Features of growth and development of the skeleton in Simmental and crossbred steers during ontogenesis

Abstract

The results of age-related changes in the morphological composition of carcasses, features of growth and development of the axial and peripheral parts of the skeleton, and their constituent bones, Simmental and crossbred steers have been presented in the paper. The purpose of the research was to study the features of growth and development of the skeleton of Simmental and crossbred steers. The research has been carried out on the basis of the Tula Scientific and Research Institute of Agriculture – a branch of the Federal Research Center “Nemchinovka”. In order to conduct experiments 3 groups of steers have been formed per 15 heads in each with using the method of analogous pairs. Animals of Simmental breed were included in the 1st control group, and in the 2nd and 3rd experimental groups consist of 1/2-blood steers of beef Simmental and Charollais breeds, respectively, obtained from crossbreeding Simmental cows with sires of these beef breeds. The experiment lasted until the 18-month-old of steers. It has been found that the intensity of bone growth in the axial and peripheral parts of the skeleton was due to age-related changes in the absolute and relative bone mass of steers. The intensity of growth of the axial part of the skeleton in the postnatal period increased, and the peripheral decreased. The ribs and spine were characterized by the increased growth rate, while the thoracic and pelvic limbs were characterized by the lower growth rate. The intensity of bone growth in the proximal parts of the limbs exceeded that of the distal parts. Age-related differences in the intensity of growth of the skeletal parts led to changes in the ratio between the linear body size and the features of the steers’ constitution. The value of the long-legness indices in Charolais crossbreds decreased from 65,4 at birth to 53,6 and 46,6 at the age of 6 and 12 months, respectively, while the lengthiness indices on the contrary increased and in these age periods amounted to 93,4, 105,4 and 114,9, respectively.