Reproductive efficiency of ostriches (Struthio camelus)

[摘要] English: South Africa is the world's largest ostrich producer, producing approximately 60% of the world's total number of ostriches slaughtered annually. Almost 90% of all ostrich products (i.e. leather, meat and feathers) generated are exported. High input costs, together with fluctuations in the exchange rate, places commercial ostrich producers under constant pressure to produce slaughter birds as cost-effectively as possible. The characteristic low reproductive performance of commercial ostrich breeding systems, as reflected in the large variation in the numbers of eggs produced, and high chick mortalities, contribute to the emphasis on the cost-effective production of slaughter ostriches. The identification of poor or non-producing breeding ostriches are hampered by a communal nesting system and the free-range conditions of commercial ostrich breeding systems. different management practices, and behavioural and physiological aspects were studied to determine their potential to identify and select breeding ostrich males and females with a higher productive performance, and thereby improving overall reproductive performance of breeding ostriches under intensive farming conditions. Maintaining ostrich males and females separately as single-sex flocks during the non-breeding resting period improved the overall reproductive performance of the breeding ostriches. The reproductive cycles of breeding ostriches can successfully be manipulated to ensure the timely production of chicks and thus slaughter birds. The successful implementation of intra-season breeding rest periods to synchronize and thus improve overall reproductive performance is however, determined by the time of the breeding season when the breeding rest is enforced. Breeding ostriches can be maintained at stocking rates higher than those currently applied. However, too high stocking densities are detrimental to the well-being of the breeding ostriches under intensive conditions. A trade-off was observed in terms of egg production and hatchability, with hatchability decreasing as average egg production/female increased. The egg production performance of ostrich females was significantly correlated with serum LH levels. Territorial aggression exhibited by breeding ostrich males did not exhibit significant genetic variation to serve as an indirect selection criterion for egg production incompanion breeding females. The territorial aggression observed in the breeding ostrich males, however, showed genetic variation, thus indicating that the temperament of ostriches may be changed through genetic selection, potentially improving their ability to adapt better to intensive husbandry practices. Ultrasound scanning of follicle development can be used to identify ostrich females with an early onset of production and selection of females on partial reproduction records will improve overall reproduction efficiency of commercial breeding systems Significant heritabilities were reported for follicle score during scanning in ostrich females. No negative correlation was reported for female live weight, body measurements, and egg production. Although no reliable .in dicator was identified to quantify the reproductive fitness of ostrich males under intensive conditions, correlations reported for phallus and semen quality traits with male fertility were in the right direction.To conclude:The implementing of flush feeding and teasing management practices will aid in thesynchronization of the reproductive cycles of breeding ostriches, thus enabling the commercial ostrich farmer to optimize the reproductive potential of breeding ostrich males and females under intensive breeding conditions. The use of these management practices, together with ultrasound scanning, will aid in the accurate identification and consequent selection of breeding ostrich females with an early onset of production Results from the study indicated that reproductive success is in part determined by an early onset of reproduction, implying that the identification and selection of breeding ostriches with an early onset of production will subsequently lead to an overall improvement and optimization of the reproductive efficiency and thus reproductive performance of breeding ostriches under intensive breeding conditions. Improving the reproductive performance ofbreeding ostrich males and females will potentially lead to an increase in the number of day-old chicks produced per female, thereby decreasing the overall costs of producing a day-old chick, as well as contribute to decreasing the feed costs of a commercial ostrich breeding operation.The observed high degree of genetic variation in the commercial ostrich breeding population implies that considerable genetic improvement is feasible through the identification of breeding ostriches with an improved reproductive performance, given the high repeatability estimates previously reported for ostriches under flock-mating conditions. It is, however, important to keep in mind the long-term goal of a breeding program, i.e. selection must be performed but without compromising production under commercial conditions.Unravelling the neuroendocrine mechanisms behind the flexibility in reproductive timing in ostriches may aid in the understanding of why ostrich males and females differ in terms of basic reproduction-related mechanisms, e.g. why some come into production earlier than others. This will aid in determining the influence of domestication on the ability of ostriches to adapt to and cope with stressful breeding environments, and also potentially assist the commercial ostrich farmer in the selection of individuals with a better reproduction efficiency under commercial conditions.

[发布机构] University of the Free State