This study investigated the impacts of feed withdrawal and addition of acetic acid in drinking water on the pH and microflora of gizzard, cecal and feces in preslaughter broiler chickens. Twenty four (24) individually caged 42 days old male Ross 308 broilers with almost equal weight were randomly divided into six treatments with four replicates each. The control group had free access to feed and water, but without supplemental acetic acid during preslaughter period. Another group was kept 8 h without feed, but with ad libitum access to unsupplemented drinking water. The other four treatment groups received 1.5, 3, 4.5 or 6% acetic acid added to their drinking water with feed withdrawal for 8 h. Fecal samples were collected 1 h before slaughter. After slaughter, gizzard and cecal contents were collected for microbiological studies. The number of Clostridium, Bacillus, Coliform and other bacteria were enumerated on appropriate bacterial media. The pH of gizzard and feces was significantly (P<0.05) lower in birds that underwent feed withdrawal combined with acidified water as compared with the control and feed withdrawal groups without acetic acid supplementation. The cecal pH was significantly lower for the 4.5 and 6% acetic acid groups compared to the control and feed withdrawal group with no acid. Also, the addition of acetic acid to drinking water resulted in significant (P<0.05) reduction ofBacillus, Clostridium, Coliform, facultative aerobic, and other bacteria in gizzard, cecal and fecal contents of birds with acidified water in comparison to the control and feed withdrawal treatments. Under the condition of this trial, addition of acetic acid in the drinking water 8 h before slaughter could reduce the concentration of certain populations of bacteria and might be a suitable approach against bacterial contamination of broiler carcass during processing.

Key words: Acetic acid, feed withdrawal, Bacillus and Clostridium, broilers.