Submitted to: Annual Meeting World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 31, 2006
Publication Date: December 15, 2006
Citation: Davis Jr, K.B., McEntire, M.E. 2006. Effect of photoperiod on feeding, intraperitoneal fat, and IGF-I in sunshine bass. Annual Meeting World Aquaculture Society. 37:431-436. Interpretive Summary: The effect of the length of the lighted component (photoperiod) during the 24 day on growth, feed conversion, intraperitoneal fat and plasma concentrations of insulin-like growth factor-I were determined in sunshine bass. Fish were held on a long or a short day length and then the photoperiod was reversed. The fish were fed to satiation once each day for five weeks and feed was withheld for the last 2 weeks of the experiment. Fish were weighed, feed consumption calculated, and the amount of intraperitoneal fat and plasma insulin-like growth factor-I determined at the end of each week. Feed consumption, body weight, intraperitoneal fat and plasma IGF-I concentrations were all high for the first three weeks of feeding, however all of these components decreased during the last 2 weeks of feeding. Neither body weight or peritoneal body fat decreased markedly during the last 2 weeks of no feeding and the IGF-I levels remained at the lowest concentration during that period. There was no apparent effect of the length of the photoperiod on any of the components measured.
Technical Abstract: Growth, feed conversion, intraperitoneal fat content and plasma concentrations of Insulin-like growth factor-I (IGF-I) of sunshine bass were compared on fish held on a short (8h), a long (16h), photoperiod, or after the fish were switched from one photoperiod to the other. Fish were fed daily to apparent satiation for up to four weeks and were not fed for the last two weeks of the experiment. Body weight and intraperitoneal fat content increased for the first 2 weeks of the experiment then remained steady for the remainder of the experiment and feed consumption decreased from 3.5% during the first 2 weeks to about 1.5% for the second 2 weeks and finally to only 1% during the last week of feeding. IGF-I concentrations fell steadily during the entire experiment and was at the lowest level during the last two weeks when the fish were not fed. There was no consistent effect of the photoperiod in any of the exposure conditions.