Effect of Bacillus Subtilis Protease on Growth, Production Performance and Feed Efficiency of Silkworm, Bombyx Mori L

Background: The effects of Bacillus subtilis protease on the silkworm ( Bombyxmori L) production performance and feed efficiency were investigated. 2250 silkworms were randomly divided into two groups, the test group and the control group, each group had three replicates. A certain concentration of protease was sprayed to the mulberry leaves of the test group, while equal volume of deionized water was sprayed to the control group. Test diets were fed in three phases: 3rd instar, 4th instar and 5th instar larval stage. Results: : The results demonstrated that: (i) final weight (FW), average daily gain (ADG), average daily feed intake(ADFI), and feed conversion ratio (FCR) in 4 th and 5 th larval instar, (ii) midgut protease activity, crude protein digestibility (CPD), crude fiber digestibility (CFD) and cocoon shell conversion rate (CSCR) (iii) the total number of bad cocoons,coarse cocoon, average pupa weight (APW), average cocoon shell weight (ACSW) and average cocoon weight (ACW) were extremely significantly higher (P<0.01) in test group as compared to control group. While, (i) the digestibility of crude lipid (EED) and (ii) the fly larvae cocoons in test group were higher significantly (P<0.05) than that of the control group. Conclusion: These results indicated that the B. subtilis protease could enhance the silkworm growth performance, feed efficiency and the cocoon quality of silkworm.