"unbred females were in estrus longer (P = 0.01) than were females that were bred (X̄ ± SE; 2.3 ± 0.3 days versus 1.3 ± 0.2 days, respectively)"

Lisa M. White, Dennis A. Hosack, Robert J. Warren, Richard A. Fayrer-Hosken, Influence of Mating on Duration of Estrus in Captive White-Tailed Deer, Journal of Mammalogy, Volume 76, Issue 4, 4 December 1995, Pages 1159–1163, https://doi.org/10.2307/1382607