饲喂高淀粉饲粮时不同瘤胃降解淀粉水平对奶牛泌乳性能、营养物质表观消化率和氮平衡的影响

Effects of Different Ruminally Degradable Starch Levels on Lactation Performance,Nutrient Apparent Digestibility and Nitrogen Balance of Dairy Cows Fed High Starch Diets

本试验旨在研究饲喂高淀粉饲粮时不同瘤胃降解淀粉水平对奶牛泌乳性能、营养物质表观消化率和氮平衡的影响。选用10头荷斯坦经产奶牛[平均泌乳天数为(214±38)d,平均乳产量为(26.2±2.4)kg/d,平均体重为(727±65)kg]作为试验动物,随机分成2组,每组5头。试验设计2种不同瘤胃降解淀粉水平的试验饲粮,分别为瘤胃降解淀粉水平为62.3%(占总淀粉的百分比)的低瘤胃降解淀粉水平饲粮(L-RDS)和瘤胃降解淀粉水平为72.1%(占总淀粉的百分比)的高瘤胃降解淀粉水平饲粮(H-RDS)。采用交叉试验设计,试验分为2期,过渡期7 d,每期试验21 d,其中适应期14 d,采样期7 d。结果显示:1)相比L-RDS组,H-RDS组有机物和淀粉的表观消化率显著升高(P<0.05),中性洗涤纤维和酸性洗涤纤维的表观消化率显著降低(P<0.05),干物质表观消化率有升高趋势(P=0.07),蛋白质表观消化率无显著差异(P>0.05)。2)相比L-RDS组,H-RDS组尿素氮及它们占摄入氮比例有降低趋势(P=0.09),摄入氮、乳氮、粪氮、尿氮和沉积氮及它们占摄入氮比例无显著变化(P>0.05),尿中总嘌呤衍生物排出量和微生物蛋白产量亦无显著变化(P>0.05)。3)饲粮瘤胃降解淀粉水平对奶牛干物质采食量、乳产量和乳成分均无显著影响(P>0.05)。综合以上结果可知,饲喂高淀粉饲粮时不同瘤胃降解淀粉水平影响饲粮营养物质的表观消化率,对泌乳性能和氮平衡无显著影响。

This trial w as performed to examine the effects of different ruminally degradable starch levels on lactation performance,nutrient apparent digestibility and nitrogen balance of dairy cow s fed high starch diets. Ten multiparous Holstein cow s [( average lactation days:( 214 ± 38) d; average milk yield:( 26. 2 ± 2. 4) kg/d;average body w eight:( 727 ± 65) kg] w ere randomly assigned to 2 groups,and each group had 5 dairy cow s.Tw o types of diets w ith different ruminally degradable starch levels w ere formulated,one of them contained62.3%( percentage of total starch) ruminally degradable starch w hich named as low-ruminally degradable starch diet( L-RDS),and the other contained 72.1%( percentage of total starch) ruminally degradable starch w hich named as high-ruminally degradable starch diet( H-RDS). A crossover experimental design w as applied.There w ere tw o experimental periods,the transition period lasted for 7 d,and each period lasted for 21 d( 14 d of pretrial period,and 7 d of sampling period). The results showed as follows: 1) the apparent digestibility of starch and organic matter w as significantly increased( P < 0. 05),the apparent digestibility of neutral detergent fiber and acid detergent fiber w as significantly decreased( P< 0.05),and the apparent digestibility of dry matter had a rising trend( P = 0. 07) for H-RDS group compared w ith L-RDS group,but no significant difference in the apparent digestibility of crude protein among them( P > 0. 05). 2) Compared w ith L-RDS group,urinary urea-nitrogen and the proportion of urinary urea-nitrogen in nitrogen intake had a decrease trend for H-RDS group( P = 0.09). The nitrogen intake,milk nitrogen,urinary nitrogen,fecal nitrogen,nitrogen retention and the proportions of them in nitrogen intake w ere not significantly affected by dietary ruminally degradable starch level( P > 0. 05),and the urinary excretion of purine derivatives and microbial protein yield w ere also not significantly affected by dietary ruminally degradable starch level( P > 0. 05). 3) Dry matter intake,milk yield and milk composition of dairy cow s w ere not significantly affected by dietary ruminally degradable starch level( P> 0.05). Results of this study show that different ruminally degradable starch levels can affect the nutrient apparent digestibility of dairy cow s fed high starch diets,w ith no significant influences on lactation performance and nitrogen balance. [Chinese Journal of Animal Nutrition,2017,29( 10) : 3541-3550]