Department of Clinical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
Vet J. 2013 Dec;198(3):560-70. doi: 10.1016/j.tvjl.2013.08.011. Epub 2013 Aug 16.
Dairy cows pass through a period of negative energy balance as they transition from late gestation to early lactation. Poor adaptation through this period, expressed as excessively elevated concentrations of non-esterified fatty acids (NEFAs) pre- or post-partum and elevated concentrations of β-hydroxybutyrate post-partum, increases an individual animal's risk of post-partum disease, removal from the herd, reproductive difficulty, and reduced milk production. Field studies have shown that subclinical ketosis often affects 40% of cows in a herd although the incidence can be as high as 80%. Peak incidence occurs at 5 days in milk, and cows that develop subclinical ketosis in the first week of lactation have a higher risk of negative effects and reduced milk production than cows that develop subclinical ketosis in the second week of lactation. Herds with more than a 15-20% prevalence of excessively elevated concentrations of NEFAs and β-hydroxybutyrate in early lactation have higher rates of negative subsequent events, poorer reproduction, and lower milk yield than herds with a lower prevalence of negative energy balance. This paper reviews (1) strategies for testing of energy-related metabolites, (2) consequences of poor adaptation to negative energy balance (for individual animals and for herds), (3) treatment approaches for affected cows, and (4) economic considerations for testing and treating cows with poor adaptation to negative energy balance.
奶牛在从妊娠后期过渡到泌乳早期时会经历一段负能量平衡期。在此期间，如果适应不良，表现为产前或产后非酯化脂肪酸（NEFA）浓度过高和产后β-羟丁酸浓度过高，会增加个体动物产后疾病、离群、繁殖困难和产奶量下降的风险。田间研究表明，亚临床酮病通常会影响牛群中 40%的奶牛，尽管发病率可能高达 80%。发病率峰值出现在产后 5 天，在泌乳第一周发生亚临床酮病的奶牛比在第二周发生亚临床酮病的奶牛更容易受到负面影响和产奶量下降的影响。在泌乳早期 NEFA 和 β-羟丁酸浓度过高的奶牛比例超过 15-20%的牛群，随后出现负事件的比率更高、繁殖性能更差、产奶量更低，而 NEFA 浓度过低的牛群则更低。本文综述了（1）与能量相关代谢物检测的策略，（2）对负能量平衡适应不良的个体动物和牛群的后果，（3）对受影响奶牛的治疗方法，以及（4）对适应不良的奶牛进行检测和治疗的经济考虑因素。
