A decades-long study of on-farm pasteurized waste milk conducted by Land O’Lakes Animal Milk Products Company reveals several gaps in nutrition, pasteurization kill rate and residual antibiotics. The study, conducted from 2006 through 2017 on 618 U.S. dairy farms, looked at herds raising from 5 to 5,000 calves. Milk samples, taken immediately after pasteurization, were collected for seven consecutive days from each farm then sent in for analysis. Fat content of the milk showed an average variation of 17.3% within farms,protein varied 7.9% and total solids varied 6.6%. This variation can come from using waste milk from cows in different stages of lactation and health status.
“This high level of variation makes it challenging to provide a consistent, nutritious diet to young calves,” says Tom Earleywine, director of nutritional services for Land O’Lakes Animal Milk Products.
On-farm pasteurization also failed more than 40% of the time on these farms when milk was tested for bacteria immediately after pasteurization. Only 58% of samples had less than 20,000 colony-forming units (CFUs) immediately after pasteurization. And only 46% had less than 20,000 CFUs in samples taken after the last calf was fed. Because the waste milk used to feed calves usually comes from treated cows, residual antibiotics can also be a concern.
In the Land O’Lakes study, 57% of the samples contained traces of antibiotics. Other studies have shown an increase in antibiotic resistance in calves fed waste milk compared to those fed milk replacer.