Milk-based semen diluents have proven to be practical and effective in protecting sperm cells during storage prior to artificial insemination; however, milk components may not be at optimal concentrations, and some may even be detrimental to sperm cells.
In the early 2000’s, The French National Institute of Agriculture Research (INRA) developed a chemically defined extender, INRA 96, which contains the purified fractions of milk micellar proteins. A study conducted over the course of three years by INRA tested the fertility of stallion semen after long-term storage using two different milk extenders, INRA 82 (Kenney formula) at 4°C under anaerobic conditions and INRA 96 at 15°C under aerobic conditions, with a goal to improve fertility of stallion semen affected by cold shock.
Results show fertility when influenced by extender, storage temperature and aerobic/anaerobic conditions. Semen stored for 24 hours using INRA 96 at 15°C under aerobic conditions improved pregnancy rate when compared with traditional milk-based extenders a 4°C under anaerobic conditions. Results indicated that from the 13 stallions collected, 9 stallions performed the same, if not better, when extended in INRA 96 at 15°C.
Results showed semen extended with INRA 96 and stored at 15°C for 72 hours maintained fertility with a 48% pregnancy rate at day 14.
Today, INRA 96 is the only ready-to-use semen extender proven to protect sperm cells at 15°C. For more information on the use of INRA 96 at 15°C under aerobic conditions, please reference:
DELAYED INSEMINATION IS SUCCESSFUL WITH A NEW EXTENDER FOR STORING FRESH EQUINE SEMEN AT 15°C UNDER AEROBIC CONDITIONS
F. Batellier,¹ G. Duchamp,¹ M. Vidament,¹ G. Arnaud,² E. Palmer,¹ and M. Magistrini¹
¹Unité de reproduction équine, I.N.R.A.-Haras nationaux, PRMD, 37380 Nouzilly, France
² Institut du Cheval, DEFI, Domaine de la Valde, 19370 Chamberet, France
Received for publication: October 31, 1997 Accepted: April 22, 1998