EFFECTS OF INITIAL BODY SIZE AND DIETARY PROTEIN LEVELS ON PRODUCTIVE PERFORMANCE OF NILE TILAPIA( Oreochromis niloticus). | ||
| Journal of Animal and Poultry Production | ||
| Article 8, Volume 29, Issue 7, July 2004, Pages 3819-3830 PDF (3.24 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/jappmu.2004.239291 | ||
| Author | ||
| A. A. Nour, | ||
| Department of Animal Production, Faculty of Agriculture {Daman hour), Alexandria University, Damanhour, Egypt. | ||
| Abstract | ||
| Nile tilapia (Oreohromis niloticus) with different initial body sizes were divided into three size groups (mean initial size): small (1.5 g), medium: (9.0g) and large : (16.0 g) and reared for 112 days in glass aquaria. Under each size, the fish were divided into five groups and fed on five experimental diets containing 15 ,20,25,30 and 35% dietary crude protein levels. Ten fish were placed randomly in each of 30 glass aquaria (100 I water capacity/each) in order to study the effects of the initial body size and dietary protein levels on the growth performance and feed and nutrients utilization of tilapia. Fish were hand fed twice daily, six days a week at rate of 4% of its body weight. The results indicated that the absolute values of fish weight (g/fish) , fish gain and average daily gains were significantly (P<0.05) increased with increasing the initial body size from 1.5 to 9.0 and 16 g /fish, receptively. However, values of specific growth rate (SGR%) were significantly (P<0.05) decreased with increasing the initial body size. On the other hand, increasing dietary protein levels from 15 to 35% CP significantly (P<0.05) increased growth performance criteria. Fish body composition at the end of the experiment showed a slight increase in carcass dry matter and crude protein contents with increasing the initial body size and dietary protein levels. However, values of carcass ether extract and ash were decreased. Energy contents (Kca1/100g) of fish carcass at the end of the experiment were similar in all treatments. The results showed that values of feed conversion ratio (FCR) , protein utilization {expressed as protein efficiency ratio (PER) and protein productive value(PPV%)}and energy utilization (EU)were significantly (P<0.05) improved with increasing the initial fish body size . However, values of FCR and EU% were significantly (P<0.05) improved but PER and PPV% were decreased with increasing the dietary protein levels. Finally, it could be concluded that small size fish was more efficient and achieved higher growth performance than large size fish. Increasing the dietary protein level from 15 to 35% CP increased the growth performance, however, feed utilization criteria were decreased. | ||
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