Relationship of Vulvar Swelling to Estrus in Mink

Abstract
A study was conducted using 103 multiparous (adult) and 93 nulliparous (kit) female mink to correlate vulvar swelling with mating performance, vaginal smears, and plasma estradiol levels during the breeding season. Vulvar swellings were classified into four stages. The 0 stage was anestrus, and little or no vulvar swelling was present. Stages 1 to 3 represented increasing levels of swelling. Most females would mate at stage 2 or 3 but not at stage 0 or 1. Not all females attained stage 3. On the average, stage 2 was attained by the adult females 16 days before kit females. Stages 0 and 3 could be readily distinguished by vaginal smears, but stages 1 and 2 were difficult to differentiate. Although vaginal smears could be used to determine when mink would not mate, they could not be used to predict when mink would mate. The estradiol levels of females in stage 0 were significantly greater than those of females in stages 1, 2, or 3 (P<01), and the estradiol levels of females in stage 3 were significantly lower than in stages 0, 1 and 2 (P<01). Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science.