Saturday, 16 January 2010: The artificial insemination debate continues with evidence produced that that questions whether the introduction of AI would improve overall fertility in the thoroughbred population and result in a narrowing of the gene pool.
AI supporters claim it will improve fertility rates and that it does not narrow the gene pool but new research conducted by Arrowfield's pedigree analyst Peter Jenkins discounts those theories.
Using the Australian standardbred industry as a model Jenkins' research shows that overall fertility, as manifested in the live foal rate, diminished with the use of AI and that there has been a significant narrowing of the gene pool since its widespread introduction into the standardbred industry.
Jenkins claims the use of the Australian standardbred industry as a model to study the effects of AI carries strong credibility due to identical geographical and climatic conditions and a common pool of veterinary expertise.
His research revealed that n 1994 the live foal rate for thoroughbreds in Australia was 63.4%, trailing by 6.4% the standardbred rate of 69.8%.
By 2008 the thoroughbred live foal rate had risen to 67%, eclipsing the standardbred rate of 61.3% by 5.7%.
Imported frozen or chilled semen was used on more than 100 standardbred mares for the first time in 1998 and was the very year that the standardbred live foal rate fell below that of the thoroughbreds, a trend that has continued over the past decade.
Jenkins says the comparative study of the top 20 most popular stallions in the standardbred code, in both the pre-AI and current era, shows that stallion numbers have been reduced by more than half with the most popular stallions serving vastly more mares.
The top five standardbred sires averaged 341 mares served per season (including chilled semen services in NZ) and the top 20 sires covered 42% of the total broodmares bred in Australia and NZ combined.
This compares with 15.8% of mares bred being covered by the top 20 stallions in the pre-AI standardbred era.
Jenkins says it is apparent that a similar pattern would develop if AI were introduced in Australian thoroughbred breeding.
“In fact, if the Australian thoroughbred industry was overlaid with the standardbred model, we could see the top 20 thoroughbred stallions 'covering' over 550 mares annually on average” said Jenkins.
“This reduction of stallion numbers and the enlarged books served by the most popular sires would logically result in a significant genetic narrowing which, using sire lines as a marker, is confirmed by our research.”
Jenkins said the impact of AI on the thoroughbred code is liable to be dramatic in terms of genetic narrowing due to the high numbers and the very strong commercial impact imported mares have enjoyed in Australian breeding in recent years.
Arrowfield chairman John Messara said the findings from Jenkins research were a c9ndemnation of the campaign to introduce AI to Australian breeding.
“I believe the standardbred experience confirms that an AI regime in thoroughbreds would result in genetic narrowing, a likely significant reduction in stallion numbers together with a large increase in the number of mares being bred by popular stallions leading to a greater concentration of power among stallion owners, and added to this no fertility advantage for the general broodmare population”, Messara said.
'Not surprisingly, the reproduction vets are supportive of the introduction of AI because it can assist them with sub-fertile breeding stock - the bane of their lives.
“However, as can be seen in standardbreds, the application of AI would not improve the fertility figures industry wide.
“While the most established stallion operators, such as Arrowfield, would be the major financial beneficiaries from the introduction of AI, my belief is that A. would have serious negative impacts on racing and the thoroughbred industry as a whole.”
A court challenge has been launched by former Sydney Turf Club chairman and breeder Bruce McHugh seeking to overturn the AI ban maintained by International Stud Book and racing suthorities,
