Induction of early breeding in red deer (Cervus elaphus) by melatonin

Abstract

Lactating (N = 12) and non-lactating (N = 6) red deer hinds and one stag at pasture were given concentrates (500 g/head) containing melatonin (5 mg/head) daily at 16:00 h from 18 June to 16 October. The stag shed the antler velvet and started rutting 5 weeks ahead of untreated stags, and hinds had their first oestrus and ovulation of the breeding season in mid-September, 5 weeks in advance of control lactating (N = 9) and non-lactating (N = 5) hinds. Treated hinds were allowed to mate with the treated stag and control hinds ran in an adjacent paddock with an untreated stag. All hinds became pregnant during the study with all but 2 melatonin-fed hinds (1 lactating, 1 non-lactating) and 1 control hind (lactating) conceiving at the first oestrus. Melatonin-treated hinds lost slightly more live weight than did controls from June to November, but their suckled calves grew throughout at a rate similar to those of control hinds.

Photoperiod and the regulation of annual and circannual cycles of food intake

“…In such circumstances, melatonin-dependent reductions in food intake may be modulated by variation in the duration of time spent grazing per day rather than the instantaneous feeding rate which may be optimized for any given level of food availability. "elatonin also advanced the timing of the onset of the breeding season, as has previously been shown for this species (Adam & Atkinson, 1984;Adam et al 1986;Milne er al. 1990).…”

Melatonin can induce year-round ovarian cyclicity in red deer (Cervus elaphus)

“…In (Adam & Atkinson, 1984;Adam et al, 1986). The sensitivity of the assay was 0-2 ng/ml, and intra-and inter-assay coefficients of variation at 1-3 ng/ml were 9 and 13% respectively.…”

Seasonal energy requirements of wapiti (Cervus elaphus) for maintenance and growth

“…These cycles are entrained by photoperiod and are associated with seasonal endocrine changes (Shi and Barrell 1992). They are expressed even in a stable nutritional environment (Kay 1979; Adam et al 1986 to maintain body energy throughout the year (Blaxter 1989 (Moen 1973(Moen , 1985 (Jiang 1993 Lignin content was determined using 72% stlfuric acid according to Goering and van Soest (1970). Chromogen determination followed the method of Reid et al (1953).…”