Old Mares: Oils and Nutrients Can Help Oocyte Metabolism

Loss of body condition and impaired fertility are often associated with old mares. While various supplemental oils are commonly fed to older mares, their effects on the ovarian follicle and oocyte are unclear, according to research presented at the 2023 AAEP Convention.

The presented study looked at feeding old mares flaxseed oil. That oil is rich in omega-3 polyunsaturated fatty acids (PUFAs; N3), compared to corn oil, which is rich in omega-6 (PUFAs; N6).

Feeding flaxseed or corn oil to old mares “is associated with more oxidative stress in skeletal muscle,” researchers found. However, providing supplemental nutrients with the oils mitigates muscle oxidative stress and improves oocyte metabolism.”

What the Research Found

Oocytes and granulosa cells from preovulatory follicles and skeletal muscle cells were collected from light-horse mares before they were divided into two groups and supplemented daily with 120mL of N3 (n=6 mares, average age of 22.6 years) or N6 (n=6 mares, average age 23.3 years) for 4 to 6 weeks before a second cell collection.

The groups were then maintained on their respective oils with the addition of reproductive support supplements (RSS; in this study they used Platinum VET Reproductive Care). This included a combination of omega-3 PUFAs, vitamins, trace minerals, amino acids, antioxidants, and probiotics. The mares remained on this regimen for four to six weeks before a third cell collection.

Cellular metabolism was assessed by microsensors (oocytes) or high-resolution respirometry (granulosa cells and muscle) in the research.

Reproductive Supplements Helped

“Aerobic metabolism in oocytes did not change after feeding either oil,” noted the research. “However, the addition of RSS with the oils resulted in greater oocyte aerobic metabolism for N3 and N6.”

The researchers noted that “skeletal muscle aerobic metabolism was not affected by diet supplementations. However, reactive oxygen species (ROS) production was greater after feeding oils, although ROS was mitigated by the addition of RSS with either oil.”

In summary, “Oils provide blends of fatty acids, which act as energy substrates that can affect cell metabolism and ROS. Support nutrients, such as RSS, help to optimize cell metabolic function in old mares.”

Editor’s note: This research was titled “Effects of Feeding Oils and Supportive Nutrients on Skeletal Muscle and Oocyte Metabolism in Old Mares.” It was authored by Giovana D. Catandi, DVM, DACT; Kyle Fresa; Ming-Hao Cheng, MS; Raul A. Gonzalez-Castro, DVM, MS, PhD; Tom Chen, PhD; Adam J. Chicco, PhD; and Elaine M. Carnevale, DVM, PhD. The presenting author was Catandi. She is an Assistant Professor of Theriogenology in the Veterinary Clinical Sciences Department at Oklahoma State University. Giovana graduated as a Doctor of Veterinary Medicine from the University of Sao Paulo, Brazil in 2016, and as a PhD in Biomedical Sciences from Colorado State University in 2023, when she also became a Diplomate of the American College of Theriogenologists.