Phenotypic characterization of Zulu sheep: implications for conservation and improvement
Loading...
Date
2012
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Zululand
Abstract
Understanding the characteristics of the Zulu sheep breed in its home tract is an essential step towards the development of a sustainable conservation and improvement programme. A survey was conducted in 11 rural areas of KwaZulu-Natal in the quest to (i) describe traditional Zulu sheep production systems, (ii) describe the morphological structure of the breed, and (iii) to quantify morphological variation among sheep populations.
Most farmers began sheep production with an initial stock size of less than four, either bought from other farmers or inherited. Sheep were mainly used as a source of food and income. Flock sizes were 39.8±7.5 on average, with each flock constituting of 3.12±0.31 rams, 21.8±5.61 ewes, 5.0±0.87 yearlings and 9.9±2.05 lambs. About 28.0% of the flocks occurred in isolation while 43.7% interacted with two or fewer neighbouring flocks. There was about 7.4% decrease in sheep numbers in the past 5 years. Drought and diseases were the major causes of sheep loss.
Principal component analysis of morphometric traits extracted two components with a total variance of 66.9% in young sheep and four components in adult sheep with a total variance of 62.1%. The first factor (PC1) in each case had high loadings for variables relating to body size, while PC2 had high association with traits reflecting body shape. PC3 had high factor loadings for head length and head width, representing head size. The use of principal components was more appropriate than the use of original correlated variables in predicting body weight of Zulu sheep.
Dark brown was the most prevalent coat colour. It occurred as either solid or mixed with white. Sheep from Nqutu measured highest in most morphometric variables whilst sheep from Empangeni measured lowest. Discriminant analysis identified rump width (RW), head width
vi
(HW), heart girth (HG), thorax depth (TD) and tail length (TL) as the most discriminative variables in differentiating Zulu sheep populations. Two major groups were identified by cluster analysis, one formed by Empangeni, Mtubatuba and Nongoma and the other by Jozini Msinga and Eshowe populations. Estcourt and Nqutu joined these major groups as individual entities at distance with the latter being furthest. Discriminant function analysis was able to correctly classify 62.2% of individual sheep into their original populations. The high morphological variation among Zulu sheep populations, infer considerable genetic variability. Maintaining this genetic variation is important if the goal is to continue and improve the productive performance of the animals and respond to change in climate, disease or consumer preference while improving the livelihoods and food security of livestock keepers.
Description
Dissertation submitted in fulfilment of the requirements for the Degree of Master of Science in Agriculture (Animal Science) in the Department of Agriculture, Faculty of Science and Agriculture at the University of Zululand, South Africa, 2012.
Keywords
Sheep breeding, Animal genetic resources