The alterations in the balance of the normal intestinal bacterial flora of chickens exposed to acidified wood-derived litter were analyzed and compared to those of a control group exposed to nonacidified litter. A total of 1,728 broilers were divided into two groups, with six replicates in each. One group was exposed to dry wood-derived litter, and the other was exposed to dry wood-derived litter sprayed with a mixture of sodium lignosulfonate, formic acid, and propionic acid. At five different times, five chickens from each pen were killed and the intestinal contents from ileum and caeca were collected. The samples were diluted and plated onto selective media to identify coliforms, Lactobacillus spp., Clostridium perfringens, and Enterococcus spp. Covariance analysis of bacterial counts showed significantly lower counts for C. perfringens in the caeca and the ileum and for Enterococcus spp. and Lactobacillus spp. in the ileum in chickens exposed to the acidified litter. Lactobacillus spp. showed significantly higher counts in the caeca in chickens exposed to acidified litter. There was no difference between the two litters with regard to coliforms in the ileum and the caeca or to Enterococcus spp. in the caeca. The study shows that exposing the chickens to acidified litter lowers the intestinal bacterial number, especially in the ileum, without negative consequences for the chicken's health or performance. Of special interest are the lower counts of C. perfringens and Enterococcus spp. that might reduce the risk of developing clinical or subclinical necrotic enteritis and growth depression.Antibiotic growth promoters (AGPs) have been used in animal production worldwide since 1946, when their positive effects were observed for the first time (29). AGPs are antibiotics added to animal feed at subtherapeutic levels to increase growth, improve feed efficiency, and decrease the incidence of diseases (1, 18).The use of antibiotics over time in human and animal medicine and for growth promotion in animals has caused a large pressure on the microfloras, with the consequent appearance of resistance to these antibiotics among pathogenic bacteria (4,35,36,37,46). A lot of attention is being focused upon this problem, which has resulted in the banning and/or regulation of the use of AGPs by a number of countries and an increasing interest in organic farming. Development of alternative products and improved management is therefore necessary to eliminate the use of AGPs while achieving the same productivity.Organic acids (OAs) have increasingly and successfully been supplemented in feed in swine and broiler production. The way of action of OAs seems to be related to a reduction of pH in the upper intestinal tract, interfering with the growth of undesirable bacteria and modifying the intestinal flora (19). OAs also improve the digestibility of proteins and amino acids and the absorption of minerals (30, 31), modulate endocrine and exocrine secretions, and influence the mucosal morphology (33). Whether these effects can be app...

No abstract