Reproduction in Horses

Mares Seasonal Anestrous

Nov - April/May

What is the imposed birth date of horses?

January 1

What is the gestation length of horses?

11 months

When is horses natural breeding season?

May to October

When is horses natural foaling season?

April to September

Increased melatonin leads to _____ ovulations

decreased

What does the pineal gland convert?

Converts neural input to hormonal input

What are two implications to increase photoperiod?

Cycle manipulations

Artificial Lighting

How much earlier can artificial lighting cause the ovulatory season?

2 months earlier

T/F: Over 15 hours of light can reduce the effect of the light.

True

Do QH or TB have a higher incidence of twinning?

TB

What do draft horses have a high incidence of twinning?

They are bigger and there bodies can handle it more.

How many estrogens have been identified for mares?

9 Estrogenic Compounds

Foal Heat

fertile estrus and ovulation

5-12 days after birth

Last 3-5 days

Slightly lower conception rates

T/F: Fetal size is influenced by paternal body size.

False, it is determined by the maternal size and uterine capacity