H. Randall Robinette

Effects of dietary cottonseed meal and gossypol on growth of young channel catfish

Abstract Ten isonitrogenous and isocaloric diets containing different percentages by weight of cottonseed ineal or gossypol acetate were fed to age-0 channel catfish Ictalurus punctatus for 8 weeks. Growth was inhibited when fish were fed diets with more than 17.4% cottonseed meal or with 0.09% and greater free gossypol. Fish fed cottonseed meal at 17.4% or greater had higher wholebody concentrations of free gossypol than fish fed lower amounts. Free gossypol in muscle tissue was less than that recommended as safe for human consumption. Free gossypol was most concentrated in liver and kidney tissue. Channel catfish utilized lysine hydrochloride when a diet was supplemented with that amino acid.

Changes in Proximate and Fatty Acid Composition of Fillets from Channel Catfish during a Two-Year Growth Period

Abstract Channel catfish Ictalurus punctatus were reared for 2 years on practical feeds with and without a topdressing of oil (50% animal, 50% vegetable). Visceral fat, fillet fat, and whole-body protein increased and moisture percentage decreased as fish size and age increased. Slopes of regression lines for these variables differed significantly between treatments. Fatty acid profiles of fillets showed essentially linear trends toward decreasing saturation and increasing unsaturation with increasing size and age of fish. Within the unsaturated fatty acids, monene levels increased, and diene and triene levels decreased. Topdressing with oil did not affect these trends. Although dietary lipid composition is a major influence on fatty acid composition in channel catfish, this study indicates that fish size and age also significantly influence fatty acid profiles.

Evaluation of Male Bluegill X Female Green Sunfish Hybrids for Stocking Mississippi Farm Ponds

Abstract Supplemental feeding and the presence of largemouth bass (Micropterus salmoides) had a positive influence on the size of male bluegill (Lepomis macrochirus) x female green sunfish (Lepomis cyanellus) hybrids in 12 Mississippi ponds during the first 24 months after stocking young-of-the-year hybrids. After 24 months, the size of hybrids that had supplemental feeding and were stocked without largemouth bass was similar to that of hybrids stocked with largemouth bass but without supplemental feeding. Nonfed hybrids stocked without largemouth bass were the smallest of the four group combinations; fed hybrids with largemouth bass were the largest. Largemouth bass predation reduced recruitment of F 2 hybrids by 98% relative to F1 hybrid populations without bass. Growth of these hybrids exceeded that reported for the same hybrid in Illinois ponds and was superior to that which can be expected from bluegills under typical pond conditions in Mississippi. Catchability experiments in two of the ponds confir...

Commercially important traits of blue and channel catfish as related to second summer, winter, and third summer growth

Abstract Several commercially important characteristics of blue and channel catfish were compared for three successive growth periods. One-year-old blue (Ictalurus furcatus) and channel catfish (I. punctatus) averaging 111 g and 117 g, respectively, were stocked into triplicate 0.05-ha ponds at 9694 fish/ha in June 1987. The same fish were restocked at 8078 and 5132 fish/ha the following winter and summer, respectively. Growth, survival, and feed conversion of the two species during summer 1987 and 1988 were not significantly different (P > 0.05), but growth and feed conversion were superior for channel catfish in the winter period; thus, channel catfish were significantly larger at the end of the winter and summer 1988 periods. Gonadosomatic indices were significantly lower in blue catfish than in channel catfish in summer 1987 and winter periods, but not different in 1988. Visceral fat percentage and whole body fat composition in blue catfish in summer 1988 were greater than in channel catfish. Protein level of whole body and fillets of the two species was not significantly different for any period. Winter whole body dress-out percentage was higher in blue catfish, but not different in summer 1988.

Polyculture of the freshwater prawn (Macrobrachium rosenbergii) with a mixed-size population of channel catfish (Ictalurus punctatus)

Abstract Channel catfish of sizes ranging from 0.03 to 0.57 kg and juvenile freshwater prawns (mean wet weight = 0.52±0.40 g) were stocked into four 0.06-ha ponds at densities of 11 120/ha and 4942/ha respectively. The growout period was 132–133 days. At harvest the mean wet weight of the catfish and prawns ranged from 0.63 to 0.72 kg and 33.8 to 42.3 g, respectively. Survival of prawns and catfish was >87% except in one pond where a disease outbreak reduced catfish survival to 70%. Prawn production averaged 172 kg/ha. Approximately 75% of all the harvested prawns had a wet weight that exceeded 30 g. Male prawn populations, composed of three morphotyes (blue claw, orange claw, small), evidenced less variation in wet weight than that previously observed in monoculture populations. Harvesting techniques which permit selective harvest of the prawns appear to be required for practical polyculture.

Effect of Selected Vitamin E Supplementations of Channel Catfish Production Feeds

Abstract Pond-raised fingerling and adult channel catfish (Ictalurus punctatus) fed commercial production feeds (which contained an estimated 13 and 25 mg/kg endogenous vitamin E in summer and winter feeds, respectively) supplemented with 72 and 144 mg vitamin E (as dl-∝-tocopherol acetate) per kilogram feed showed no significant differences (P > 0.05) in mean survival, feed conversion, weight gain, hematocrit, or erythrocyte fragility compared with channel catfish fed the same production feed supplemented with 36 or 66 mg/kg vitamin E.

Role of Stocking Sequence on Survival of Fingerling Channel Catfish Cultured in Mixed-Size Populations

Abstract Replacement channel catfish Ictalurus punctatus are typically stocked as fingerlings into commercial grow-out ponds following partial harvest of large fish. To determine if timing of subsequent stocking of fingerlings into mixed-size populations influences fingerling survival, we examined the effects of stocking large and small fish 2 weeks after initial stocking of large fish. Fifty large (mean weight = 374 g) and 50 small (25 g) catfish were stocked into two 1,323-L tanks. Tank 1 was stocked with large fish and maintained for 14 d; on day 14, small fish were added. Tank 2 was stocked with large and small fish simultaneously on day 14. A third tank was stocked with 100 small fish only on day 14. Three ponds (0.05-ha each) were also used in the same design with large fish (240 g) and small fish (30 g). On day 15, all fish were harvested and counted to determine 24-h survival. This procedure was replicated over three trials in both the tank and pond studies. Survival of small fish stocked 14 d aft...

Competitive Feeding Interactions between Small and Large Channel Catfish Cultured in Mixed-Size Populations

Abstract Production of channel catfish Ictalurus punctatus in ponds may be affected by competitive feeding interactions between large fish that remain after incomplete harvest and small fish that are stocked following harvest. To study the effect of channel catfish size on competition for feed, we examined consumption by feeding colored feeds sequentially to fish held either in raceways or ponds. Colored feeds were created by adding pigments to a floating catfish feed (35% crude protein). A preliminary study showed no significant differences in consumption of the colored feeds, suggesting no selection for color. Following a 2-week conditioning period in the raceway or pond, mixed-size fish populations were fed a red and green feed sequentially at 1% body weight for each. Fish were subsequently sacrificed and red and green colored feeds were separated from the stomach contents. In the raceway, small fish consumed a significantly higher mean percentage of red feed (59.3%) than large fish (50.4%). In an unre...

Reproductive Isolation between a Hybrid Sunfish and Its Parental Species

Abstract Attempts to backcross F1 male bluegill (Lepomis macrochirus) x green sunfish (Lepomis cyanellus) hybrids with females of each parental species were unsuccessful both in ponds and in the laboratory. In laboratory experiments, fertilization was accomplished but embryos failed to survive longer than 36 h. In ponds, nesting and courting activity were observed but successful reproduction did not occur. Additionally, 1,874 of 1,983 F1 hybrids examined (94.5%) were males.

Effects of Dietary Catfish and Menhaden Oils on Hybrid Striped Bass Production

Abstract Hybrids of female striped bass Morone saxatilis and male white bass M. chrysops were stocked at 14,000 fish/ha in earthen ponds and fed an experimental diet supplementally sprayed (2.5% by weight) with either catfish oil (CO) or menhaden oil (MO). The sprayed diet contained n-3 highly unsaturated fatty acids (HUFA, with four or more double bonds) at 1.10% and 1.54% of diet for CO and MO, respectively. Fish were fed to apparent satiation twice daily for 212 d in three replicate 0.05-ha ponds per diet. There were no significant differences (P < 0.05) between CO and MO diets in mean total weight offish at harvest (590 and 585 g, respectively), percent weight gain (584% and 576%), survival (87% and 91%), or feed conversion (weight of feed as fed/fish weight gain: 2.50 and 2.31). Mean intraperitoneal fat (IPF) to body weight ratios of fish were not different (4.8% for CO and 4.4% for MO). Females had a significantly higher IPF ratio (5.2%) than males (4.7%) across both diets. There were no significant...