Krnjaić Srđan, Cincović Marko, Djoković Radojica, Belić Branislava, Ježek Jožica, Starič Jože
Department of Veterinary Medicine, Faculty of Agriculture, Novi Sad, University of Novi Sad, Trg Dositeja Obradovića 8, 21000 Novi Sad, Serbia.
Department of Animal Science, Faculty of Agronomy Čačak, University of Kragujevac, Cara Dušana 34, 32000 Čačak, Serbia.
Metabolites. 2022 Nov 10;12(11):1090. doi: 10.3390/metabo12111090.
Increasing milk production requires increasing milking frequency (MF) from two times daily (2X) to three (3X) or more. High milk production leads to negative energy balance (NEB) and homeorhesis, characterized by lipolysis, ketogenesis, and endocrinological changes. The relationship among energy balance (EB), lipolysis, and ketogenesis with endocrine and metabolic parameters in blood of cows milked 2X and 3X daily was studied. Holstein Friesian cows milked 2X ( = 45) and 3X ( = 45) were analyzed, with approximately 50% of cows in each group in positive EB (PEB) and 50% in NEB. After determining EB, blood samples were collected from all cows and blood serum was analyzed for non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHB), glucose (GLU), cholesterol (CHOL), triglycerides (TGC), total bilirubin (TBIL), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), calcium (Ca), inorganic phosphate (P), total protein (TPROT), albumin (ALB), urea, insulin (INS), T3, T4, and cortisol (CORT), and the RQUICKIBHB index of insulin resistance was calculated. Cows milked 3X in NEB represent a special cluster that partially overlaps with cows milked 2X in NEB and has no contact points with cows in PEB. Cows milked 3X had higher levels of NEFA, BHB, AST, GGT, TBIL, and CORT and lower levels of GLU, Ca, INS, and T4. Cows milked 3X in NEB had higher levels of NEFA, BHB, AST, GGT, TBIL, and CORT and lower levels of GLU, CHOL, TGC, TPROT, P, INS, RQUICKIBHB, and T3 compared with cows milked 2X in NEB and cows in PEB. In cows milked 3X, lipolysis and ketogenesis were much more prominent, and EB levels were lower, implying a pronounced shift in homeorhesis. Metabolic and endocrinology parameters were determined mainly by the values of EB, NEFA, and BHB in cows milked 3X in NEB compared with other categories of cows. The results confirm the peculiarity of metabolic adaptation in cows with increased MF, characterized not only by differences in the concentration of metabolites but also in their interactions.
提高产奶量需要将挤奶频率（MF）从每天两次（2X）增加到三次（3X）或更多。高产奶量会导致负能量平衡（NEB）和同态调节，其特征为脂肪分解、生酮作用以及内分泌变化。本研究探讨了每天挤奶2X和3X的奶牛血液中能量平衡（EB）、脂肪分解、生酮作用与内分泌和代谢参数之间的关系。分析了每天挤奶2X（n = 45）和3X（n = 45）的荷斯坦弗里生奶牛，每组中约50%的奶牛处于正能量平衡（PEB），50%处于负能量平衡。确定EB后，采集所有奶牛的血样，分析血清中的非酯化脂肪酸（NEFA）、β-羟基丁酸（BHB）、葡萄糖（GLU）、胆固醇（CHOL）、甘油三酯（TGC）、总胆红素（TBIL）、天冬氨酸转氨酶（AST）、γ-谷氨酰转移酶（GGT）、钙（Ca）、无机磷（P）、总蛋白（TPROT）、白蛋白（ALB）、尿素、胰岛素（INS）、T3、T4和皮质醇（CORT），并计算胰岛素抵抗的RQUICKIBHB指数。处于负能量平衡的每天挤奶3X的奶牛代表一个特殊群体部分与处于负能量平衡的每天挤奶2X的奶牛重叠，与处于正能量平衡的奶牛没有接触点。每天挤奶3X的奶牛NEFA、BHB、AST、GGT、TBIL和CORT水平较高，而GLU、Ca、INS和T4水平较低。与处于负能量平衡的每天挤奶2X的奶牛和处于正能量平衡的奶牛相比，处于负能量平衡的每天挤奶3X的奶牛NEFA、BHB、AST、GGT、TBIL和CORT水平较高，而GLU CHOL、TGC、TPROT、P、INS、RQUICKIBHB和T3水平较低。在每天挤奶3X的奶牛中，脂肪分解和生酮作用更为显著，EB水平较低，这意味着同态调节发生了明显变化。与其他类别奶牛相比，处于负能量平衡的每天挤奶3X的奶牛的代谢和内分泌参数主要由EB、NEFA和BHB的值决定。结果证实了挤奶频率增加的奶牛代谢适应的特殊性，其不仅表现为代谢物浓度的差异，还表现为它们之间的相互作用。
