Insoluble fiber sources in mash diets for broiler starters (D1-21): the impact on growth performance, foregut development, and the utilization of nutrients and energy

Abstract

Even though insoluble fiber (IF) is considered a nutrient diluent in poultry diets, the potential of IF to improve gut health by developing the chicken foregut has been recognized. A 21-day experiment evaluated the effect of IF on growth performance, nutrient, and energy utilization, and foregut organ development of broiler starters fed mash diets. Four dietary treatments were developed with a control (a commercial broiler starter diet) and three experimental diets by diluting the control diet (60 g/kg [w/w]) with three IF sources (rice hulls [RH], lentil hulls [LH], and wood shavings [WS]). A total of 120, one-day-old broilers (6 birds/cage; 5 cages/treatment) were used in a completely randomized design. No difference (P>0.05) in growth performance parameters was observed up to d7. At d14, however, birds fed control and RH diets showed the lowest (P<0.05) feed conversion ratio (FCR; 1.079 and 1.129, respectively). Overall, birds fed the control diet had the highest body weight gain and lowest feed intake and, consequently, the lowest FCR (P<0.05; d1-21). Nevertheless, when corrected for the IF inclusion to consider the feed intake only, FCR was not affected by dietary treatments (P>0.05). Feeding RH and WS improved the crop weight (g/kg of body weight; P<0.05) compared to the control. By incorporating RH with the diet, the highest (19.2%; P<0.05) gizzard growth compared to the control (14.58 vs 12.23 g/kg of body weight) was achieved. Birds fed RH and LH had lower (P<0.05) gizzard pH (2.97 and 2.99, respectively) compared to those fed WS. Despite being considered a nutrient diluent, tested IF did not impair (P>0.05) the apparent metabolizable energy and apparent ileal protein and fat digestibility. With the highest improvement in gizzard growth and consequent low gizzard pH, 60 g RH/kg diet suggested the possible manipulation of RH as a functional ingredient in broiler starter diets.