MARE REPRODUCTIVE PERFORMANCE

The following figures for reproductive performance of mares may be of interest - see how you compare! The figures are compiled from a survey of six (6) thoroughbred farms in Victoria and South Australia. Where applicable, the results are compared with previous surveys conducted in Australia and overseas.

SERVED OESTRUS CYCLES

• Average number of served oestrus cycles per pregnancy was 1.83 overall.
• For mares 3 to 5 years old it was 1.79
• For mares 6 to 10 years old it was 1.72
• For mares 11 to 15 years old it was 2.03
• For mares over 15 years old it was 2.08 OR
• For maiden mares it was 1.79
• For dry mares it was 2.06
• For wet mares it was 1.72

PREGNANCY RATES

• Overall pregnancy rate was 83.9%.
• The pregnancy rate per served oestrus cycle was 54%.
• For mares 3 to 5 years old it was 84.8%
• For mares 6 to 10 years old it was 87.7%
• For mares 11 to 15 years old it was 79.0%
• For mares over 15 years old it was 71.0% OR
• For maiden mares it was 87.3%
• For dry mares it was 82.3%
• For wet mares it was 84.0%

MULTIPLE PREGNANCIES

• The overall twinning rate was 7.8%.
• For mares 3 to 5 years old it was 6.0%
• For mares 6 to 10 years old it was 6.9%
• For mares 11 to 15 years old it was 10.1%
• For mares over 15 years old it was 13.9% OR
• For maiden mares it was 5.7%
• For dry mares it was 11.3%
• For wet mares it was 6.6%

Where twin pregnancy was diagnosed and one twin was manually crushed (on average at 22 days); 59% went on to foal normally and 44% lost the second pregnancy as well. I think we can do better than that!

FOALING RATES

• The overall foaling rate was 69.3%.
• For mares 3 to 5 years old it was 75.2%
• For mares 6 to 10 years old it was 72.8%
• For mares 11 to 15 years old it was 62.4% OR
• For maiden mares it was 76.6%
• For dry mares it was 67.6%
• For wet mares it was 68.6%

PREGNANCY LOSS

• The overall pregnancy loss was 19.5% made up of 7.5% (excluding twins) prior to a 45 day test and 12% after the 45 day test:
• For mares 3 to 5 years old it was 12.8% (3.0 & 9.8%)
• For mares 6 to 10 years old it was 19.3%. (7.8 & 11.5%)
• For mares 11 to 15 years old it was 22.4% (9.7 & 12.8%)
• For mares over 15 years old it was 40.6% (15.9 & 24.6%) OR
• For maiden mares it was 12.4% (1,3 & 11.2%)
• For dry mares it was 19.7% (8.0 & 11.7%)
• For wet mares it was 20.9& (8.5 & 12.4%)

It is interesting to note that the overall pregnancy rate of 83.9% is the highest recorded in Australia or overseas (previously it has been updated as anywhere between 66 & 79%). However the pregnancy rate per oestrus cycle and the foaling rates have not improved the past 25 years. Mares with only one served oestrus cycle per breeding season had the highest foaling rate of 77.8% and with increased numbers of served oestrus cycles per breeding season, the foaling rate decreases; i.e.: mares that are served on 3 or more oestrus cycles had only a 42.9% chance of conceiving and carrying a foal to term. So the mares that cause you the most problems and cost you the most in Veterinary fees still have less than 50% chance of having a foal.

I'm sure we've all experienced the mare with a long history of infertility or pregnancy loss which will go in foal and carry the pregnancy if you can get her in foal on their first service. It would be interesting to know why!

In summary the average twelve (12) year old mare has a 62% chance of going in foal and delivering a live foal. I will try and get some figures together to see what chance that foal has of getting to a yearling sale; racing; and actually winning a metropolitan race. That should really depress you!