An investigation of the relationships between body temperature and implantation and lambing rates in the New Zealand Romney ewe

F.R.M. Cockrem and M.F. McDonald

Massey University, Palmerston North

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Proceedings of the New Zealand Society of Animal Production. 1969, 29: 195-207

Rectal temperatures of Romney ewes, of four different ages, were measured at four observation periods during the mating season, using an experimental design to allow for ambient temperature and other effects. The number of eggs shed (represented by fresh corpora lutea) at the first two oestrous periods were determined for half the sheep by laparotomy. The numbers of lambs born to each ewe were recorded.

Real effects (P<0.05) were found in that 2- and 3-year-old ewes had higher body temperatures (103.2, 103.0°F), than older ewes (102.8°F) . In addition, the body temperature fell during the oestrous cycle with a rise (+ 0.35°F) about the time of oestrus and ovulation.

The body temperature at about the time of implantation of the blastocyst was higher for ewes having no lamb, and for those having singles, than for those having twins (103.4, 103.2, 103.1°F, respectively). Results from laparotomy showed that ewes failing to implant two eggs had higher body temperatures than those failing to implant one egg, or of ewes successfully implanting all the eggs shed (103.4, 103.2, 103.1°F, respectively). It appears that a body temperature greater than 103.2°F may affect implantation and the consequent number of lambs born.

Keywords: NZSAPAB;

Last Updated 24-08-2000