This is the first report of pregnancy in the Caspian miniature horse using frozen semen, and these results seem to be a promising start to an extensive program to assist with the breeding of this endangered breed.
Hiva Alipour DVMa, Mina Sharbatoghli MSc a, Poopak Eftekhari Yazdi PhD a, Abdolhossein Shahverdi PhD a, Mohamad Taghi Daneshzadeh DVMa, Masoud Afshani DVMa, Seied Jalal Mirian DVMb, Hormoz Hamidi DVMb, Ahmad Reza Mohammadi DVMb, Mojtaba Rezazadeh Valojerdi PhD a
a Department of Embryology, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
b Agricultural and Resource Research Center, Jihad-e-Agriculture, Tehran, Iran
Journal of Equine Veterinary Science , Volume 33, Issue 4, April 2013, Pages 266-271
Abstract
The primary goal of this project was to establish a protocol to freeze the sperm of the Caspian miniature horse in an attempt to start an intensive artificial insemination program to effectively increase the population of this breed, which has been listed as “Critical Rare Breed” by the American Livestock Breed Conservancy and is in danger of extinction.
Commercially available equine freezing medium (EquiPRO CyoGuard Complete egg-yolk extender) was used for the initial setup of two different freeze protocols: slow and fast.
The fast-freeze protocol had slightly better postthaw results and was used for a fertility demonstration.
Five mares of proven fertility, aged 3 to 12 years, were used in the fertility trials, two of which resulted in pregnancy.
This is the first report of pregnancy in the Caspian miniature horse using frozen semen, and the results seem to be a promising start to an extensive program to help this endangered breed, although
further research on freezing protocols and conditions for this process are necessary to further improve the survival of semen and pregnancy rate.
Keywords: Caspian miniature horse, Sperm freeze, Equine AI , Cryopreservation, EquiPRO CryoGuard
Discussion
The protocol used to transfer semen from the farm to the laboratory in this study was very similar to and supported previous studies [19] in which stallion spermatozoa was centrifuged to remove the seminal plasma at 25C.
In this study, a dose of 500 106 progressively motile spermatozoawas used based on a previous study by Loomis and Squires [23], which reported a 52.7% per-cycle pregnancy rate when mares were bred using frozenethawed semen, with doses equal to 240-600 106.
The semen used to inseminate the mares in this study was also similar to the 500 106 progressively motile spermatozoa dose that has shown to yield maximum pregnancy rates using fresh semen.
In the current study, we successfully used frozene thawed sperm at the same concentration as recommended for fresh semen [25].
Furthermore, we used a single insemination (2-4 hours after ovulation) rather than the recommended 48-hour interval of inseminations after estrus using fresh semen.
Further research to improve insemination success needs to be performed to optimize factors such as insemination time after ovulation, increasing the number/percentage motile sperm, and repeated inseminations shortly after ovulation.
This is the first report of pregnancy in the Caspian miniature horse using frozen semen, and these results seem to be a promising start to an extensive program to assist with the breeding of this endangered breed.
This study also suggests that further research on freezing protocols and conditions for this process are necessary to further improve the survival rate of semen and pregnancy in the Caspian miniature horse.