UNIVERSITY PARK, Pa. -- Like milk, baby formula has an expiration date beyond which it is unfit for human consumption. Manufacturers, who must discard millions of pounds of outdated formula annually, have been searching for better options.
Research in Penn State's College of Agricultural Sciences shows that one promising alternative to putting formula in landfills is to use it for animal feed, an option that would save livestock producers money and cut manufacturers' disposal costs.
"Formula has great potential as animal feed because it's made of nutritious ingredients that maintain their quality well beyond the expiration date for human consumption," says Randy Swope, graduate student in animal science.
Swope and Harold Harpster, associate professor of animal science, have been looking at various food processing by-products for cattle feed. "Feeding food industry by-products to animals typically results in a win-win situation," Swope says. "The manufacturer cuts disposal costs, and the producer gets a source of nutrients that costs less than conventional feeds."
After comparing the nutrient content of infant and geriatric formulas with the nutritional needs of different animals, Swope and Harpster determined that geriatric formula might be good for swine, while infant formula would work for calves.
"Just as with human infants, a young calf's diet must be carefully selected to avoid upsetting its digestive system," Swope says. "Geriatric formula contains corn oil, which would give calves diarrhea, but the ingredients in the baby formula seem ideally suited to a calf's digestive system."
The researchers randomly assigned 30 calves at Penn State's Dairy Breeding Research Center to one of three liquid diets. Ten calves received a control diet of commercial milk replacer, while the other two groups received infant formula supplemented with either soy or whey protein concentrate. For six weeks, calves were fed the experimental diets. Then all of the calves were weaned and fed the same dry diet for four weeks to see if the experimental diets had any lingering effects.
The results show that outdated infant formula, when supplemented with a high-quality protein source such as whey, can be used safely in calf-rearing systems with substantial savings in feed costs. "The calves fed infant formula supplemented with whey protein performed just as well as the calves fed the commercial milk replacer," Swope says. "Those fed infant formula supplemented with soy protein had inferior growth during the first six weeks of the experiment, but they improved in the last four weeks."
The milk replacer cost $2.21 per kilogram of live weight gain during the first period, compared to only $.55 for formula supplemented with soy and $1.04 for formula supplemented with whey protein. "For the best combination of performance and savings on feed costs, formula with whey protein was the best option," Harpster says.
Swope and Harpster also collaborated with Ken Kephart, associate professor of animal science at Penn State, to study the effect of geriatric formula on swine performance. They fed 152 pigs either a conventional corn and soybean-meal diet or one that included three-quarters of a gallon of geriatric formula as well as supplemental dry feed.
"At first, pigs on the experimental diet spent six to eight hours consuming each of their twice-daily allotments of geriatric formula," Swope says. "But as they adapted to the new feed source, they ate the formula more quickly. In human terms, the pigs had to develop a taste for the formula. That's important because a farmer trying the product might be disappointed with low intakes for the first few days. It may take a little more time."
Pigs fed the geriatric formula grew faster during the first half of the experiment and weighed more at 84 days. "Growth rates evened out over the entire experiment, so slaughter weights were similar for both groups," Swope says. "However, pigs fed the geriatric formula consumed 65 percent less dry feed than those in the control group. Pigs fed the geriatric formula had a 16 percent improvement in overall feed efficiency."
At slaughter, pigs fed the geriatric formula had less fat, more muscle, and a higher percentage of lean cuts, so they were worth about $3.50 more per pig on a commercial grading program.
The research has given producers a new source of inexpensive feed. "The cost savings from using waste formula already are very good, and they will look even better if grain and feed costs rise," says Harpster. "The formula manufacturer already is shipping tractor trailer loads of the geriatric formula to some of the largest hog farms in the country."
EDITORS: For more information, contact Harold Harpster at 814-863-0734, Randy Swope at 814-863-4199 or Ken Kephart at 814-863-3671.
Contacts: Eston Martz Eston_Martz@agcs.cas.psu.edu 814-863-3587 814-865-1068 fax