Exploratory Principal Component Analysis of Body Morphometric Traits as Affected by Age and Sex in Donkeys

Abstract

An experiment was conducted to determine the principal component analysis of body morphometric traits as affected by age and sex in donkeys reared on a research station in the National Animal Production Research Institute, Shika-Zaria, Nigeria. This was based on the objective of classifying age and sex using the multivariant method of principal component analysis (PCA) on morphometric traits of donkeys. Data were collected from a total of 101 donkeys based on age and sex on body wright, heart girth, body length, height at withers, tail length, shoulder width, head width, ear length, head length, neck circumference and neck length. The data obtained were subjected to multivariate factor analysis with varimax rotation using IBM® SPSS® Version 21. The results obtained revealed that the age group ≤ 1 year had one PCA, 2–3 years age group had four PCA, 4–5 years group had three PCA while those ≥ 6 years had two PCA. Most of the variables in combination with age largely formed the block of PC1 while other PCA had one or two variables correlating with them. Most of the variables formed PC1 for the Jacks while head width (HW) and ear length (EL) formed PC2. The Jennies had its entire variable in one PCA. Therefore, PC1 had the highest loading for the variables both by age and by sex as the animals are relatively well adapted to their environment. It can be concluded that donkeys between 2-3years have more PC correlation proportions.