Aspects of reproduction in New Zealand dairy herds. 1. Gestation length

Authors: Macmillan KL, Curnow RJ
Publication: New Zealand Veterinary Journal, Volume 24, Issue 11, pp 243-252, Nov 1976
Publisher: Taylor and Francis

Animal type: Cattle, Livestock, Production animal, Ruminant
Subject Terms: Pregnancy, Reproduction, Reproduction - female
Article class: Scientific Article

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Abstract: In New Zealand dairy cattle, the average gestation length is commonly accepted as 282 days. This is slightly longer than that reported in European and American studies of Jersey and Holstein or Friesian cattle (Anderson and Plum, 1965; O`Conner et al 1968). A feature of these reports and previous New Zealand studies is the differing variation associated with the mean gestation lengths. Part of this may be due to sex, season, breed of sire, age of dam and unspecifieid herd effects, but is largely the result of excluding or including abnormal gestation periods. The criteria for determining normality have been rather arbitrary in most cases. Abnormally short and long gestation periods may result from disease or from, incomplete data recording for conception dates. In this investigation, data frolm several recent extensive surveys were analysed to estimate what could be defined as a “normal” gestation perioid and to assess the effects of some factors that may contribute to its variation.

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