تاثير سال فصل و سطح تغذيه بر عملكرد هيبريدهاي كرم ابريشم

Effect of Year and Season on Feed Efficiency in Silkworm Hybrids

For investigation on study and compare nutritional efficiency in six hybrids including 103x104, 31x32, 107x110, 104x103, 32x31 and 110x107 in several nutrition management conditions, these hybrids were reared at three rearing duration and 4 and 5 instar. Hybrids were reared under four feeding levels including 5% higher than standard feeding table for silkworm htbrids, equal to standard table, 5% lower than standard table and 10% lower than standard table. Rearing duration included spring 2003, spring 2004 and autumn 2004. The parameters studied were included amount of ingestion and digestion, percentage of ingestibility and digestibility, reference ratio, cocoon weight, cocoon shell weight, cocoon shell percentage, efficiency of conversion of ingested (ECI) and digested (ECD) food into cocoon weight and cocoon shell weight. From obtained results, it was showed at all rearing periods, four nutritional indices including amount of ingestion and digestion, ingestibility percentage and digestibility percentage in reverse hybrids(B, D and F) were higher than un-reverse hybrids(A, C and E). Furthermore at each three rearing periods, ECI and ECD into cocoon shell weight and ECI and ECD into cocoon weight in reverse hybrids(B, D and F) were less than unreverse hybrids(A, C and E). Investigation on ECI and ECD into cocoon weight and cocoon shell weight at second period showed these parameters were littile in hybrids E and F. Meanwhile these parameters decreased at autumn season. ECI and ECD into cocoon weight and cocoon shell weight in all hybrids at autumn season were less than spring season.