An apparent nutritional lactational stress infertility in dairy herds

Abstract

Extract

In 1955, 1956, and 1957, 66 dairy herds in. the Waikato district of New Zealand, with mating seasons restricted to the September–December, period, were examined in a survey designed to find the incidence of each of the known causes of herd infertility McClure, 1959). More than half of the 31 problems, as defined by a first service non-return rate of less than 50 per cent, were of unknown cause. Most of these herd problems were of female origin and were equally divided between those in which the fertility of cows of all ages above yearlings was poor and. those in which the fertility of the adults (three-year-old cattle and older) was poor, while that of the two-year-old (first lactation) heifers was good. Field observations made during the survey suggested that the feeding of short, rapidly growing pasture, containing little clover, was associated with many of the infertility problems of the type described. It was also observed that the herds which were fed at least 5 lb hay or 15 lb silage per cow per day over the mating period, in addition to pasture, did not suffer from low fertility. It was not possible to determine whether the association was with quantitative or qualitative nutritional factors. Dairy meal was not fed to these herds at any time of the year.