Abstract
The purpose of the present study was to test the hypothesis that season has an affect on semen quality and scrotal circumference of Dorper rams. The experiment was carried out with six Dorper rams aged between 15 and 18 month. Semen samples were collected with artificial vagina and volume, concentration (x 109/ml), total sperm number/ejaculate (x 109), mass motility (0–5), progressive motility (%), scrotal circumference (cm) was observed. Significant differences (P<0.05) were observed in concentration, total sperm number/ejaculate, scrotal circumference in different seasons. Volume was the highest in autumn (1.4±0.5 ml) and the lowest in the spring (1.3±0.4 ml). Concentration of semen was lower in spring (2.6±1.5 x 109) and summer (3.3±1.5 x 109) as compared to fall (4.1±1.1 x 109) (P<0.05). Regarding total sperm number/ejaculate (x 109), scrotal circumference (cm) all the seasons differed significantly (P<0.05), although the season had no effect on mass motility and progressive individual motility (P<0.05). In conclusion the present study showed that semen quality parameters and scrotal circumference of Dorper rams were better in autumn than in the other sea- sons.
Highlights
Dorper is a mutton sheep developed for the arid regions of South-Africa between 1945–1950, in order to improve the carcass size and quality
Dorper is one of the most fertile of the sheep breeds with 150% lambing percentage resulting in 2.25 lambs/year, as the breeding interval can be shortened to 8 months or 3 times in 2 years
In sheep testicular size and semen production has been shown to be influenced by nutrition and season (Evans and Maxwell, 1987)
Summary
Dorper is a mutton sheep developed for the arid regions of South-Africa between 1945–1950, in order to improve the carcass size and quality. Decreasing daylight enhances spermiogenesis and scrotal circumference, which is strongly related to semen production capacity of the ram. It is usually larger in the fall breeding season and can decrease by 2–3 cms in the spring (Horváth, 1983; Gergátz, 2007). Some breeds (e.g. Dorset, Merino, Finnsheep, Romanov and hairsheep, like Somali) are much less seasonal in their breeding behaviour, though rams are less affected than ewes (Net 1). The purpose of our study was to determine the effect of seasonal fluctuation on seminal characteristics, testicular size in mature Dorper rams under the Eastern-Hungarian climatic conditions
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