Long-term micronutrient and amino acid supplementation increases embryo recovery per flush and ovarian responsiveness in donor mares.

BACKGROUND

Nutritional strategies may modulate ovarian function and embryo recovery in donor mares, but field evidence for long-term multinutrient supplementation remains limited.

AIMS/

OBJECTIVES

To determine whether long-term micronutrient and amino acid supplementation increases embryo recovery per flush and ovarian responsiveness in donor mares.

METHODS

A total of 115 uterine flushes were performed under a crossover design across two consecutive breeding seasons in 12 multiparous, non-lactating crossbred donor mares (4-12 years). Mares received a basal diet or the same diet plus 40 g/day of a multinutrient supplement for 150 days; treatments were reversed after a 6-month washout. Follicular development was monitored by transrectal ultrasonography, and ovulation was induced when preovulatory criteria were met. Fixed-time artificial insemination with frozen semen was performed 24 h after ovulation induction. Ovulation was assessed 48 h after induction; if ovulation had not occurred, mares were rechecked every 12 h until ovulation was detected. Day 0 was defined as the day ovulation was first detected for scheduling embryo recovery.

RESULTS

Of the 115 flushes (supplemented: 60; control: 55), embryo recovery rate was higher with supplementation (49/60, 81.7%) than in controls (36/55, 65.4%), risk difference +16.2 percentage points (95% CI 0.3-32.1; P = 0.048). Mare-level follicle counts increased during supplementation for multiple small follicles (≤15 mm; 115.3 ± 10.3 vs 112.7 ± 11.0; P = 0.003) and follicles ≥30 mm (24.7 ± 3.1 vs 23.1 ± 2.9; P = 0.012).

CONCLUSION

Long-term multinutrient supplementation increased embryo recovery per flush and mare-level ovarian follicular activity in donor mares; embryo morphology-based quality grade distributions were similar between the control and supplemented phases.