ANIMAL BY-PRODUCTS CONTAMINATED WITH SALMONELLA IN THE DIETS OF LACTATING DAIRY-COWS

As part of a total mixed ration, two rumen-fistulated dairy cows were fed meat and bone meal that had been artificially contaminated with Sa lmonella spp. Samples from the rumen, feces, and milk were taken 3 d/w k and cultured for salmonella. Rectal temperatures and rumen pH were a lso measured at the time of sample collection. Over the 2-mo study, sa lmonella were intermittently recovered from rumen contents, from feces , and from necropsy specimens of rumen contents, cecal contents, and m esenteric lymph nodes. No excretion of salmonella in milk was detected . An elevated rumen pH was associated with increased isolation of salm onella. No clinical illness was observed for either cow. Meat and bone meal that has been contaminated with low concentrations of salmonella is unlikely to result in clinical illness in healthy adult lactating cows. However, dairy producers should continue to be concerned about f eed biosecurity and water contamination of animal by-products to preve nt and control contamination by salmonella.