Racial difference in the efficiency of food utilization of silkworm, Bombyx mori L.
Racial difference in the efficiency of food utilization of silkworm, Bombyx mori L.
Sardar M. Rafique and Ghulam Ali Bajwa
ABSTRACT
Coefficients of food utilization namely, ingestibility, efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD) and approximate digestibility (AD), vis-a-vis larval body weight gain (LBWG) were calculated for seven silkworm strains (J-99, J-101, 205-MKD, 206-MKD, 206-PO, 207-PO, 208-PO) during Spring (26±1°C, 75±5% RH) and Autumn (30±2, 80±1% RH) rearing seasons. The results revealed a significant difference among the silkworm strains for ingestibility, ECI, ECD, AD and LBWG During spring season maximum and minimum ingestibility, ECI, ECD and AD were 69 08% (J-101, 5th instar), 34.93% (205-MKD, 5th instar), 54 4% (205-MKD, 5th instar), 56 48% (J-101, 4th instar) and 39.63% (207-PO, 4th instar), 18 86% (205-MKD, 4th instar), 23.85% (205-MKD, 4th instar), 43.86% (207-PO, 5th instar), respectively. Ingestibility, ECI and ECD increased with the development of larvae but AD decreased. Overall maximum and minimum larval body weight gain was recorded in 206-MKD and 207-PO, respectively During autumn season the highest and lowest ingestibility, ECI, ECD and AD were 62.09% (206-MKD, 5th instar), 20.86% (208-PO, 5th instar), 31.24% (208-PO, 5th instar), 60 75% (207-PO, 4th instar) and 40 54% (207-PO, 5th instar), 16.95% (208-PO. 4th instar), 19.26% (208-PO, 4th instar), 40.26 (207-PO, 5th instar), respectively. A slight increase in ECI and ECD was observed with the age of larva however, AD showed negative relationship with age. Overall maximum (2014.13 g larva-1) and minimum (1547.75 g larva-1) larval body weight gain was displayed by 206-MKD and 207-PO, respectively. During penultimate larval stage there was non-significant difference between spring and autumn season. On the other hand at high temperature (autumn season) ingestibility, ECI, ECD and LBWG were reduced drastically during final instar. It is therefore, recommended that for efficient utilization of food silkworm should not be reared above 26±1°C and 75±5% RH.
Key words: Silkworm Bombyx mori. Strains, Food consumption and utilization, ingestibility, ECI, ECD, AD, rearing season Larval body weight.
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March 2004
Vol. 54, Iss. 1
