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Acta veterinaria Scandinavica1991; 32(3); 319-325; doi: 10.1186/BF03546961

Onset of luteal activity in non-foaling mares during the early breeding season in Finland.

Abstract: The luteal activity in mares was studied in the Equine Research Station (ERS) and in trotting stables (TS) in South-Finland. The mares were Standardbreeds in the TS and mainly Finnhorses in the ERS. Between January and June blood was collected once a week for serum progesterone determinations. The mares in the ERS were distributed in 1 of 3 groups: three-years old not yet in training (N = 38), brood mares (N = 21) and mares in training (N = 47). A 4th group was the mares in training in the trotting stables (N = 73). Every 5th mare in the ERS and every 4th mare in the trotting stables were cycling already at the beginning of the year. Onset of luteal activity in anoestrous mares was most common in the middle of May. Over 95% of the mares were cycling at the beginning of June. In the ERS 40% of the Finnhorse mares in training were cycling through the winter. The three-years old and the brood mares were all anoestrous during winter. They started to cycle on average before the middle of May. Anoestrous training mares started before the middle of April. Anoestrous Finnhorse mares began to cycle later than warm blooded mares in all of the groups studied. Mares which had foaled the previous year were more often anoestrous during the winter than dry mares. The time of year when cycling began in a particular mare tended to be the same from year to year (p less than 0.01). Lutealfunktionen hos ston undersöktes vid Hästforskningsstationen (HF) samt vid någon travcentral i södra Finland (TC). Stona vid TC utgjordes av varmblodiga travhästar och vid HF av finnhästar. Progesteron i serum bestämdes en gång i veckan under tiden januari-juni. Stona vid HF indelades i 3 grupper: treåriga ston som ännu inte börjat tränas (N = 38), fölston (N = 21) och ston i träning (N = 47). Den 4. gruppen utgjordes av ston i träning vid TC (N = 73). Brunstcykeln var igång hos vart femte sto i HF-gruppen och hos vart fjärde sto i TC-gruppen redan i början av året. Lutealfasen hos de anöstrala stona började oftast i mitten av maj. Brunstcykeln var igång hos mer än 95 % av stona i början av juni. Fyrtio procent av de finnhäststona i träning hade brunstcykel under hela vintern, medan stona i de 2 andra grupperna vid HF var anöstrala hela vintern. Deras brunstcykel började i medeltal före mitten av maj, medan första brunstcykeln hos de anöstrala stona i träning inleddes före mitten av april. Av de olika grupper var de anöstrala finnhäststona sist med igångsättningen av sin brunstcykel. Vin-teranöstrus forekom oftare hos ston som hade fölat under foregående år än hos sådana som inte fölat. Tidpunkten på årstiden då brunstcykeln började tenderade att vara den samma hos de individuella stona under flera år (p < 0.01).
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Publication Date: 1991-01-01 PubMed ID: 1814181PubMed Central: PMC8127913DOI: 10.1186/BF03546961Google Scholar: Lookup
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Summary

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This research study investigates the onset of luteal activity in non-foaling (non-pregnant) mares during the early breeding season in Finland. The findings suggest that over 95% of mares start cycling at the beginning of June, while onset of activity among anoestrus mares is most common in mid-May.

Research Setting and Methodology

  • The study was conducted at the Equine Research Station (ERS) and trotting stables in South Finland.
  • The horses studied were mostly Standardbreds in the trotting stables and Finnhorses at the ERS.
  • Blood samples were collected weekly between January and June to determine serum progesterone levels, which indicate luteal activity.
  • The mares in the ERS were divided into three groups: three-year-olds not yet in training (38 mares), brood mares (21 mares), and mares in training (47 mares). A fourth group comprised mares in training at the trotting stables (73 mares).

Luteal Activity Results

  • At the start of the year, every 5th mare at ERS and every 4th mare in the trotting stables were already cycling.
  • In the middle of May, onset of luteal activity was most common among anoestrus mares (mares not in oestrus or “heat”).
  • By the start of June, over 95% of the mares had begun cycling.

Luteal Activity Among Specific Groups

  • 40% of the Finnhorse mares in training at the ERS cycled through the winter.
  • All the three-year olds and brood mares at ERS were anoestrus during winter, but started to cycle on average before mid-May.
  • Anoestrus mares in training started their cycle before mid-April.
  • Anoestrus Finnhorse mares began to cycle later than warm-blooded mares in all groups studied.
  • Mares that had foaled the previous year were more frequently anoestrus during winter than mares that had not foaled.
  • The timing of the onset of cycling in a specific mare tended to be consistent from year to year.

Overall, the study provides insights into luteal activity patterns in non-foaling mares, which may inform breeding and mare management strategies.

Cite This Article

APA
Koskinen E, Katila T. (1991). Onset of luteal activity in non-foaling mares during the early breeding season in Finland. Acta Vet Scand, 32(3), 319-325. https://doi.org/10.1186/BF03546961

Publication

Acta veterinaria Scandinavica
ISSN: 0044-605X
NlmUniqueID: 0370400
Country: England
Language: English
Volume: 32
Issue: 3
Pages: 319-325

Researcher Affiliations

Koskinen, E
  • Agricultural Research Centre, Equine Research Station, Ypäjä, Finland.
Katila, T

    MeSH Terms

    • Age Factors
    • Anestrus / physiology
    • Animals
    • Breeding
    • Corpus Luteum / physiology
    • Female
    • Finland
    • Horses / physiology
    • Seasons

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    Citations

    This article has been cited 3 times.
    1. Salazar-Ortiz J, Camous S, Briant C, Lardic L, Chesneau D, Guillaume D. Effects of nutritional cues on the duration of the winter anovulatory phase and on associated hormone levels in adult female Welsh pony horses (Equus caballus). Reprod Biol Endocrinol 2011 Sep 29;9:130.
      doi: 10.1186/1477-7827-9-130pubmed: 21958120google scholar: lookup
    2. 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.
      doi: 10.1186/BF03548080pubmed: 9050273google scholar: lookup
    3. Koskinen E, Kurki E, Katila T. Onset of luteal activity in foaling and seasonally anoestrous mares treated with artificial light. Acta Vet Scand 1991;32(3):307-12.
      doi: 10.1186/BF03546959pubmed: 1814179google scholar: lookup
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