Показатели оценки племенной ценности по линейной оценке экстерьера в зависимости от коэффициента инбридинга и уровня гомозиготности

Abstract

Abstract. Purpose. A study was carried out to assess the influence of the inbreeding coefficient, calculated according to the Wright – Kislovsky formula, and level of homozygosityon calculated on STR-markers the indicators of the assessment of breeding value according to the linear assessment of the exterior. Methods. The object of the study were the daughters (n = 42 245) of 355 Black-and-White and Holstein sires in the Moscow region. The calculation was made taking into account at least 10 daughters per sire. The entire data array for EBV amounted to 42076 heads of cattle, for 318 sires and was divided into four groups with respect to (Fx): the first included outbred animals (0 %), the second with Fx = 0…3.125, the third with Fx = 3.126…6.25, in the fourth with Fx ≥ 6.25, and in the fifth all animals except outbreds. For the STR calculation, the total sample was 306 sires for 39,590 daughters. So, the first group included heterozygous individuals Ca = 0 %, the second individuals with Ca = 8…50 %, the third with Ca = 55…77 %, the comparison group consisted of individuals with Ca = 8…77 %, which is on average sample 28.74 %. Results. It was noted that there was no significant difference “classic” calculation by means of gradation of the coefficient inbreeding between the studied groups of animals, with the exception of body depth, rear legs set, teat length, chest width and angularity (p ˂ 0.05... – p ˂ 0.001) according to the “B” rating system. The results of calculations by STR markers in general had similar dependencies: the angle of the hind legs in the side view from –0.055 in the first group to 0.109 in the third, the location of the front nipples from –0.129 to 0.179. The regression coefficient increased along with the minimum number of daughters per sire used in the calculations in terms rear legs set, rear udder height and udder depth. Scientific novelty. For the first time in Russia, the influence of the astimated breeding value according to the linear assessment of the conformation, depending on the coefficient of inbreeding and the level of homozygosity, calculated by STR markers, will be investigated.