PRODUCTION ABILITY OF DIFFERENT LINES OF CARP FRY AT DIFFERENT LEVEL OF PROTEIN IN FEED

Intensity of growth and ability to utilize feeds were studied in ten different strains of carp fry of the generation F1 of domestic and imported parental carps. The trials were performed in comparable experimental conditions eliminating the presence of natural food. The carp fry was tested for the production effect of feedstuffs of different protein contents (12; 24; 34 %). Two feed mixtures were used (S1 and S3) and wheat as a control feed. In the tested strains of carp fry, different demand for proportion of protein in the feed was manifested by differentiated intensity of the growth, feed conversion and protein utilization for increment. By comparatively highest growth intensity and the best feed conversion were distinguished the populations of hybrid scaly strains of carp fry marked C 591, C 626, C 667 and C 700. The carp fry of the strains C 623 and C 700 manifested also comparatively higher ability to utilize the cereal feed ration. Of the used feeds, a mixture with higher proportion of protein (S3) stimulated the indicators under study, under the given conditions of the trial. A higher daily increment was recorded on an average by 24 % in application of the mixture S3 in comparison with the mixture S1, and the specific growth rate was higher by 29.5 %; the feed consumption was lower by 5.8 % and the PER values were higher by 6.6 % than in the application of the mixture S1. The knowledge obtained was used in the breeding programmes studying the introduction of re-bred strains of fry carp marked by high performance and resistance into the breeding practice.