Andersson L
Swedish Association for Livestock Breeding and Production, Animal Health Department, Eskilstuna.
Vet Clin North Am Food Anim Pract. 1988 Jul;4(2):233-51. doi: 10.1016/s0749-0720(15)31046-x.
Subclinical ketosis is defined as a preclinical stage of ketosis. The peak prevalence of subclinical ketosis occurs during the fourth week of lactation. Herd-related factors, breed, parity, and season are other important determinants. Subclinical ketosis can be revealed by determining levels of plasma glucose, plasma NEFA and blood, and milk or urine ketone body concentration. There are theoretical and practical advantages of using milk ketone bodies. Most authors are agreed on approximate lower and upper borderlines for subclinical ketosis. The risk of an outbreak of clinical symptoms has been evaluated by some authors. Most authors have found significant negative relationships between energy balance and ketone body concentration. Some disagreement may be attributable to the fact that the diets used in different experiments can have different glucogenic potential, even if the energy content is the same. This affects the relationship between energy balance and ketone body concentration, as the ketone body level is influenced by both the energy balance and plasma glucose. Feeding silage with high butyric acid content increases the risk of subclinical ketosis. There are indications that cows with the highest milk yield directly after calving are at greatest risk for developing ketosis. Increased ketone body level secondarily reduces milk production, a decrease that has been quantified by some authors. Subclinical ketosis causes delayed reproductive functions return to normal after calving, increased intervals from calving to first and last service, and an increased frequency of ovarian cysts. The routine determination of milk acetone levels in control programs can be used to evaluate the status of individual cows, to indicate the energy feeding in early lactation at a herd level, and to evaluate sires for breeding. The heritability and the tendency toward a positive genetic correlation between milk acetone and milk yield have also been discussed, as have aspects of nutritional prevention. Factors such as energy- and protein-rich roughage, tasty high-energy concentrates, suitable feeding during the dry period, and division of the concentrates into at least four meals are considered to be important.
亚临床酮病被定义为酮病的临床前期阶段。亚临床酮病的发病高峰出现在泌乳第四周。与畜群相关的因素、品种、胎次和季节是其他重要的决定因素。通过测定血浆葡萄糖、血浆非酯化脂肪酸以及血液、牛奶或尿液中的酮体浓度，可以发现亚临床酮病。使用牛奶酮体有理论和实际的优势。大多数作者对亚临床酮病的大致下限和上限达成了共识。一些作者评估了临床症状爆发的风险。大多数作者发现能量平衡与酮体浓度之间存在显著的负相关关系。一些分歧可能归因于这样一个事实，即即使能量含量相同，不同实验中使用的日粮可能具有不同的生糖潜力。这会影响能量平衡与酮体浓度之间的关系，因为酮体水平受能量平衡和血浆葡萄糖两者的影响。饲喂丁酸含量高的青贮饲料会增加亚临床酮病的风险。有迹象表明，产后直接产奶量最高的奶牛患酮病的风险最大。酮体水平升高继而会降低产奶量，一些作者已经对这种降低进行了量化。亚临床酮病会导致产后繁殖功能恢复正常的时间延迟，从产犊到首次配种和末次配种的间隔时间延长，以及卵巢囊肿的发生率增加。在控制程序中常规测定牛奶丙酮水平可用于评估个体奶牛的状况，指示畜群水平上早期泌乳的能量饲喂情况，并评估种公牛的繁殖性能。牛奶丙酮与产奶量之间的遗传力以及正遗传相关性的趋势也已得到讨论，营养预防方面也是如此。富含能量和蛋白质的粗饲料、美味的高能精饲料、干奶期的适当饲喂以及将精饲料分成至少四餐等因素被认为很重要。
