Every dairy farmer in the country is well aware that somatic cell counts must be below 400,000 cells per ml to qualify for international sales.
But that’s just the beginning, say milk quality experts who routinely deal in global dairy trade. More
extensive testing is becoming standard operating procedure in U.S. dairy manufacturing plants.
“We produce about 15 million servings of dairy every day for our global market that includes North and South America, Asia, Oceania and Europe,” says Karen McCarty with the Davisco Business Unit of Agropur. Many of
Davisco’s end users include infant nutrition and pharmaceutical products.
“These high end users of our products drive us to focus on trace contaminants like cleaning agent residues, pesticide residues and antibiotics outside the scope of the Pasteurized Milk Ordinance Appendix N testing,” she says.
“There are gaps between what we are legally required to test for in the U.S., what our customers internationally require and the tolerances of the things we do have in common,” adds Tonya Schoenfuss, a dairy foods specialist with the University of Minnesota.
“Because of the high percentage of our milk that is being exported, everyone in the production supply chain needs to be aware of the issues important for export and how they can contribute to providing a high-quality product that will continue to be in high demand,” Schoenfuss explains.
In a few cases, U.S. requirements are more stringent. “But in general, the European Union (EU) and Russian Federation maximum residue levels (MRLs) are set for a broader variety of drugs within a drug class and have lower limits for some residues, such as tetracyclines and Novobiocin,” Schoenfuss says.
The U.S. requires testing six beta-lactam drugs; the EU and Russia require testing for 13. Many countries also require routine testing for aflatoxins while some U.S. states require testing only during wet times.
McCarty adds that Davisco does quarterly screening for a whole range of trace contaminants. They include heavy metals, pesticides, enterotoxins, melamine and cleaning compound residues.
On the pesticide front, no news is good news. “Our historical multi-residue methods (that tests for pesticides, insecticides, herbicides and fungicides) screening of all Davisco products has not detected a residue since we began testing in 2001,” she says.
Even so, Davisco expects farmers to maintain full records of their feed supply. Both the 2001 Bioterrorism Act and the 2011 Food Modernization Act require such traceability. The EU does as well. “The regulations
require a ‘one step forward, one step back’ approach; our customers require us to know the origin of all ingredients used and location of all product produced,” McCarty says.
Melamine contamination, which can cause renal failure and death in infants, is another critical issue in milk quality. In 2008, rogue Chinese dairy manufacturers used melamine to falsely raise the protein content of
infant formula. It led to nearly 300,000 illnesses and three confirmed deaths.
“Most dairy processors have implemented monitoring programs for melamine to ensure the milk supply in the U.S. continues to be safe,” McCarty says.
One of the emerging issues in global milk quality is spore-forming organisms. One such spore former is Clostridium botulinum, which can lead to botulism in infants.
“The suspected presence of C. botulinum spores led to a recall in 2013 of Fonterra infant formula, whey powder and sports drinks and the temporary banning of [New Zealand] imports in Russia, China and Sri Lanka,” Schoenfuss explains.
Later testing determined it was another, far less harmful Clostridial strain. But the initial reports were enough to shut down New Zealand exports for a time and cause a global market disruption.
Spore formers are particularly nasty because they can survive heat treatment and then grow rapidly once they are rehydrated. But even if spore formers in raw milk are killed, high loads of organisms that contain heat-stable proteases can cause gelation and bitter off-flavors.
Preventing spore formers from entering milk is key, but specific on-farm management practices to prevent them are still in their infancy. Good silage preservation, bunk and bedding management along with milking hygiene are crucial to this prevention.
At the same time, those countries and manufacturers who can consistently provide low-spore milk powder will have a competitive advantage in global markets, Schoenfuss says.