May 09, 2006
Experimental drug for cows shows promise
CARBONDALE, Ill. -- It was a good news/not-so-good news study outcome, but Southern Illinois University Carbondale animal scientist Karen L. Jones remains optimistic about the chances of increasing reproductive success in cows with an experimental drug.
"All the data related to hormone levels turned out just as we expected, but only two out of six cows that should have gotten pregnant actually ended up pregnant, though both of them were in the group receiving the drug," she said.
"We hope to use this data to go after funding that would allow us to develop this drug further."
The medication, originally formulated to treat horses, counteracts the effects of a fungus common in pasture grass. That fungus, which lives in fescue stems and blades, produces a toxin that throws animal reproductive systems out of whack and messes with their health and growth to boot, at a cost to cattle producers of some $800 million each year.
For the last three years, Jones, SIUC colleague Sheryl S. King and Dee L. Cross, a Clemson University colleague who holds the patent for this drug, have been trying it out with cows, hoping to boost conception and birth rates as well as overall weight gains — a key concern for farmers who often sell animals by the pound.
Their first study, involving a small number of cows, showed that the blood of cows receiving daily injections of the drug registered nearly normal levels of progesterone, a hormone that helps maintain pregnancy. Treated cows also gained weight at near normal rates.
"While the results we got were very promising, we knew that no farmer would give a herd a shot every single day," Jones said.
"We needed to come up with a practical way to administer the drug and still retain the effects."
Patrick J. Burns of Burns BioSolutions, a Kentucky firm specializing in drug delivery systems, tinkered with the formula and transformed it into a slow-release medication with effects lasting more than 20 days. Last summer, Jamie L. Schulze, a graduate student in animal science, tried it out in a small-scale study of 30 grazing cows where half got the drug and half did not. The research team aimed to replicate the earlier study of hormone levels, but they followed that work by inseminating the animals to see if those higher levels produced pregnancies.
The study produced the hoped-for results. In treated cows, the researchers found that levels of both progesterone and prolactin (a hormone that stimulates mammary glands) increased. They also found significant increases in body weight and decreases in body temperatures.
"High temperatures are a source of stress — it's like they're walking around with a fever all day," Jones said.
The cows did not, however, get pregnant at the rate Jones had hoped for. Timing may have had something to do with that. The researchers inseminated the cows in August, and fescue's ill effects grow more pronounced in hot weather.
Jones had also chosen to use artificial insemination for experimental design purposes though it generally proves less effective than the services of an honest-to-gosh bull.
But the failure might also indicate that the reproductive problem lies not in maintaining a pregnancy but rather in conceiving.
"Based on the other literature that was out there, we gave the drug only two days before the cows should have ovulated with the idea of trying to fix the progesterone problem (so the cows wouldn't miscarry)," Jones said.
"But it could be that the eggs themselves aren't viable, in which case we would need to give the drug earlier. I really think it's the eggs."
Jones hopes to test that hypothesis with another small-scale study, this time with funding from the federal government's Small Business Innovative Research program, designed to turn scientific discoveries into commercial products.
"This drug is something we want to commercialize for cattle," Jones said.
"The SBIR program involves a two-step process where you start with a small amount of money to gather preliminary data followed by many more thousands of dollars for Stage Two."
Commercialization would mean not only a larger calf crop but also an extended breeding season, as cattle producers would no longer be held back by fescue problems.
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