Effects of dietary protein levels on the growth of Luciobarbus xanthopterus juveniles (Heckel, 1843)

Abstract

The aim of the present study is to investigate the effect of four fish dietary protein levels (30%, 35%, 40% and 45%) on the growth of Luciobarbus xanthopterus juveniles. About 240 fish of average weight of 18.4 g were kept in eight small letter tanks for 8 weeks at the Marine Science Center aquaculture room. Two replicates for each treatment with 30 fish for each replicate were used. A number of growth parameters were estimated during the experiment. The environmental factors measured were; water temperature, DO, salinity and pH. The highest average weight gained was 21.14 g ± 0.33 with the 40% dietary protein level, while the lowest average weight was 19.68 g ± 0.50. The highest weight gained was recorded at 40% dietary protein level. The highest weight gain and weight increase were significantly different (p<0.05) at 40% dietary protein level. Their values were 21.14 g ± 0.33 and 2.11 ± 0.06, respectively. The lowest weight gain and weight increase were at 45% protein level, with values of 19.68 g ± 0.50 and 1.09 ± 0.05, respectively. The weight increase was 2.11 ± 0.06. Significant differences (p<0.05) have been noticed in this protein level, however, the other dietary levels showed no significant increase. The highest rate of daily weight increase were recorded at the 30%, 35% and 40% levels and the significant differences (p<0.05) among these levels were in apparent. However, the weight increase rate of 2.12 was dropped at 45% level to 1.41 ± 0.033. The highest rate of specific growth was recorded at the 35% protein level with value of 0.31 g/day with no significant differences (p<0.05) between the various levels. Finally, it could be concluded from this study that the lowest specific growth 5.64% was recorded at the 45% protein level and the highest relative growth 11.06% was recorded at the dietary protein level of 35%.