Phenotypic Characteristics and Factors Associated with Assaf Lamb Body Weight and Morphology

The phenotypic characteristics of animals are the result of the interaction of genetic and non-genetic factors that act simultaneously, and it is difficult to determine the degree of influence of each of them. The goal of this study was to describe Assaf lamb morphology and its relationship with body weight (BW) at various ages. BWs and phenotypical characteristic measurements were taken on 392 lambs: 204 lambs at birth (±3 days of birth), 87 lambs at weaning (around 60 days), and 101 lambs at marketing age (around 120 days). The measurements were withers height (WH), body length (BL), chest girth (CG), chest depth (CD), head length (HL), head width (HW), rump length (RL), RW (RW), shoulder width (SW), shin circumference (SC), foreleg height (FLH), rump height (RH), and rear leg height (RLH). Month of birth (MO) affected (P<0.001) BW and all morphological characteristics except CD and RW at birth. At weaning, BW, HL, CG, RL, CD, SW, and RW were affected (P<0.001) by MO. The sex of the lamb, birth type, and dam age also affected (P<0.001) different morphological characteristics. Furthermore, BW was positively correlated with different morphological characteristics at different ages. Meanwhile, equations were developed to predict BW at birth, weaning, and marketing based on various morphological characteristics while taking height into account.