Influence of Dietary Fibers on Performance and Fermentation Characteristics of Gut Contents from Growing Chicks

Abstract

Four experiments were conducted to evaluate the inclusion of fiber from various sources and of various particle sizes in both semipurified and corn-soybean meal diets fed to chicks. Growth rate and feed efficiency were the performance measurements tested. In Experiment 1, 8-day-old New Hampshire × Columbian female chicks were fed polyethylene (PE) and alfalfa cell walls (ACW) of varying particle sizes (<300 μm, 300 to 600 μm, and 600 to 1200 μm), incorporated into diets at the 8% level. A 0% fiber and an 8% solka floc treatment were used as controls. Consumption of ACW resulted in higher (P<.05) growth rates (6.5 vs. 5.4 g/day) and better (P<.05) feed efficiencies (.46 vs. .41) compared with chicks fed PE, regardless of particle size. In Experiment 2, two levels (4 and 8%) of pectin, lignin and xylose:gum arabic (50:50 mix), were tested using 8-day-old chicks of the same strain. Both levels of lignin and xylose:gum arabic (50:50 mix) resulted in superior grains compared to chicks fed control diets, while 8% pectin resulted in lower (P<.05) growth rates (3.3 g/day) than controls (5.2 g/day). Feed efficiencies followed the same pattern as growth rate. In Experiments 3 and 4, 1-day-old chicks (Experiment 3) and 8-day-old chicks (Experiment 4) of the Hubbard strain were fed two levels (5 and 10%) of gum arabic, xylose, and lignin substituted for corn in practical-type diets. Controls included 0% fiber and 5% arenaceous flour treatments. In Experiment 3, chicks fed both levels of xylose and lignin gained better (P<.05) than controls, whereas those fed 5% gum arabic performed poorer (12.3 g/day for controls; 9.6 g/day for gum arabic). Feed efficiency results showed similar trends. Growth rates of 8-day-old chicks fed 10% gum arabic and 10% xylose were lower (P<.05) than controls (28.4 and 30.7 vs. 31.6 g/day, respectively). Only chicks fed 10% gum arabic had lower feed efficiencies than controls. Cecal and large intestinal contents from chicks fed 10% xylose contained the highest concentration of volatile fatty acids (VFA) (83.5 and 79.9 μmoles/ml). Chicks fed lignin had the least cecal VFA (60.8 μmoles/ml) while chicks fed lignin and those fed the control diet had the least large intestinal VFA. Acetate was the predominan t VFA while propionate was present in the lowest molar concentration.