Implication of Poor Body Condition to Reproductive Performance in Mares

Body condition score (BSC) on brooding mares plays important roles in their reproductive performance. Mares with poor BSC are commonly observed with perineal anatomical deformity manifested by vulva inclination. These conditions cause stretching of the vulva opening reaching the point of pelvis ischium that compromised vulva’s function as the barrier to the reproductive tract protecting it from contaminants. Physical examination was conducted on 116 mares to determine the severity of inclined vulva using Castlick’s Index. Mares with the severe vulva inclination were large breeds, had pregnancy several times, and were pregnant before two years old. These mares have a high number of bacterial isolates due to fecal urine backflow entering their reproductive tracts from the compromised protective mechanism of the labia. The contamination of the reproductive tract, was mostly at the fornix and uterus of mares with severe vulva inclination. These mares were observed exhibiting extended standing heat and strong stallion receptiveness, which is coherent with the endocrine dynamics of the affected mares. This behavior matched the situation of lower plasma estrogen concentration during the follicular phase, suggesting a delayed luteinizing hormone surge in facilitating ovulation. The condition causing erratic behavior during estrus creates difficulty in managing reproduction.