The dissertation is devoted to studying polymorphism in genes of growth promoting hormone GH and pituitary-specific positive transcription factor PIT-1, genetic structure of the herd and associations with polymorphism in milk productivity genes, bio-energetic features, signs of pulmonary respiration, gas-energy exchange, age of early insemination, fertility, measurements and indices of the exterior, skin thickness, linear characteristics of the type, indicators of economic efficiency with intensive use of Holstein cows.
It was determined that milk yields, milk fat and protein yield in the GHLL genotype and PIT-1AB genotype of cows were larger (Р > 0,95-0,999) during the first and second lactations. The greatest lactotropic effect was shown by the paired genetic complex LL/AB with the part of influence on the main indicators of milk productivity from 26.6 to 30.2% at P > 0.999.
During the first two lactations, a positive correlation was found with the homozygous genotype of GHLL of milk yield (r = +0,503…0,505 with Р > 0,999), milk fat yield (r = +0,503…0,505 with Р > 0,999) and milk protein yield (r = +0,520…0,530 with Р > 0,999), with their high frequence (rw = 0,673…0,884 with Р > 0,99-0,999).
According to the results of bioenergy assessment, it was found that cows of genotype GHLL and genotype PIT-1AB, as well as paired genetic complexes LL/AB and LL/BB, compared to peers of genotype LV, BB and LV/BB had higher values of pure milk energy, total net energy outgo, energy index, productivity index, amount of energy released with milk per 1 kg of metabolic mass with a reliable result (Р > 0,99-0,999) in most cases.
When comparing the influence of L and V alleles of AluI-polymorphic site of the growth promoting hormone GH gene and A and B alleles of HinfI-polymorphic site of the pituitary-specific positive transcription factor PIT-1 on pulmonary respiration and gas-energy exchange, a higher metabolic status was revealed in LL/AB and LL/ВB genotypes of cows, which lung ventilation was more intensive per 1 kg of body weight, the amount of consumed oxygen and released carbon dioxide was greater, and heat production was higher compared to their peers of the LV/BB genotype (P > 0.95)
The influence of polymorphism in GH and PIT-1 genes on the age of early insemination of replacements was revealed (P > 0.95). It was found that the reduction of this age is possible by selecting animals of the LL/AB and LL/BB genotypes, they have this age occurred a month earlier (7.7 and 7.0%) compared to heifers of the LV/BB genotype.
Studies of measurements and exterior indices, as well as signs of linear type assessment showed that cows of complex genotype LL/AB were higher at the shoulder and rump compared to peers of genotype LV/BB and LL/BB; they received a higher score for height, breast width, width of loin in pin bones, the strength of rear udder attachment, the strength of the body structure (P > 0.95–0.99).
Compared with peers of the LV/BB genotype, more incremental main product was obtained from cows of the complex genotype LL/AB (13.9%) and LL/BB (9.6%) during 305 days of the second lactation, and the cost of incremental main product per cow amounted to 12,901.6 UAH and 8,573.9 UAH, respectively.
