Vazquez-Añon M, Bertics S, Luck M, Grummer R R, Pinheiro J
Department of Dairy Science, University of Wisconsin, Madison 53706.
J Dairy Sci. 1994 Jun;77(6):1521-8. doi: 10.3168/jds.S0022-0302(94)77092-2.
Nine pregnant, nonlactating cows were used to monitor liver triglycerides before and after parturition. Estimates were made of the contribution of depressed feed intake and parturition to plasma NEFA concentrations and development of fatty liver. Liver biopsies and plasma samples were obtained on d 19, 10, 5, 3, and 1 prior to calving and on d 1, 7, 14, and 21 after calving. Depression of DMI started on d 2 prior to calving and was 40% of DMI on d 3 prior to depression of feed intake. Elevation of plasma NEFA concentrations started prior to DMI depression, on d 5 before parturition. Liver triglyceride infiltration did not occur until the concentration of plasma NEFA was maximized on d 1 after calving. This result implicated the acute rise in NEFA at calving as a contributing factor to triglyceride accumulation in the liver. The increasing plasma glucose and decreasing plasma BHBA prior to calving may have reflected metabolic changes toward gluconeogenesis. Liver glycogen decreased 70% during the final 19 d prior to calving. Hepatic triglyceride infiltration (7.7% DM basis) on d 1 post-partum and duration of DMI depression prepartum were less severe than those observed in previous studies. Frequent liver biopsies did not affect DMI.
选用9头妊娠但未泌乳的奶牛，监测其分娩前后肝脏甘油三酯的情况。评估采食量下降和分娩对血浆非酯化脂肪酸（NEFA）浓度及脂肪肝发展的影响。在产犊前第19、10、5、3和1天以及产犊后第1、7、14和21天采集肝脏活检样本和血浆样本。采食量下降始于产犊前第2天，在采食量开始下降前第3天，采食量下降了40%。血浆NEFA浓度在采食量下降前即开始升高，在分娩前第5天。直到产犊后第1天血浆NEFA浓度达到最大值时，肝脏才出现甘油三酯浸润。这一结果表明，产犊时NEFA的急性升高是肝脏甘油三酯积累的一个促成因素。产犊前血浆葡萄糖升高和血浆β-羟基丁酸（BHBA）降低可能反映了糖异生的代谢变化。产犊前最后19天肝脏糖原减少了70%。产后第1天肝脏甘油三酯浸润（以干物质计为7.7%）和产前采食量下降的持续时间比之前研究中观察到的情况要轻。频繁的肝脏活检未影响采食量。
