Study: Growth Rates Not Affected by MRLS

While mare reproductive loss syndrome has had a devastating effect on in-foal mares in 2001, a just-released study indicates it had no affect on the growth rate of foals of 2000 and 2001 raised on Central Kentucky farms and foals of 2001. The study was conducted by Dr. Joe D. Pagan, owner of Kentucky Equine Research in Versailles, Ky., using data collected with Steve Caddel of Farmers Feed Mill.

Pagan said whatever caused the reproductive problems experienced in Kentucky broodmares in April and May of 2001 did not affect the growth of foals that were born in 2001 or of yearlings that were raised in Kentucky during the same time.

The study shows there has been no variation in the average body weight and withers height of the horses when measured against a historical average of Kentucky-raised Thoroughbreds. Pagan's study of 700 Thoroughbred foals in Central Kentucky during a three-year period (1993-1995) was used as the historical reference point.

This year's study was conducted by measuring the body weight and growth rate of 160 Thoroughbred yearlings born in 2000, and 275 Thoroughbred foals born in 2001. The foals of 2000 were measured on nine different Bluegrass-area farms and the foals of 2001 were housed on 14 different farms.

The average body weight and withers height was calculated for each month of age. Body weights of foals were measured monthly with a portable electronic scale.

The growth rates of the 2000 foals, who had an average foaling date of March 10, showed no reduction in body weight, either before, during, or after the outbreak. In fact, weight gains tended to be slightly higher. As well, withers height was also similar, or slightly taller, in the 2001 foals compared to the historical average.