Evidence of differences in growth and food intake regulation in different genetic strains of channel catfish |
| |
Authors: | J T Silverstein ‡ W R Wolters M Holland † |
| |
Institution: | USDA/ARS Catfish Genetics Research Unit, P.O. Box 38, Thad Cochran National Warmwater Aquaculture Center, Stoneville, MS 38776, U.S.A.;Mississippi State University, College of Veterinary Medicine, Department of Radiology, Mississippi State, MS 39762, U.S.A. |
| |
Abstract: | Norris and USDA-103 strains of channel catfish Ictalurus punctatus were compared for growth rate and food conversion ratio under satiation feeding and restricted feeding (1% body weight day?1) regimes. At the start of the experiment Norris fish weighed 2·8 g, USDA-103 fish weighed 14·0 g. Therefore, a regression of the loge of specific growth rate against the loge of mean body size with an empirically derived fixed slope of -0·37 was used to compare growth rates. Under both feeding regimes the USDA-103 strain had faster specific growth rates and more efficient food conversion. In subsequent studies, voluntary food intake of size matched fish (60 g average) from these two strains was compared using a radiographic method. Fish were acclimatized to tank conditions for 3 weeks prior to voluntary food intake measurement. Half of the groups were deprived of food for 2 days prior to food intake measurement, while the remaining groups were fed 1% body weight day?1. The USDA-103 strain fish ate significantly more food and grew faster than the Norris strain fish. Previously fasted Norris fish subsequently ate more than their fed counterparts, whereas the fed USDA-103 fish consumed more food than the fasted USDA-103 group. When the USDA-103 strain fish were deprived of food for 4 , 2 or 0 days, all groups subsequently consumed between 4·5 and 5·0% of body weight in one meal. The USDA-103 fish, unlike the Norris fish were not stimulated to consume more after short-duration fasting. Taken together, these results suggest that there are genetic differences in growth, food conversion ratio and regulation of food intake between Norris and USDA-103 strains. |
| |
Keywords: | channel catfish Ictalurus punctatus food intake regulation growth |
|
|