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首页> 外文期刊>Assiut Veterinary Medical Journal >Milk production and nutrient utilization responses to reduced diet-crude protein level and methionine supplementation for dairy cows.
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Milk production and nutrient utilization responses to reduced diet-crude protein level and methionine supplementation for dairy cows.

机译：奶牛的产奶量和养分利用率降低了日粮粗蛋白水平和蛋氨酸的添加量。

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This study was carried out to determine whether the addition of rumen-protected Met to ration formulation allowed a reduction in dietary crude protein (CP) without jeopardizing total milk or milk protein yields. 28 multiparous Holstein-Friesian cows in a commercial dairy herd were randomly assigned to the trial. Rations differed in percentages of CP level (H, 19.3% or L, 16.9%), with or without supplementation by protected methionine. Milk yield was recorded individually at each milking and milk samples were taken during the experimental period. In addition, four digestion trials were conducted on three cows of each group to evaluate the digestibility coefficients of used diets using the acid insoluble ash technique. No effects of pMet supplementation or interactions between CP levels and methionine supplementation were detected on any of the parameters measured for digestibility coefficients of nutrients. In early lactation, milk production response to pMet supplementation was greater with the low level of CP diets compared with the high level (2.00 vs. 0.300 kg/day, respectively). The pMet supplementation by CP level interaction was significant for protein concentration, while it was not significant for fat and lactose concentration during early and mid lactation period. Every one percentage unit increase in dietary CP above 16.9%, MUN concentrations were, in average, increased 2.2, 2.0, and 1.6 mg/dl in early, mid and late lactation, respectively. The feed and N utilization efficiencies were improved by feeding low CP diets supplemented with pMet in early lactation. Cows fed diets reduced in CP level had a reduction in cost of feed per kg milk in various stages of lactation. In early lactation, feeding diets supplemented with pMet reduced the cost of feed per kg milk by 0.04 L.E. In conclusion, a reduction in dietary protein to 16.9% and supplemented with protected AA, particularly the first limiting AA, is an acceptable new nutritional strategy for improving productive performance in dairy cattle and may be used as an approach for reformulating lactating cows rations based on AA profile, rather than CP as simple or metabolizable protein. This strategy, with prevailing feed prices, could be compatible with maximum profit and a moderate amount of nitrogen excretion to the environment..
机译：进行这项研究是为了确定在定量配方中添加瘤胃保护的Met是否可以减少日粮粗蛋白（CP）而不会损害总牛奶或牛奶蛋白的产量。将商业奶牛场中的28头荷斯坦-弗里斯兰奶牛随机分配到试验中。定量的CP水平百分比不同（H，19.3％或L，16.9％），有或没有受保护的蛋氨酸补充。在每次挤奶时分别记录牛奶产量，并在实验期间采集牛奶样品。此外，对每组三头母牛进行了四次消化试验，以使用酸不溶性灰分技术评估用过的日粮的消化系数。在测定营养物消化率的任何参数上均未检测到pMet补充作用或CP水平与蛋氨酸补充作用之间的相互作用。在早期哺乳期，低CP饮食水平与高水平（分别为2.00 vs. 0.300 kg /天）相比，补充pMet的产奶量更大。通过CP水平相互作用的pMet补充对于蛋白质浓度具有重要意义，而在哺乳初期和中期对脂肪和乳糖的浓度则无意义。饮食中CP的每增加1个百分点，高于16.9％，则在哺乳初期，中期和晚期，MUN浓度平均分别增加2.2、2.0和1.6 mg / dl。通过在哺乳初期饲喂补充了pMet的低CP饲料，可以提高饲料和氮的利用率。在泌乳的各个阶段，饲喂日粮中CP水平降低的奶牛每公斤牛奶的饲料成本降低。在哺乳初期，饲喂补充了pMet的饲料可使每公斤牛奶的饲料成本降低0.04L.E。总之，将日粮蛋白质减少到16.9％并添加受保护的氨基酸，尤其是第一个限制性氨基酸，是可以提高奶牛生产性能的可接受的新营养策略，并且可以用作重新调整奶牛日粮的方法。 AA谱，而不是简单或可代谢蛋白CP。这种策略以及当前的饲料价格可以与最大的利润和适量的氮排泄到环境中相适应。

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