Comparison of the digestibility of diets based on fish meal and soybean meal in Litopenaeus vannamei Boone 1931, using different temperatures and salinities for culture

The digestibility of fish meal and soybean meal by Litopenaeus vannamei was determined at different temperatures (22 degreesC and 28 degreesC) and sal inities (16 parts per thousand and 35 parts per thousand) using practical d iets based on ingredients available in Mexico. The digestibility of soybean meal was consistently higher compared to that of fish meal, in terms of th e apparent digestibilities of dry matter, crude protein and aminoacids, sug gesting that soybean meal proteins are more readily digested. For fish meal , the apparent digestibility of the dry matter was reduced by high salinity at 28 degreesC, and the carbohydrate apparent digestibility was reduced by high salinity at both temperatures. The high salinity also reduced the dig estibility of dry-matter, lipids and carbohydrates in soybean meal at 28 de greesC, but had no effect on crude protein digestibility. This may have imp lications for the role of carbohydrates as source of energy in practical di ets for shrimp. The results also suggest that the fish meal used might have been of reduced quality.