瘤胃可降解淀粉水平对饲喂低玉米淀粉日粮奶牛的生产性能、氮平衡及养分消化率的影响。
Effects of ruminally degradable starch levels on performance, nitrogen balance, and nutrient digestibility in dairy cows fed low corn-based starch diets.
作者信息
Luo Guobin, Xu Wenbin, Yang Jinshan, Li Yang, Zhang Liyang, Wang Yizhen, Lin Cong, Zhang Yonggen
机构信息
College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China.
出版信息
Asian-Australas J Anim Sci. 2017 May;30(5):653-659. doi: 10.5713/ajas.16.0371. Epub 2016 Sep 19.
OBJECTIVE
This trial was performed to examine the effects of ruminally degradable starch (RDS) levels in total mixed ration (TMR) with low corn-based starch on the milk production, whole-tract nutrient digestibility and nitrogen balance in dairy cows.
METHODS
Eight multiparous Holstein cows (body weight [BW]: 717±63 kg; days in milk [DIM]: 169±29) were assigned to a crossover design with two dietary treatments: a diet containing 62.3% ruminally degradable starch (% of total starch, low RDS) or 72.1% ruminally degradable starch (% of total starch, high RDS). Changes to the ruminally degradable levels were conducted by using either finely ground corn or steam-flaked corn as the starch component.
RESULTS
The results showed that dry matter intake, milk yield and composition in dairy cows were not affected by dietary treatments. The concentration of milk urea nitrogen was lower for cows fed high RDS TMR than low RDS TMR. The whole-tract apparent digestibility of neutral detergent fiber, acid detergent fiber and crude protein decreased, and that of starch increased for cows fed high RDS TMR over those fed low RDS TMR, with no dietary effect on the whole-tract apparent digestibility of dry matter and organic matter. The proportion of urinary N excretion in N intake was lower and that of fecal N excretion in N intake was higher for cows fed high RDS TMR than those fed low RDS TMR. The N secretion in milk and the retention of N were not influenced by the dietary treatments. Total purine derivative was similar in cows fed high RDS TMR and low RDS TMR. Consequently, estimated microbial N flow to the duodenum was similar in cows fed high RDS TMR and low RDS TMR.
CONCLUSION
Results of this study show that ruminally degradable starch levels can influence whole-tract nutrient digestibility and nitrogen balance in dairy cows fed low corn-based starch diets, with no influence on performance.
目的
本试验旨在研究低玉米淀粉全混合日粮（TMR）中瘤胃可降解淀粉（RDS）水平对奶牛产奶量、全消化道养分消化率及氮平衡的影响。
方法
选用8头经产荷斯坦奶牛（体重[BW]：717±63千克；泌乳天数[DIM]：169±29天），采用交叉设计，设置两种日粮处理：一种日粮含62.3%瘤胃可降解淀粉（占总淀粉的百分比，低RDS），另一种含72.1%瘤胃可降解淀粉（占总淀粉的百分比，高RDS）。通过使用细磨玉米或蒸汽压片玉米作为淀粉成分来改变瘤胃可降解水平。
结果
结果表明，日粮处理对奶牛的干物质采食量、产奶量及乳成分无影响。饲喂高RDS TMR的奶牛，其乳尿素氮浓度低于饲喂低RDS TMR的奶牛。与饲喂低RDS TMR的奶牛相比，饲喂高RDS TMR的奶牛全消化道中性洗涤纤维、酸性洗涤纤维和粗蛋白的表观消化率降低，淀粉表观消化率升高，日粮对干物质和有机物的全消化道表观消化率无影响。饲喂高RDS TMR的奶牛，其尿氮排泄占氮摄入量的比例较低，粪氮排泄占氮摄入量的比例较高。日粮处理对乳中氮分泌和氮保留无影响。饲喂高RDS TMR和低RDS TMR的奶牛总嘌呤衍生物相似。因此，饲喂高RDS TMR和低RDS TMR的奶牛十二指肠微生物氮流量估计相似。
结论
本研究结果表明，瘤胃可降解淀粉水平可影响低玉米淀粉日粮奶牛的全消化道养分消化率和氮平衡，但对生产性能无影响。
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