Effects of a new injectable short-term release deslorelin in foal-heat mares.

This research paper investigates the impacts of a new deslorelin product on foal-heat mares, particularly with regards to hastening ovulation and preserving the number of large follicles. The findings demonstrated that the product was successful in these objectives, reducing the need for covers, increasing instances of ovulation within 2 days of treatment, and maintaining normal pregnancy rates without leading to follicular suppression.

Research Objective

• The main objective of this research was to assess the effectiveness of a new injectable short-term release deslorelin product on early foaling first postpartum (after birth) estrus mares (mares in heat following foaling), with a specific focus on whether the product would accelerate ovulation whilst maintaining the number of large ovarian follicles at early pregnancy examinations.

Methodology

• From approximately 5-6 days after birth, first postpartum estrus mares were tested daily and examined three times a week via transrectal ultrasonography.
• Estrus mares with a follicle of 34 mm or larger in diameter were randomly given one of two treatments: 1.5 mg of injectable deslorelin, or no treatment (control).
• The testing schedule was designed to accurately determine the number of mares that ovulated within 2 days of treatment.
• Once ovulation had been confirmed or estrus behavior had ceased, mares were mated every two days.
• Pregnancy status and ovarian follicles were assessed 14-15 days after ovulation using transrectal ultrasonography.

Findings

• The deslorelin treatment was shown to be effective, as fewer matings were required and a higher number of mares ovulated within 2 days of treatment compared to the control group.
• The pregnancy rates in the deslorelin-treated mares remained normal, at 69%.
• No significant difference was seen in the number of large follicles 14-15 days after ovulation between the control and treated groups, suggesting this formulation of deslorelin did not result in follicular suppression.