Destruction of Mycobacterium paratuberculosis, Salmonella spp., and Mycoplasma spp. in raw milk by a commercial on-farm high-temperature, short-time pasteurizer

Abstract

The 2002 NAHM's Dairy Survey indicated that 87.2% of dairy farms in the United States feed waste milk to their neonatal calves. Although cost-effective, this practice can lead to increased calf morbidity and mortality due to ingestion of pathogenic agents. In an effort to reduce the risk of infection, dairy producers are implementing on-farm pasteurization of the waste milk as a control procedure before feeding the milk to calves. In the present study, the efficacy of a commercial high-temperature, short-time (HTST) on-farm pasteurizer unit to destroy Mycobacterium paratuberculosis, Salmonella enterica spp., and Mycoplasma spp. in raw milk was evaluated. Replicate experiments were run for 3 isolates of M. paratuberculosis, 3 serovars of Salmonella (derby, dublin, typhimurium); and 4 species of Mycoplasma (bovis, californicum, canadense, serogroup 7) at 2 different levels of experimental inoculation. In addition, HTST pasteurization experiments were performed on colostrum experimentally inoculated with M. paratuberculosis. After culture of the pasteurized milk samples, no viable M. paratuberculosis, Salmonella, or Mycoplasma were recovered, regardless of species, strain, or isolate. Pasteurization of colostrum was also effective in the destruction of M. paratuberculosis but resulted in an average 25% reduction in colostral immunoglobulin. These results suggest that HTST pasteurization is effective in generating a safer product to feed to young calves.