THE EFFECT OF LOW-PROTEIN FEEDS WITH FAT SUPPLEMENTS ON THE PRODUCTIVE PERFORMANCE OF CARP FRY

Productive effect was investigated of addition of fat supplements in f orm of rape-seed lecithin to feed pellets with differentiated protein content (20%, 26% and 32% crude protein) as exerted on carp fry. The t rial was carried out in controlled conditions with no natural food ava ilable. The results have shown that the favorable values of the indica tors of growth, feed coversion and protein efficiency ratio with respe ct to weight gains are depending upon the higher dietary supply of ene rgy in form of feed supplements if low-protein feed pellets are admini stered. All the investigated indicators were stimulated by supplementa tion of lecithin at a rate 6% of the feed weight. Administration of fa t-enriched feed pellets increased the relative daily weight gain on av erage by 60% and specific growth rate by 45% while the protein level w as identical. Feed conversion ratio decreased by 30% and PER values in creased by 43%. There were no differences in the values of the investi gated indicators between the 26% and 32% dietary protein levels when f at-enriched pellets were fed. Better conversion in the fat-enriched pe llets reduced the feed costs on average by 5.60 Kc per kg weight gain. On the basis of the above results it is possible to recommend for car p fry cultures in ponds the feeding of low-protein pellets (20-25% cru de protein) with increased contents of fat (7-8%) and digestible energ y (13 700-14 300 kJ(kg).