CHANGES IN THE REPRODUCTIVE FUNCTION OF FEMALES AND MALES OF SILVER-BLACK FOXES WITH DIFFERENT VARIETY OPTIONS
The age structure of the total number of silver and black foxes for breeding in the basic farm is determined. It is found that the largest share in the total mass of livestock is occupied by one-year individuals (44.0-34.3%). While the lowest in number were females of five and six years of age, who were similar in proportion and occupied 0.5%.An analysis was made of race data and variants of age-matched selection of parental pairs were evaluated by such indicators as the number of female puppies, the number of newborn puppies per main female and the female. t was found that in the homogeneous selection of parental pairs by age, the most successful were combinations of three and four-year-old individuals, which outnumbered the other groups by 61.0 and 4.3%. There were no significant differences in the fertility of females between variants of heterogeneous selection of parental pairs by age. According to the level of preservation of the offspring obtained in variants of homogeneous selection of parental pairs, which averaged 87.7 and 85.7%, with fluctuations ranging from 86.7% to 88.5% at the time of removal and from 83.3% to 87 , 4% before slaughter, no group difference. With the use of heterogeneous selection of parental pairs, the mean values of this indicator were almost similar in all variants of combinations (87.4–86.2%). Although, for the first time breeding females and males of all age groups, there were lower retention rates of puppies both from birth to breeding (by 2.4–2.7%) and from breeding to slaughter (0.9 -1.9%) than two, three and four years of age. The worst viability of young animals (83.3%) during the whole period of its cultivation was noted by the pair ♀1x♂1. Based on the distribution of females by the number of born puppies, it was found that 72.6% of the females, regardless of the choice of parental pairs, were multiple-fertile, 22.4% - medium-fertile and only 5.0% - infertile. It was found that, based on a single breeder in the case of production operation of homogeneous selection of parental pairs, the best puppy yield indicators were characterized by ♀3–4♂3–4 combinations, which outweigh the ♀1x ♂1 pairs by 2.16 heads or 82.4% (g <0.05) and a combination of пар2х♀2 pairs - by 0.39 heads or 8.9%. In the heterogeneous variant of parenting, the most puppies were characterized by pairs of ♀3–4x♂≥5 (6 heads), whereas the least successful were the під1x♂2 and ♀1x♂3–4 pairs (3.55–4.44 heads).