The effect of high and low dietary fiber diets on the performance of two lines of chickens with divergent growth rates

An experiment was designed to determine the effects of feeding high dietary fiber on the performance, cecal short chain fatty acid (SCFA) concentration and cecal microbial ecology of broiler and layer chicks. All diets were formulated to meet or exceed NRC (1994) standards for starter chicks with the lower fiber diet based on corn-soybean meal (SBM) and the higher fiber diet formulated using corn-SBM-dried distillers grains with solubles (DDGS) and wheat bran. The higher fiber diet contained 60.0 g/kg of both DDGS and wheat bran from 1-12 d and 80.0 g/kg of both DDGS and wheat bran from 13-21 d. The experiment utilized a completely randomized design with a 2 x 2 factorial arrangement of treatments consisting of two dietary concentrations of fiber (lower and higher fiber) and two chicken lines (broiler and layer) fed from 1 to 21 d. The Ross 308 broiler chicks and Hy-line W36 male chicks were housed in battery cages in an environmentally controlled room with ad libitum access to feed and water. Average daily gain (ADG), average daily feed intake (ADFI) and feed efficiency (FE) were calculated over the 1-12 and 1-21 d feeding periods. Excreta samples were collected at the end of the experiment to determine nitrogen corrected apparent metabolizable energy (AMEn) and Neutral Detergent fiber (aNDF) digestibility. Cecal samples were collected at the end of the experiment to determine SCFA concentration and microbial ecology. The results indicate that the higher dietary fiber diet significantly reduced broiler ADG for the 1-12 d and 1-21 d periods, but had no effect on layer chick ADG resulting in a significant interaction (P&le0.01). Neutral detergent fiber digestibility was higher in layer chicks in comparison to broiler chicks regardless of the diet (P\u3c0.01), and higher dietary fiber concentration resulted in increased ileal (P\u3c0.01) and total track (P\u3c0.02) aNDF disappearance, across both lines. Although aNDF disappearance was altered between line and diet, AMEn was not different (P\u3e0.41), suggesting that dietary energy was not limiting growth performance. Cecal short chain fatty acid analysis showed an increase in the concentration of acetic acid (P=0.02) and propionic acid (P\u3c0.01) in broiler chicks in comparison to layer chicks and increasing dietary fiber resulted in a significant reduction of butyric acid (P=0.03). There was variation in the cecal microbial communities as a result of chick line and diet modification. These results suggest that high fiber feed ingredients are suitable substitutes for supplementation in layer chick starter diets but not in broiler chicks