Center for Free Radical and Biomedical Research (CEINBIO) Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
Departamento de Producción Animal y Pasturas, Facultad de Agronomía, Universidad de la República, Montevideo, Uruguay.
PLoS One. 2019 Mar 14;14(3):e0213780. doi: 10.1371/journal.pone.0213780. eCollection 2019.
Early lactation is an energy-deming period for dairy cows which may lead to negative energy balance, threatening animal health and consequently productivity. Herein we studied hepatic mitochondrial function in Holstein-Friesian multiparous dairy cows during lactation, under two different feeding strategies. During the first 180 days postpartum the cows were fed a total mixed ration (70% forage: 30% concentrate) ad libitum (non-grazing group, G0) or grazed Festuca arundinacea or Mendicago sativa plus supplementation (grazing group, G1). From 180 to 250 days postpartum, all cows grazed Festuca arundinacea were supplemented with total mixed ration. Mitochondrial function was assessed measuring oxygen consumption rate in liver biopsies revealed that maximum respiratory rate decreased significantly in grazing cows during early lactation, yet was unchanged in non-grazing cows during the lactation curve. While no differences could be found in mitochondrial content or oxidative stress markers, a significant increase in protein lysine acetylation was found in grazing cows during early lactation but not in cows from the non-grazing group. Mitochondrial acetylation positively correlated with liver triglycerides β-hydroxybutyrate plasma levels, well-known markers of negative energy balance, while a negative correlation was found with the maximum respiratory rate sirtuin 3 levels. To our knowledge this is the first report of mitochondrial function in liver biopsies of dairy cows during lactation. On the whole our results indicate that mitochondrial function is impaired during early lactation in grazing cows that acetylation may account for changes in mitochondrial function in this period. Additionally, our results suggest that feeding total mixed ration during early lactation may be an efficient protective strategy.
泌乳早期是奶牛能量需求旺盛的时期，可能导致奶牛处于负能量平衡状态，从而威胁奶牛健康和生产性能。本研究旨在研究泌乳期荷斯坦奶牛肝脏线粒体功能，在两种不同的饲养策略下：产后 180 天内，奶牛自由采食全混合日粮（粗饲料：精饲料=70:30，非放牧组，G0）或放牧芦竹或紫花苜蓿并补充精饲料（放牧组，G1）；从 180 天到 250 天，所有放牧芦竹的奶牛都补饲全混合日粮。通过测量肝活检中的耗氧量来评估线粒体功能，结果表明，放牧奶牛在泌乳早期的最大呼吸速率显著下降，但非放牧奶牛在泌乳曲线中没有变化。虽然在线粒体含量或氧化应激标志物方面没有差异，但放牧奶牛在泌乳早期的蛋白质赖氨酸乙酰化水平显著增加，而非放牧奶牛则没有。线粒体乙酰化与肝甘油三酯和β-羟丁酸血浆水平呈正相关，这些是负能量平衡的已知标志物，而与最大呼吸速率和 sirtuin 3 水平呈负相关。据我们所知，这是首次报道泌乳期奶牛肝脏线粒体功能的研究。总的来说，我们的研究结果表明，放牧奶牛在泌乳早期的线粒体功能受损，乙酰化可能是该时期线粒体功能变化的原因。此外，我们的结果表明，在泌乳早期补充全混合日粮可能是一种有效的保护策略。
