Veterinarian’s Corner: Impact of Waste Milk Quality on Calf Health and Performance

By Dr. Jeremy Schefers, University of Minnesota, and Dr. Noah Litherland, Vita Plus dairy youngstock technical specialist
Quality and hygiene are important considerations when feeding waste milk to nursery calves.  Benefits of on-farm pasteurization include reduced diarrhea and respiratory disease.  Proper pasteurization also kills Mycobacterium paratuberculosis (responsible for Johne’s disease), Salmonella and Mycoplasma, if present in milk.

What are the potential impacts of poor waste milk hygiene?

1. Bacteria cell walls in waste milk can result in an inflammatory response in the calf’s intestine.
2. Milk from mastitic cows is typically higher in sodium and lower in lactose than milk from healthy mammary glands.
3. Both bacteria and sodium in milk increase the milk osmolality, which will delay the abomasal emptying rate and increase water movement from blood into the intestine, which will increase passage through the gastrointestinal (GI) tract and cause loose stool.
4. Pasteurization is not sterilization.  On-farm pasteurization of waste milk will significantly decrease viable bacteria count, but some bacteria will survive pasteurization.
5. Bacteria surviving pasteurization will proliferate post-pasteurization unless milk is effectively cooled.
6. Data consistently shows an increased number of beneficial bacteria and decreased number of potentially pathogenic bacteria in calves fed both heat-treated colostrum and pasteurized waste milk versus calves fed raw colostrum and waste milk.
7. Unlike a mature human stomach, the calf stomach (abomasum) does not produce adequate amounts of acid to kill, or greatly reduce, bacteria.

What are key critical control points to optimize waste milk quality?

1. Do not collect waste milk for calf feed if milk has an abnormal visual appearance.
2. Include transition milk with waste milk for calves.  Transition milk typically contains higher protein and fat content than high-somatic-cell-count milk.
3. Transition milk also contains antibodies, minerals, and vitamins that protect the intestines and promote intestinal development.
4. Milking staff should know that pipeline flush water is not to be included with waste milk.
5. Vessels used to transport milk should be sanitized between uses (warm water rinse, detergent and scrubbing with hot water, hot water rinse, followed by acid sanitizer rinse).
6. Milk should be pasteurized and cooled as soon as possible after milking.  Monitor milk cooling temperature, agitation and milk cooling tank hygiene, especially at connection points entering and exiting the cooler.
7. Maintain pasteurizer hygiene and functionality with regular inspection and maintenance.
8. Run routine (weekly or at least monthly) total bacteria and total coliform count on pre- and post-pasteurized milk samples to double-check the pasteurizer effectiveness.
9. Monitor waste milk pH.
   • Normal pH of milk is between 6.5 and 6.7.  Once milk sours, the pH will decrease sharply.  One pH unit change, for example 6.0 to 5.0, indicates a 10-fold change in hydrogen ion concentration.
   • pH values higher than 6.7 indicate mastitic milk.
   • pH values lower than 6.5 may indicate presence of bacterial deterioration of lactose into lactic acid.
10. If these procedures do not fit within your maternity and/or milking protocols, consider feeding milk replacer instead.