The early period of postnatal ontogeny of sheep is characterized by a variety of metabolic processes that result in the formation and consolidation of a certain type of metabolism. A special role is played by lipids, which together with proteins and carbohydrates constitute the bulk of organic compounds, cells and the organism as a whole. The purpose of this research was to study the polymorphism of CAST and GH genes as well as its association with the fatty acid composition of blood plasma lipids in lambs. The content of fatty acids was determined by gas-liquid chromatography in the form of methyl esters. From the data obtained, it follows that in all studied ontogeny periods the peripheral blood of sheep with CASTNN and CASTMM genotypes had a higher concentration of fatty acids such as palmitic, stearic, linoleic, and arachidonic acids. The content is as follows: 27.58, 45.40, 3.16, 0.28% vs. 26.21, 45.31, 3.62, 0.18% at the age of 2 months; 25.07, 43.25, 6.05, 1.74% vs. 23.24, 38.76, 6.49, 1.32% at the age of 4 months; 20.64, 22.26, 14.17, 3.38% vs. 17.64, 19.91, 15.07, 2.46% at the age of 8 months (P ˂ 0.05), (P ˂ 0.01). Studies of blood lipid composition of GHBBand GHAA genotype carriers showed that palmitic, stearic, linoleic, and arachidonic acids were dominant: 27.95, 27.96, 19.04% vs. 26.08, 23.88, 17.56% at the age of 2 months, 46.87, 39.87, 22.37% vs. 3.24, 6.87, 15.56% at the age of 4 months; 0.45, 1.68, 3.81% vs. 0.29, 1.29, 3.19% at the age of 8 months (P ˂ 0.05), (P ˂ 0.01). Thus, this study emphasizes that there is a close relationship between the ratio of fatty acids in total blood lipids in lambs and the intensity of growth and development, ensuring and controlling the direction of biochemical processes in the growth and development of young sheep.
