Breeding horses Flashcards
At what age do mares and stallions go through puberty?
1-2 years old
At what age can you breed mares? What is the optimum age?
2 years old
Optimum = 5-6
What is the optimal BCS at conception?
3
What should be done to athletic horses before conception and why?
‘Let down’ 1 month before conception
Athletic fitness suppresses regular ovarian function
Why may horses with a winter coat struggle to conceive?
Winter coat = rarely exhibits regular cyclicity
It is essential for horses to have integrity of the 3 seals in the caudal repro tract. What are these?
Vulva seal
Vestibule seal
Cervical seal
What happens if the seals of the caudal repro tract are insuffiecient?
Air borne contamination
Causes endometritis
What degree should the craniocaudal vulva slope be? What can be done to alter this?
10 degrees of vertical
Vulvo-plasty
What type of breeders are horses?
Seasonal, long day polyoestrus breeders
Ponies very seasonal
When is horse repro status maximal?
During longest day length - Spring to early Summer
How can lighting be used for breeding mares?
Extend light to 16 hours a day - switch on just before sunset
Effect in 2-3 months
In Spring, horses have irregular oestrus behaviour and multiple follicles on the ovary. How long is the normal cycle in a horse?
21 days
How long is oestrus in a horse?
3-7 days
When does ovulation occur in a horse? Where do horses ovulate from?
24-48 hrs before end of oestrus
Ovulator fossa
Are the corpus luteum palpable on a horse? How many follicular waves do they have?
No
Usually one follicular wave but can have two
How long is diestrus (not receptive) in a horse?
14-17 days
When does spontaneous luteolysis occur in a horse? What hormone causes this and where is it released from?
13-16 days after ovulation
PGF2a - from endometrium
Superovulation is the drug induced production of multiple eggs for IVF. What anatomical fetaure of the horse stops super ovulation from being possible?
Ovulatory fossa
At what ages does an embryo become reabsorbed if it dies?
0-40 days
At what age does an embryo become stillborn/premature if it dies?
300-335 days
If a horse has a uni-cornual twin pregnancy, what is the outcome for the foetuses?
Usually one survives
If a horse has a bicornual twin pregnancy, what is the most likely outcome for the foetuses?
One foetus aborts
physically destroy smaller twin
What causes a foetus to die in a twin pregnancy?
Placental insuffficiency
How can pregnancy diagnosis be carried out in a horse?
Rectal ultrasound
Rectal palpation
Blood endocrinology
At what day of the pregnancy can ultrasound be used? What about rectal palpation? What about blood endocrinology?
Ultrasound from day 11
Manual from day 30
eCG in blood from day 40
What is the HBLB code of practice?
Mares certified free of transmissible ventral disease before arriving for swabs
(Clitoral and endometrial swabs)
What hormone can be given if corpus luteum are minimum, and you are preparing a mare for stud? What does this cause?
PGF2a
Luteolysis
How can teasing be done for mares?
Vasectomised stallion
What size should corpus luteum and follicles be?
> 35mm for CL
Follicles 2x10mm
What needs to happen before a natural service with a mare?
Wash vulva and penis immediately before
Restrain mare with twice and hobbles
Protect mares neck with neck cover
Breeding rolls to limit penetration
At what age do stallions usually become used for natural service?
3-5 years old
What are the 5 function requirements for a stallion?
Libido Mount and serve Semen quality and quantity Free from disease Longevity
How does exercise and access to the outside affect a stallions hormone levels?
Increases testosterone
What should the scrotal witdth of a stallion be and at what age?
81 mm at 2-3 y/o
85 mm at 4-6 y/o
95 mm at 7+ y/o
What % of their BW should stallions consume? And what proportion should be roughage and protein?
2-3% of BW per day
50% should be roughage
10% should be protein
What is a common nutritional problem with stallions?
Obesity - mating is not intensive like sheep (do not need high BCS)
What vitamin do they require and how is this supplied?
Vitamin A
Leafy greens
In which horses is AI prohibited in?
Thorough bred
What is the normal behaviour leading up to semen collection in stallions?
Immediate interest and erection in 2 mins
Ready to mount straight after erection
Ejaculate after 5-6 pelvic thrusts
How long does sperm survive when fresh, chilled and frozen?
Fresh = 72 hrs Chilled = 36 hrs Frozen = 12 hrs
When should insemination take place?
48hrs before to 6 hrs after ovulation (fresh)
24hrs before to 6 hrs after ovulation (chilled)
12 hrs before to 6 hrs after (frozen)
When does the udder develop prior to foaling?
3-6 wks prior
What is teat waxing? When does it occur?
A way to tell she will give birth - droplets form at bottom of each teat = colostrum
6-48hrs prior to birth
What happens in preparation of foaling?
Udder preparations Teat waxing Ligaments soften Drop in body T Milk electrolytes
Horses are unique in the way their oestrogen and progesterone levels change prior to foaling. Describe how the hormone levels change
Oestrogen decreases
Progesterone increases for few weeks then rapidly declines in days before parturition
What is different about the placenta of the horse?
It is ‘inside out’
Has a calcified remnant of the yolk sac
What happens to the navel of a foal?
Ruptures within minutes of birth
