机构地区:[1]河北农业大学动物科技学院,保定071001 [2]河北农业大学动物医学院,保定071001 [3]河北省牛羊胚胎工程技术研究中心,保定071001
出 处:《畜牧兽医学报》2019年第2期332-342,共11页ACTA VETERINARIA ET ZOOTECHNICA SINICA
基 金:公益性行业(农业)科研专项(201503134);国家现代农业(奶牛)产业技术体系建设专项资金(CARS-36);河北省科技计划项目(16226604D)
摘 要:旨在研究饲粮能量水平对育成牛养分表观消化率、生长性能和瘤胃发酵的影响。本研究选取8月龄中国荷斯坦育成奶牛45头,采用单因素完全随机设计,分为3组,每组15头牛。Ⅰ组饲喂低能日粮(NEL5.64 MJ·kg-1),Ⅱ组饲喂中能日粮(NEL5.94MJ·kg-1),Ⅲ组饲喂高能日粮(NEL6.21 MJ·kg-1),各试验组的饲粮蛋白质水平基本相同(CP14.04%)。试验期110d。测定每组育成牛的生长性能指标(体重、体高、体长、胸围、管围、乳头长度、乳头间距);采集粪样用于测定营养物质表观消化率;采集瘤胃液样品用于测定瘤胃发酵指标(pH、微生物蛋白、氨态氮、挥发性脂肪酸)。结果表明:1)与试验Ⅰ、Ⅱ组相比,试验Ⅲ组中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)表观消化率显著降低(P<0.05);与Ⅰ组相比,Ⅱ组和Ⅲ组NDF表观消化率分别下降4.84%和7.03%,ADF表观消化率分别下降2.99%和7.50%。各组间干物质采食量(DMI)、粗蛋白质(CP)、粗脂肪(EE)、钙(Ca)和磷(P)的表观消化率均无显著差异(P>0.05)。2)Ⅰ、Ⅱ、Ⅲ组育成牛平均日增重(ADG)分别为0.70、0.80、0.91kg·d-1,与Ⅰ组相比,Ⅱ组和Ⅲ组分别显著提高了14.28%和30.00%(P<0.05);各组牛体尺指标(体高、体长、胸围、管围)差异均不显著(P>0.05)。3)与Ⅰ组和Ⅲ组相比,Ⅱ组牛前乳头平均长度分别高出4.15%(P>0.05)和9.06%(P<0.05),后乳头平均长度分别高出9.02%(P<0.05)和11.54%(P<0.05)。4)各组间瘤胃pH、微生物蛋白(MCP)产量、乙酸、丁酸、总挥发性脂肪酸(T-VFA)含量及乙酸/丙酸(A/P)差异不显著(P>0.05);氨态氮(NH3-N)含量以Ⅱ组最低,较Ⅰ组显著降低了3.56%(P<0.05),与Ⅲ组相比差异不显著(P>0.05);Ⅲ组丙酸含量分别比Ⅰ、Ⅱ组高4.99%(P<0.05)、4.83%(P>0.05)。综上所述,在本试验中,8~11月龄育成牛日粮适宜产奶净能水平为5.94MJ·kg-1,粗蛋白质水平为14.03%。The objective of this study was to investigate the effect of dietary energy levels on nutrient apparent digestibility,growth performance and rumen fermentation of Chinese Holstein heifers.Forty-five Chinese Holstein heifers averaged at aged 8 months were selected and randomly allocated into 3 groups with 15 heifers in each group.Animals in group Ⅰ were fed a low-energy diet(NEL 5.64 MJ·kg^-1),those in group Ⅱ were fed a medium energy diet(NEL 5.94 MJ·kg^-1),and those in group Ⅲ were fed a high-energy diet(NEL 6.21 MJ·kg^-1).The experiment lasted for 110 d.Protein levels of the 3 diets were similar(CP14.04%).The growth performance indicators of heifer,including body weight,withers height,body length,heart girth,circumference of cannon bone,teat length and teat spacing,were determined,and fecal samples were collected for the analysis of apparent digestibility of nutrient,and the rumen fluid samples were collected for the determination of rumen pH,microbial protein(MCP),NH3-N and volatile fatty acid(VFA).The results showed that:1)Compared with group Ⅰ and Ⅱ,the apparent digestibility of neutral detergent fiber(NDF)and acid detergent fiber(ADF)in group Ⅲ were significantly decreased(P﹤0.05).Compared with group Ⅰ,the apparent digestibility of NDF in group Ⅱ and Ⅲ were decreased by 4.84% and 7.03%,and the apparent digestibility of ADF were decreased by 2.99% and 7.50%,respectively.There was no significant difference in the dry matter intake(DMI),the apparent digestibility of crude protein(CP),crude fat(EE),calcium(Ca)and phosphorus(P)among group Ⅰ,Ⅱ and Ⅲ(P﹥0.05).2)The average daily gain(ADG)in group Ⅰ,Ⅱ and Ⅲ were 0.70,0.80 and 0.91 kg·d^-1,respectively.Compared with group Ⅰ,ADG in group Ⅱ and Ⅲ were increased by 14.28% and 30.00%(P﹤0.05),respectively.There was no significant differences in body measurements(withers height,body length,heart girth,circumference of cannon bone)among group Ⅰ,Ⅱ and Ⅲ(P﹥0.05).3)Compared with group Ⅰ and Ⅲ,the average length of anter
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