The breeding season of pubertal red deer hinds
J.A. Duckworth, G.K. Barrell
Animal and Veterinary Sciences Group, Lincoln University,
Canterbury, New Zealand
Proceedings of the New Zealand Society of Animal Production.
1992, 52: 183-186
In a study of seasonality of reproduction, 4 pubertal red deer
hinds were monitored for live weight and plasma hormone concentrations
from December 1987 to October 1988 (i.e. 12-22 months of age). On 7
occasions blood samples were collected every 20 minutes for 4 h to
monitor secretion of luteinising hormone (LH) and response to an i.v.
injection of 2 µg gonadotrophin releasing hormone (GnRH). Plasma
progesterone profiles indicated that 4-6 ovarian cycles, lasting about
19 days each, occurred for each hind. Regular ovarian cycles commenced
in late April (26 April ± 3.4 d, mean ± S.E.M.) and ceased about 3
months later. The number of LH pulses/4 h was higher in June than
during the non-breeding season, but there was no change in the LH
response to GnRH. These data showed that the breeding season of non-
pregnant yearling red deer hinds was shorter than that reported for
older hinds. Constancy of pituitary responsiveness to GnRH indicated
that, as in other species, breeding seasonality is determined by changes
in the output of GnRH from the hypothalamus rather than seasonal changes
in sensitivity to GnRH.
Keywords: NZSAPAB;
Red deer hinds; puberty; breeding season; progesterone; LH; live
weight.
Download abstract in text format
Last Updated 25-01-1997
