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Information regarding morphology of indigenous sheep in South Africa is scant, and even where data exist it is rarely presented using standardised methodologies. Principal component analysis (PCA) was applied to 13 body measurements in order to provide an objective description of the body shape and size of 1665 Zulu sheep, obtained from rural communities of KwaZulu Natal. Data was analysed separate for young (no permanent incisors) and adult sheep (≥2 pairs of permanent incisors). On average mature males measured higher than mature ewes in most morphometric traits. The correlation coefficients between different body measurements in young sheep were all significant except for correlation between ear length and tail length whilst in adult sheep 79 out of 96 combinations showed significant correlation. Body weight and heart girth had the highest correlations in both age groups. Ear length and tail length related combinations had lower correlation coefficients in both age groups. The PCA of morphometric traits extracted two components with a total variance of 66.85% in young sheep and four components in adult sheep which explained a total variance of 62.13%. The first factor (PC1) in each case had high loadings for variables relating to body size, whilst PC2 had high association with traits reflecting body shape. The PC3 had high factor loadings for head length and head width, and thus defined head size. Tail length, ear length and whither height on the other hand contributed least towards total variation. The use of principal components was more appropriate than the use of original correlated variables in predicting body weight of Zulu sheep. PCA was able to identify traits with greater variability, these can be improved with greater success in breeding programmes and also the number of variables was reduced to give a concise picture of morphological structure (body size and shape) of a Zulu sheep. These components can as well be used in predicting body weight of Zulu sheep http://www.journals.elsevier.com/small-ruminant-research/ http://www.sciencedirect.com/science/article/pii/S0921448812004154 doi:10.1016/j.smallrumres.2012.09.008 National Department of Agriculture, Forestry and Fisheries, the NRF (Gun number: 76352) and the University of Zululand (project number: 5509/04)

Background To enhance and extend the knowledge about the global historical and phylogenetic relationships between Merino and Merino-derived breeds, 19 populations were genotyped with the OvineSNP50 BeadChip specifically for this study, while an additional 23 populations from the publicly available genotypes were retrieved. Three complementary statistical tests, Rsb (extended haplotype homozygosity between-populations), XP-EHH (cross-population extended haplotype homozygosity), and runs of homozygosity (ROH) islands were applied to identify genomic variants with potential impact on the adaptability of Merino genetic type in two contrasting climate zones. Results The results indicate that a large part of the Merino’s genetic relatedness and admixture patterns are explained by their genetic background and/or geographic origin, followed by local admixture. Multi-dimensional scaling, Neighbor-Net, Admixture, and TREEMIX analyses consistently provided evidence of the role of Australian, Rambouillet and German strains in the extensive gene introgression into the other Merino and Merino-derived breeds. The close relationship between Iberian Merinos and other South-western European breeds is consistent with the Iberian origin of the Merino genetic type, with traces from previous contributions of other Mediterranean stocks. Using Rsb and XP-EHH approaches, signatures of selection were detected spanning four genomic regions located on Ovis aries chromosomes (OAR) 1, 6 and 16, whereas two genomic regions on OAR6, that partially overlapped with the previous ones, were highlighted by ROH islands. Overall, the three approaches identified 106 candidate genes putatively under selection. Among them, genes related to immune response were identified via the gene interaction network. In addition, several candidate genes were found, such as LEKR1, LCORL, GHR, RBPJ, BMPR1B, PPARGC1A, and PRKAA1, related to morphological, growth and reproductive traits, adaptive thermogenesis, and hypoxia responses. Conclusions To the best of our knowledge, this is the first comprehensive dataset that includes most of the Merino and Merino-derived sheep breeds raised in different regions of the world. The results provide an in-depth picture of the genetic makeup of the current Merino and Merino-derived breeds, highlighting the possible selection pressures associated with the combined effect of anthropic and environmental factors. The study underlines the importance of Merino genetic types as invaluable resources of possible adaptive diversity in the context of the occurring climate changes.