Effects of interrupted photoperiods on the induction of ovulation in anestrous mares.

K. Malinowski, A. L. Johnson, C. G. Scanes

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

The ability of interrupted photoperiods to induce early estrus and ovulation was examined. Horse mares were exposed to long (16 h light) or short (10 h light), noninterrupted photoperiods, ambient light, or various interrupted photoperiod treatments from December 1 to April 15 (135 d). Follicular development was assessed by rectal palpation and estrous behavior was determined by teasing with a stallion. Serum concentrations of progesterone were used as an indicator of corpus luteum function. Differences among the light treatment groups were compared for the following behavioral and ovarian characteristics: days to first detectable 3-cm follicle, days to first estrous behavior, days to first ovulation, the number of mares ovulating within the treatment period, and the number of ovulations within the treatment period per mare. Compared with the ambient and 10L:14D (L = h of light and D = h of darkness) photoperiod treatments, ovulation was advanced to the greatest extent by a photoperiod of 16L:8D and the interrupted photoperiod 10L:8D:2L:4D. These two stimulatory photoperiod treatments were characterized by the presence of light 8 to 10 h after dusk. Therefore, the present data are consistent with an external coincidence model for the induction of seasonal breeding in horses, with the photoinducible phase occurring within the period 8 to 10 h after dusk.

Original languageEnglish (US)
Pages (from-to)951-955
Number of pages5
JournalJournal of animal science
Volume61
Issue number4
DOIs
StatePublished - Oct 1985

Fingerprint

Ovulation Induction
Photoperiod
mares
ovulation
photoperiod
Ovulation
Light
Horses
Therapeutics
teasing (breeding)
Digital Rectal Examination
Aptitude
livestock breeding
follicular development
Corpus Luteum
Darkness
Estrus
stallions
corpus luteum
Breeding

All Science Journal Classification (ASJC) codes

  • Food Science
  • Animal Science and Zoology
  • Genetics

Cite this

Malinowski, K. ; Johnson, A. L. ; Scanes, C. G. / Effects of interrupted photoperiods on the induction of ovulation in anestrous mares. In: Journal of animal science. 1985 ; Vol. 61, No. 4. pp. 951-955.
@article{567566e154404557a38b1d3be5bcf678,
title = "Effects of interrupted photoperiods on the induction of ovulation in anestrous mares.",
abstract = "The ability of interrupted photoperiods to induce early estrus and ovulation was examined. Horse mares were exposed to long (16 h light) or short (10 h light), noninterrupted photoperiods, ambient light, or various interrupted photoperiod treatments from December 1 to April 15 (135 d). Follicular development was assessed by rectal palpation and estrous behavior was determined by teasing with a stallion. Serum concentrations of progesterone were used as an indicator of corpus luteum function. Differences among the light treatment groups were compared for the following behavioral and ovarian characteristics: days to first detectable 3-cm follicle, days to first estrous behavior, days to first ovulation, the number of mares ovulating within the treatment period, and the number of ovulations within the treatment period per mare. Compared with the ambient and 10L:14D (L = h of light and D = h of darkness) photoperiod treatments, ovulation was advanced to the greatest extent by a photoperiod of 16L:8D and the interrupted photoperiod 10L:8D:2L:4D. These two stimulatory photoperiod treatments were characterized by the presence of light 8 to 10 h after dusk. Therefore, the present data are consistent with an external coincidence model for the induction of seasonal breeding in horses, with the photoinducible phase occurring within the period 8 to 10 h after dusk.",
author = "K. Malinowski and Johnson, {A. L.} and Scanes, {C. G.}",
year = "1985",
month = "10",
doi = "10.2527/jas1985.614951x",
language = "English (US)",
volume = "61",
pages = "951--955",
journal = "Journal of Animal Science",
issn = "0021-8812",
publisher = "American Society of Animal Science",
number = "4",

}

Effects of interrupted photoperiods on the induction of ovulation in anestrous mares. / Malinowski, K.; Johnson, A. L.; Scanes, C. G.

In: Journal of animal science, Vol. 61, No. 4, 10.1985, p. 951-955.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Effects of interrupted photoperiods on the induction of ovulation in anestrous mares.

AU - Malinowski, K.

AU - Johnson, A. L.

AU - Scanes, C. G.

PY - 1985/10

Y1 - 1985/10

N2 - The ability of interrupted photoperiods to induce early estrus and ovulation was examined. Horse mares were exposed to long (16 h light) or short (10 h light), noninterrupted photoperiods, ambient light, or various interrupted photoperiod treatments from December 1 to April 15 (135 d). Follicular development was assessed by rectal palpation and estrous behavior was determined by teasing with a stallion. Serum concentrations of progesterone were used as an indicator of corpus luteum function. Differences among the light treatment groups were compared for the following behavioral and ovarian characteristics: days to first detectable 3-cm follicle, days to first estrous behavior, days to first ovulation, the number of mares ovulating within the treatment period, and the number of ovulations within the treatment period per mare. Compared with the ambient and 10L:14D (L = h of light and D = h of darkness) photoperiod treatments, ovulation was advanced to the greatest extent by a photoperiod of 16L:8D and the interrupted photoperiod 10L:8D:2L:4D. These two stimulatory photoperiod treatments were characterized by the presence of light 8 to 10 h after dusk. Therefore, the present data are consistent with an external coincidence model for the induction of seasonal breeding in horses, with the photoinducible phase occurring within the period 8 to 10 h after dusk.

AB - The ability of interrupted photoperiods to induce early estrus and ovulation was examined. Horse mares were exposed to long (16 h light) or short (10 h light), noninterrupted photoperiods, ambient light, or various interrupted photoperiod treatments from December 1 to April 15 (135 d). Follicular development was assessed by rectal palpation and estrous behavior was determined by teasing with a stallion. Serum concentrations of progesterone were used as an indicator of corpus luteum function. Differences among the light treatment groups were compared for the following behavioral and ovarian characteristics: days to first detectable 3-cm follicle, days to first estrous behavior, days to first ovulation, the number of mares ovulating within the treatment period, and the number of ovulations within the treatment period per mare. Compared with the ambient and 10L:14D (L = h of light and D = h of darkness) photoperiod treatments, ovulation was advanced to the greatest extent by a photoperiod of 16L:8D and the interrupted photoperiod 10L:8D:2L:4D. These two stimulatory photoperiod treatments were characterized by the presence of light 8 to 10 h after dusk. Therefore, the present data are consistent with an external coincidence model for the induction of seasonal breeding in horses, with the photoinducible phase occurring within the period 8 to 10 h after dusk.

UR - http://www.scopus.com/inward/record.url?scp=0022141619&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0022141619&partnerID=8YFLogxK

U2 - 10.2527/jas1985.614951x

DO - 10.2527/jas1985.614951x

M3 - Article

C2 - 4066545

AN - SCOPUS:0022141619

VL - 61

SP - 951

EP - 955

JO - Journal of Animal Science

JF - Journal of Animal Science

SN - 0021-8812

IS - 4

ER -