Metallurgical enterprises are the main source of environmental pollution with heavy metals. Toxicants pose a serious threat to the consumer's health, so scientific research on diminishing their adverse effect on sanitaryhygienic properties of poultry meat is of high importance when organizing effective environmental management and ensuring food security. The purpose of the study is to devise a method for reducing a negative impact of heavy metals on productivity and sanitary-hygienic properties of meat by admixing adsorbents to a formulation of animal feeds. To analyse the concentration of heavy metals, the atomic adsorption method was applied. Experimental data were statistically processed using SNEDECOR application package. In the industrial territory of RNO-Alania, the prudent use of the adsorbents such as citrus pectin in the amount of 200 g/ton and Toxiban Max in the amount of 1000 g/ton admixed to barley-corn-soybean based feeds of local production allows achieving the maximum effect. Due to the synergistic effect of the tested drugs, there was an increase in the number of red blood cells, haemoglobin and bactericidal and lysozyme activities in the blood of the experimental birds; at the same time, the concentration of zinc lowered 1.98 times, lead-2.71 times and cadmium-2.03 times. The broiler chickens of the 4-experimental group were different from the 1-control analogues in weight parameters, slaughter yield and protein qualitative index which increased by 12.9%, 0.74% and 17.8% respectively. Zinc concentration in the examined muscle samples was 3.48 times lower than in the 1-control group, lead concentration-3.11 times and cadmium concentration-3.54 times.

This paper presents the results on the study of melanocortin-4 receptor (MC4R) gene polymorphisms in sheep of the Karachai breed. AA, AG, and GG genotypes were determined to have allele frequencies of 47%, 37%, and 16%, respectively, indicating that allele A and the homozygous AA genotype occurred the most frequently. Analysis of the meat productivity of sheep, with respect to the MC4R genotype, showed a higher slaughter yield in sheep with the AA genotype compared to those with either the GG or AG genotypes. The variability at these loci provides a basis for controlling the meat productivity of sheep in the Karachai sheep population; therefore, this polymorphism should be monitored and melanocortin-4 receptor (MC4R) gene selection considered in pedigree farms.

The article compares merino sheep imported from Australian plants in 2004 and 2007 compared and domestic merinos of leading breeding plants of Russia and Stavropol. Australian merinos imported in 2004 did not have a positive effect when crossed with Manich merino ewes. At the same time, the 2007 importation of Australian rams by differentiated selection of Manich merinos depending on their live weight and age, increased meat productivity of their offspring but reduced the level and nature of their wool productivity and comprehensive assessment of animals. In the herds of the Stavropol and Caucasian breeds, the best results were obtained when using stud rams of domestic breeding plants.

In the course of the research conducted at Agro-Soyuz LLC (Kabardino-Balkarian Republic, Chegemsky district), the goal was to study the productivity of 69 first-calf cows of the Gomitinsky black-andwhite breed, the daughters of three breeding bulls, depending on the forms of inheritance or the leading breeding characteristics of dairy productivity (milk yield, fat content), for the definitions of which were used by a new methodology, which is a modified version of the methodology widely used in breeding work with dairy cattle.As a result of determining the forms of inheritance of milk yield in experimental first-calf cows, it was found that the largest share among them fell on animals with milk yield due to such a form of inheritance as regression of the mother (44.9%), the smallest share – on first-calf cows with milk yield due to the dominance of the father (7.3%). When determining the forms of inheritance of fat milk, the same trend was observed as when determining the forms of inheritance of milk yield, that is, among 659 first-heifer cows, the most animals were from the mother regression group (42%), and the least were animals from the father dominance group (4,4%). The established difference between groups of first-calf cows with different forms of inheritance of the breeding trait turned out to be quite significant and reached, in some cases, 2368 kg in milk yield per lactation (p>0,999), 0,32% in fat content (p>0,99).

The problems of adaptation of a highly productive Holstein breed to new natural and climatic conditions and using their productive qualities are relevant. In order to study the influence of paratypical factors on the productive characteristics of Holstein cows, productive qualities of Holstein cows and their paternal half-sisters brought from the USA were compared. It has been established that during their first, second and third lactation periods, Holstein cows had better milk yield parameters than their paternal half-sisters brought from the USA. In Holstein cows, values of repeatability and heritability of milk yield parameters were higher than in their half-sisters. The influence of the “Region of reproduction” factor was observed for the milk yield per lactation. To the least extent, it was observed for the mass fraction of protein. The highest frequency, heritability, and factoriality of milk yield parameters were observed in Pilot’s daughters.