SOME EFFECTS OF FEEDING PASTURE SILAGE AS A SUPPLEMENT TO PASTURE ON REPRODUCTIVE-PERFORMANCE IN LACTATING DAIRY-COWS

Supplementation of a ryegrass/white clover pasture diet with pasture s ilage is a common management practice in New Zealand dairy herds. The effect of this supplementation on reproductive performance has not bee n investigated. Five herds of 20 cows were formed before calving comme nced on 1 June 1992. From 5 August to 4 September, two of these herds were fed 5 kg/cow/day of pasture silage in addition to the ryegrass/wh ite clover pasture offered to all herds. Pasture silage supplementatio n did not alter the intervals from calving to first ovulation, first o estrus, or to conception. However, it reduced the first service concep tion rate (37.5% v. 53.3%; difference +/- sed = 15.8 +/- 10.0%, for pa sture and silage and pasture only cows, respectively). A positive effe ct on reproductive performance of pasture silage supplementation was n ot demonstrated in this trial.