Feed conversion efficiency is an important determinant of profitability in catfish production. Understanding factors affecting feed conversion efficiency (FCE) at a physiological level could lead to improvement of FCE at production scale. Effects of sex, family and size grading within full-sib families on juvenile channel catfish (Ictalurus punctatus) growth, feed consumption, feed conversion, visceral fat accumulation, and weight loss during feed deprivation were determined. Correlations between traits were determined for each treatment within a trial.
In Trial 1, fingerlings from 5 channel catfish families were graded by weight into small, large and random mixed-size groups, fed for 8 weeks, subjected to 2 weeks of feed deprivation, and then euthanized to determine sex. In Trial 2, all-male, all-female and mixed-sex groups of channel catfish fingerlings were subjected to the same feeding regime and then euthanized to confirm sex and weigh visceral fat. Effect of fish sex, family, and size group within family were determined for mean increase in weigh, percent wait gain, residual feed intake, feed conversion ratio, weight-loss during feed deprivation, survival; and correlations among measured traits.
Males had a higher percent weight gain, better feed conversion, and less percent visceral fat than females; mixed-sex fish were generally intermediate between all-male and all-female groups. Feed conversion was positively correlated with visceral fat percentage in the all-female treatment (i.e. fatter fish had poor feed conversion), but feed conversion and visceral fat were not correlated in the mixed-sex or all-male treatments. Family had a significant effect on weight increase, percent weight gain, feed intake, feed conversion efficiency, and percent weight loss during feed deprivation. Within families, large fish had better growth, feed conversion efficiency, and lower percent weight gain than small fish. Mixed-sized fish were generally intermediate to small and large fish treatments for all measured traits. The correlation among weight loss during feed deprivation and feed conversion ratio for treatment effects was only marginally significant or not significant. Survival was near 100% in all treatments, and treatment had no effect on survival.
Family, fish size within family, and sex all affect feed conversion in juvenile channel catfish. The basis for the effect of fish sex (males superior to females for percent increase in weight, feed conversion, and less fat) should be determined in future research projects.