Heat Stress and Animal Productivity by Anjali Aggarwal & Ramesh Upadhyay

Author:Anjali Aggarwal & Ramesh Upadhyay
Language: eng
Format: epub
Publisher: Springer India, India

Physical Characteristics of Semen

The quantity and quality of semen vary with seasons, although the degrees of response to seasonal effects vary according to species, breed and locality. Season affects ejaculate volume; however, information on influences of high environmental temperature on semen–ejaculate volume is conflicting. The studies of Zeidan (1989) and Marai et al. (1996) showed that semen–ejaculate volume decreased, while studies of Fawzy (1982) showed remarkable increase with heat elevation. The highest mean value (3.7  ±  0.1 ml) was recorded in winter and the lowest (2.4  ±  0.1 ml) in spring. Mean values of 2.9  ±  0.2 and 2.6  ±  0.l ml were recorded in summer and autumn, respectively. The effects of season on motility of spermatozoa are inconclusive and conflicting. The initial motility of spermatozoa has been observed to decrease in hot climate conditions (Ax et al. 1989; Zeidan 1989). Other studies indicated that motility of spermatozoa either increased (Oloufa et al. 1959; El-Azab 1980) or did not show any change due to season of the year or elevation of temperature (Zeidan 1989; Silvia et al. 1991).

Zeidan (1989) observed that live sperm were 87.5  ±  0.5, 76.2  ±  0.8, 74.5  ±  1.5 and 85.8  ±  0.6% during spring, summer, autumn and winter, respectively. Everett et al. (1978) recorded the highest total sperm output during summer season. Spring and summer seasons were characterised by the highest percentage of ejaculates with white milky (47.4%) and opaque creamy (28.5%) appearance and by the lowest percentage with greyish soapy (14%) and translucent watery (10%) appearance. In contrary, autumn showed the highest percentage of bad semen appearance. In other words, the highest percentage (47.4%) of ejaculates showed a white milky appearance, whereas (28.5%) was opaque creamy, 14% greyish soapy and 10% translucent white watery. Generally, semen appearance varied from opaque creamy to translucent watery. The difference in the results may be due to type and duration of heat exposure, intensity of environmental heat and differences in species, breed and age of the experimental animals.

Murrah buffalo bulls subjected to surface cooling had good quality (creamy and light creamy) semen more frequently with high sperm concentration, mass activity, motility % and live sperm production in cooled than uncooled cows but had no effect on semen volume and pH (Mandal et al. 2002).

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