An attempt to advance seasonal reproductive activity in stoats (Mustela erminea) by use of an artifical photoperiod: A dissertation submitted in partial fulfilment of the requirements of the Degree of Bachelor of Science with Honours at Lincoln University

Abstract

To develop reproductive control technologies for wild stoat (Mustela erminea) populations there is a requirement for year-round breeding in captive animals. This study tested the hypothesis that a long-day photoperiod applied to stoats during winter months would stimulate reproduction in these animals. Adult stoats (12 males and 12 females) were captured from the wild during summer and autumn. From 14 May half of the animals were subjected to artificial lighting, which reached 16 h/day on 30 June and continued at this daily duration until November. Controls experienced natural changes in daylight. Faecal samples were collected for hormone analysis. Vaginal cytology and physical changes associated with oestrus were monitored in females and scrotal size was monitored in males. In early spring months there was a high incidence of keratinised vaginal epithelial cells and signs of oestrus in light-treated females that were absent in the controls. Mean faecal oestradiol concentration was highly variable (1- 20 ng/g dry weight), and was not different between treated and control groups of females. Light-treated males had higher (P < 0.05) mean faecal testosterone concentrations than controls ( e.g. 272 ±. 32 versus 163 ±. 31 ng/g dry weight respectively, on 4 September) and larger (P < 0.05) scrotal dimensions in August. These results show that stoats are amenable to photoperiodic stimulation of breeding activity and provide some of the first reproductive endocrinology data for this species in New Zealand.