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A b s t r a c tMetabolic processes in milk-producing cows are substantially modified that is the main reason of different abnormalities in the reproductive function. At the same time the pattern of metabolic changes and its influence on the reproductive capacity in high-producing dairy goats (Capra hircus) are yet unknown. The aim of the present work was to study the activity of metabolic enzymes in the blood of Saanen goats depending on the period of the reproductive cycle and the competence for pregnancy maintenance. We analyzed for the first time alterations in the serum activity of enzymes, regulating the intensity of protein-carbohydrate and energy metabolism including integration of metabolic processes, at different stages of goat gestation as well as prior to the mating period in animals with the negative outcome of the subsequent pregnancy. The enzyme status of animals was assessed during the pre-mating period, the first half of pregnancy (1.5-2.5 months), and the second half of pregnancy (3.5-4.0 months). Goats were divided into two groupswith the completed reproductive cycle (the birth of viable offspring, n = 15) and with the interrupted reproductive cycle (abortions in the second half of pregnancy, n = 6). Samples of blood serum were tested to determine concentrations of total protein and activities of several enzymes: aspartate aminotransferase (AST, EC 2.6.1.1), alanine aminotransferase (ALT, EC 2.6.1.2 ), gamma glutamyltransferase (GGT, EC 2.3.2.2), creatine phosphokinase (CPK, EC 2.7.3.2), alkaline phosphatase (ALP, EC 3.1.3.1), lactate dehydrogenase (LDH, EC 1.1.1.27), and alpha hydroxybutyrate dehydrogenase (isoenzymes of LDH: LDH-1 and LDH-2). In goats with the completed reproductive cycle, the blood activity of AST in the second half of pregnancy was found to be 1.2 times lower (p < 0.05) than during the pre-mating period or the first half of pregnancy. The activity of ALT in the blood serum of the animals increased 1.3 times (p < 0.01) by 1.5-2.5 months of pregnancy as compared with the pre-mating period and then decreased 1.9 times (p < 0.001) by 3.5-4.0 months of pregnancy. Furthermore, there was a decline in the blood activities of GGT (1.3 times, p < 0.05), CPK (1.9 times, p < 0.01), and isoenzymes LDH-1 and LDH-2 (1.3 times, p < 0.05) and a rise in the activity of ALP (1.4 times, p < 0.05) between the first and the second half of pregnancy. During the pre-mating period, a lower activity of ALT and GGT was revealed in goats with the interrupted reproductive cycle as compared with animals retained pregnancy (14.4±2.9 vs. 20.1±0.7 U/l, p < 0.05 and 43.8±2.4 vs. 54.7±4.2 U/l, p < 0.05, respectively). The results of this research suggest a reduction in the intensity of some metabolic processes in the goats by the fourth month of pregnancy to maintain increased fetus demands. Analysis of the findings also indicates that the activity of enzymes, regulating the coupling of protein and carbohydrate metabolism, in the blood of goats during the pre-mating period may be related to their subsequent ...

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In our study, we estimated the frequency of haplotype for cholesterol deficiency (HCD) carriers in the Russian Holstein cattle population. We studied 1817 random samples of cows born in 2010-2017 from ten herds and 331 cows and heifers from the other three herds born in 2016-2019, fathers or fathers of mothers of which were HCD carriers. The method of AS-PCR was used for animals genotyping. In the first group of animals, the incidence of HCD carriers was 8.09%, and in the second one -23.26%. Our results demonstrated the necessity to test cows for the carriage of the HCD genetic defect in the Russian population of Holstein cattle.

The purpose of the work is to analyze the dynamics of the biochemical parameters of blood in the interlactation (dry) period in connection with the duration of the service period in the subsequent lactation in cows with different genotypes of the SCD1 gene according to rs41255693. The studies were carried out on Holstein cows with an average milk yield of 9807 ± 606 kg for 305 days of lactation. Animal genotypes (n = 23) were determined by PCR-RFLP: CC genotype (n = 9) and CT genotype (n = 14). Blood biochemical parameters were analyzed with an interval in the calving date of no more than 20 days: the CC genotype (n = 6) and CT genotype (n = 6). In cows with the CC genotype in the first month of the dry period, the concentration of total cholesterol in the blood was higher (p < 0.05), and AST activity tended to increase (p = 0.08) as compared with animals with the CT genotype. 30–10 days before calving, the total cholesterol content and AST activity in cows decreased (p < 0.05 and p = 0.055, respectively), while in animals with the CT genotype they did not change. Correlation analysis showed that the nu mber of correlation links was three times lower in cows with the CC genotype. The service period of more than 100 days is observed 2.3 times more frequent in cows with the genotype CC. The dynamics of metabolic processes and the peculiarities of the relationships between metabolic components in cows with the CC genotype are less optimal than in animals with the CT genotype, which may be associated with an increased frequency of a longer service period in cows with the CC genotype.