1. Discipline of Genetics, College of Agriculture, Engineering and Science, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa.
2. ARC-Animal Production, Private Bag X2, Irene, 0062, South Africa.
3. Department of Animal Sciences, Faculty of Science, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa.
4. Department of Agriculture and Animal Health, University of South Africa, Private Bag X6, Florida 1710, South Africa.