A Study on Raising the Fifth Instar Silkworms with Mulberry Leaves Economically and Rationally
Zhang Guoji, Sha Wenyi(Teaching and Research Section of Raising Silkworm, Shandong Agricultural College) Liu Fuchen (Silk Cloth Company, Wulian County)
Optimum economical amount of mulberry leaves has been studied for raising the fifth instar silkworms incubated from the eggs on each piece of paper,i.e.20,000 silkworms. The experiments of the ration of the feeding weight have been carried out for many times. The results showed that during the 5th instar the relationship of the changes between various feeding weight and main economical properties of the silkworms follows a certain law in designed ranges, There is an evident limit of the "amount" in the changes. The lower limit is 350kg, and the upper 450kg. When the feeding weight is below the lower limit, although the cocoon production of each 50kg blades lightly increases, the cocoon shell weight of each 50kg blades significantly dicreascs and the period of the fifth instar is markedly prolonged. When the feeding weight goes beyond the upper limit, although the cocoon production of the same amount of silkworms gradually increases, the cocoon production and the cocoon shell weight obviously dicreases and the amount of the leaves in producing cocoon per 0.5kg evidently increases. Usually, the reasonable litnit of the blades for the fifth instar of 20,000 silkmorms is 350-450kg and the optimum economical amount is about 400kg.