The present study was designed to test the intra-specific crossing of two Egyptian populations from African catfish （Clarias gariepinus）, EI-Manzalah catfish （MCF） characterized by tolerates for poor water quality...The present study was designed to test the intra-specific crossing of two Egyptian populations from African catfish （Clarias gariepinus）, EI-Manzalah catfish （MCF） characterized by tolerates for poor water quality and easily farmed in captivity and EI-Qanater catfish （QCF） characterized by rapid growth and high quality flesh, for hybrid vigor, production and food processing to create new high quality products. Crosses of these populations were carried out in EI-Gamalia hatchery, EI-Manzalah, Egypt, during spring of 2008 between MCF~~ QCF~. African catfish hybrid, MCF and QCF fingerlings with a mean weight of 24.02 ＋ 1.38 g were stocked at a density of 50-fish per m3 in cages （112 m3 each） suspended in lake El-Manzalah. Fish were fed a formulated diet containing 31.20% crude protein and cultured for 214 days. The growth, survival and production data confirmed that catfish hybrid has been successful and showed a strong heterotic effect. Hybrid catfish had a significantly highest production, 47.5 kg per m3 and best feed conversion ratio （1.33） which demonstrates that cages are a viable alternative to ponds for the commercial production of African catfish and its hybrids. Recently, the African catfish market has required more processed products. The results indicated that： （1） there are slightly variations in African catfish population＇s products quality; and （2） the hot-smoked and fried-coated fish fillets products are more safe foods and acceptable to consumers due to their physic-chemical properties and microbial load acceptable results.展开更多
A 10-week rearing trial was conducted in cages with average initial weight of 9.15 ± 0.2 g/fish and average initial length of 9.2 ± 0.02 cm/fish of meagre, Argyrosomus regius, to examine the effect of three ...A 10-week rearing trial was conducted in cages with average initial weight of 9.15 ± 0.2 g/fish and average initial length of 9.2 ± 0.02 cm/fish of meagre, Argyrosomus regius, to examine the effect of three stocking density on growth performances, production traits, feed utilization and body composition. Nine cages 24 m3 each (4 × 6 × 1.5 m, long, width and height) were stocked with either 1200, 3600 and 6000 fish for each cage to give a stocking rate of 50, 150, and 250 fish/m3 respectively and fish fed daily, slightly in excess of satiation to eliminate the possibility of food supply being a limiting factor to growth. The results revealed that, mean final weight (g/fish), gain in weight, SGR (%per day), feed conversion ratio, protein efficiency ratio and total feed intake (g/fish) were significantly (P ≤ 0.01) influenced. The best at the lowest stocking density, while, the total production and net production exhibited significantly the opposite trend. Harvest and production estimates increased with increasing stocking density. Fish body composition% of moisture, protein, fat and ash were significantly (P ≤ 0.01) influenced by stocking density. From the above results and the economic information of the study, it can be concluded that stocking density of 50 fish/m3 of meagre exhibited the highest net profit and would seem to be the most desirable density in the system studied.展开更多
文摘The present study was designed to test the intra-specific crossing of two Egyptian populations from African catfish （Clarias gariepinus）, EI-Manzalah catfish （MCF） characterized by tolerates for poor water quality and easily farmed in captivity and EI-Qanater catfish （QCF） characterized by rapid growth and high quality flesh, for hybrid vigor, production and food processing to create new high quality products. Crosses of these populations were carried out in EI-Gamalia hatchery, EI-Manzalah, Egypt, during spring of 2008 between MCF~~ QCF~. African catfish hybrid, MCF and QCF fingerlings with a mean weight of 24.02 ＋ 1.38 g were stocked at a density of 50-fish per m3 in cages （112 m3 each） suspended in lake El-Manzalah. Fish were fed a formulated diet containing 31.20% crude protein and cultured for 214 days. The growth, survival and production data confirmed that catfish hybrid has been successful and showed a strong heterotic effect. Hybrid catfish had a significantly highest production, 47.5 kg per m3 and best feed conversion ratio （1.33） which demonstrates that cages are a viable alternative to ponds for the commercial production of African catfish and its hybrids. Recently, the African catfish market has required more processed products. The results indicated that： （1） there are slightly variations in African catfish population＇s products quality; and （2） the hot-smoked and fried-coated fish fillets products are more safe foods and acceptable to consumers due to their physic-chemical properties and microbial load acceptable results.
文摘A 10-week rearing trial was conducted in cages with average initial weight of 9.15 ± 0.2 g/fish and average initial length of 9.2 ± 0.02 cm/fish of meagre, Argyrosomus regius, to examine the effect of three stocking density on growth performances, production traits, feed utilization and body composition. Nine cages 24 m3 each (4 × 6 × 1.5 m, long, width and height) were stocked with either 1200, 3600 and 6000 fish for each cage to give a stocking rate of 50, 150, and 250 fish/m3 respectively and fish fed daily, slightly in excess of satiation to eliminate the possibility of food supply being a limiting factor to growth. The results revealed that, mean final weight (g/fish), gain in weight, SGR (%per day), feed conversion ratio, protein efficiency ratio and total feed intake (g/fish) were significantly (P ≤ 0.01) influenced. The best at the lowest stocking density, while, the total production and net production exhibited significantly the opposite trend. Harvest and production estimates increased with increasing stocking density. Fish body composition% of moisture, protein, fat and ash were significantly (P ≤ 0.01) influenced by stocking density. From the above results and the economic information of the study, it can be concluded that stocking density of 50 fish/m3 of meagre exhibited the highest net profit and would seem to be the most desirable density in the system studied.
