全混合日粮粗饲料水平对奶牛的挑食行为、瘤胃内容物及血清指标的影响

Effects of Forage Level of Total Mixed Ration on Sorting Behavior,Rumen Content and Serum Indicators of Dairy Cows

本试验旨在研究全混合日粮粗饲料水平对奶牛挑食行为、瘤胃内环境及血清指标的影响。选用12头泌乳中期[泌乳天数(119±26)d]经产荷斯坦奶牛[体重(629±46)kg],随机分为4组,每组中1头安装瘤胃瘘管,按4×4拉丁方设计,饲喂粗饲料水平分别为40%、50%、60%和70%(干物质基础)的4种全混合日粮。共进行4期动物试验,每期试验21 d。结果表明:饲粮粗饲料水平对奶牛挑食行为有显著(P<0.05)或极显著(P<0.01)影响。饲粮粗饲料水平为40%时,奶牛喜食粒度≥4 mm饲粮,厌食粒度<4 mm饲粮,但饲粮粗饲料水平>40%时,奶牛喜食粒度<4 mm饲粮,厌食粒度≥4 mm饲粮。饲粮粗饲料水平对瘤胃内容物各层粒度分布无显著影响(P>0.05)。随饲粮粗饲料水平的增加,瘤胃液外流速度和瘤胃固相外流速度呈显著线性增加(P<0.05),瘤胃内容物重量和瘤胃液体积无显著变化(P>0.05);血清胰岛素样生长因子-1(IGF-1)含量呈显著线性增加(P<0.01),瘦素(LEP)和非酯化脂肪酸(NEFA)含量有线性增加趋势(0.05≤P<0.10),血清生长激素(GH)和胰岛素(INS)含量有线性降低的趋势(0.05≤P<0.10)。综上所述,饲粮粗饲料水平是影响奶牛挑食行为、瘤胃内容物及血清指标的重要因素。

This experiment was conducted to study the effects of forage level of total mixed ration on sorting behavior,rumen content and serum indicators of dairy cows.Twelve multiparous Holstein dairy cows[body weight was(616.8±44.3)kg]at mid-lactation[days in milk was(119±26)d]were randomly assigned to 4 groups in a 4×4 Latin square experiment with one cow surgically fitted with rumen cannula in each group.Cows were fed total mixed rations containing 40%,50%,60%and 70%roughage(dry matter basis),respectively.There were 4 stage animal tests,each stage lasted for 21 days.The results showed that dietary forage level significantly affected sorting behaviour of cows(P<0.05 or P<0.01).Cows sorted particles retained above 4 mm sieves and sorted against particles retained below 4 mm sieves when dietary forage level was 40%;However,cows sorted particles retained below 4 mm sieves and sorted against particles retained above 4 mm sieves when dietary forage level was greater than 40%.Dietary forage level did not affect the particle size distribution in rumen(P>0.05).When dietary forage level increased,the rumen liquid outflow velocity and rumen solid outflow velocity were linearly increased(P<0.05),but the rumen content weight and rumen liquid volume did no changed(P>0.05),the serum insulin like growth factor-1(IGF-1)content was linearly increased(P<0.05),the contents of leptin(LEP)and non esterified fatty acids(NEFA)in serum tended to increase(0.05≤P<0.10),and the contents of growth hormone(GH)and insulin(INS)in serum tended to decrease(0.05≤P<0.10).In conclusion,dietary forage level is an important factor on sorting behavior,rumen content and serum indicators.