Carcass characteristics of South African native chicken lines

Carcass characteristics of the Koekoek, New Hampshire, Naked-Neck, Lebowa-Venda and Ovambo chicken lines were evaluated. The highest dressed-carcass mass was recorded for Ovambo chickens and the highest percentage breast muscle was recorded for Naked-Neck chickens. Percentage fat and fatty acid composition differed between lines (p < 0.05). Carcass mass and fat content of the native chicken lines were less than in a commercial broiler line. It was concluded that the Ovambo and New Hampshire chicken lines appear to have the most suitable carcass characteristics for low-input systems where poultry production is aimed at household food security. (South African Journal of Animal Science: 2000, 30(1): 53-56

Genetic characterization of native southern African chicken populations: evaluation and selection of polymorphic microsatellite markers

This study presents the first results on the evaluation and selection of polymorphic microsatellite markers for the genetic characterization of native chicken populations in southern Africa. Blood samples for DNA extraction were obtained from five chicken lines from South Africa (Koekoek, New Hampshire, Naked-Neck, Lebowa-Venda and Ovambo), and from one population each from Mozambique and Botswana. Twenty-three markers were found to be polymorphic in most of the lines studied. The mean number of alleles observed for all markers was 6.1, and varied from 2.3 (Koekoek) to 4.3 (Mozambique population). The lowest heterozygosity was found in the Koekoek line (31.4%), and the highest in the populations from Mozambique (60.7%) and Botswana (61.2%). It was concluded that this particular set of microsatellite markers can be of use a measure of genetic variability in native chicken lines in southern Africa, and should be evaluated as diagnostic tools for breed identification. (South African Journal of Animal Science, 2000, 30(1): 1-6

Genetic diversity and population structure of locally adapted South African chicken lines: Implications for conservation.

In this study microsatellite markers were applied to investigate the genetic diversity and population structure of the six local chicken lines kept in the “Fowls for Africa” program, for better clarification of parameters for breed differentiation and genetic conservation of this valuable resource. The lines included the Black Australorp, Potchefstroom Koekoek, New Hampshire, Ovambo, Lebova- Venda and a Naked Neck line. Unbiased estimates for heterozygosity ranged from 50% in the Potchefstroom Koekoek to as high as 65% in the Naked Neck chickens. FIS values varied from as low as 0.16 for the Black Australorp line to as high as 0.35 for the Ovambo chickens. The FST values indicated moderate to high genetic differentiation between the Naked Neck and New Hampshire (0.11); Ovambo and Naked Neck lines (0.12), and Naked Neck and Lebowa- Venda (0.14). A total of 13% of the total genetic variation observed was between the chicken lines and 87% within the lines, supporting moderate genetic differentiation. Population structure was assessed using STRUCTURE where the Black Australorp was genetically best defined. Although six clusters for the different populations could be distinguished, the other lines were not as clearly defined, with individual birds tending to share more than one cluster. Results support a broad classification of these lines and further investigation of unique alleles is recommended for conservation of the lines within the program

Comparison of on-farm progeny performances from local and imported boar semen used in the South African pig industry

The widespread use of artificial insemination in the pig industry has provided breeders with access to genetic material from superior boars from around the world. Selection of parent stock is based on estimated breeding values (EBVs), which are regularly computed in all countries performing genetic evaluations. The purpose of this study was to evaluate the value of foreign sires in the South African (SA) pig industry by comparing the on-farm performances of progeny for average daily gain (ADG), feed conversion ratio (FCR) and back fat thickness (BF) from progeny sired by USA and Canadian born sires to the performance of progeny from local sires and to progeny with paternal USA grandsires (F1-US sires). The breeds analysed comprised of Duroc, Landrace and Large White pigs. Males outperformed females for all traits measured (P &lt;0.0001). Large differences (P &lt;0.0001) were observed between on-farm performances which had similar climatic regions for all traits except Duroc BF (P &lt;0.05). Farm differences were consequently attributed to management rather than environmental influences. The effect of country was significant (P &lt;0.05) in all the models tested with the USA-sired progeny having the best overall performance. However, as measured by a stepwise R2, country remained the smallest contributor to variation across all models (except BF in Landrace), with farm, sex and year-season contributing larger portions to the variation observed in the on-farm performances of progeny. These results indicate that most of the variation observed could be attributed to differences in farm as explained by management, rather than superiority of the imported boar semen.Keywords: Average daily gain, back fat thickness, feed conversion ratio, on-farm performanc

Residual feed intake as selection tool in South African Bonsmara cattle

In South African Bonsmara cattle, feed conversion ratio (FCR) is mostly used as a measure of feed efficiency in selection programs but has the disadvantage of being a ratio trait and unfavourably correlated to weight and mature size. Residual feed intake (RFI) overcomes both these disadvantages. The purpose of this study was to evaluate RFI as a potential trait in a selection programme by determining its correlations with growth related traits as well as other efficiency traits. Data of 5981 Bonsmara bulls that participated in centralised growth tests was analysed. In this study, RFI was calculated within contemporary groups of more than ten animals. The h2 for RFI, FCR and KR were 0.27±0.02, 0.23±0.02 and 0.18±0.02 respectively. The genetic correlation between RFI and FCR, and RFI and KR were 0.65±0.04 and 0.12±0.07 respectively. Correlations approaching zero were estimated between RFI and shoulder height (SH), body length (BL), scrotal circumference (SC), average daily gain (ADG), weaning weight (WW) and metabolic mid-weight (MMW), and a strong correlation of 0.79±0.03 with daily feed intake (DFI). This study shows sufficient genetic variation for RFI to be considered by the Bonsmara breed as a measure of feed efficiency and confirms its independence from growth and size traits.http://www.elsevier.com/locate/livscihb201

Population structure and genetic trends for indigenous African beef cattle breeds in South Africa

The aim of this study was to investigate population structure and genetic trends based on pedigree and performance records of five indigenous African beef cattle breeds (Afrikaner, Boran, Drakensberger, Nguni and Tuli) in South Africa. Pedigree completeness over six generations was higher than 88.5% in the first generation for all breeds, except for the Boran, which was introduced to South Africa only recently. The average generation interval ranged between 6.0 and 6.4 years. The rates of inbreeding per generation varied between 0.18% and 0.52%, while the effective population sizes ranged between 89 and 364. This is sufficient to maintain the genetic diversity within all of these populations. Inbreeding and effective population size for the Boran breed could not be accurately estimated, because it was introduced into South Africa only recently. Estimated breeding values for growth traits and scrotal circumference were also included for analyses to determine genetic trends of the same five breeds. Breeding values were regressed on birth year from 1986 to 2012. Genetic progress has been made in weaning and post weaning weights for all the breeds. This study has confirmed the benefits of having sufficient pedigree and performance data available for genetic evaluations and application in selection for genetic improvement.USAID and Virginia Polytechnic Institute and State University (USA) are acknowledged for funding and support of the first author.http://www.sasas.co.zaam2016Animal and Wildlife Science

Genomiese seleksie : 'n nuwe rigting in genetiese verbetering

No abstract available.http://reference.sabinet.co.za/sa_epublication/vp_stud?am201

Genetic and Phenotyic characterization of native fowl populations in South Africa

Native fowl populations in South Africa were characterized genetically and phenotypically. Four South African native populations, two dual-purpose breeds, and two populations from Mozambique and Botswana were included for genetic analysis. For phenotypic characterization, two commercial lines were also included as a benchmark. Twenty-three micro satellite markers were selected and tested to obtain genetic data for estimation of genetic variability and distance. Growth (weight gain) and egg production were included for phenotypic characterization. A relatively high (53% -64%) genetic variation was found among the populations, which suggests conservation as a genetic resource for future use. The lowest genetic variation (53%) was found for the Koekoek and Australorp populations, which are the two populations that were subjected to formal selection, while the highest variation was observed in the Naked Neck population (64%). The New Hampshire has often been included in upgrading programs and this is evident from the close relationship with both the Lebowa-Venda and Naked Neck fowls. Phenotypic trials indicated significant differences among the populations included for growth, carcass and egg production traits. The Koekoek and New Hampshire populations had the best performance for egg production and growth (weight gain) in the study. Genetic and phenotypic differences indicate that the populations can be distinguished as different breeds or groups of fowl. The results of this study may contribute to selection for improved performance for household food production, as well as conservation of the populations as a genetic resource

Description of the Friesian Horse population of South Africa and Namibia

Data obtained from the Friesian Horse Studbook of Southern Africa and Friesian Horse Breeders\' Society of South Africa were analyzed to describe and evaluate the population regarding inbreeding and morphological body measurements. Eight different body measurements (height at withers, height of back, height of croup, body length, length of cannon forelimb and hind limb, circumference of cannon bone fore- and hind limb) recorded on 232 horses were included for analyses. The pedigrees of 696 horses were used for estimation of inbreeding coefficients. A total of 25% of the horses included in the data was inbred, with inbreeding coefficients ranging from 0.07% to 27.8%. A positive trend in the average inbreeding per year was observed, but the rate of inbreeding was relatively low. Recording of pedigree information will be essential for long-term evaluation of inbreeding in the Friesian Horse and the recording of objective body measurements is recommended for inclusion in selection programs. Key Words: Body measurements, Linear scoring, Heritability, Inbreeding South African Journal of Animal Science Vol.34(3) 2004: 149-15