(P<0.05),丙酸、正戊酸含量显著低于CK组(P<0.05),pH、乙酸含量、乙酸/丙酸显著低于M组(P<0.05)。综上所述,添加2 mL/kg甲酸可改善饲料桑青贮营养和发酵品质、有氧稳定性及体外瘤胃发酵功能。

The purpose of this study was to explore the effects of formic acid on the nutrition and fermentation quality,aerobic stability and in vitro rumen fermentation characteristics of whole plant forage mulberry silage,and to provide more scientific and effective theoretical support for the development and utilization of whole plant forage mulberry.The experiment was divided into 5 groups,and the 5 groups were supplemented with 0(control group,CK group),2(FA2 group),4(FA4 group),6(FA6 group)and 8 mL/kg(FA8 group)formic acid in the forage mulberry,respectively,each group contained 4 replicates,and silage for 90 days.The samples were collected on the days 0(intraday),3,6,9 and 12 of aerobic exposure to determine the silage quality and aerobic stability,to select the optimal formic acid supplemental level.Subsequently,the effects of formic acid addition on rumen fermentation of dairy cows was further explored,the forage mulberry was divided into 3 groups:the forage mulberry silage raw material group(M group),the silage forage mulberry group not supplemented with formic acid(CK group)and the silage forage mulberry group with screened optimal supplemental level of formic acid(FA2 group),each t contained 3 replicates,and the in vivo degradation test and in vitro fermentation test were carried out for 48 h.The results showed as follows:1)during the aerobic exposure period,the dry matter(DM)content of FA4 group was always the highest,and significantly higher than that of CK and FA6 groups on days 0,3,6 and 12 of aerobic exposure(P<0.05);the contents of neutral detergent fiber(NDF)and acid detergent fiber(ADF)of FA2 and FA4 groups were significantly lower than those of CK and FA8 group on day 9 of aerobic exposure(P<0.05).2)On day 0 of aerobic exposure,the pH,ammonia nitrogen(NH_(3)-N)and acetic acid(AA)contents of FA2,FA4,FA6 and FA8 groups were significantly lower than those of the CK group(P<0.05).With the extension of aerobic exposure time,the pH of the FA2 group was stable and always the lowest.3)During the aerobic exposure period,the feed temperature of the FA2 group was always lower than that of the CK group and the ambient temperature.Therefore,the suitable formic acid supplemental level was 2 mL/kg.4)The dry matter digestibility(DMD)of the FA2 group was significantly higher than that of the CK group(P<0.05),the propionic acid and valeric acid contents were significantly lower than that of the CK group(P<0.05),and the pH,acetic acid content and acetic acid/propionic acid were significantly lower than that of the M group(P<0.05).In conclusion,the addition of 2 mL/kg formic acid can improve the nutrition and fermentation quality,aerobic stability and in vitro rumen fermentation function of forage mulberry silage.