Breeding measures for the reproduction of first-time spawning female hybrids of carp and return crossing carp with the cultivation of their offspring

During the implementation of selection activities to develop a new highly productive breed of carp, a study was conducted on the production characteristics of the first-time spawning producers of the third generation of carp hybrids and backcrossed carp with an improver breed (Moscow scaly). As a result, the reproductive indices for working and relative reproductive capacity in backcrossed carp females were distinguished by higher values than in the third generation of carp hybrid females. Analysis of fishbreeding and biological parameters during pond rearing of five-year-olds and their offspring — yearlings of the studied carp groups revealed an insignificant difference in their average weight, but at the same time, a higher fatness coefficient according to Fulton in backcrossed carp, as well as their effective plastic metabolism in comparison with hybrids, which was confirmed by the obtained values of the feed coefficient. The exterior indicators for the running index in backcrossed carp had relatively lower values than those of hybrids, therefore, as a result of backcrossing of carp hybrids with the improver breed, a more pronounced high-backedness was observed. The use of the mass accumulation coefficient, reflecting the weight gain of carp over a certain period of time, made it possible to establish its synchronous change in the values of two age groups of carp (yearlings and five-year-olds) of carp hybrids and backcrossed carp during the vegetation period of the studies. The highest indicators for the mass accumulation coefficient were noted for both five-year-olds and yearlings of the two groups of carp in the period from June to July, which also corresponded to the intensive development of the natural food supply in the nursery ponds during this period of time.