Management Strategies Aiming to Improve Horse Welfare Reduce Embryonic Death Rates in Mares

Abstract

The objective of this retrospective study was to evaluate the effect of management strategies aiming to improve animal well-being on pregnancy and embryonic death (ED) rates. Breeding records of a cohort of 1206 Thoroughbred mares brought to a stallion station facility, to be bred with the stallions housed there, were evaluated during ten breeding seasons. Mares were blocked according to management strategies in two groups: Stress and Relax. Strategies used to improve animal well-being (Relax group) were as follows: stopping the teasing routine, reducing or eliminating stall confinement, reducing the number of mares per group and maintaining herd stability during the breeding season. In barren mares, the pregnancy rate was higher in the Relax group (91.8%) when compared to the observed in Stress group (84.7%). However, no difference in pregnancy rates were observed (Stress = 85.2% vs. Relax = 86.2) in foaling mares. ED rate was higher in barren and foaling mares of the Stress group mares (25.5% and 26.8%, respectively) compared with the Relax group (16.1% and 14.7%, respectively). No significant differences were observed on foal heat pregnancy rate between groups; yet, the embryo loss on foal heat was significant reduced in Relax mares (Relax = 8.7% vs Stress = 24.5%). In conclusion, management strategies aimed to reduce social stress can reduce early pregnancy losses and the average cycles per pregnancy, improving reproductive performance in mares.

Pregnancy outcomes in thoroughbred mares inseminated with fresh semen from either stallion or jack at foal heat or subsequent estrus

“…The foal heat has been reported to occur usually from 4 to 14 days after foaling and can occur 11 to 20 days after foaling Blanchard 2005, Ricardo et al 2020). In another report, 93% of foaling mares came into foal heat 5 to 18 days after parturition, and 77% of foaling mares 7 to 10 days after foaling (Malschitzky et al 2002, Malschitzky et al 2015. The mating in foal heat does not affect the initial pregnancy (up to 60 days) rates significantly.…”

“…However, effect of mating type was significant (P≤0.01) on pregnancy rate at day 90 and foaling rate. The pregnancy rate following breeding at the foal heat was reported to be under 50% in most studies (Malschitzky et al 2002, Morris and Allen 2003, Malschitzky et al 2015. The mares mated in foal heat recorded lower pregnancy rate, higher embryonic death and foaling percentage.…”

“…In these situations, mares should be properly treated and reevaluated before presenting for breeding (Sharma et al 2010). Several studies reported lower conception rates (Malschitzky et al 2002, Sharma et al 2010, Lane et al 2016) and higher embryonic mortality and abortion rates (Malschitzky et al 2015) in mares bred at the first postpartum estrus, even without any pathological situation. In some studies, pregnancy rates and embryonic losses have been similar in mares bred either on FH or on later postpartum period (Blanchard et al 2004, Sharma et al 2010.…”

“…The goal of producing one foal/ mare/year is achievable only if broodmares conceive within first 25d postpartum. This necessitates breeding mares during the three weeks after foaling to produce a foal each year (Malschitzky et al 2015, Ricardo et al 2020.…”

Single‐incision drilling technique to achieve hemiepiphysiodesis of the distal metacarpus – complications and outcome in 207 foals with metacarpophalangeal varus deformities

“…Stress in mares is associated with early embryonic loss, and reducing mare stress by avoiding transport to the surgical facility and separation from the foal during the procedure is another probable advantage of this procedure. [31][32][33] Three horses developed calcinosis circumscripta at the surgery site, requiring a second surgery to remove the lesions. Calcinosis circumscripta, also called tumoral calcinosis, is characterized by tissue deposition of mineral calcium salts.…”