Sexual Dimorphism in Morphometric Traits of the African Giant Rats (Cricetomys gambianus).

Abstract

The experiment analysed the sexual dimorphism in six morphometric traits of forty (20 bucks and 20 does) African giant rats (Cricetomys gambianus) at an average age of 3 months using a t-test, Pearson’s correlations, and linear regression models in GenStat (11th edition). Linear body measurements (body length, heart girth, neck circumference, height at withers, tail length, and head length) were measured fortnightly for up to 22 weeks for the male and female African giant rats in captivity. An increase in the trend of all the linear body measurements was observed throughout the weeks that measurements were taken in both sexes with males significantly (P < 0.05) outperforming the female counterparts. At the 22nd week of the measurements, the body weights were taken alongside morphometric traits. All parameters assessed showed highly significant differences (P < 0.01) with strong positive correlation in both sexes with higher values found among the males. However, the highest positive correlation coefficient was found to be between body weight and heart girth in the males (r = 0.9997) with the females recording a value of 0.9919. This is an indication of the possibility of using heart girth to predict the body weight of the African giant rats. All the morphometric traits recorded a higher coefficient of determination (R2) with higher significant differences (P ˂ 0.01) in predicting body weight in males, females, and pooled sex. It was concluded that sexual dimorphism in morphometric traits exists in the African giant rats. In the absence of conventional scales, farmers could use morphometric traits such as heart girth, body length, tail length, neck circumference, head length, and height at withers to accurately predict body weight of the African giant rats.