Effects of Mixed Feeding Schedules with Two Dietary Protein Levels on Growth Performance, Body Composition and Serum Biochemical Indexes of Junvenile Hybrid Tilapia (Oreochromis niloticus♀×O.aureus♂)

The present experiment was conducted for 60 days to investigate the suitability of cyclical feeding with two dietaries on the growth performance, feed utilization, body composition and serum biochemical indexes of hybrid tilapia (Oreochromis niloticus♀×O.aureus♂) with the initial body mass of (3.10±0.05) g. Seven different feeding regimes employed were: 27.49% protein diet (hereafter referred to as a) continuously (group A), 20.55% protein diet (hereafter referred to as b) continuously (group B), one day a followed by one day b ( group 1A/1B), 2 day a followed by 2 day b (group 2A/2B), 2 days of a followed by 3 days of b (group 2A/3B), 3 days of a followed by 2 days of b (group 3A/2B) and 3 days of a followed by 3 days of b (group 3A/3B). Each feeding regime fed three replications. The results were as follows: group B had the worst growth performance. Compared to specific growth rates of 1A/1B, 2A/3B and 3A/2B were not significantly different from group A (P>0.05), but their protein efficiency ratios and protein retention rates were remarkably higher (P<0.05), and feeding costs were significantly lower (P<0.05). Viscerosomatic indexes of group A, group 3A/2B and group 3A/3B were significantly lower than those of the other groups (P<0.05). Survival rate of group 1A/1B was not significantly different from that of group A (P>0.05), but it was obviously lower than that of the other groups (P<0.05). Whole body moisture contents of group A, group 1A/1B, group 2A/3B and group 3A/2B were obviously lower than those of group B (P<0.05). Crude fat content of group A was obviously lower than that of the other groups (P<0.05). All the groups except group B had no significantly different crude protein contents compared with group A. Mixed feeding schedules had a significant influence on serum biochemical indices (P<0.05): compared with group A, the activities of aspartate amino-transferase and glutamic-pyruvic transaminase in the serum decreased, the levels of albumin, globulin and total protein rose, and the contents of total cholesterol, high density lipoprotein cholesterol and low density lipoprotein cholesterol increased. This experiment indicated that group 3A/2 B was the best feeding regime.