In solving the problem of qualitative improvement of beef breeds, it is important to improve the methods of practical use of existing parent couples selection methods, using histocompatibility antigens, polymorphic proteins and blood group systems. The purpose of the thesis is to determine the influence of homogeneous and heterogeneous selection of parent couples by blood group factors on the weight and linear growth of bulls of Ukrainian beef breed. The Ukrainian beef breed was bred using four breeds and is characterized by high variability in polymorphic features. The type of parent selection was determined by the index of B antigen similarity (ras) of cattle blood groups. The formula of D.A. Zhyvotovskyi and A.M. Mashurov was used to calculate the index of antigenic similarity of parents. Selection by ras of parents ≥ 0,268 was considered homogeneous, and by ras ≤ 0,267 heterogeneous. It has been proven that bulls that are descended from their parents with more ras pravail in the test on average daily gains and have a higher live weight. If ras of the parents is over 0.268, animals tend to improve their growth rate up to 8 months of age. After weaning this trend persists. The average daily gain of bulls obtained from parents with ras up to 0.267 is better in the period from 15 to 18 months, which indicates their lower precocity. If the antigenic similarity index of parents is more than 0.268, the animals are better in terms of the severity of meat forms at the age of 15 and 18 months. At the age of 15 months, bulls obtained from homogeneous selection by ras have smaller height measurements, better developed front of the torso in width and depth of the chest, longer torso and buttocks. Homogeneous selection of parental couples according to the B antigen similarity index of blood groups leads to improvement of weight growth and severity of meat forms of bulls of Ukrainian beef breed.
During reproductive crossing, the genetic diversity of animals increases and the problem of consolidating livestock by type and productivity arises. Blood group antigens are one of the factors that indicate genetic variability, so they can be used as markers when selecting parent pairs. The purpose of this study was to analyse the meat productivity, development of internal organs and accumulation of adipose tissue in 18-month-old bulls derived from different selection of their parents according to the index of antigenic similarity (ras) of the B system of blood groups at the first stages of a complex reproductive cross between Simmental and grey Ukrainian cattle with breeders of Charolais and Kian breeds. According to the value of ras, the bulls were divided into two groups. In the first – from a homogeneous selection of parents (over 0.268; n=9); in the second – from heterogeneous (ras up to 0.267; n=7). After slaughtering the bulls, the meat productivity, mass, and output of the head, liver, lungs, and other organs and glands of internal secretion were determined. Intermuscular, interstitial, perirenal, pregastric, intestinal, and pericardial fat were separated and weighed. With homogeneous selection of parents, their sons, in comparison with their peers from heterogeneous mating, show a tendency to increase the content of muscles (by 4.2%), fat tissue in carcasses (by 12.4%), including between muscles (by 1.1 points). There is 11.6% less pulp per kilogram of bones, 17.2% worse muscle tissue index, 7.8% less absolute weight of liver, 10.0% of kidney, 27.8% of heart, head – by 2.0% and lungs – by 11.6%. In bulls, from the heterogeneous selection of parents with ras to 0.267, there is 7.2% more fat tissue in the body, including internal fat tissue by 7.8%, the relative mass of bones is 0.8 points higher. The practical use of homogeneous selection according to antigens of blood groups of crossbreed parents allows improving the morphological composition of the carcasses of their offspring. Heterogeneous selection promotes better development of internal organs, which are less valuable slaughter products
During the selection of parents of future bulls of meat breeds, the problem of improving the main signs of meat productivity is a priority. Search for techniques that would additionally influence the effectiveness of using future bulls using conventional breeding methods determines the relevance of this study. The purpose of the study was to determine the influence of the selection of parent pairs based on antigens of the B blood group system on the results of lifelong use of bulls of Ukrainian beef cattle, created by the method of the complex reproductive crossing of four different breeds. The study was conducted by comparing the performance of bulls assigned to different groups by the antigenic similarity index (ras) of their parents. By ras value over 0.150 formed a group of progenies from a homogeneous selection of parents (n=5). In the group from a heterogeneous selection of parents (n=5), the indicator ras less than 0.150. The libido of bulls was tested in the arena by the time of manifestation of sexual reflexes when receiving sperm on an artificial vagina. Within the groups, the age of bulls at the time of first sperm collection, life and productive use, the number of ejaculates received and culled, and the quality and fertilising ability of sperm were determined. It was identified that in bulls obtained from the homogeneous selection of parents by ras compared to peers from heterogeneous mating, there is a tendency to increase the age of initiation of sperm collection by 33.9%. They also have a longer productive use expectancy by 6.3% and a longer life expectancy by 21.5%. Bulls obtained from heterogeneous selection during use have more leads to the scarecrow by 13.6% and predominate in the number of ejaculates obtained. The percentage of ejaculate culled is twice as high. Bulls from homogeneous selection have a higher (by 15.3 points) share of active manifestation of sexual reflexes, a larger volume of ejaculate, better indicators of sperm motility and concentration, fewer culled ejaculates, and a higher fertilisation capacity of sperm by 18.2 points. The results obtained should be used in the selection of bulls for potential mothers of valuable bulls of the Ukrainian beef breed and in other livestock populations created by the method of complex reproductive crossing
Various molecular genetic markers are used to comprehensively assess the breeding value of animals based on genetic information. Therefore, an important place in the qualitative improvement of beef cattle breeds is occupied by the improvement of methods of animal selection using the immunogenetic characteristics of their blood. The purpose of the study is to determine the dependence of weight growth and meat productivity of animals of the Ukrainian beef breed on the number of similar antigenic factors of the B blood group system in them and their mothers. After weaning, the first group contained bulls (n = 12) who had similar antigens from 2 to 6 inclusive. The second group (n = 15) – from 7 to 13. When studying the features of weight gain and meat productivity of bulls, it was proved that the similarity in the B system of cattle blood groups between mother and offspring is informative regarding the homo- or heterozygosity of the latter. It was found that animals with a lower amount of antigens similar to the mother outperformed (by 9.3%) homozygous peers in the test from 8 to 18 months of age in terms of average daily weight gain and had a higher live weight (by 8.0%) at 18 months, indicating their better early maturity. With lower antigenic similarity between mother and offspring, the expression of meat forms is 7.8% and 6.0% higher, respectively, at 15 and 18 months of age.After slaughter, there is no significant difference between homozygous and heterozygous bulls in terms of meat productivity, including pre-slaughter live and slaughter weight. When selecting offsprings with fewer antigens similar to their mother, they tend to reduce the slaughter yield (by 0.5 points) and the muscle content in carcasses (by 3.2%). The selection of bulls of Ukrainian beef breed with a smaller number of antigens of the B blood group system, similar to mothers, will help to improve their weight growth and the expression of meat forms, and will allow predicting future meat productivity
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