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.
Seasonal Variations in Semen Parameters of Zulu Rams Preserved at 10°C for 72 H During Breeding and Non-Breeding Season
The study was conducted to evaluate the seasonal variations in semen parameters of Zulu rams preserved at 10°C for 72 h. The study site was the Agricultural Research Council (ARC) Irene, during the breeding season and the non-breeding season. Zulu rams (n = 6, age = 3 years and average weight = 35 kg ±2.29) were used in this study. Semen was collected with the aid of artificial vagina. Macroscopic (volume and pH), microscopic (sperm concentration, progressions, velocities and velocity ratios and morphology) semen parameters were evaluated immediately after semen collection. Data were analyzed using General Linear Model (GLM) in Minitab 17®. Semen volume was higher during breeding season (0.97±0.25 mL) than non-breeding season (0.72±0.5 mL). Total sperm motility was higher (92.01±1.40%) at 24h during breeding season than non-breeding season (88.69±1.40%), thereafter declined drastically in both seasons. However, non-breeding season yielded a high progressive motility (50.86±1.63%, 33.77±1.63% and 27.56±1.63%) after 24, 48 and 72 h than breeding season (21.32±1.63%, 11.89±1.63% and 10.29±1.63%). It was concluded that, semen parameters from Zulu rams does vary with seasons. Nevertheless, despite seasonal variations observed, Zulu rams’ semen quality is acceptable in both breeding and non-breeding season hence can breed throughout the year. Notwithstanding, studies involving fertility are recommended and the nutrition effect of lambing during dry period should be considered.
Testicular development in Dorper, DOhne Merino and crossbred rams
Testicular development from 3 to 14 months of age was examined in Dorper (DD), Dohne Merino (DM) and crossbred (Meatmaster; MM) rams. Testicular measurements included testis volume (TV), diameter (TD), length (TL) and scrotal circumference (SC). Soth TD and SC were highly repeatable and positively correlated with live body mass and other testicular measurements. Soth SC and TD showed significant breed differences (P<O,05) from 3 to 10 months of age which disappeared later on. Non-linear equations were fitted for testicular measurements on age for each breed group. Testicular growth pattems are more similar in the mutton breed types (DD and MM) and differfrom dual-purpose DM. This difference probably indicate earlier puberty in the DD and MM breeds. In an attempt to accountfor body size differences, a SC : live body mass ratio is recommended as a practical selection criterion. A more rapid decrease in this ratio is indicated in the DD and MM breeds compared to the DM, probably because of later puberty in the latter. Individual ratios within and between breed groups varied from 0,378 to 0,948 em/kg.  Testisontwikkeling is tussen 3 en 14-maande-ouderdom in Dorper (DD), Dohnemerino (DM) en kruisings (Vleismeester; MM) ondersoek. Testismates hetvolume (TV), deursnee (TD),lengte (TL) en skrotumomtrek (SC) ingesluit. Seide TD en SC is hoogs herhaalbaar en positief met Iiggaamsmassa en ander testismaatstawwe gekorreleer. Seide SC en TD het betekenisvol (P<0,05) tussen rasse vanaf 3-tot 10-maande ouderdom verskil, waama geen betekenisvolheid aangetoon is nie. Nie-lineere vergelykings vir testismates op ouderdom is vir elke ras gepas. Die patroon van testisgroei stem meer ooreen tussen die vleistipes (DD en MM) en verskil van die dubbeldoel-DM. Hierdie verskil is moontlik die gevolg van vroeer puberteit by die DD en MM. In 'n poging om die effek van verskille in liggaamsgrootte te oorkom is 'n SC : lewendemassa-verhouding as 'n moontlike praktiese seleksiemaatstaf aanbeveel. 'n Vinniger afname in hierdieverhouding is in die DD en MM in vergelyking met die DM aangedui, waarskynli k as gevolg van later pUberteit in die geval van laasgenoemde. Individuele verhoudings binne en tussen groepe het vanaf 0,378 tot 0,948 em/kg gevarieer. Keywords : Testicular development, repeatability, Dorper, Dohne Merino, crossbred, rams