The Use of Hormonal Assay, Phenotypic Morphometry, and CASA Semen Analysis to Estimate Attainment of Puberty in Indigenous Ram Lambs

Abstract

Ruminant landraces that are locally adapted have become crucial for sustainable farming considering climate change. This study sought to evaluate the commencement of reproductive capability of Bapedi, Namaqua-Afrikaner and Zulu ram lambs. Data were collected from a total of 21 ram lambs (7/breed) starting from 3–8 months of age. From four months of age, the scrotal circumference of rams was measured using a flexible tape and it was found that it differed significantly between breeds (P < 0.05). Blood was collected from the jugular vein using a 21-gauge needle and red cap vacutainers. Blood serum testosterone levels were obtained using a competitive enzyme immunoassay. It was found that Bapedi, Namaqua-Afrikaner and Zulu ram lambs had similar blood serum testosterone levels (P > 0.05). At 7 months, semen was collected using an electro-ejaculator and analysed using a Sperm Class Analyser©. There were significant differences found in semen quality between the studied breeds for various semen parameters (P < 0.05). There was a weak positive correlation between blood serum testosterone and scrotal circumference (r = 0.30). Conclusively, this study highlights the importance of characterisation for the conversation of landrace breeds.