Evaluation of the breeding soundness test for Bonga sheep in the context of a community-based breeding programme in Ethiopia

Abstract

The aims of this study were to evaluate sire selection traits and semen characteristics for Bonga sheep. A total of 101 sires with different birth year from the Bonga sheep community based breeding programme (CBBP) were used to collect data. The data was analysed by using the GLM procedure of SAS and least square means was separated by using adjusted Tukey-Kramer method. The breeding soundness tests consisted of physical examinations, sire body condition score (BCS), scrotum circumference, estimated breeding value (EBV), six months body weight (SMWT), and semen characteristics (volume, motility, and concentration) collected using an artificial vagina. The overall least square means ± SE for scrotum circumference, EBV, and six-month body weight of Bonga sheep were 28.20 ± 0.381 cm, 2.13 ± 0.326, and 24.69 ± 0.547 kg, respectively. Similarly, semen volume, mass motility, sperm concentration, and total spermatozoa of Bonga sheep was 1.14±0.076 ml, 4.28±0.138 million/ml, 4.25±0.195 billion/ml, and 4.86±0.393 billion/ml, respectively. A sire with thin BCS resulted in low scrotum circumference (P < 0.001) and questionable semen characteristics (P < 0.05). The body weight and the scrotum circumference of the Bonga sheep increased with age, but the breeding value fluctuated. . Both a large scrotum and a good BCS sire produce a high volume of semen and has simultaneously better motility and concentration. This will enable to increase the fertility of a sire under CBBP. The scrotum circumference of Bonga sheep in relation to their body weight can be categorised as either satisfactory or excellent. Body weight of Bonga sheep was increased across sire birth year but fluctuating trend for breeding value. Scrotum circumference increased with increasing age from grower to mature stage of a sire. Both large scrotum circumference and good BCS sire produces high semen volume and has simultaneously better motility and concentration. This will enable to increase fertility of a sire under CBBP. We can categorize scrotum circumference of Bonga sheep either satisfactory or excellent with the proportion of their body weight.

Keywords

• breed improvement
• optimisation
• selection
• semen
• sire