Objectives

The objectives of the study were primarily:

• to compare the performance of the Red Maasai and Dorper breeds and their crosses in terms of their productivity under high disease risk

• to study genetic sources of variation among lambs within the two breeds and their crosses

The first objective was examined in Case Study 3 using weaning weight as one of the performance criteria.

Here we examine the second objective, namely incorporation of random effects to study variations among rams (sires) and ewes (dams) and their influences on lamb weaning weight.