Some factors affecting weaning weights of calves.

Thesis (M.Sc.Agric.)-University of Natal, Pietermartizburg, 1996.A mixed model study was carried out on the field data records of 9798 Simmmental and 1725 Hereford calves born during the period 1992 to 1994, and obtained from the Animal Improvement Institute, Irene. The records were used to evaluate the influence of type of management systems used by breeders, type of vegetation, sex of calf, age of dam, year of birth and season of birth on 205 day weight of calves and some two way interactions between these effects. The analysis were carried separately for each breed. Type of management did not significantly affect the 205 day weight of Hereford calves, the least-squares means of calves from extensive, semi-extensive and intensive systems were 195.8, 196.9 and 197 kg, respectively. However, the effect was highly significant (P<.01) for Simmmental calves with weaning weights of 217.4, 238.3 and 261.2 kg for extensive, semi-extensive and intensive production systems, respectively. The Simmmental data were divided for further analysis according to the three management systems. All the main effects on the 205 day weight of Simmmental calves were highly significant for all the management systems. Simmmental calves raised in the combination of fynbos and pastures under the semi-extensive management system weaned the heaviest calves (295.8 kg) and those raised in the mixed grassveld under the extensive system weaned the least (202.4 kg) . The Simmmental male calves were 10, 9.8 and 17.9 kg heavier than female calves in the extensive, semi-extensive and intensive systems respectively. The mature age of the dam was between the 52 to 57, 58 to 117 and 52 to 57 month age groups with weaning weights of 230.7, 257.7 and 266.4 kg in the extensive, semi-extensive and intensive systems respectively. The deviations of weight of calves of the mature dams from those of young dams (16 to 27 months) were 26.9, 30 and 20 kg under the extensive, semi-extensive and intensive systems, respectively. The main effects on the 205 day weight of Hereford calves, except the type of management, were highly significant (P<.01). The Hereford calves raised in the sweetveld areas produced the highest weights (218.6 kg) but those raised on the karroo were the lightest (188.1 kg). The best calving seasons were autumn and winter, with the mean weight of 215.1 kg and 202.9 kg, respectively. Summer and spring born calves weighed 180.2 and 188.2 kg, respectively. The Hereford male calves were 13.2 kg heavier than the heifers. The maturity age of the dams was between the 72 to 95 month age group with the deviation of 20 kg in weaning weight of their calves from those of the young dams (22 to 27 months old). The sex and age-of-dam interaction for both breeds indicated an overall correction factor for sex of calf and of age of dam. Multiple adjustment factors were used to remove sex of calf differences, whereas additive adjustment factors were used to remove age-of-dam differences

Characterisation of indigenous Zulu (Nguni) sheep for utilisation improvement and conservation.

Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.The Nguni sheep of Zululand, South Africa, are called the Zulu sheep. They are a source of food and cash for the rural farmers of KwaZulu-Natal. There is insufficient information available about the characteristics of this breed and accordingly the breed is classified as “insecure”. Documentation of characteristics of a breed is important for its utilisation, improvement or conservation. This study was undertaken to document (i) the utilization of the Zulu sheep, (ii) some morphological characteristics, (iii) establishing a cost effective body measurement recording means and (iv) the intra- and inter-population genetic variation of the breed using random amplified polymorphic DNA markers. A survey was conducted to investigate the socio-economic and cultural values of the farmers attached to livestock including the Zulu sheep. A total of 76 rural farmers were interviewed in the areas of the Mhlathuze district in northern KwaZulu-Natal. Constraints and the indigenous knowledge of the farmers on livestock production were also recorded. The results confirmed that the Zulu sheep in the rural areas are indeed used as a source of protein and cash when necessary. Farmers reported that the Zulu sheep are tolerant to ticks and able to withstand the hot and humid conditions of northern KwaZulu-Natal. Goats and cattle as well as the Zulu sheep are also used for payment of dues in the tribal courts. Even so, Zulu sheep are not used for any cultural purposes. The system of management is fairly extensive. Some farmers apply indigenous knowledge as part of management practices. For instance, they use indigenous plants as nutrient supplements and for increasing the reproduction rate of these animals. Lack of modern animal husbandry skills was declared by the farmers as one of the main challenges. A perception among the farmers was that the Government could assist in addressing this challenge. Three populations of Zulu sheep reared extensively in three localities were used for the morphometric and genetic studies. The areas were the community of KwaMthethwa (Enqutshini), University of Zululand (UNIZULU) and Makhathini Research Station. Makhathini and KwaMthethwa are 260 and 40 km, respectively, away from UNIZULU. The morphometric study was undertaken to determine the extent of phenotypic diversity between Zulu sheep populations using six morphological characteristics. Effects of some factors (location, age, sex and season) on some of these traits were estimated. Results showed that the size of the body measurements, wither height (WH), heart girth (HG), live weight (LW) and scrotal circumference (SC) were significantly different between the populations. Variation in these body measurements was influenced significantly by the location, season, the sex and the age of sheep. Mature ewes weighed up to 32 kg whereas the rams weighed up to 38 kg. The differences in LW, HG and WH between the seasons were small. The SC increased with the age of the ram up to 28 cm for mature rams. Other traits observed were the colour and the ear length of Zulu sheep. Ear size ranged from ear buds to the most common large ears (9 to 14 cm). The dominating colours observed were brown and a combination of brown and white. Live weight prediction equations were estimated employing HG, WH and SC data. The LW prediction equations showed that the regression of HG and WH produce the best estimate equations of LW; however the HG alone also showed reliable LW estimates. Scrotal circumference was more precise for estimating the LW of younger rams below 22 months of age (R2 = 0.64 – 0.78). Fifty-two Zulu sheep from the three locations were used to assess the genetic variation within the Zulu sheep breed. A total of 2744 RAPD bands were generated ranging from 0.2 to 2 kb; ~46% of these bands were polymorphic. The genetic diversity was the lowest (5.17%) within the UNIZULU population, 8.62% within the KwaMthethwa population and highest (11.04%) within the Makhathini population. The genetic diversity between all populations was estimated at 21.91 %. Phenotypic diversity was relatively similar for the UNIZULU and Makhathini populations (41.25% and 45.63%, respectively). The phenotypic diversity between the three populations was 48.26%. Genetic and phenotypic diversity was lower for Makhathini and UNIZULU populations than for the KwaMthethwa population. It was concluded that the Zulu sheep is a smaller sized breed compared to the other South African indigenous sheep breeds like the Dorper which has been reported to have some similar characteristics to the Nguni sheep. The results confirmed that the Zulu breed has the capacity to survive without dipping and supplements during the dry season. This adaptation is of value to the communities of KwaZulu-Natal. Such characteristics warrant conserving the breed to prevent genetic erosion. The phenotypic and genetic diversity between the three populations of Zulu sheep may indicate that there is an opportunity of genetic exploitation by selecting animals based on phenotypic as well as genetic characteristics. In order to promote the conservation and sustainable use of the Zulu sheep, it was recommended that an open nucleus breeding scheme from lower-tier flocks (of the farmers) for pure breeding to nucleus flocks (in Government ranches) could be appropriate. The scheme would also address the challenges of animal husbandry as well as contribute to the improvement of the livelihood of the farmers. Farmers could use a tape measure to estimate the LW of sheep when they cannot afford scales. The morphological characteristics and the genetic diversity data generated from this study could be combined into a single data base for this sheep breed. More extensive studies, using the same or some additional phenotypic characters such as reproductive performance, need to be done. Genetic characteristics of Zulu sheep using microsatellites and mitochondrial DNA should be done to complement the present study

A review of some characteristics, socio-economic aspects and utilization of Zulu sheep: implications for conservation

Zulu sheep are Nguni sheep of Zululand and are adapted to the harsh conditions of KwaZulu-Natal. They are used by rural farmers for economic purposes. Their numbers are declining, indicating a potential extinction threat. Knowledge of their phenotypic and genotypic characteristics is essential for conservation planning. In this review, there is a focus on the utilization, socio-economic aspects, phenotypic and genotypic characteristics as well as a proposed breeding programme. A survey has shown that rural farmers in the areas of northern KwaZulu-Natal prefer to keep this breed for its adaptability, resistance to diseases and meat quality. Zulu sheep are small-framed multi-coloured animals. Mature males weigh up to 38 kg and females up to 32 kg. Based on four morphological traits and live weight, phenotypic diversity between three populations was estimated at 48%. A genetic diversity between these three populations was estimated at 22%. Live weight of Zulu sheep can be estimated using the heart girth and wither height measurements. Scrotum circumference of young rams (up to 22 months old) is reliable for estimating the live weight. Animals that were characterized in the studies were grazed extensively and no supplements were provided. There is therefore a potential of weight increase if these animals are reared in a semi-extensive environment. An open nucleus breeding scheme is thus recommended for a sustainable use and conservation of this breed. For more conclusive results, larger numbers of phenotypic and genetic characteristics, in larger numbers of Zulu sheep populations, should be investigated.http://dx.doi.org/10.1007/s11250-011-9823-

Genetic structure of South African Nguni (Zulu) sheep populations reveals admixture with exotic breeds

<div><p>The population of Zulu sheep is reported to have declined by 7.4% between 2007 and 2011 due to crossbreeding. There is insufficient information on the genetic diversity of the Zulu sheep populations in the different area of KwaZulu Natal where they are reared. The study investigated genetic variation and genetic structure within and among eight Zulu sheep populations using 26 microsatellite markers. In addition, Damara, Dorper and South African Merino breeds were included to assess the genetic relationship between these breeds and the Zulu sheep. The results showed that there is considerable genetic diversity among the Zulu sheep populations (expected heterozygosity ranging from 0.57 to 0.69) and the level of inbreeding was not remarkable. The structure analysis results revealed that Makhathini Research Station and UNIZULU research station share common genetic structure, while three populations (Nongoma, Ulundi and Nquthu) had some admixture with the exotic Dorper breed. Thus, there is a need for sustainable breeding and conservation programmes to control the gene flow, in order to stop possible genetic dilution of the Zulu sheep.</p></div

Representation of sample size (indicated by diameter of the pies) and of relative admixture distribution (indicated by different colour) inferred by STRUCTURE at <i>K</i> = 4.

<p>JO, Jozini; MT, Mtubatuba; NG, Nongoma; ES, Eshowe; UL, Ulundi; NQ, Nquthu; UZ, UNIZULU research station; MS, Makhathini research station; DO, Dorper; DA, Damara; ME, South African Merino.Source: figure taken from <a href="http://www.d-maps.com/" target="_blank">http://www.d-maps.com</a> and adapted for illustrative purpose only.</p

Genetic diversity of the studied sheep breeds obtained from the analysis of 26 microsatellite loci.

<p>Genetic diversity of the studied sheep breeds obtained from the analysis of 26 microsatellite loci.</p

Genetic relationship among the 11 sheep populations using reynolds genetic distance according to the neighbour-joining algorithm.

<p>JO, Jozini; MT, Mtubatuba; NG, Nongoma; ES, Eshowe; UL, Ulundi; NQ, Nquthu; UZ, UNIZULU research station; MS, Makhathini research station; DO, Dorper; DA, Damara; ME, South African Merino.</p

Pairwise <i>F</i>_ST among the studied breeds/populations (with confidence intervals at 95%).

<p>Pairwise <i>F</i>_ST among the studied breeds/populations (with confidence intervals at 95%).</p

Genetic clustering of 11 sheep population with STRUCTURE.

<p><b>(a) Analysis of the entire data set obtained from 10 runs for each number of assumed populations (<i>K</i>) value ranging from 2 to 9; (b) further analysis obtained from four populations (NG, UL, NQ and DO).</b>JO, Jozini; MT, Mtubatuba; NG, Nongoma; ES, Eshowe; UL, Ulundi; NQ, Nquthu; UZ, UNIZULU research station; MS, Makhathini research station; DO, Dorper; DA, Damara; ME, South African Merino.</p