Author
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Small, Brian |
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Submitted to: Book of Abstracts World Aquaculture Society
Publication Type: Abstract Only Publication Acceptance Date: 11/25/2003 Publication Date: 3/1/2004 Citation: Small, B.C. 2004. Differences in feed efficiency and nutrient utilization between and within channel catfish strains and families. Aquaculture 2004, Honolulu, HI. p. 548. Interpretive Summary: Technical Abstract: Improving channel catfish growth and feed utilization are two important goals of selective breeding programs. The newest channel catfish strain (NWAC103) to be introduced to the United States catfish industry was selected for increased growth rate. Researchers and farmers alike attribute the 10-20% higher growth rates of the NWAC103 strain to increased food intake relative to other strains of catfish. It is not clear, however, whether feed efficiency or nutrient utilization were improved with selection for growth rate. NWAC103 strain fish were compared to Norris strain catfish in an effort to determine differences in feed efficiency and nutrient utilization. Variability within strains was also assessed by randomly selecting four families from each strain for comparison. A double-blind study was conducted in 23-L aquaria each stocked with ten 25 g full-sib fish, and families were replicated in four aquaria. All fish were fed to near satiety daily for 6-wk. Upon study completion, indices of weight and length gain, feed efficiency, body composition, and nitrogen and energy balance were determined. On average, NWAC103 fish gained significantly (P<0.05) more weight (51.2 vs.31.7 g) and length (4.7 vs. 4.1 cm), respectively compared to Norris fish. Significantly (P<0.05) poorer feed consumption (41.3 vs 56.6 g) and feed efficiency (89.9 vs.95.7) for Norris fish no doubt contributed to the lower growth rates. Family differences in weight and length gain and feed intake were significant (P<0.05) between NWAC103 families, whereas only differences in feed intake and feed efficiency were significant (P<0.05) between Norris families. Significant (P<0.05) differences in nitrogen and gross energy intake within both strains were positively correlated to feed consumption. Norris strain catfish, however, had significantly (P<0.05) higher overall nitrogen retention (35.6%) relative to the NWAC103 strain average (31.0%). Norris strain catfish also had higher (P<0.1) body protein and lower (P<0.1) body fat composition. These results reiterate the superior growth of the NWAC103 strain catfish due to increased feed consumption, and demonstrate improved feed efficiency relative to Norris strain catfish. The slower growing strain of catfish (Norris) appears to be more efficient in converting consumed protein to body protein. To our knowledge this is the first study to compare differences in nitrogen and energy balance between NWAC103 and another strain of catfish. |
