A recent lay publication demonstrated an apparent transitory beneficial effect of acidifying drinking water over the first 14-days post hatch to suppress Salmonella Heidelberg infection. The trial involved 200 broilers receiving Salmonella Heidelberg at day-one, compared to a control group receiving water with a neutral pH.
At 14 days of age, recovery of Salmonella, presumably from feces, was significantly lower in the group receiving acidified water with a pH of 4.2 compared to untreated controls. The effect of water treatment on recovery of Salmonella was not significantly different at 28-days of age.
This experiment as reported has little or no relevance to suppressing Salmonella colonization of the intestine for practical production. If the authors were able to demonstrate a difference in intestinal colonization rate with Salmonella Heidelberg at the time of harvest or if treatments were responsible for lower recovery on carcass washes, the claims would have some relevance.
The issue of deterioration of drinking systems as a result of supplying water with a low pH is a practical consideration. Corrosion of balls within drinkers if it occurs will lead to leakage that in itself would potentially represent problems of coccidiosis and enteritis.
Based on established knowledge concerning the development of the intestinal biome of broiler chicks and the data presented, providing water with a low pH will have no material effect on suppression of Salmonella Heidelberg at harvest. Trials involving acidification of drinking water for variable periods up to 72 hours prior to slaughter have not shown any consistent effect on in-plant carcass contamination. There is a marked lack of correlation between recovery rates from either live birds or Salmonella counts and actual carcass wash data under practical plant operation.