Abstract
The present study examined the effect of stroking pregnant heifers on the kicking behavior and physiological response of primiparous cows at milking. Three experimental groups were designed : udder group (the experimenter stroked the udder of pregnant heifers, 10 cows), neck group (the experimenter stroked the neck of pregnant heifers, 9 cows), control group (the experimenter stood by the side of pregnant heifers, 9 cows). Treatments were conducted once a week from 30 to 28 weeks before calving to just before calving. Heifers were stroked for 10 minutes each time. Within 1 day of calving, within 1 day after being transferred from the calving pen to the milking herd, 30, 60, and 90 days after calving, the number of kicking events were counted, the heart rate increase (HR : 5 seconds interval, times/min) at milking was recorded, and the flight distance (FD) was measured for each cow. The number of kicking events per cow within 1 day of calving, 30, 60, and 90 days after calving were significantly lower for the udder group than the control group (respectively, P < 0.05). Until 30 days after calving, the number of kicking events per cow for the neck group was similar to those of the control group, after 60 days post calving, those for the neck group decreased and equaled the lowest number of kicking events for the udder group. HR increments at milking for the udder group were generally lower than those of the other 2 groups. The plasma concentration of cortisol (ng/mL) of all three groups increased after milking within 1 day of calving and after being transferred from the calving pen to the milking herd compared to those before milking, however, the effect of stroking was not clear. The FD of the two treatment groups was shorter than at the time they were separated into groups. The tendency of FD for the neck group was more significant. In conclusion, regular stroking of the udder after a heifer became pregnant to 2 weeks before expected calving, lowered the stress responses and the amount of kicking at milking for primiparous cows. Stroking the neck improved the relationship between the human and cow, and the decrease of the number of kicking events at milking for the neck group was slower than those for udder group and became the same as the udder group at 60days after calving.
