The Thai Journal of Veterinary Medicine


This study was carried out to investigate sperm production in tropical area of boar stud which has been free from porcine reproductive and respiratory syndrome (PRRS) more than ten years and kept in evaporative cooling system, in relation to season and breed influence. Semen production data from 19,966 ejaculates of 517 boars (164 Duroc, 31 Pietrain, 268 Landrace x Yorkshire: LY, 54 Pietrain x Duroc: PD) were collected. Semen parameters; volume (ml), sperm concentration (x106 sperm/ml) and total number of sperm per ejaculate (x109 sperm/ejaculate) were evaluated. The semen production was shown by month and group in relation to season as summer (Mar-Jun), rainy season (Jul-Oct) and winter (Nov-Feb). On average, the semen volume, concentration, and total sperm per ejaculate were 249.7±97.5 ml, 335.7±95.9x106 sperm/ml and 78.9±28.4x109 sperm/ejaculate, respectively. For the effect of season, the total number of sperm per ejaculate in winter was higher than a period in rainy season (Aug-Oct) (p< 0.05) while the concentration in early winter (Nov and Dec) was lower than summer and a month in rainy (Jul) (p< 0.05). Effect of breed, the total sperm production of LY crossbred boar (88.2±27.2 x 109 sperm/ejaculate) was higher than purebred Duroc boar (60.2±21.9 x 109 sperm/ejaculate, p= 0.01) and purebred Pietrain boar (76.5±21.8x109 sperm/ejaculate, p= 0.03). The seasonal variation effect was most pronounced in purebred Duroc and Pietrain boars rather than LY and PD crossbred boars. The fertility data using Duroc semen (total number of piglets born and born alive) tended to increase during Mar-Jun and Oct-Dec. The lowest total number of piglets born and born alive were shown in Oct (p< 0.05). It can be concluded that season and breed influencing the sperm production was found in boars kept in EVAP with free PRRS in Thailand.

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