Advances

(Advances gives a glimpse of the many significant research projects at the university. Tell us about your discoveries by e-mailing: wisweek@news.wisc.edu.)

Research shows ways to improve forage grasses
Recent findings are leading to new insights into how best to improve the nutritional value of forage grasses and which approaches aren’t likely to pay off for producers.

Improved grass varieties are becoming more important in Wisconsin, where producers have increased their reliance on grazing as the low-cost way to produce milk and beef. Almost one-quarter of state dairy farmers now use management-intensive rotational grazing — more than triple eight years ago.

In trying to improve agronomic traits, researchers must alter the basic nature of grasses, says Michael Casler, a university plant breeder. In doing so they often run into problems but they also have experienced successes. “Plant breeders began efforts to develop improved grass varieties 40 years ago,” Casler says. “They’ve released many new varieties that animals find easier to digest.”

Steers thrive on kura clover
Holstein steers can pack on the pounds grazing kura clover/grass pastures, trials at UW–Madison’s Lancaster Agricultural Research Station have shown. Steers grazing kura clover/grass outperformed those on red clover/grass, and far surpassed gains on alfalfa/grass reported in earlier studies at Lancaster. The kura clover-based pastures had no problems handling intensive grazing pressure, according to researchers at the College of Agricultural and Life Sciences.

Says CALS agronomist Ken Albrecht: “Animal performance on kura clover during our first three years was better than the best single-year performance during trials in the 1960s and 1970s.”

Alfalfa, red clover and birdsfoot trefoil generally succumb to winter-kill or disease after two to five years. Kura clover, thanks to its rhizome system, can survive Wisconsin’s harshest winters. Kura clover originated in Caucasian Russia and is grazed in native meadows there.

Study suggests how to keep milk free of antibiotic residue
It’s important to keep antibiotic residues out of milk, and few dairy producers think they will ever have a problem on their farms. But producers whose herds’ somatic cell counts are high have reason to be concerned, says a university dairy scientist.

“The risk that producers will violate the law prohibiting antibiotics in milk increases as their herds’ somatic cell counts rise,” says Pamela Ruegg, the lead author of a recent article in the Journal of Dairy Science. A high somatic cell count, or SCC, indicates that a herd has a high prevalence of subclinical mastitis.

The pasteurized milk ordinance prohibits antibiotic residues in milk primarily to protect consumers who may have an allergic reaction to the compounds. Treating mastitis is the most common use of antibiotics on dairy farms.

Wisconsin dairies with serious subclinical mastitis problems are up to seven times more likely to have antibiotic residues in milk than producers with herds that have a low incidence of mastitis, says the study.

“Most dairy farms do an excellent job of preventing antibiotic residues in milk. Our study suggests that a cost-effective way to prevent antibiotic residues in milk may be to target programs to farms with high SCC,” says Ruegg. She leads educational programs to help farmers improve milk quality.

To look for a relationship between SCC and antibiotic residues, Ruegg and dairy scientist Tom Tabone analyzed more than 805,000 milk tests on Wisconsin’s grade A dairy farms, from January 1995 until December 1998.