Equine Artificial Examination (AI)
Onset of breeding season and cycling
In the Southern hemisphere the breeding season starts in September, which coincides with the cycling activity of the mare (seasonal polyoestrous). Each natural oestrus cycle last 21 days, which equates to approximately 1 week in season and two weeks off. Artificial insemination or natural mating can start anytime after the mare has started cycling. Alternatively hormonal intervention can possible advance cycling activity.
We recommend that mares that are taking part in an artificial insemination program are kept locally for ease of repeated scanning. It also ensures maximum safety for all involved by using appropriate crush and restraining methods. Semen needs to be ordered 24-36 hours prior to insemination which is why it is important to scan your mare regularly for impending ovulation to better predict when the semen will be required.
Advantages of Artificial insemination
No need to transport stallions or transport the mare to a stud farm
In the mare Artificial Insemination conception rates are high, approximately 85% when scanning to monitor follicle development
It only requires once off insemination if using fresh, chilled semen or natural mating
Reduces the risk of spread of venereal diseases
Suggested AI Protocols
Chilled Semen Protocol (starting after September 1st)
Day 1 (eg Thursday) – Scan the mare to determine If cycling activity has commenced and to rule out any uterine infections/abnormalities. For synchronization and to ensure timing of AI commence a daily dose of regumate (in feed orally or in a syringe) for a duration of 10 days. This temporality stops the mare cycling and increases the concentrations of sex hormones in the pituitary gland.
Otherwise if appropriate cycling activity has started then treat according to stage of cycle. Prostaglandin or continued scanning and induction of ovulation
Day 10 (Sunday) – Give the last dose of regumate plus an IM dose of prostaglandin F2 alpha
Day 13 (Wednesday) – Begin alternate day examinations of the mares ovaries
Or Day 15 (Friday) – Scan the mares ovaries if a dominant follicle >35mm in diameter is present place the order for fresh of chilled semen to be available the next day
Give the mare a single IV injection of Chorulon (36 hours +/- 4 hours) or ovuplant (41 hours +/- 4 Hours) to induce ovulation
Day 16 (ie Tuesday) inseminate the mare with -10 ml of fresh/chilled semen
Day 18 eg (Thursday) Scan the mare’s ovaries and uterus to confirm ovulation and check if fluid has accumulated in the uterine lumen. If it has then give an IV injection of 20iu of oxytocin
Day 33 (15 days after ovulation) scan the mares uterus to confirm pregnancy
Fixed-Time AI with frozen (thawed semen)
Frozen semen has a shorter lifespan in the mares reproductive tract. Thus insemination needs to be within 12 hours of ovulation. Best to monitor ovulation or do fixed time insemination with an ovulating agent. Ideally within 3 hours before and after ovulation.
Day 1 Commence a daily dose of regumate (in feed orally or in a syringe) for a duration of 10 days. This temporarily stops the mare cycling and increases the concentrations of sex hormones in the pituitary gland
Day 10 Give the last dose of regumate plus an IM dose of prostaglandin F2 alpha
Day 16 (between 8am and 10am) Scan the mare to seek a dominant follicle >35cm. Give the mare a single IV injection of Chorulon (36 hours +/- 4 hours) or ovuplant (41 hours +/- 4 Hours) to induce ovulation
Day 17 (at 6pm) – at around 32 hours after chorulon. Inseminate the mare once with the frozen-thawed semen. First checking sperm motility (need >40%)
Day 18 scan the mares ovaries to confirm ovulation and her uterus to check for fluid accumulation. Give 20 IU oxytocin IV if fluid present
Day 33 Scan for pregnancy (15 days after ovulation)
If not pregnant repeat protocol (day 16 & 17)
Other notes and AI protocols
Examine mare daily and inseminate every 48 hours while in season starting from Day 3
Want mare to ovulate after inseminate 12-24 hours. Ideally want semen in before ovulation. If ovulated have to put semen in within 6 hours.
Can irrigate mare 4-8 hours after insemination (<4 hours can wash out semen, >8 hours severe inflammation, 6 hours is best)
Wash with 1L of Hartmanns/saline. Use tube, 1 bag in one out and wash until clean – water transparent