Research conducted by a former food science professor at the University of Wisconsin-Madison shows that the state's larger dairy operations tend to put out a higher quality product than smaller farms.
Steve Ingham says he looked at milk quality data from over 14,500 dairies around Wisconsin--of which 14,591 were classified as small farms with fewer than 118 cows; 1,565 had between 119-713 cattle; and 160 milked more than 714 cattle.
"I wanted to test this belief that I've heard a lot--that little farms are better," said Ingham, who now serves as the food safety division administrator at the Wisconsin Department of Agriculture. "The take-home message is that when you group farms according to size the way we did, small doesn't appear to be better in terms of milk quality."
His team used two common metrics of milk quality: reported bulk tank standard plate count and somatic cell count, which together are also seen as good indicators of farm sanitation and animal-handling practices.
Across the board, the larger farms reported the lowest mean milk quality scores for both SPC and SCC.
Mean SPC (reported in colony forming units per milliliter or cfu/mL) was found to be 35,000 cfu/mL for the CAFO group; 36,300 for large farms; and 58,700 for small farms. Mean SCC (in cells per milliliter or cells/mL) was found to be 240,000 cells/mL for the CAFO group; 273,000 for large farms; and 369,000 for small farms. In all cases, mean SPC and SCC scores were far below the grade A maximum values, easily meeting the federal standards for milk intended to be pasteurized and sold for fluid consumption.
"The CAFO category had the lowest counts. It could be that they have more money to spend on good equipment. It could be that they have the ability to cull out cows with mastitis more quickly," says Ingham, who is aware that some groups may take issue with the farm size categories he created or the milk quality measures he chose to use. "Overall, I feel the numbers speak for themselves. They give a good snapshot of the industry right now."
Meanwhile, Ingham points out that all of the state's farms, both large and small, produced milk that easily met federal food safety guidelines.
The results of the study have been published in the August issue of the Journal of Dairy Science.