Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract Only
Publication Acceptance Date: October 6, 2004
Publication Date: January 5, 2005
Citation: Davis Jr, K.B. 2005. Influence of the photoperiod on feed consumption, growth, intraperitoneal fat composition and insulin-like growth factor-i on sunshine bass [abstract]. Book of Abstracts, Aquaculture America. p. 100. Technical Abstract: Sunshine bass (Morone chrysops X Morone saxatilis) about one year old were raised for 7 weeks in round 700 liter tanks supplied with 23 oC flowing well water and air. Four tanks were randomly stocked with 30 sunshine bass which weighed 131.4 + 1.63g. Two tanks were exposed to a 16 hour photoperiod (L) and two tanks were exposed to an 8 hour photoperiod (S) for the first three weeks. At the end of the first three weeks one of the tanks on the L photoperiod was changed to the S photoperiod (LS) and one of the tanks on the S photoperiod was changed to the L photoperiod (SL). Fish were fed to satiation by hand during the first 2 hours of the light period by offering feed until 1 minute passed with feed in the tank without any feeding. Beginning at the end of the second week of the study all fish in each tank were weighed and 6 fish from each treatment were bled and the intraperitoneal fat (IPF) was dissected, weighed and expressed as a % of the body weight (IPF%). Blood samples were centrifuged and the plasma frozen and later analyzed for insulin-like growth factor-I (IGF-I) concentration and expressed as ng/ml. Individual body weight of the fish grew for the first month of the study and were stable for the last three weeks. Feed consumption decreased during each sample period. These effects were attributed to the increased size of the fish and to the decreasing density of the fish as samples were removed from each tank each week. By the end of the experiment only six fish remained in most tanks. Feed consumption decreased during the experiment from an initial 3 to 4% of the body weight per day during the first 2 weeks to about 1 % of the body weight per day for the last week. IPF was increased during the experiment from about 4.5% at the first sample to about 6.4% by the end of the experiment. IGF-I concentrations were higher in the long photoperiod group than other treatments only in the third week sample and did not correlate with size of the fish. There was no consistent effect of the length of the photoperiod on any of the parameters measured.