Effect of Different Feeding and Feed Deprivation Cycles on Growth Performance of Nile Tilapia (Oreochromis niloticus)
By
A.Suloma, M.A. Elnady, M.A. Salem
M.M. Abd El Hamid
(Department of Animal Production. Faculty of Agriculture. Cairo University, Cairo, Egypt).
Abstract:-
Nile Tilapia juveniles (24.8g/fish) were subjected to four feeding regimes (32 fish per tank) that included three deprivation and re-feeding cycles for a duration of 84 days. Each feeding cycle constituted one treatment. The one day deprivation cycle included feed deprivation for one day followed by three days re-feeding period. The two-day deprivation included feed deprivation for two days followed by six-day re-feeding period. The three days deprivation cycle included feed deprivation for three days followed by nine-day of re-feeding period. All food deprivation cycles were repeated all over the experimental period. The control treatment was fed to satiation every day without any period of food deprivation. Nile tilapia was fed with commercial extruded diet (32% crude protein). Starting with initial weights of 24.4-25.2 g/fish at the start of the experiment. Nile tilapia grew to 55.0 -71.3 g/ fish at harvest time, with significant differences in growth patterns among treatments (P<0.05). Fish within food deprivation treatment did not differ significantly in terms of final body weight which ranged from 55.0 to 63.02 g/fish (p<0.05). However, the control treatment had a higher body weight by 13 to 29% compared with all feed deprivation treatments. This was expected since the control fish groups that consumed more food intake 0.86 g diet/fish/day compared to all feed deprivation groups consumed 0.54 to 0.7 g diet/fish/day during the course of the experiment (P<0.05). when comparing weight gain and total feed intake of the 3 days fasting cycle (42.08 g diet/fish and 59.0 g diet/fish, respectively) with those of the control treatment (46.6 g/ fish and 72.7 g/ fish, respectively), it can be concluded that despite fish were exposed to three-day fasting cycle, weight gain was lower by 19% while total feed intake was lower by 18% compared to the continuous feeding control treatment. During fasting period (21 days in each of the three cycles) Fish consumed energy for routine metabolism needed for survival. Energy required for fish survival during the fasting period (21 days) was obtained from dietary energy consumed during re-feeding periods. This should have negatively affected feed conversion ratio if this energy were to be deduced from the feed intake fed during the experiment. All fasting treatments had similar feed conversion ratio compared to the continuos feeding ( control) group (P<0.05) which indicate that FCR in the food deprivation groups was compensated during re-feeding by a decrease in metabolic costs or an improvement in feed utilization.
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