Feedlot managers want beef cattle to produce less lactic acid; producers of lactic acid for food and industrial uses want to beef up production while cutting costs. Both groups may get their wish as researchers move closer to solving a $40-100 million headache for the U.S. beef industry. When cattle switch from a high-forage diet to a finishing ration loaded with energy-rich grains, they sometimes get lactic acidosis--a giant stomachache. Sometimes life-threatening, lactic acidosis inhibits animals' weight gain and results in liver abscesses and other abnormalities. That's because millions of the bacterium Streptococcus bovis in the rumen--the animal's stomach compartment--gobble up more glucose from the grain than they need and expel an abundance of lactic acid. ARS scientists have sorted out the composition of the S. bovis gene behind the enzyme that produces lactic acid. Through biotechnological tinkering with the gene, they may someday manipulate S. bovis to produce less lactic acid in cattle or transform some microbial species to make more lactic acid for manufacturing of products such as biodegradable plastic.
Fermentation Biochemistry Research, Peoria, IL
Michael A. Cotta, (309) 681-6273

Two new tidbits about piglets: The little porkers like it hot, and telltale hormones can reveal whether they're stressed or healthy. ARS researchers were the first to study the effects of temperature on luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Both LH and FSH influence reproduction and are excreted by the pituitary gland. Newborn pigs are more comfortable in a hot environment, while cool temperatures create mild stress. These studies were "piggybacked" with results from other swine experiments on temperature and exposure to disease.
Animal Physiology Research, Columbia, MO
Robert L. Matteri, (573) 882-1047

If farmers want their livestock to eat more and gain more weight, they'd better make hay while the afternoon sun shines. A new study shows that sheep, goats and cattle all prefer grass hays harvested in the afternoon over those cut in the morning. A possible explanation: Plant carbohydrate production peaks at midday. Researchers suspect animals "remember" the afternoon-cut hays give them more energy than morning-cut hays. It's long been known livestock grazing peaks in the afternoon. This led researchers to explore whether cutting hay later in the day could boost consumption.
Plant Science Research, Raleigh, NC
Dwight Fisher, (919)515-7597

The same natural substances that help pigs and other livestock cope with stress could make it more difficult for the animals to fight off common infections. ARS scientists have discovered that pigs agitated in simulated shipping conditions had higher levels of cannabinoids, a chemical produced by the brain that helps calm the pig. The bad news: The same tests indicate that when pigs' cannabinoid levels stayed high over a long period of time, their natural immune defenses were weakened. These findings could help animal breeders select the right pigs to stand up to stress, and also give growers important clues to possible causes of herd health problems.

Livestock Behavior Research Unit, West Lafayette, IN
Gary Weesner, (317) 494-6983, gweesner@ansc.purdue.edu

Extra fat in a cow's diet for the last 6 weeks of pregnancy could help her newborn calf fare better in cold temperatures, according to preliminary results by ARS scientists. An estimated 95,000 calves die each year from cold stress. In tests, researchers added safflower with a high concentration of linoleic fatty acid to the diets of 12 cows for 53 days before calving. Another 11 ate a standard feed ration. For the first five hours after birth, the calves stayed at room temperature. Then they were put in a room at 32 degrees Fahrenheit. During this 140-minute experiment, calves from mothers that ate the extra fat maintained their body temperatures better than did those from cows fed the standard diet. The effect on calf survival is still under study. But the scientists believe the calves born to cows on the high-fat diet had more "brown" fat. Brown fat surrounds organs such as the kidneys and helps the animals generate body heat immediately after birth. Researchers are repeating the experiment to confirm the results.
Fort Keogh Livestock and Range Research Lab, Miles City, MT
Robert Bellows,(406) 232-4970, bob@larrl.ars.usda.gov

Last Updated: April 25, 1997
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