Fishery and biological evaluation of breeders of Galician and scaleless inbred types of the Ukrainian frame breed carp

Identifying the most optimal combinations of existing carp breeds enables achieving a desirable balance between growth, development, reproductive performance, resistance to various disease agents, and adaptability to cultivation conditions. Therefore, this study aimed to conduct a fishery and biological evaluation of breeders belonging to the Galician and the newly developed scaleless Lebedyn factory line inbred types of the Ukrainian frame carp breed. The research was carried out at the state enterprise Experimental Farm “Nyvka”. For the evaluation of external and productive characteristics, breeders of the Galician and scaleless Lebedyn factory line inbred types of the Ukrainian frame carp breed were selected. Based on measurement indicators, selection indices were calculated, including the condition factor, relative mass index, body length-to-height ratio, girth index, head index, and body thickness index. For the reproductive assessment of females, individual working fecundity and the average egg weight were measured. An analysis was conducted on the characteristics of male sexual products, including ejaculate volume, overall motility, the proportion of spermatozoa exhibiting linear progressive and circular movements, and the percentage of non viable spermatozoa. The findings revealed that females of the scaleless and Galician types demonstrated superior high-backed indices and relatively smaller heads based on morphological traits. However, no significant differences were observed in critical parameters such as body mass, body length-to-height ratio, and condition factor. Under factory reproduction conditions, females of both inbred types exhibited positive responses to hormonal stimulation. Fertility indicators for Galician-type females showed a working fecundity range of 476.0-576.0 thousand eggs, with an average relative fecundity of 89.55 ± 2.25 thousand eggs/kg. In scaleless females, working fecundity ranged from 372.0 to 543.6 thousand eggs, with an average relative fecundity of 74.83 ± 2.89 thousand eggs/kg. The practical significance of these findings lies in their application to further research on the cultivation and performance evaluation of hybrid offspring produced through reciprocal crossbreeding, compared to the original forms