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Stellenbosch University (2022)

The refinement of an artificial insemination protocol in ostriches

Muvhali, Pfunzo Tonny

Titre : The refinement of an artificial insemination protocol in ostriches

Auteur : Muvhali, Pfunzo Tonny

Université de soutenance : Stellenbosch University

Grade : Doctor of Philosophy (PhDAgric) 2022

Résumé
This study refined artificial insemination (AI) in ostriches by conducting several studies that covered a range of topics. The first of these determined seasonal effects on male traits and suggested that sperm characteristics were compromised only around the winter solstice, while male libido (measured as the willingness to ejaculate in the dummy female) was at its lowest around the autumn equinox. Collectively, the best periods to collect semen were around spring equinox and summer solstice dates when sperm output and male libido were at their best. The second study determined the optimal sperm dose and frequency of insemination that maintained fertility throughout the laying period and resulted in chick production. AI with various sperm doses per week were used (<2.5 × 109, 2.5-5 × 109, 5-7.5 × 109 and 7.5-9.6 × 109 sperm) and resulted in lower fertility of eggs with sperm doses less than 2.5 × 109 sperm/week. Increasing the sperm dose to 2.5-5 × 109 sperm/week improved fertility and the fertile period (the number of days fertilized eggs were laid after the last AI), with the latter reaching an average of 12 days. However, a further increase in the sperm dose per week (5- 7.5 × 109 and 7.5-9.6 × 109 sperm) did not further improve fertility, fertile period and the rate of sperm loss in females. Therefore, it was suggested that the optimal sperm dose for insemination in ostriches was 2.5 × 109 sperm/week. This sperm dose was able to maintain fertility when inseminated on a weekly basis for five weeks and chicks were produced after AI. This highlighted the potential ability of chick production in ostriches after AI and suggests that this technology could be useful in breeding ostriches. Thirdly, it was established that heritability estimates (h²) were moderate (0.13) for monthly egg production and high (0.40) for mean egg weight for individually penned female ostriches (AI females). This implies that egg weight and production in an ostrich AI flock are heritable and could be improved by selection. Fourthly, significant correlations of the affordable traditional mass sperm motility scoring method with ostrich sperm motility traits measured by the advanced, yet expensive computer-aided sperm analysis system were determined. These findings suggest that screening of males for sperm motility could be done using the affordable traditional method. Fifthly, juvenile ostriches subjected to positive interactions with humans were more likely to associate and less likely to keep a distance from their human handlers. Likewise, birds of the South African Black (SAB) strain and crosses of the SAB with Zimbabwean Blues (ZB) and Kenyan Reds (KR) also interacted more with their human handlers than purebred ZB and KR birds. Behaviour traits used to identify birds for recruitment in the AI program were all heritable and should respond to selection. No unfavourable genetic correlations were recorded between these behavioural responses towards humans and most traits in the slaughter bird complex. These results suggest that temperament in ostriches can be improved by selecting birds willing to associate with humans, without compromising slaughter weight. Hence, the study demonstrated that AI is a feasible and economically viable breeding alternative in ostriches whilst also pointing out areas that still need further research. If implemented correctly, AI is likely to benefit the genetic evaluation of breeder birds, while improving human occupational health and safety and animal welfare. Combined, these aspects are likely to contribute to ethical and sustainable ostrich production.

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Page publiée le 21 janvier 2023