Replacing three levels of fish meal with soybean meal in diets of Cyprinus carpio cultured at salinity

Abstract

This  research was conducted to evaluate the effect of partial replacement of fish meal with soybean meal on the growth of common carp Cyprinus carpio (Linnaeus, 1758)  cultured at 12‰   salinity in the period (15 April-29June)2022.

The fingerlings of common carp were brought from Al-Sen Research Center of the General Commission of Fisheries Resources and then they were transferred directly to the fish laboratory at the Faculty of Agriculture  and  were left  for two days to rest, , and then part of the carp were acclimatized  with salinity12‰ in glass basins 40*50*70equipped with a filter and an oxygen pump in each of them within repeaters throughout the research period, ,then started applying the pre-prepared diet with different protein ratios, where specific percentages of fish meal are replaced with specific percentages of soybean meal, the first diet T1 (soybean meal 40gꓽ 20g fishmeal ), the second diet T2 (soybean meal 50gꓽ 10g   fishmeal ),  the third diet T3 (soybean meal 60 g without adding fishmeal ), with total protein 35.75% in each diet.  The fish were fed twice  day and hydrological measurements (temperature, salinity, pH, oxygen) of the water will be done daily,  25% of the water changed every two days and 100% weekly.

The highest value of the percentage weight gain PWG was recorded at 18.79%, as the weight gain reached 4.76 grams, with the best feed conversion factor 1.05 in the treatment (T2) with 25% replacement soybeans at a salinity of 12‰, with no significant differences in the values ​​of the weight percentage PWG, And the feed conversion rate (FCR), however  2.25% was also recorded as the highest value for the specific growth rate (SGR) in the month of June in the treatment (T2) with 20% replacement of soybeans with a salinity of 012%, with strong significant differences between the diets (P<0.05).