Department of Population Health and Reproduction, University of California, Davis 95616.
Purina Animal Nutrition, Gray Summit, MO 63090.
J Dairy Sci. 2022 Aug;105(8):7036-7046. doi: 10.3168/jds.2021-21599. Epub 2022 Jul 2.
Mitochondria are central to metabolism and are the primary energy producers for all biosynthesis, including lactation. The objectives of this study were to determine if high- and low-producing dairy cows exhibit differences in peripheral blood mononuclear cell mitochondrial enzyme activities of citrate synthase, complex I, complex IV, and complex V during early lactation and, thus, to determine whether those differences were related to differences in lactation performance in the dairy cow. Fifty-six Holstein cows were assigned to 1 of 4 groups: (1) primiparous high, (2) primiparous low, (3) multiparous high, or (4) multiparous low. Primiparous and multiparous cows were analyzed separately. Then, cows were divided into high or low production groups for each production parameter [peak milk, average milk, energy-corrected milk (ECM), fat-corrected milk (FCM), milk lactose, milk fat, milk protein, total solids (TS), solids-not-fat, feed efficiency, and somatic cell count (SCC)]. For all data analysis, production parameters are expressed as yields (kg/d) and SCC (10 cells/mL). High and low production groups were defined by their respective mean production parameters for the 56 cows, with below average cows defined as low and above average cows defined as high. Whole blood samples were collected at one time point, approximately 70 d in milk at 0800 h, and processed for crude mitochondrial extracts from peripheral blood mononuclear cells to determine the activity rates of mitochondrial enzymes. Milk samples were collected 9 times (3 d, 3 times per d) during the week of blood collection and analyzed for major components (fat, protein, lactose, TS, and SCC). Multiparous cows had lower citrate synthase activity than primiparous cows across all production parameters. High-producing cows had greater complex I activity for peak milk, milk yield, ECM, FCM, milk fat, TS, and feed efficiency, and greater complex V activity for ECM, FCM, milk lactose, milk fat, and TS across parities. These findings imply that the most influential respiratory chain enzymes on the level of milk production are those responsible for electron transport chain initialization and ATP production.
线粒体是新陈代谢的核心，也是所有生物合成的主要能量产生者，包括泌乳。本研究的目的是确定高产奶牛和低产奶牛在泌乳早期外周血单个核细胞线粒体柠檬酸合酶、复合物 I、复合物 IV 和复合物 V 的酶活性是否存在差异，以及这些差异是否与奶牛泌乳性能的差异有关。将 56 头荷斯坦奶牛分为 4 组中的 1 组：（1）初产高产，（2）初产低产，（3）经产高产，或（4）经产低产。分别分析初产和经产奶牛。然后，根据每个生产参数[峰值奶、平均奶、能量校正奶（ECM）、脂肪校正奶（FCM）、奶乳糖、奶脂肪、奶蛋白、总固体（TS）、非脂固体、饲料效率和体细胞计数（SCC）]将奶牛分为高产或低产组。所有数据分析中，生产参数均表示为产量（kg/d）和 SCC（10 细胞/mL）。高产和低产组由 56 头奶牛各自的平均生产参数定义，低于平均值的奶牛定义为低产奶牛，高于平均值的奶牛定义为高产奶牛。在一个时间点采集全血样本，大约在产奶第 70 天 0800 时，从外周血单个核细胞中提取粗线粒体提取物，以测定线粒体酶的活性率。在采血周内采集 9 次（3 天，每天 3 次）奶样，分析主要成分（脂肪、蛋白质、乳糖、TS 和 SCC）。所有生产参数中，经产奶牛的柠檬酸合酶活性均低于初产奶牛。高产奶牛在峰值奶、奶产量、ECM、FCM、奶脂肪、TS 和饲料效率方面的复合物 I 活性更高，在经产方面在 ECM、FCM、奶乳糖、奶脂肪和 TS 方面的复合物 V 活性更高。这些发现表明，对产奶水平影响最大的呼吸链酶是那些负责电子传递链初始化和 ATP 产生的酶。
