During this morning's chores, the mixer wagon was loaded with a variety of feedstuffs - probably corn, soybean meal, corn silage and cottonseed, among other things. Did the issue of milk quality enter your mind as feed ingredients were purchased and cows fed?

Obviously, a top-notch feeding program is important for healthy immune systems, optimum milk production, and profitable levels of protein and fat in milk. But, are there other milk quality factors to consider when purchasing feedstuffs, putting together rations and feeding cows? If you've ever tasted milk after a group of cows got into a patch of garlic, you'll agree that what you feed may impact milk quality.

Recently, there has been a great deal of discussion about biotech crops. Many producers raise or feed them from Bt corn to Roundup Ready(r) soybeans and meal. Today, the list of biotech plants that have been successfully reviewed by the U.S. regulatory system exceeds 50; Canada's approval list is substantial, also. However, for social reasons, the list of approved biotech crops in some other countries is not quite as extensive.

To protect domestic and export markets for our dairy products, many have asked me whether feeding biotech crops will allow others to differentiate their milk from milk sold by producers who don't feed biotech crops. The short answer today is, "no," but I encourage you to read on for more insight into this Dairy Quality Link.

This issue is likely to become more important as the list of available biotech crops lengthens. And the dairy industry needs to know how to reply when neighbors, farm visitors, friends, and even off-the-farm family members ask questions.

As we all have heard by now, biotech crops that are available commercially today include a novel gene or genes that allow the plant to exhibit specific characteristics. Some biotech crops are resistant to pests like the European Corn Borer; others are tolerant of herbicides such as Roundup(r).

The novel genes in today's roster of biotech crops allow the plants to produce unique proteins that normally are not present, conferring upon the plants desirable traits such as pest resistance, herbicide tolerance, and eventually improved nutritional value.

Can a marketer, retailer, or exporter check your milk to see whether your cows have been exposed to these novel proteins in biotech plants?

At Iowa State University, we conducted a study to look at this. Cows in our dairy herd were fed rations that contained either normal corn or biotech corn from one of two different Bt hybrids. Throughout the two-week study, we collected milk samples from all cows. When these milk samples were analyzed, no Bt proteins were detected. Other studies have since been completed, and have reported similar findings - no transgenic proteins have been detected in milk from cows fed Bt corn or Roundup Ready(r) soybean meal. Further, our work, as well as results from numerous other studies have detected no differences in composition of milk when cows are fed biotech crops.

What's the bottom line? At this time and for today's roster of biotech crops, milk from cows fed biotech and non-biotech crops cannot be differentiated.

If we think about it, we don't expect to find proteins that have passed through the digestive system to be intact in milk. So, these research results are no surprise. However, studies such as these are important to dairy producers who are actively working to improve their Dairy Quality Link.

Marj Faust is an associate professor and extension dairy specialist at Iowa State University.