共查询到19条相似文献,搜索用时 140 毫秒
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乳中尿素氮在奶牛营养检测中的应用 总被引:3,自引:3,他引:3
奶牛营养检测技术是衡量奶牛营养工程技术中各种营养措施的系统集成度的重要技术手段。检测乳中尿素氮(MUN)可评定泌乳奶牛日粮中蛋白质的利用率和蛋白质与能量的配比关系。研究表明,当MUN值过高时子宫内环境不利于胚胎着床,从而使牛的受胎率降低。因此,可用MUN来检测奶牛的受胎率。1MUN的形成饲料中的蛋白质在瘤胃中被降解成氨,一部分氨被瘤胃微生物所利用,过量的氨被瘤胃壁吸收通过血液循环进入肝脏合成了尿素,生成的尿素一部分从尿中排出,另一部分尿素进入了体组织、血液和奶。尿素是由碳、氢、氧、氮组成的有机小分子,而且是血液和… 相似文献
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采用4×4的拉丁方试验设计,将体重、奶产量和泌乳天数接近的4头经产荷斯坦牛饲喂四种等能量水平不同蛋白质水平(13.2%,14.1%,15.0%和16.2%,干物质基础)的日粮,来研究奶牛乳尿素氮浓度及氮利用率的变化情况。整个试验期共56d,每期14d,1-10d为调整期,11-13d为粪尿收集期。结果发现,随着日粮蛋白质水平的增加,乳尿素氮浓度极显著升高(P<0.01),而氮的利用率随着蛋白质水平的增加而显著下降(P<0.05);乳尿素氮和氮利用率间存在显著的二次曲线关系(P<0.01)。乳尿素氮可以作为反映奶牛日粮蛋白质水平变化的指标,也有可能作为估测奶牛氮利用率的指标发挥作用。 相似文献
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In blood serum of dairy cows of the Slovak Pied breed with high and low performance, the levels of total protein, urea, amino nitrogen, non-protein nitrogen and uric acid were studied over the period of four to six weeks after calving. Total protein was determined by the Bio-La-test, amino nitrogen by means of ninhydrin, non-protein nitrogen by Berthelot agent and uric acid by Benedict agent. In comparison with dairy cows with low performance, the dairy cows with high performance had a statistically significantly higher level of total protein, urea, amino nitrogen and non-protein nitrogen. The differences in uric acid content were statistically insignificant. 相似文献
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dDietary protein and dairy cow fertility. Feeding more dietary protein has been negatively associated with dairy cow fertility in some but not all studies. We used meta-analysis to examine the relationship between dietary crude protein and conception rate. While a higher intake of dietary crude protein significantly lowered conception rate, the potential for feeding less degradable dietary protein to modify this relationship was not demonstrated. dMilk urea concentrations and dairy cow fertility. The use of milk urea as an indicator of dietary energy and protein intake and as an indictor of reproductive performance has been questioned. We found that changes in urea concentration in body fluids explained only 25% (p = 0.08) of the variance in conception rate after conducting a meta-analysis of available studies. dInterpretation of milk urea concentrations. High intakes of dietary protein may induce adaptations in urea metabolism, and the negative relationship identified between high intakes of dietary protein and fertility for Northern Hemisphere dairy herds may not necessarily apply in Australasian dairy herds. Because of the potential for cows to adapt to high protein diets, the use of a single milk urea determination on a herd will have limited value as an indicator of nutritional status and little value as a predictor of fertility. 相似文献
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Pelletier G Tremblay AV Hélie P 《The Canadian veterinary journal. La revue veterinaire canadienne》1985,26(10):306-311
Forty Holstein dairy cows were used to determine the effects of forage feeding system, season and stage of lactation on some blood parameters. Blood urea nitrogen was higher for cows consuming higher levels of crude protein and particularly for the ones on pasture. Hemoglobin and packed cell volume values were correlated with the level of crude protein intake and stage of lactation. Lower values of these parameters were observed with lower crude protein intake and in early lactation. Serum levels of albumin, calcium, inorganic phosphorus, sodium and potassium were not affected either by forage system, season or stage of lactation. Serum magnesium level was lower for forage system containing corn silage. Blood glucose was lower for cows in early lactation but was not affected by feeding systems during winter. Cows on pasture had higher blood glucose levels. Lower total protein concentration in blood was observed between 90 and 180 days of lactation as a result of lower gammaglobulins. Blood parameters are good indicators of nitrogen and energy nutritional status of dairy cows. However, blood mineral concentrations are not related to the level of mineral intake of animals. 相似文献
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DIETARY PROTEIN AND DAIRY COW FERTILITY: Feeding more dietary protein has been negatively associated with dairy cow fertility in some but not all studies. We used meta-analysis to examine the relationship between dietary crude protein and conception rate. While a higher intake of dietary crude protein significantly lowered conception rate, the potential for feeding less degradable dietary protein to modify this relationship was not demonstrated. MILK UREA CONCENTRATIONS AND DAIRY COW FERTILITY: The use of milk urea as an indicator of dietary energy and protein intake and as an indicator of reproductive performance has been questioned. We found that changes in urea concentration in body fluids explained only 25% (p = 0.08) of the variance in conception rate after conducting a meta-analysis of available studies. INTERPRETATION OF MILK UREA CONCENTRATIONS: High intakes of dietary protein may induce adaptations in urea metabolism, and the negative relationship identified between high intakes of dietary protein and fertility for Northern Hemisphere dairy herds may not necessarily apply in Australasian dairy herds. Because of the potential for cows to adapt to high protein diets, the use of a single milk urea determination on a herd will have limited value as an indicator of nutritional status and little value as a predictor of fertility. 相似文献
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ZHAO Shanjiang HAO Haisheng LIU Yunxiang WANG Xianjun XU Li LI Laibao HU Zhihui ZHU Huabin 《中国畜牧兽医》2007,47(11):3618-3625
Under the modern large-scale and intensive dairy farming production mode,the continuous supply of feed with high nutrition level is the material basis for maintaining the rapid growth and development of reserve cows and the high lactation performance of lactating cows.However,after the genetic quality reaches the "bottleneck period",although the milk yield of dairy cow can continue to maintain a certain high level with the continuous improvement of the nutrient concentration of feed and the increase of dry matter intake (DMI),the incidence of nutritional metabolic diseases of high-yield dairy cows also shows a rapid growth trend,especially ketosis caused by the negative energy balance in perinatal period,acidosis caused by high-precision diet and the increase of blood urea nitrogen caused by high-protein diet,negatively regulate the reproductive performance of dairy cows,resulting in inconspicuous postpartum estrus,decreased mating rate and conception rate of dairy cows,which directly affect the update speed of dairy cows production groups,the normal performance of high-quality cattle and the economic benefits of dairy farming.In this paper,the author introduced in detail the relevant research on the current situation and its mechanism influence of different nutritional metabolic diseases on the reproductive performance of dairy cows in recent years,and focused on analyzing the molecular mechanism of nutritional and metabolic diseases with high perinatal incidence such as ketosis,low blood calcium and moderate gastric acid,and put forward the prospect and thinking on the future research direction of nutritional and metabolic diseases and reproductive performance of high-yielding dairy cows,in order to provide some reference and theoretical basis for improving the reproductive efficiency of high-yielding dairy cows in large-scale pastures in China and the perinatal nutrition management level of dairy cows. 相似文献
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现代规模化、集约化奶牛养殖生产模式下,不断供给高营养水平日粮是维持后备牛快速生长发育和泌乳母牛高泌乳性能的物质基础。然而,在遗传品质到达"瓶颈期"后,尽管随着日粮营养浓度的不断提高和干物质采食量(DMI)的增加,奶牛单产水平可以继续维持在一定的高水平状态,但是高产奶牛的营养代谢性疾病的发病率也呈现快速增长趋势,特别是围产期能量负平衡(negative energy balance,NEB)引起的酮病,高精日粮引发的酸中毒、高蛋白质日粮引起的血液中尿素氮升高等营养代谢性疾病,负调控奶牛繁殖性能,造成奶牛产后发情不明显,配种率和受胎率下降等,直接影响奶牛生产群的更新速度、优质牛群泌乳性能正常发挥以及奶牛养殖的经济效益。作者详细介绍了近年来国内外不同营养代谢性疾病对奶牛繁殖性能影响的相关研究资料,重点分析了酮病、低血钙、瘤胃酸中毒等围产期高发的营养代谢性疾病影响奶牛繁殖性能的分子机制,并对营养代谢性疾病与高产奶牛繁殖性能今后研究的方向提出了展望和思考,以期为提高中国规模化牧场高产奶牛群繁殖效率和母牛围产期营养管理水平提供一定的借鉴和理论依据。 相似文献