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.
Assessment of the reproductive and growth performance of two sheep composites, developed from the Finnish Landrace, compared to the Dorper
Genes were introduced from the prolific Finnish Landrace sheep breed by crossbreeding with indigenous breeds to produce several composites. In this study, two of these composites were compared to the Dorper in terms of reproductive characteristics and growth. Mean ovulation rate of Composites 1 and 2 was 1.93 and 1.67, respectively, compared to 1.13 of the Dorper. Composites were subsequently also mated to Dorper rams. Prolificacy was 1.35, 1.48, and 1.08 lambs born per lambing to Composites 1 and 2 and Dorpers, respectively. Birth mass differed between the Dorper and composites. Neither weaning mass (at 62.6 days) nor 100-day mass differed between composites and the Dorper. There was a higher fat content in the milk of the composites. Although the preliminary assessment is based on relatively low numbers, there is, however, some potential in these dam lines for future crossbreeding purposes.
Mitochondrial aquaporin-8-mediated hydrogen peroxide transport is essential for teleost spermatozoon motility
Reactive oxygen species (ROS), particularly hydrogen peroxide (H2O2), cause oxidative cell damage and inhibit sperm function. In most oviparous fishes that spawn in seawater (SW), spermatozoa may be exposed to harmful ROS loads associated with the hyperosmotic stress of axonemal activation and ATP synthesis from mitochondrial oxidative phosphorylation. However, it is not known how marine spermatozoa can cope with the increased ROS levels to maintain flagellar motility. Here, we show that a marine teleost orthologue of human aquaporin-8, termed Aqp8b, is rapidly phosphorylated and inserted into the inner mitochondrial membrane of SW-activated spermatozoa, where it facilitates H2O2 efflux from this compartment. When Aqp8b intracellular trafficking and mitochondrial channel activity are immunologically blocked in activated spermatozoa, ROS levels accumulate in the mitochondria leading to mitochondrial membrane depolarisation, the reduction of ATP production, and the progressive arrest of sperm motility. However, the decreased sperm vitality underlying Aqp8b loss of function is fully reversed in the presence of a mitochondria-targeted antioxidant. These findings reveal a previously unknown detoxification mechanism in spermatozoa under hypertonic conditions, whereby mitochondrial Aqp8b-mediated H2O2 efflux permits fuel production and the maintenance of flagellar motility.