Equine breeding management

Question 1

Horses are seasonal long day breeders and seasonally polyoestrous what does this mean

Answer 1

Seasonal ‘long day’ (spring/summer/early autumn) breeders
Seasonally polyoestrous (21 days between each ovulation)
2week dioestrus, 1week oestrus

Question 2

When to breed a horse

Answer 2

First Ovulation April ongoing to September

Question 3

Outline Spring transition manipulation (breed during spring transition)

Answer 3

Photostimulation Length = 14.5 h (14 – 16 h)
Artificial light (8-10weeks prior to when breeding commences)
Progesterone intravaginal devices

Question 4

On average what month would you expect a sexually mature mare to have had her first ovulation of the breeding season

Answer 4

April

Question 5

What is the function of teasing

Answer 5

Mare is exposed to a stallion and behaviour is assessed for evidence of receptivity
Differentiates oestrus from dioestrus
LACK OF PROGESTERONE that drives mating behaviour

Question 6

Signs of Oestrus during teasing

Answer 6

Quiet and calm & ears forward
Tail up, urinating and winking

Question 7

Can you use palpatation to determine state of mare’s oestrous cycle

Answer 7

Can assess cervical and uterine tone
Dioestrus: high PROGESTERONE = uterine tone prominent and cervix is closed (cigar like)
Oestrus: high Oestrogen & low Progesterone = soft uterine tone and relaxed open cervix
Can’t palpate CL

Question 8

5 ways to determine mare’s state in her heat cycle

Answer 8

Teasing
Rectal palpation
Ultrasound
Endocrinology
Vaginal speculum

Question 9

Describe oedema differences in different stages in heat cycle

Answer 9

Oestrus - oedema increases each day until maximum and then starts to reduce prior to or at time of ovulation
Dioestrus – no oedema
Anoestrus – no oedema

Question 10

Phyometra

Answer 10

Air in uterus- No good

Question 11

Outline using endocrinology to determine stage in mare’s heat cycle

Answer 11

Serum Progesterone conc >1ng/ml dioestrus
<1ng/ml in oestrus or anoestrus

Question 12

Progesterone increases or decreases during horse’s oestrous

Answer 12

DECREASES

Question 13

Which of the following methods would accurately confirm that a mare has recently ovulated?
Indifferent teasing behaviour
Vaginal speculum exam showing a raised cervix
Transrectal palpation of the ovaries
Ultrasound visulising a Corpus Haemorrhagicum on her ovary
Breeding records indicating 3 weeks from previous ovulation

Answer 13

Ultrasound visualizing a Corpus Haemorrhagicum on her ovary.

Question 14

Main idea of oestrous cycle control in the mare

Answer 14

Shortening of CL lifepsan

Question 15

Drug used to shorten CL lifespan to control oestrous cycle

Answer 15

Prostaglandin
Dinoprost tromethamine (Lutalyse®)
Cloprostenol (Estrumate®)

Question 16

Two drugs used to induce ovulation in the mare

Answer 16

Human chorionic gonadotropin (hCG (Chorulon®)
Biorelease Deslorelin

Question 17

Outline Oestrus suppression in mare

Answer 17

Determine if ovaries /ovarian hormones are the cause of undesirable behavior
History, physical exam and reproductive exam to check stage of the oestrous cycle and determine pathology
Keep a behaviour diary and track undesirable behaviour
Treatment trial with oral progestin (30days)

Question 18

Name of drug used to suppress oestrous in mare

Answer 18

Oral progestin- Altrenogest

Question 19

4 methods to suppress oestrous in mare

Answer 19

Progestin treatments
Intrauterine marble
Ovariectomy
Equity®Oestrus Control Vaccine

Question 20

The use of the GnRH analogue Deslorelin is used most in the mare for
Oestrous suppression
Vernal transition manipulation
Ovulation induction
Oestrus synchronization
Shortening of CL lifespan

Answer 20

Ovulation induction

Question 21

How does Equity® Oestrus Control Vaccine control oestrous

Answer 21

Administer the vaccine to produce antibodies against GnRH, reducing LH and FSH release.

Question 22

How does Intrauterine Marble control oestrous

Answer 22

Presence of the marble mimics the presence of an embryo, which can prolong the luteal phase and prevent the mare from returning to estrus.

Question 23

How does Progestin Treatments control oestrous

Answer 23

The synthetic progestins maintain elevated levels of progesterone in the mare’s system. High progesterone levels inhibit the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus, which in turn prevents the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland. Without LH and FSH, the follicles in the ovaries do not mature and ovulate, thus preventing the mare from coming into estrus (heat).

Question 24

What is handmating

Answer 24

When a stallion and mare are handled in such a way that they are both restrained, and the act of breeding is orchestrated in a controlled environment.

Question 25

How often can mare be handmated

Answer 25

Mares can be hand mated every other day when in oestrus or by a single breeding during oestrus.

Question 26

Advantages of mare handmating

Answer 26

Breeding’s can be scheduled and the mare can be examined prior to and after breeding to confirm ovulation occurred and no reproductive issues are present.

Question 27

disadvantages of mare handmating

Answer 27

Increased time required for teasing mares, more personnel required for the breeding process and risk of injury to personnel in breeding shed.

Question 28

Advantages of AI

Answer 28

Semen Evaluation: Quality can be assessed after collection and before insemination.
Multiple Doses: One ejaculate can be processed into multiple doses for inseminating mares.
Reduced Contamination: Hygiene measures and semen extenders with antibiotics minimize the introduction of organisms into the uterus.
Injury Prevention: Reduces risk of injury to mare, stallion, and personnel compared to hand or paddock mating.
Genetic Diversity: Chilled and frozen semen provide access to a broader selection of stallions and a larger genetic pool.

Question 29

Sperm viability once thawed

Answer 29

12-24 h

Question 30

How many hours after can you see oocyte during after ovulation

Answer 30

6 – 12 h post-OV
Check every 6 to 8 h

Question 31

How many days after ovulation can you see pregnancy in mare and diagnosis

Answer 31

14-15 days post-ovulation
Palpation per rectum
U/S

Question 32

Which of the following breeding management practices is most intensive with regards to the number of mare examinations required per cycle?
Frozen semen single dose AI
Chilled semen AI
Natural paddock serve mating
Frozen fixed time double dose AI

Answer 32

Frozen semen single dose AI