Fertility comparison between breeding at 24 hours or at 24 and 48 hours after collection with cooled equine semen.
Abstract: It has become a common practice in the equine breeding industry to send 2 insemination doses for breeding with transported cooled semen, one to be used for the initial insemination upon arrival, and the other to be held a second insemination the next day. One fertile stallion and 36 fertile mares were used to determine if breeding once with 1 dose of semen cooled for 24 h would improve fertility compared with breeding twice, 1 d apart, with half the dose of semen cooled for 24 h on the first day of breeding and half cooled for 48 h on the second day of breeding. Mares were given two intramuscular injections of 10 mg PGF2 alpha 14 d apart. Following the second injection, mares were teased with a stallion and their ovaries were scanned by transrectal ultrasonography daily. When a dominant follicle (> 35 mm diameter) was detected, 1500 units hCG were injected intravenously, and the mares were inseminated. Semen was collected in advance of anticipated breeding, mixed in nonfat dry milk solids-glucose extender to a concentration of 25 million sperm/mL, and placed in 2 commercial cooling containers for 24 or 48 h of storage prior to breeding. Mares were randomly assigned to 1 of 2 insemination treatment groups: 1) Group T1 (n = 18), in which mares were inseminated on the day of hCG injection with 500 million spermatozoa cooled for 24 h, or 2) Group T2 (n = 18), in which mares were inseminated on the day of hCG injection with 250 million spermatozoa cooled for 24 h, and again on the following day with 250 million spermatozoa cooled for 48 h. Pregnancy status was confirmed by transrectal ultrasonographic examination at 14 and 16 d after ovulation. Pregnancy rates were the same for both insemination treatment groups (12/18; 67%). There was no advantage to holding half of the insemination dose for rebreeding on the following day.
Publication Date: 2000-03-29 PubMed ID: 10734443DOI: 10.1016/s0093-691x(98)00174-5Google Scholar: Lookup
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- Clinical Trial
- Comparative Study
- Journal Article
- Randomized Controlled Trial
Summary
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This research studies the efficacy of using cooled equine semen for a single insemination 24 hours after collection, versus two inseminations – one at 24 hours and another at 48 hours after collection. The experiment involved 36 mares and one fertile stallion, and concluded that both methods offer the same result, implying there’s no advantage to holding half of the insemination dose for an additional day.
Research Methodology
- The research involved the use of a fertile stallion and 36 fertile mares.
- Two intramuscular injections of 10 mg PGF2 alpha were given to the mares 14 days apart. Post second injection, mares were stimulated with a stallion and subjected to daily transrectal ultrasonography.
- When a dominant follicle of > 35mm diameter was detected within the ovaries, 1500 units of hCG were injected intravenously, proceeding with the insemination.
- The semen used was collected in advance of anticipated breeding, mixed in a glucose extender, and cooled in two commercial containers for 24 or 48 hours before the breeding.
Research Groups
- The mares were split into two groups. The first group (T1) involved 18 mares which underwent insemination on the day of the hCG injection with 500 million spermatozoa that was cooled for 24 hours.
- The second group (T2) also had 18 mares. They were inseminated on the day of the hCG injection, and again on the following day, both with 250 million spermatozoa – the first was cooled for 24 hours and the second for 48 hours.
Research Findings
- Pregnancy status was confirmed through an ultrasonographic examination at 14 and 16 days after ovulation.
- The research found that both methods gave the same pregnancy rates (12 out of 18 mares; 67%).
- The study concluded there was no advantage to holding half of the semen dose for insemination a day later.
Impact on Equine Breeding Practices
- The results of this research could influence practices within the equine breeding industry, particularly those using cooled equine semen for insemination.
- It suggests a simplification of the process, implying a single dose of semen, cooled for 24 hours, is as effective as dividing the same quantity for two inseminations at different timings.
- This finding could help streamline procedures, save time, resources and reduce unnecessary handling of animals.
Cite This Article
APA
Shore MD, Macpherson ML, Combes GB, Varner DD, Blanchard TL.
(2000).
Fertility comparison between breeding at 24 hours or at 24 and 48 hours after collection with cooled equine semen.
Theriogenology, 50(5), 693-698.
https://doi.org/10.1016/s0093-691x(98)00174-5 Publication
Researcher Affiliations
- Department of Large Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University College Station 77843-4475, USA.
MeSH Terms
- Animals
- Chorionic Gonadotropin / administration & dosage
- Cold Temperature
- Dinoprost / administration & dosage
- Female
- Fertility
- Horses / physiology
- Insemination, Artificial / methods
- Insemination, Artificial / veterinary
- Male
- Pregnancy
- Semen Preservation
- Sperm Count
- Sperm Motility
- Time Factors
Citations
This article has been cited 2 times.- Sati L, Bennett D, Janes M, Huszar G. Next day determination of ejaculatory sperm motility after overnight shipment of semen to remote locations. J Assist Reprod Genet 2015 Jan;32(1):117-25.
- Brito LFC, Linardi RL, Rosales LAS, Balamurugan NS, Hernández-Avilés C, Ramírez-Agámez L. Evaluation of a Chemically Defined, Long-Term Extender for Liquid Storage of Stallion Semen. Reprod Domest Anim 2025 Sep;60(9):e70126.
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