Feed Utilization Efficiency of Eri-Silkworm (Samia cynthia ricini Boisduval) (Lepidoptera: Saturniidae) on Eight Castor (Ricinus communis L.) Genotypes

Abstract

Eri silk production and productivity depends highly on feeds consumed by eri silkworms (Samia cynthia ricini B.), which will be a function of feed sources. Preferred feed of eri silkworms is castor, however, there is an important difference in feed utilization efficiency when different castor genotypes were used as feed source for this silkworm. In this experiment, feed utilization efficiency of eri silkworm was studied on eight different castor genotypes namely Abaro, Acc 106584, Acc 203241, Acc 208624, Ar sel, Bako, Hiruy and local genotypes in Melkassa Agricultural Research Center, Ethiopia. The treatments were laid out in a Completely Randomized Design (CRD) in three replications. Fifty worms after their fourth molt were placed on rearing trays provided with castor leaves harvested from the eight different genotypes. The genotypes caused significantly different feed utilization efficiency on eri silkworm. Among castor genotypes, Abaro and Acc 208624 expressed better performance in all evaluated variables simultaneously. These genotypes yielded 6.672 and 6.904 g/larva of ingesta, 3.379 and 3.574 g/larva of digesta, 50.637 and 51.766 % approximate digestibility, 2.026 and 2.073 reference ratio, 0.814 and 0.862 relative consumption rate, 33.164 and 31.406 % efficiency to convert ingested leaves to larval biomass, 19.811 and 19.236 % efficiency to convert ingested food to cocoon as well as 39.126 and 37.173 % efficiency to convert digested food to cocoon, respectively. As a result, these castor genotypes were recommended to future research and development endeavors of integrated eri silkworm farming and castor seed production.