The effect of the Afrikaner infusion project on longevity: A survival analysis

• Published in: Livestock science 2023-10, Vol.276, p.105323, Article 105323
• Main Authors: Steffl, A.M. Bot, Gonda, M.G., Scholtz, M.M., MacNeil, M.D.
• Format: Article
• Language: English
• Subjects: Backcross; Cox regression; Selection decisions
• ISSN: 1871-1413; 1878-0490
• DOI: 10.1016/j.livsci.2023.105323

•Infusion of Bonsmara into Afrikaner immediately increased length of life.•Effects of infusion of Bonsmara into Afrikaner dissipated as backcrossing progressed.•Alternative strategies may be needed to increase length of life. The Afrikaner breed of cattle is indigenous to South Africa and due their hardiness has been used in forming several new composite breeds. In the 1980′s, Afrikaner breeders became concerned about a perceived loss in fertility and the lack of attention to performance traits. The “infusion project” was developed to target shortcomings of the Afrikaner breed with the introgression of Bonsmara alleles into Afrikaner cattle. However, documented evidence of resulting changes in the fitness of Afrikaner cattle is scant. A survival analysis of the infusion project's impact on longevity has been completed with the Cox model. The first backcross generation (BC1) and the initial Afrikaner-Bonsmara cross generation (F1) had the lower risk ratios at 0.815 and 0.837, respectively, when compared to the purebred Afrikaner indicating their greater longevity. The second (BC2) backcross generation did not differ in longevity relative to the purebreds (P ≥ 0.05). The infusion of Bonsmara impacted longevity in the short-term, possibly due to increased retained heterosis or the breed substitution effect. However, the effect on longevity diminished as the generations of backcrossing to Afrikaner progressed.