INFLUENCE OF STRAIN OF SIRE ON CHANNEL X BLUE F1 HYBRID CATFISH FRY PRODUCTION AND FINGERLING PERFORMANCE UNDER FARM CONDITIONS
Channel x blue hybrid catfish is presently the desired aquaculture species in US farm-raised catfish industry. Even though production and performance has improved over the last two decades, several production and performance parameters needs to be improved to maximize the genetic potential of this superior aquaculture species.
D&B and Rio Grande strain of blue catfish, Ictalurus furcatus are the only domesticated strains of blue catfish sired with stripped channel catfish, I. punctatus eggs to produce channel x blue F1 catfish hybrid embryos in commercial catfish hatcheries. Production performance of hybrid catfish fingerling and food fish vary because of the variation in heterosis and combining ability among strains. Hence, the present study was conducted to examine the influence of strain of the sire (D&B and Rio Grande blue catfish) on hybrid catfish embryo production and fingerling performance in four replicated ponds under commercial farm conditions.
Eight spawning trials were conducted with 400 four-year old female Gold Kist strain of channel catfish in a commercial catfish hatchery. Female catfish were induced to spawn with 10 mg common carp pituitary extract (CPE) /kg BW. The stripped eggs were fertilized with sperm of either D&B or Rio Grande blue catfish to produce either D&B or Rio Grande hybrid catfish embryos. Average testes weight (g /kg BW) was higher (P<0.05) in Rio Grande (1.98+0.28) compared to D&B (1.02+ 0.12) blue catfish males. Hatching parameters between Rio Grande and D&B hybrids did not differ (P>0.05).
Approximately 100,000 hybrid catfish fry produced (D&B or Rio Grande hybrids) from each spawning trial were stocked in individual 0.4 ha pond to raise fingerlings. The average individual body weight between D&B hybrid and Rio Grande hybrid fingerling did not differ at 9 months of age. However, mean survival (99.3%), production (8875 kg/ha), and feed conversion (1.14) of D&B hybrids were superior (P <0.05) to Rio Grande hybrid catfish fingerlings survival (88.0), production (7469 kg/ha) and feed conversion (1.25) raised in replicated ponds under farm conditions.
The implications of the study to further improve hybrid catfish fry production in commercial hybrid catfish hatcheries and fingerling production in production ponds will be discussed.