December and January, respectively. For the red deer and F wapiti hybrids, between-hind
1
variation in OR was not randomly distributed across the treatment dates, indicating that the individuals varied significantly in their ability to respond to oFSH, at least within a given season.
In conclusion, the study has shown that relative to red deer, F wapiti hybrid hinds exhibit a
1
higher sensitivity to oFSH, whereas 1 4 PD hybrid hinds have a lower sensitivity. However, individual variation within genotype was very marked. A seasonal effect was apparent for all
genotypes, although some F wapiti hybrid hinds exhibited ovulatory responses throughout the
1
year. q 2000 Elsevier Science B.V. All rights reserved.
Keywords: Red deer; Genetics; Seasonal; Dynamics; Superovulation
1. Introduction
Ž .
Ž Multiple ovulation-embryo transfer MOET protocols for red deer CerÕus elaphus
. scoticus have been established commercially over the last decade, particularly within
the New Zealand deer farming industry. However, inconsistency of the superovulatory Ž
responses of donor hinds has been a general feature of all programmes Fennessy et al., .
1994; Asher et al., 1995 . Seasonality and donor genotype are considered to be two major factors that may contribute to the wide variation of ovarian response to exogenous
gonadotrophins. The highly seasonal nature of luteal cyclicity of red deer hinds has been well
Ž .
documented Guinness et al., 1971; Duckworth and Barrell, 1992; Asher et al., 2000 . Ž
. The ‘‘rut’’ i.e., the season of intense sexual activity occurs during the early part of the
hinds’ potential breeding seasons. It is also the time when most of the MOET programmes are performed. However, seasonal constraints on an optimal calving season
in early summer often necessitate the instigation of MOET programmes prior to the rut Ž
. Fennessy et al., 1994 , at a time when a proportion of hinds may be exhibiting
anovulation and luteal absence. It seems likely that this would lead to highly variable superovulation responses. Conversely, few studies have considered ovarian responses to
exogenous gonadotrophins in the period after the rut. This has relevance to the programmes of repeated embryo collections from elite donors.
Previous studies have demonstrated genetic influences on the timing and duration of Ž
the breeding season of ‘‘red deer’’ C. e. scoticus vs. subspecies and species hybrids; .
Asher et al., 2000 , which may influence the superovulatory responses early in the breeding season. There are also putative direct genetic effects on ovarian responses to
exogenous gonadotrophins. Anecdotal evidence indicates variable sensitivity to exoge- Ž
nous FSH amongst various genotypes, with the deer of eastern European origin C. e. .
Ž hippelaphus being reputably more reliably responsive to treatment N. Beatson, per-
. Ž
sonal communication , and the North American wapiti C. e. nelsoni, C. e. rooseÕelti, .
C. e. manitobensis, etc. characteristically exhibiting very poor responses to treatment Ž
. Bringans, 1987, 1989 .
The objective of the present study was to evaluate the influences of season and Ž
. genotype on superovulatory response of red deer i.e., C. e. scoticus
and various hybrids to a standardised superovulatory regimen used commonly in the deer farming
industry.
2. Materials and methods
