Abstract
During July, 1989, fourteen lactating, nonpregnant and normally cycling Holsteins were assigned randomly to pens in freestall barn with fan or without fan- to observe the effect of forced ventilation on cortisol and estradiol-1713 concentrations. After an adjustment period of 21 days, jugular cannulae were inserted and 25 mg prostaglandin (PG)Fla (Lutalysef-, The Upjohn Co., Kalamazoo, MI) was injected. All animals were in their luteal phase at the time of injection as determined by previous observations for oestrus and palpation. After PGFla, blood samples were collected at 6 h interval from 0 to 36 h, 4 h intervals from 36 to 88 hand 3 times weekly (MWF) for three weeks thereafter. Blood samples were assayed for cortisol, and estradiol-FIji. Daily rectal temperatures and ambient condition data were recorded. Average daily rectal temperatures were lower (P<0.05) in the fan (39.10 0 C) than in the control group (39.48 C). Cortisol did not show diurnal pattern and the values did not differ (P<0.05) between treatment groups. The values of pre- and post -oestrus estradiol-1713 were analysed separately and were also not different in groups.
