Abstract
The article presents the results of the study conducted in 2024 to determine the effect of IGF1 gene polymorphism on the predisposition of cows to ketosis. The objects of the study were first-calving cows of the Kostroma breed from pedigree farms in the Kostroma region (n = 127). In the first 10 days after calving, peripheral blood in clinically healthy cows was analyzed for ketone bodies. As a result, the animals were divided into groups 1 and 2 with 0 -1.2 mmol/l ketone body content and above 1.2 mmol/l, respectively. The samples of DNA were isolated from the whole blood of experimental animals and genotyping was performed at the rs109763947 locus of the IGF1 gene by real-time polymerase chain reaction (RT PCR) with melting of fluorescent probes. It has been established that the studied cattle population is polymorphic at the IGF1 locus and is characterized by the complete absence of AA genotype carriers, the predominance and statistically significant (P<0.001) excess of AG heterozygotes (0.551–0.714), accompanied by an increased level of ketone bodies in the blood by 0.05 mmol/l (P<0.001) and a positive correlation of the concentration of ketones in the blood with a protein content in milk (r ho = 0.349, P<0.05), which indicates a possible breeding advantage of heterozygotes. The frequency of the A allele in group 1 was 0.078 less than in group 2 (P<0.001), which corresponded with the entry trend of A carriers to healthy group 2.06 times less often than to the group with subclinical ketosis. However, the odds ratio for these events is not significant, and the high coeffic ient of variation in ketone body levels among AG and GG carriers in group 2 (43.05 and 64.4 %, respectively) compared with group 1 (5.6 and 5.96 %, respectively) indicates the influence of other genetic factors on the predisposition to ketosis. This indicates the necessity to study the rs109763947 locus in combination with other DNA markers.