Effects of type of cereal, heat processing of the cereal, and fiber inclusion in the diet on gizzard pH and nutrient utilization in broilers at different ages
2009
Jiménez-Moreno, E. | González-Alvarado, J.M. | Lázaro, R. | Mateos, G.G.
An experiment was conducted to study the effects of type of cereal (60% corn or 60% rice), heat processing of the cereal (raw or steam-cooked), and fiber source (control without hulls, 3% oat hulls, and 3% soy hulls) on gizzard pH and total tract apparent retention (TTAR) of nutrients in broilers at different ages. There were 12 treatments arranged factorially (2 x 2 x 3) and 6 replicates (8 chicks) per treatment. The 2 basal diets were based on soy protein concentrate and fish meal and had a neutral detergent fiber content of 3.5% for the rice and 7.3% for the corn diet. Gizzard pH was lower at 13 d than at 8 or 20 d of age (P [less-than or equal to] 0.05) and was lower for the corn than for the rice diets (P [less-than or equal to] 0.001). The inclusion of additional fiber reduced gizzard pH in broilers fed rice but not in broilers fed corn (P [less-than or equal to] 0.001). Except for acid soluble ash, TTAR of nutrients increased from 4 d to 8 or 13 d of age (P [less-than or equal to] 0.001) and then remained constant until 20 d. Nutrient retention was higher for the rice than for the corn diets (P [less-than or equal to] 0.001) at all ages. The inclusion of oat hulls or soy hulls improved TTAR of nutrients and the effects were more pronounced for the rice than for the corn diet (P [less-than or equal to] 0.001). Also, the beneficial effects of fiber inclusion on TTAR of ether extract and AMEn of the diet were higher at younger ages (P [less-than or equal to] 0.05). It is concluded that rice is a cereal of choice in prestarter diets for broilers. The reduction in gizzard pH and the improvement of TTAR of nutrients observed with additional fiber suggests that young broilers might need a minimal amount of fiber in the diet for optimal performance.
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