The objective of the current study was to determine the effect of fans and showers on the physiological measures and reproductive performance of Holstein Friesian bulls during subtropical summer in Pakistan. Thirty-six bulls with an average body weight of 898.0 ± 135.2 kg (mean ± SD) and an average age (4 to 6 years) were randomly divided into three treatment groups: (1) CTL, bulls kept under shade only; (2) FN, bulls provided with fans under shade; and (3) FNS, bulls provided showers in addition to fans under shade. The trial was carried out for 6 months from April to September 2016 and was categorized into two seasons (dry summer and humid summer). Ambient temperature, relative humidity, temperature-humidity index, dry matter intake (DMI), water intake, rectal temperature (RT), pulse rate (PR) and respiration rate (RR) were recorded daily. Semen characteristics and selected blood metabolites were measured every 2 weeks. The results indicated that the DMI of the bulls was similar between the treatment groups. Water intake, RT, PR and RR were significantly lower in the FNS group than in the CTL and FN groups (P < 0.001). Semen characteristics, including semen concentration, post-thaw semen motility, progressive motility, amplitude of lateral head displacement, straightness, live-to-dead ratio, plasma membrane integrity, normal acrosomal ridge and DNA integrity, were not different between the treatment groups (P > 0.05). The FNS group tended to have a higher semen volume than that of the FN and CTL groups (P = 0.10). Blood glucose levels were significantly lower in the FNS group than in the FN and CTL groups (P < 0.05). Blood urea nitrogen and testosterone were not different among the treatment groups (P > 0.05). The current results indicated that showers with fans improved the welfare of Holstein Friesian bulls by lowering physiological measures in addition to increasing trends in semen volume during subtropical summer.
Keywords: Bull welfare; Heat stress; Semen characteristics; Showers.