Term
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Definition
- Some variability among mares
- Evolutionary, mare may be in transition from seasonal to nonseasonal (as one moves closer to the equator, breeding season is extended---geographically dependent)
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Term
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Definition
- Approx. 22 days
- unusual pattern of gonadotropin secretion during estrous compared to other farm species
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Term
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Definition
- prolonged rise and fall in plasma levels
- rises several days before ovulation and continues for some time after ovulation
- Lasts about 10 days with peak observed after ovulation
- Compared to most farm species (12-24 hrs.)
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Term
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Definition
- One peak follows LH pattern
- Second peak at mid to late in the cycle
- Waves of follicular growth occur at 10 day intervals (coincide w/ FSH secretion)
- Peak that is w/ LH peak is associated with preovulatory discharge of gonadotropins at ovulation
- Second peak associated with supporting the dominant follicle destined for ovulation
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Term
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Definition
- 6-7 days (longest of livestock)
- Ovulation 24-48 hours before the end of estrus
- Phase of estrogen domination
- Uterus undergoes only a slight increase in tone
- Cervix is very responsive to estrogen
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Term
| Mare's Cervix during estrus |
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Definition
- Very responsive to estrogen
- at onset of estrus, cervix begins to relaxe and folds of external os becomes swollen and less defined
- Folds continue to enlarge, remain soft through estrus and redden
- Under progesterone, cervical folds are pale and contracted
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Term
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Definition
| days on non-receptivity (1-2 days) are interspersed among days of receptivity |
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Term
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Definition
- CL lifespan is prolonged (1-2 months)
- "foal heat"
- Conception rates @ foal heat tend to be lower than at regular estrus cycle
- if not bred at foal heat, mares resume normal cycles w/ estrus at intervals of 22 days (despite suckling)
- Most mares foal during breeding season due to 340 day gestation
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Term
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Definition
| Estrus and ovulation within 6-12 days after parturition |
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Term
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Definition
- Cortical tissue is confined to one area of ovary and medullary tissue nearly surrounds it
- One side of cortical tissue, the side not surrounded by medullary tissue, is the site where follicles will develops and ovulation occurs
- follicle development and ovulation occurs only at the ovulation fossa
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Term
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Definition
- Only place where follice development and ovulation will occur
- The side of cortical tissue not surrounded by medullary tissue where follicles develope and ovulation occurs
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