Abstract

The aim of the study was to research the polymorphism of allelic variants of somatotropin GH genes and pituitary-specific transcription factor PIT-1 and its influence on bioenergetic parameters of high-yielding of Holstein breed cows in intensive milk production technology (cold method of growing heifers, early insemination of heifers. high daily operating loads on the body, etc.). Genotypes of cows were determined by PCR. Blood DNA was examined in a genetic laboratory. Isolation of genomic DNA was performed using resin “Chelex-100”. The reaction was performed in an amplifier “Tertsyk”. For the energy assessment of first-born cows used indicators of net maintenance energy (MJ per day), net milk energy (MJ per day), total net energy consumption (MJ per day), the value of the energy index (the share of energy released from milk, %), productivity index (kilogram of 4 % milk per 1 MJ), net energy consumption per 1 MJ of milk (MJ), energy released with milk per 1 kg of metabolic mass (MJ). The best energy parameters in cows by GH gene – LL genotype, by pituitary-specific transcription factor PIT-1 – AB genotype, and among paired genotypes – LL/AB and LL/BB. In these animals, bioenergetic indicators for the first and second periods of lactation were higher than their peers of LV, BB and LV/BB genotypes by 2.0–15.2 %, with a reliable result for most traits. In particular, during the first lactation period, the advantage of cows of the LL/AB genotype over the LV/BB genotype in terms of bioenergetic indicators was 3.9–15.2 %, significantly less than in the second lactation period in the range of 1.8–7.4 %. In the genome of pituitary-specific transcription factor PIT-1, better bioenergetic parameters were found in cows of genotype AB than in cows of genotype BB. The difference in bioenergetic parameters is explained by the higher lactotropic function of the L and A alleles, and is the result of a greater complementary effect on the functioning of the alleles of the associated genes in the complex genotype. This was confirmed by the analysis of variance of one-factor complexes, which revealed a stronger influence of genotypes on bioenergetic parameters during the first period of lactation than the second. However, the strength of the influence of the paired genotype on the GH and PIT-1 genes was always high regardless of the lactation period and ranged from 8.9 to 20.9 % (P < 0.01–0.001). In the future, it is of interest to study the formation of the exterior and constitution of cows of different genetic influences under the influence of polymorphisms in the GH and PIT-1 genes.

Highlights

  • For the development of dairy farming requires new methods for assessing the biological characteristics of the animal body in terms of intensive technology of milk production at high operating loads on the body (VanRaden & Sullivan, 2010; Mylostyvyi et al, 2019; Trakovická et al, 2019)

  • While analyzing the collected scientific data (Table 1), it can be noted that according to the results of energy evaluation of Holstein cows of different genotypes by the GH gene for the first lactation, animals of the LL genotype were the best

  • Our data coincide with the results of research by other scientists (Krupin & Shakirov, 2019), who evaluated the energy performance of cows depending on the polymorphism in several genes, including the GH and PIT-1 genes

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Summary

Introduction

For the development of dairy farming requires new methods for assessing the biological characteristics of the animal body in terms of intensive technology of milk production at high operating loads on the body (VanRaden & Sullivan, 2010; Mylostyvyi et al, 2019; Trakovická et al, 2019) One such method is the assessment of energy metabolism in dairy cows, in particular the determination of energy expenditure for live weight maintenance and milk synthesis (Petrenko et al, 2005). Some scientists have established the influence of the type of constitution on the energy performance of cows (Chernenko, 2012; Chernenko & Chernenko, 2018) and ecogenesis (Denysyuk, 2009). Studies of the influence of the genotype of cows on the genes of somatotropin GH and pituitary-specific transcription factor PIT-1 have not been conducted before, which determines the relevance and scientific novelty of this problem

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