Equine Breeding Management

Question 1

what is breeding management?

Answer 1

• activity of controlling the mating and production of offspring of animals

Question 2

types of breeding programs

Answer 2

• natural service (thoroughbreds)
• artificial insemination (most common globally)

Question 3

factors that affect pregnancy rates

Answer 3

• breeding managment!! (#1 factor affecting preg rate)
• stallion fertility
• mare fertility
• early pregnancy detection
  
  • twins
  • early embryonic death
  • ~30% lost in first 30 days of pregnancy

Question 4

evaluating stallion fertility

Answer 4

• history
  
  • athletic
  • breeding
• breeding soundness
  
  • annual exam
  • physical health
  • semen quality
  • venereal disease

Question 5

evaluating mare reproductive health

Answer 5

• fertility history
• foaling history
• type of breeding program
• breeding soundess exam

Question 6

approach to equine breeding management

Answer 6

• heat detection (when is mare in estrus)
• monitoring the repro tract
• induction of ovulation
• breeding
• post-breeding mgmt
• pregnancy detection

Question 7

when do horses cycle?

Answer 7

• seasonally polyestrus
  
  • longer days (June/July)= shorter esturs period
  • shorter days (December/Jan)= longer estrus period

Question 8

equine estrous cycle

Answer 8

estrus: follicular phase
diestrus: luteal phase

Question 9

heat detection in mare

Answer 9

• estrus
  
  • 4 to 7 days
  • estrogen influence
    
    • tail up, urinate, wink
    • position herself to be bred
• diestrus
  
  • 14 days
  • progesterone influence
    
    • ears back, strike, kick
  • not receptive!

Question 10

monitoring reproductive tract of mare

Answer 10

• transrectal palpation and u/s
  
  • ovaries: follicular dvpt
  • uterus: tone and edema
  • cervis: tone/relaxation
    
    • fully muscular in mare
    • cervix relaxes and widens (estrogen/estrus) or becomes toned and long (progesterone/diestrus)

Question 11

transrectal ultrasonography

Answer 11

• mare with fluid/edema (wagon-wheel)= indicates estrus
• seeing CL on u/s= mare is in diestrus

Question 12

where do the follicles develop in the mare ovary?

Answer 12

• on the inside (inside out)
• ovulate through ovulation fossa

Question 13

ovarian palpation in mare

Answer 13

• palpation through rectum
• can’t palpate CL
  
  • can see with ultrasound
    *

Question 14

“short cycling”

Answer 14

• prostaglandin- takes mare out of diestrus (lyse CL and bring her into heat)
  
  • PGF_2a - endometrial origin
  • analogs - Dinoprost, Cloprostenol
  • causes luteolysis
    
    • 5 days post-ovulation
  • results in onset of estrus
    
    • depends on follicular activity
    • 5-7 days average
    • take away CL (progesterone) and see if she gets pregnant
• depends on: time of year and size of follicles

Question 15

how is ovulation predicted in mare?

(when do we know to breed them)

Answer 15

• follicular size (≥ 35 mm)
• follicular texture (softening)
• follicular shape (irregular shape means you’re close to ovulation)
• uterine edema

Question 16

ovulatory agents

Answer 16

• MARE MUST BE IN HEAT!
• Deslorelin acetate (GnRH analog)
  
  • estrus edema
  • relaxed cervix
  • when follicle ≥ 30 mm
  • ovulation 40-48h
• Human chorionic gonadotropin (hCG)
  
  • acts like LH
  • estrus edema
  • relaxed cervix
  • when follicle ≥ 35 mm
  • ovulation 24-48h

Question 17

when do we breed?

Answer 17

• as close to ovulation as possible***
• oocyte longevity
  
  • once ovulated oocyte lives for 24 (12) hours
• sperm longevity
  
  • fresh semen: 48+ hours
  • chilled semen: 24-48 hours
  • frozen semen: 12 hrs post-thaw

Question 18

Natural Service Breeding Program

Answer 18

• pasture mating
• hand mating
  
  • booking for satllion
• breed every 48 hours

Question 19

Artificial Insemination (AI) Program

Answer 19

• fresh semen
• cooled-shipped semen
• frozen-thawed semen

Question 20

Insemination with fresh semen

Answer 20

• breeding on the farm
• 500 x 10⁶ progressively motile sperm (minimum)
  
  • diluted with extender
• breed every 48 hrs

Question 21

AI with fresh cooled semen

Answer 21

• timed breeding
  
  • semen shipped via FedEx-24 hour lag
• ≥ 1 x 10⁹ pm sperm/dose
  
  • 50% attrition (1/2 will die)
  • 2 doses
• ovulatory agent
• breed every 24-48 hours

Question 22

Timed AI protocol for cooled semen

“conservative approach”

Answer 22

day 0 = in heat-call for semen!

• >35mm follicle, uterine edema, relaxed cervix

24 h = 1st AI, hCG

36 h = check fo ovulation?

48 h = 2nd AI

60 h = ovulation

• 80% of horses ovulate at 36 h mark

Question 23

timed AI protocol for cooled semen

“daredevil approach”

Answer 23

day 0 = give hCG, call for semen!

24 h = semen arrives, 1st AI

36 h = ovulation

48 h

60 h

Question 24

equine pregnancy examination

Answer 24

• 14 days post-ovulation
• look for twins
• monitor pregnancy
  
  • early embryonic death