日粮类型对奶牛能量代谢的影响

Effects of dietary types on dairy cow energy metabolism

为了探讨日粮类型对泌乳奶牛能量代谢的影响,以进一步了解奶牛日粮能量的摄入及损失情况,本试验选用12头体重、年龄相近的中国荷斯坦奶牛为试验动物,分为3组,分别饲喂粗料为干秸秆玉米,精粗比40∶60的A组日粮及粗料均为玉米青贮,精粗比分别是40∶60和60∶40的B和C组日粮,进行了奶牛甲烷能、粪能、尿能、消化能等指标的测定。试验结果表明,B组和C组日粮粪能分别比A组日粮减少了37.69%和31.70%,能量消化率分别比A组日粮提高了16.41%和16.76%,差异均显著(P<0.05),粗料均为青贮玉米时,粪能和能量消化率随着精料比例的提高而增加,差异不显著(P>0.05);尿能显示结果为C组日粮﹥B组日粮﹥A组日粮,差异不显著(P>0.05);A组日粮的甲烷能分别比B组和C组日粮提高了24.60%和34.26%,差异显著(P<0.05),粗料均为青贮玉米条件下随日粮精料水平的增加甲烷能下降了7.19%,差异不显著(P>0.05);结果同时表明,三组日粮从粪便、尿液、甲烷途径损失的总能量占摄入总能的比例分别为51.65%、42.63%、41.05%,其中粪能占损失能的比例分别为79.84%、73.94%、76.48%,尿能占损失能的比例为6.57%、9.85%、9.33%,甲烷能占损失能的比例为13.59%、16.21%、14.19%。因此,奶牛日粮中粗料由青贮玉米代替干秸秆玉米或适当增加日粮中精料比例均可以减少能量的损失,而且奶牛能量的损失主要通过粪便,其次为甲烷气体和尿液途径,这和日粮类型无关。

Twelve Holstein dairy cows of similar weight and age were selected to investigate the effect of diet types on energy metabolism of diary cows and energy intake and losses.The dairy cows were divided into 3 groups,which were fed with Diet A （coarse material was dry corn stalks,the forage to concentrate rate is 40：60）, Diet B（coarse material was corn silage, the forage to concentrate rate is 40：60）and C （corn silage, the forage to concentrate rate is 60：40） respectively to determine the methane energy, fecal energy, urinary energy, digestible energy and other indexes.The results showed that, the fecal energy of Diet B and C reduced by 37.69 % and 31.70 % respectively,while energy digestibility increased by 16.41%（P 〈 0.05） and 16.76 %（P 〈 0.05）respectively compared with Diet A.When the coarse material was corn silage, the fecal energy and energy digestibility would increase with the increase of concentrate rate.The difference was insignificant （P 〉 0.05） ;The results of fecal energy showed Diet C 〉 Diet B 〉 Diet A and the difference is not distinctive （P 〉 0.05 ）.The energy of methane for Diet A increased by 24.60 % and 34.26 % respectively compared with Diet B and C, but with no difference （P 〈 0.05）.When the coarse material was corn silage,the methane energy decreased by 7.19 % with increasing refined materials （P 〉 0.05）.The results also showed that,general energy lost in form of fecal,urinary and methane energy accounted for 51.65 % ,42.63 % and 41.05 % respectively,among which the fecal energy took up 79.84 % ,73.94 % and 76.48 % ;the loss in urinary energy was 6.57 % ,9.85 % and 9.33 % ;the energy of methane accounted for 13.59 %, 16.21% and 14.19 % respectively.Consequently,replacement of dry corn stalks by corn silages for diary cows or proper addition of refined materials into the diets was able to lessen losses in energy.Further,energy in diary cows were mainly lost in forms of fecal materials, methane gas and urines, not associated with diet classification.