Effect of stocking density and dietary protein level on growth performance, feed utilization, blood parameters and body composition of mono-sex nile tilapia, Oreochromis nilotic'us (L.) [electronic resource].

Includes references.

The present study was carried out to determine the optimal level of dietary protein and rearing density on growth performances, feed utilization, blood parameters and body composition of monosex male Nile tilapia during the period from June to September, 2013. In a 2x3 factorial design, fish were stocked into two main groups ( l 00 and 200 fish/m3 ). Each group was divided into 3 sub-groups; the first, the second and the third were fed on a diet with 25, 30 and 35% crude protein, respectively. The obtained results could be summarized as follows: Fish group stocked at high density significantly (P<0.01) decreased by 31.85 and 34.38% in live body- weight and daily weight gain, \ respectively, more than low density. Daily feed intake in fish stocked at high density decreased with 21.54 %, more than those stocked at low density. On the other hand feed conversation was impaired with 18.75% in fish group stocked at high density when compared with those stocked at low level. Interaction of fish stocking density and dietary protein level, insignificantly affected live body weight, daily gain weight, feed intake and feed conversion. Alanine amino transferase (ALT) concentration only significantly (P<0.01) affected with stocking density, while serum total protein and albumin significantly (P<0.01 or 0.05, respectively) affected with dietary protein level. But, the other blood parameters studied insignificantly affected with stocking density, dietary protein level and their interaction. Dry matter of body composition significantly (P<0.01) affected with stocking density only, while crude protein, ether extract and ash insignificantly affected with stocking density, dietary protein level and their interaction. The best final profit margin recorded in fish group stocked at normal density and fed on diet with low protein level (25%). Based on the obtained results in the present study it could be concluded that, using stocking density by 100 fish/m3 and 25% crude protein resulted in the best performance and final profit margin.

Summary in Arabic.

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