Why all Aussie thoroughbred horses have the same birthday
IN THE southern hemisphere, thoroughbred horses celebrate their birthday in August, as a means of standardising horse-related events.
This is important for the "racing industry” and is the focus of most horse sports events in Australia, other breeds may have a different birthday.
Standardbreds,(i.e. trotters and pacers) have their official 'birthday' for foals on September 1.
Horses born in the northern hemisphere celebrate their birthday on January 1. August 1 was selected in the southern hemisphere as with weather at the start of September is beginning to warm up, prompting mares to commence their oestrus cycle, or "come into season”.
As horses are raced according to age and in order to alleviate confusion, when entering horses in races a fixed birthday for all was deemed necessary.
So back in 1860, August 1 was selected as the birthday for all racing horses.
This date is close to the beginning of spring when the weather is milder and there is fresh, good-quality pasture to enable the broodmares to produce enough milk for their offspring.
Having an official breeding season is beneficial to foals by helping them to get the best start to life.
A mare's oestrus cycle is stimulated by extended daylight, nature intending that foals be born eleven months later through spring and summer when feed is plentiful.
Mares successfully bred early in September will produce foals in early August.
The first of August date was decided upon when breeding was natural, but today breeders can use artificial light and hormone injections to induce cycling so mares can conceive earlier in the year.
Breeding a mare a little early to get a more mature foal, or when mares produce their foals short of the 11-month pregnancy, has created situations where some foals are born before August 1.
Technically this means that those foals a considered one year old just a few days after being born.
It appears that some foals may be hidden 'in the back paddock' until August 1, before their birth is declared and the Australian Stud Book shows many more foals born on that date compared to the next few days in the season.
Despite early September being the time when most owners start the breeding process, there are many factors involved to get a successful outcome.
Inadequate cycling by the mare is one factor as to why the majority of mares don't conceive until October or November.
A percentage of mares miss on their first service and cannot be accurately pregnancy tested until 14 - 16 days after service.
This means that most thoroughbred foals are born in September and October, months which are not too hot and when the grass is at its most nutritious.
If the official start date for the season was September 1, most foals would be born a month later when heat, flies and dust can start to become a problem.
Breeding outside the local gene pool can be exciting as "new blood” is introduced.
It is now common to use artificial insemination to do this using chilled or frozen semen and is often preferable and cheaper than transporting your mare to a distant stud or stallion.
This technique allows semen to be collected by a veterinarian and shipped anywhere in the country in a chilled shipping container.
For this to be successful the mare's reproductive cycle needs to be timed to perfection and the ovulation of the mare must be monitored by a veterinarian using ultrasound.
The semen is extended with a solution containing antibiotics and semen extenders to ensure semen survival and optimum quality on arrival at the mare.
It also reduces the risks of infection of mares with diseases such as Equine herpes, Equine Contagious Metritis, Klebsiella and Psuedomonas.
The conception rate for chilled semen is around 62% in research studies, which in practical terms correlates to an owner budgeting for two cycles before success may be achieved.
Factors involved in the success of this technique range from the skill of the veterinarians involved in the processes of collecting the semen and doing the actual insemination, as well as transport schedules to enable the shortest possible transit times of the semen.
This process allows your mare to remain close to home and be monitored closely for optimal time of coverage.
While it does increase the cost of a pregnancy, this would appear a small factor when you can breed to some of the best horses in the country from the comfort of your local vet, so why not?
The end progeny will be likely more valuable and improve the genetic pool of the area.
Some stallion owners with busy or successful animals can have semen frozen for use in the future and there are also some international stallions, which have been cleared by AQIS for their semen to be imported to Australia.
Freezing allows stallion genetics to remain in liquid nitrogen storage tanks well after they are deceased and some frozen semen has been used up to 20 years after a horse has died with a live foal produced.
Using frozen semen can be very time consuming and frustrating for the owner and veterinarian alike, as the insemination has to be done much closer to ovulation than that with chilled semen.
Mares with very good behaviour, ease of handling and good reproductive history are the best candidates for frozen insemination success but the conception rate is only reported to be 30-56%, so an owner going down this route needs to budget for up to three mare cycles before a pregnancy may be achieved.
So while we hope all horse owners celebrated August 1 with their horses.
It is really the signal that if you are breeding this year, now is the time to speak to your vet and start making decisions about your mare and the stallion you want to breed with and the techniques and costs that may be involved.
As local veterinarians can become very busy at this time of year, it is important to consider this month as the time to get the plans and process in place to ensure you have a healthy foal on the ground ready to celebrate next year.