Senior mares can be notoriously difficult to get and keep in foal. Yet simply recovering oocytes and embryos and transplanting them into young surrogates to carry to term has not been the panacea that equine reproductive specialists had once hoped. However, Colorado State University (CSU) researchers recently confirmed that nutrition plays a key role in improving oocyte quality, which can be a boon to overcoming fertility problems in older mares.
Indeed, a young uterus does not overcome all the problems with eggs collected from older mares, said Giovana D. Catandi, DVM, a PhD student and research assistant at CSU’s College of Veterinary Medicine & Biomedical Sciences, during the opening remarks of her presentation at the 65th American Association of Equine Practitioners Convention, which is currently underway in Denver.
Catandi reported that research she and colleagues in CSU’s Equine Reproduction Lab conducted in 20 mares ages 13-23 suggests that a diet rich in omega-3 fatty acids and antioxidants allows oocytes to mature and metabolize energy more efficiently. Further, oocytes from older mares receiving these supplements were also more likely, when fertilized, to develop into normal blastocysts (an early stage of the developing embryo) that could result in viable pregnancies.
The team divided 20 light horse mares into two groups. They fed one group a typical “modern” horse diet, said Catandi, comprising grass/alfalfa along with supplementary grain and corn oil. They offered the second group grass/alfalfa forage and several supplements, which included micronutrients, pre- and probiotics, antioxidants, L-carnitine, and different sources of omega-3s, including flaxseed oil. She said these were specially formulated by Platinum Performance to enhance wellness, especially of the gastrointestinal tract, and to improve fertility. The mares consumed the diets for six weeks prior to sampling.
The researchers then quantified changes in oocyte metabolism utilizing a special microchamber designed to measure fluctuations in oxygen consumption and pH. Then they collected and fertilized additional oocytes using intracytoplasmic sperm injection (ICSI) and assessed cleavage rates (division of cells in the early embryo). In comparing the two groups they observed that more fertilized eggs developed into blastocysts from the mares consuming the omega-3 fatty acid supplement (58%) than from the grain and corn oil supplement group (15%).
Catandi and her colleagues concluded that dietary supplements consisting of a complex of nutrients with omega-3 fatty acids might increase the overall fertility of older mares by improving oocyte metabolic function and embryo development.
Editor’s note: The researchers disclosed in their abstract that they used an aqueous solution of deslorelin acetate to induce follicular maturation to maintain consistency with previous research. They noted that compounded products can vary significantly with respect to potency of the active ingredient(s).