Młynek Krzysztof, Strączek Ilona, Głowińska Beata
Faculty of Agrobioengineering and Animal Sciences, Institute of Animal Science and Fisheries, Siedlce University of Natural Sciences and Humanities, 08-110 Siedlce, Poland.
Faculty of Animal Breeding and Biology, Department of Animal Physiology and Physiotherapy, Bydgoszcz University of Science and Technology, 85-084 Bydgoszcz, Poland.
Metabolites. 2022 May 17;12(5):448. doi: 10.3390/metabo12050448.
Intensive lactation (lactogenesis) in cows is conducive to a negative energy balance (NEB), so the search for traits associated with the physiological capacity to cope with its consequences is a current area of research. This is especially important because NEB overlaps with the resumption of the reproductive cycle, which determines the profitability of herds. This study analysed the relationship between NEB and the time of resumption of reproductive activity in cows with varying genetic potential (Simmental and Holstein-Friesian), fed a similar diet (TMR). The aim of the study was to analyse the dependencies between NEB markers and changes in progesterone levels between 25 and 31 days postpartum. A strong positive correlation was shown between daily milk production (DMP) and loss of body condition (LBCS; 0.772; ≤ 0.05). These parameters were associated with the levels of NEB biomarkers. Higher values of NEB indicators (LBCS, C16:0, C18:1, NEFA, and BHBA) were usually noted during periods with higher DMP (II and III). The trends observed were confirmed by positive correlation coefficients (r), which ranged from 0.324 to 0.810 ( ≤ 0.05). The reverse trend was noted for glucose and leptin, which decreased as productivity increased, as confirmed by r values from -0.368 to -0.530 ( ≤ 0.05). In both breeds, the glucose and leptin levels decreased as DMP increased. Higher values for NEB indicators were shown to be negatively correlated with progesterone levels (r from -0.300 to -0.712; ≤ 0.05), and a lower progesterone level was associated with a longer calving-to-first-service interval and calving-to-conception interval. The rate of postpartum triglyceride release depends on daily milk production, and therefore the adaptability of the liver should be considered an important element of mitigation of the consequences of NEB. This may have practical applications by extending productive life, which is often shortened due to deteriorating reproductive performance.
奶牛的高强度泌乳（泌乳生成）会导致能量负平衡（NEB），因此寻找与应对其后果的生理能力相关的性状是当前的一个研究领域。这一点尤为重要，因为能量负平衡与繁殖周期的恢复重叠，而繁殖周期决定了牛群的盈利能力。本研究分析了不同遗传潜力（西门塔尔牛和荷斯坦 - 弗里生牛）、采食相似日粮（全混合日粮）的奶牛能量负平衡与繁殖活动恢复时间之间的关系。该研究的目的是分析能量负平衡标志物与产后25至31天孕酮水平变化之间的相关性。日产奶量（DMP）与体况损失（LBCS；0.772；≤0.05）之间呈现出强烈的正相关。这些参数与能量负平衡生物标志物的水平相关。在日产奶量较高的时期（II期和III期），通常会观察到能量负平衡指标（LBCS、C16:0、C18:1、非酯化脂肪酸和β - 羟基丁酸）的值更高。观察到的趋势通过正相关系数（r）得到证实，其范围从0.324至0.810（≤0.05）。葡萄糖和瘦素则呈现相反的趋势，随着生产力的提高而下降，r值范围为 - 0.368至 - 0.530（≤0.05），证实了这一点。在两个品种中，随着日产奶量的增加，葡萄糖和瘦素水平均下降。较高的能量负平衡指标值与孕酮水平呈负相关（r从 - 0.300至 - 0.712；≤0.05），较低的孕酮水平与较长的产犊至首次配种间隔和产犊至受孕间隔相关。产后甘油三酯的释放速率取决于日产奶量，因此肝脏的适应性应被视为减轻能量负平衡后果的一个重要因素。这可能通过延长生产寿命而具有实际应用价值，生产寿命常常因繁殖性能下降而缩短。
