Influence of season and age on reproductive activity in pony mares on the basis of a slaughterhouse survey.
Abstract: Reproductive tracts were collected monthly over a 3-year period from 1,003 nonpregnant ponies at a slaughtering plant in Wisconsin. Ages of the animals were estimated from tooth replacement and wear. Ovaries were examined for follicular and luteal activity. There were no differences between left and right ovaries in size or occurrence of ovulation. The frequency of multiple ovulations, 10%, was higher than previously reported for ponies. The follicular changes during the ovulatory cycle did not support a two-wave theory of follicular growth. Ovarian activity changed seasonally, a finding similar to that reported previously in palpation studies of the pony. The ovulatory season appeared to be shorter, with fewer ponies ovulating throughout the year, than had previously been reported for horses. There were significant differences between animals of different ages in ovarian endpoints and in the proportion of mares that were ovulatory. The percentage of mares ovulatory during the fall was lower in the younger age groups (less than 5 years) than in the older groups, indicating a shorter breeding season for young mares. Ovarian activity appeared to decrease after 15 years. Examination of luteal structures from pre-pubertal and pubertal fillies indicated that the onset of puberty occurred at 12 to 15 months of age.
Publication Date: 1981-01-01 PubMed ID: 7195392DOI: 10.2527/jas1981.521119xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research study investigates the influence of different seasons and age on the reproductive activity of pony mares, based on data collected from slaughterhouses over a three year period. It concluded that ovarian activity in mares changes seasonally, and varies significantly based on age, with activity declining after 15 years and onset of puberty occurring between 12 to 15 months of age.
Methodology
- Reproductive tracts were collected monthly over a 3-year period from 1,003 nonpregnant ponies from a slaughterhouse in Wisconsin.
- The ages of the animals were estimated based on tooth replacement and wear, which is a common method of age estimation in horses.
- The researchers examined the ovaries for activity of follicles and corpora lutea, structures involved in the reproductive cycle of mares. The examination included assessment of ovulation occurrence, size variation between the right and left ovary, and the frequencies of multiple ovulations.
Findings
- The study found no size difference or ovulation discrepancies between the left and right ovaries.
- The frequency of multiple ovulations was higher in ponies than previously reported, at a rate of 10%.
- Ovarian activity was found to change with seasons, similar to findings from earlier studies on pony mares.
- The duration of the ovulatory season was found to be shorter with less ovulating ponies all year round than previously observed in horses. This indicates that ponies have a shorter breeding season than horses.
- Significant differences were found in ovarian activity and the proportion of ovulating mares among different age groups. Younger mares, less than 5 years old, were less likely to ovulate during the fall, indicating a shorter breeding season for them. Ovarian activity was found to decrease after the age of 15 years.
- The onset of puberty, as determined by the examination of luteal structures, was observed to occur between 12 to 15 months of age.
Conclusion
- This study provides valuable insights into the reproduction dynamics of pony mares, suggesting that age and seasonal variations significantly influence reproductive activity.
- The findings help in understanding the reproductive cycle of pony mares, which can offer practical implications for breeders and veterinarians.
Cite This Article
APA
Wesson JA, Ginther OJ.
(1981).
Influence of season and age on reproductive activity in pony mares on the basis of a slaughterhouse survey.
J Anim Sci, 52(1), 119-129.
https://doi.org/10.2527/jas1981.521119x Publication
Researcher Affiliations
MeSH Terms
- Abattoirs
- Animals
- Estrus
- Female
- Horses / physiology
- Ovarian Follicle / physiology
- Ovary / physiology
- Ovulation
- Pregnancy
- Reproduction
- Seasons
Citations
This article has been cited 5 times.- Takahashi Y, Akai M, Murase H, Nambo Y. Seasonal changes in serum progesterone levels in Thoroughbred racehorses in training.. J Equine Sci 2015;26(4):135-9.
- Ono M, Akuzawa H, Nambo Y, Hirano Y, Kimura J, Takemoto S, Nakamura S, Yokota H, Himeno R, Higuchi T, Ohtaki T, Tsumagari S. Analysis of the equine ovarian structure during the first twelve months of life by three-dimensional internal structure microscopy.. J Vet Med Sci 2016 Jan;77(12):1599-603.
- Hedberg Y, Dalin AM, Santesson M, Kindahl H. A preliminary study on the induction of dioestrous ovulation in the mare--a possible method for inducing prolonged luteal phase.. Acta Vet Scand 2006 Jul 26;48(1):12.
- Koskinen E, Huhtinen M, Katila T. Serum progesterone levels in mares in winter and during transitional periods.. Acta Vet Scand 1996;37(4):409-14.
- Koskinen E, Katila T. Onset of luteal activity in non-foaling mares during the early breeding season in Finland.. Acta Vet Scand 1991;32(3):319-25.
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