Evaluation of non-genetic factors affecting birth weight of Kalahari red goats in South Africa

Abstract

The objective of this study was to evaluate the effect of some non-genetic factors on birth weight of Kalahari Red goats. Data on pedigree, breeding and performance records (N=1902) of Kalahari Red goat kids born in the Northern, Southern and Eastern regions of South Africa during the period from 2008 to 2017 were used. Least squares analysis revealed that season of birth, sire age, dam age, sex of kid, breeder, year of birth and Litter size were significant (p<0.05) sources of variation for birth weight in Kalahari Red goats kids. The average birth weights (BW) were 2.45 ± 0.57 kg, 3.33 ± 0.15 kg and 3.14 ± 0.08 kg kg for Eastern, Northern and Southern regions, respectively. Kids born in the Northern region were heavier (3.33 ± 0.158 kg) than those born in the Eastern regions (2.45 ± 0.57 kg). However, region had no significant effect (p>0.05) on birth weight. Breeder effect was significant (p<0.05). Kidding interval was not significant (P>0.05). The average birth weight of male kids was higher than female kids (3.05 ± 0.21 kg: 2.89 ± 0.20 kg), and the difference was significant (P<0.05). The research found a significant effect (p<0.05) of Litter size with the average birth weight of single, twins, triples and quadruplets kids being 3.10 ± 0.19 kg, 2.9 ± 0.20 kg, 2.99 ± 0.20 kg and 2.87 ± 0.36 kg respectively. The kids that were born as single were heavier than those that were born as multiple (twins, triplets and quadruplets). There were four seasons of birth analysed in the study, which were found to be highly significant (P<0.05) on birth weight. Year of birth had significant effect (p<0.05) on birth weight. The kids born in the year 2015 were heavier in BW (3.39 ± 0.23 kg) than those born in the other years, while the kids born in 2016 had the lowest BW (1.91 ± 0.21 kg). Age of dam and sire had a significant effect (p<0.05) on birth weight. It was then concluded that season of birth, sire age, sex of kid, dam age, breeder, year of birth and Litter size significantly influence birth weight of Kalahari Red goat’s kids and, therefore, need to be included in genetic evaluation models. Keywords: Adaptability, Growth potential, Parental effects, Reproduction potential.