Non-infectious factors affecting the presentation of dairy cows to artificial insemination and the result of mating in south western Victoria.
The records kept by 4 artificial breeding centres in south western Victoria were examined and analysed by multiple regression analysis to determine whether daily fluctuations in the number of dairy cows presented for insemination, and daily, monthly and annual fluctuations in the result of first service, were associated with either climatic conditions or nutritional factors assessed as the availability of conserved hay and oats as feed supplements in the district. Over a 122 day observation period from July to October 1974, the number of cows presented daily for insemination was negatively correlated with daily rainfall total (p less than 0.01), wind speed (p less than 0.001) and barometric pressure (p less than 0.05). When the mean value for barometric pressure was used in the regression equation, rainfall totals and wind speeds above zero were associated with a mean reduction of 13.8% in the number of cows presented daily for insemination. The daily percentages of cows not resubmitted for service within 60 days of first service (non-return rates) were unrelated to climatic conditions and to the number of cows presented for insemination. The monthly non-return rate had a negative correlation (p less than 0.001) with the cost of oats but was not related to corresponding climatic changes. Annual non-return rate fluctuations were negatively correlated with the cost of oats (p less than 0.001) and with the July to October rainfall total (p less than 0.01). It is suggested that the correlation of non-return rate with the July to October total rainfall was due to an effect of rainfall total on the nutritional value of the pasture.
D000818:Animals; D002417:Cattle / Q000502:physiology*; D007315:Insemination, Artificial / Q000662:veterinary*