Comparative evaluation of reproductive performance and some egg quality parameters of black and white skinned snails.

摘要

One hundred sexually matured snails, fifty each of the black skinned and white skinned ectotypes were used in the evaluation of reproductive performance and egg quality traits in a study that lasted for eighty-four days. The reproductive performance traits measured included clutch size (number of eggs laid per clutch), incubation period (days) of eggs, percent hatchability, and percent mortality and survivability, while the egg quality traits evaluated included egg weight and length. Results obtained showed significant differences at different levels among parameters measured in the two ectotypes of snails studied. The results of reproductive traits showed that mean clutch sizes were 5 and 4 for black skinned and white skinned ectotypes respectively. Mean incubation periods were 25.8 days for the black skinned ectotype and 22 days for the white skinned ectotype. The values for mean percent hatchability were 26.8% and 22.8% for the black skinned and white skinned ectotypes respectively. Mean survivability values were 22.8% for black skinned ectotype and 20% for the white skinned ecotype. The mean egg quality parameters were 2.7 g and 2.4 g, weight for black skinned and white skinned ectotypes respectively. The mean egg lengths were 4.6 mm and 4.2 mm for black skinned and white skinned, ectotypes respectively. Among the measured parameters clutch size and egg length had very high significant difference (P<0.001), incubation period had high significant difference (P<0.01) while percent hatchability, survivability and egg weight were significantly different at (P<0.05) level of probability. Strong positive correlation was observed for hatchability and survivability in both ectotypes. All other trait pairs evaluated except percent hatchability. Clutch size in the white ectotype were positively correlated. Strong positive correlations imply that selection for one trait will lead to improvement in the other.