Many mechanisms could be responsible for improved
performance with formic acid or formate salts. A trend
toward improved DM digestibility was observed by
Franco et al. (2005) in nursery pigs fed diets containing
formic acid as well as diets containing other acids. Increased
apparent ileal digestibility and N retention
were observed in growing-finishing pigs fed diets varying
in content of organic acids, including formic (Mroz
et al., 2000). Total anaerobic bacteria and lactic acid
bacteria decreased along the gastrointestinal tract in
weaned pigs after 7 d of feeding wheat-based diets containing
K-diformate. By 28 d of treatment, total anaerobes
decreased in the stomach and small intestine,
whereas lactic acid bacteria and yeast decreased
throughout the tract. Formic acid concentration increased
in the stomach and small intestine in response
to dietary inclusion. Decreased microbial populations
could result in improved digestibility of feed (Canibe
et al., 2001). In growing-finishing pigs, feeding a diet
containing formic acid decreased total anaerobes in the
proximal gastrointestinal tract and decreased lactic
acid bacteria, enterobacteria, and yeasts throughout