The effect of various feed additives on growth performance, nutrient utilization, and cecal microbial populations in poultry

Experiments were conducted to evaluate the effects of several oligosaccharides, organic acids, an enzyme, and whole grains on growth performance, nutrient utilization, and select cecal microbial populations in poultry. Unless otherwise noted, all diets were corn soybean meal. In the first study, inulin, oligofructose, short-chain fructooligosaccharide (SCFOS), mannanoligosaccharide (MOS), and transgalactooligosaccharide (TOS) were fed to adult roosters at a concentration of 4 or 8 g/kg. Data showed that the true digestibility of amino acids (AA) and metabolizable energy (MEn) were not negatively impacted. Each oligosaccharide was then evaluated at 4 or 8 g/kg in day-old chicks. Metabolizable energy and AA digestibility were generally decreased (P<0.05) at 21 days when an oligosaccharide was fed at 8 g/Kg. In contrast, 4 b/kg of any of the five oligosaccharides increased MEn at 21 d. When chicks were fed a dextrose-isolated soy protein diet, the cecal concentration of Clostridium perfringens was decreased (P<0.05) when 4 g/kg SCFOS or MOS was fed. In the organic acid study, gluconic, citric, fumaric, and malic acids were evaluated. Those results indicated that gluconic and citric acids were not effective at affecting microbial populations and nutrient digestibility, and none of the organic acids had effects on growth performance. The next study measured growth performance of young chicks fed a diet containing a proteolytic enzyme, Versazyme. The addition of Versazyme resulted in no significant improvements in weight gain and feed efficiency in any dietary treatment. The final study evaluated whole wheat, whole sorghum, and whole barley. In general, the results showed that whole wheat, whole sorghum, and whole barley could be included in a young chick's diet from 0 to 21 d without compromising growth performance. Including a whole grain in the diet of young chicks resulted in an increase in gizzard weight. Whole grains had no significant effect on cecal pH and short-chain fatty acid concentration, suggesting no effect on cecal microbial populations.