Abstract
The purpose of research is to study the growth and development of bulls in the conditions of JSC Krasnoyarskagroplem in the Krasnoyarsk Region. Objectives: to study changes in live weight, linear measurements and body composition indices during ontogenesis. The object of the study is bulls of the Holstein (red-motley) (n = 11) and red-motley (n = 4) breeds aged from one to five years. Study period: 2014–2019. Calculation of absolute growth, taking body measurements, and calculation of indices were carried out according to generally accepted methods. Holstein bulls at all age periods exceeded red-motley bulls in height at the withers and oblique length of the body. Bulls of the red-motley breed in chest width at one year of age exceeded Holstein sires by 3.25 %; at 1.6 years – by 13.8 (P > 0.95); in the 2-year period – by 14.1 (P > 0.999); in a 3-year-old – by 7.59; in a 4-year-old – by 6.1; in a 5-year-old – by 9.7 % and metacarpal girth: by 3.1; 2.4; 1.3; 4.5 % (P > 0.95), by 2.4 and 1.2 %, respectively. The variabi-lity of traits in bulls of the Holstein and red-motley breeds was characterized by a low degree at all age periods, which indicates the homogeneity of the population and high stability of exterior qualities. Calculation of indices characterizes red-motley bulls as compact with a low-set body, having a long body and a deeper chest. Holstein bulls have higher legs. Red-mottled breed and Holstein bulls have a pronounced milk type.
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