Resumen de Effects of type and level of fiber on digestive traits and growth performance in young broilers
The fibrous feedstuffs have not been used in monogastric diets because of theirs detrimental effect on voluntary ingestion and digestibility of nutrients. However, numerous reports have demonstrated that the inclusion of moderate amounts of fiber in the diet improves growth performance in broilers fed low-fiber diets. Therefore, six experiments (Exp.) were conducted to study the effects of fiber inclusion in the diet on growth performance and digestive traits in broilers.
In Exp. 1 was designed to study the influence of cereal, HP of the cereal, and inclusion of additional fiber [control without hulls, 3% oat hulls (OH), and 3% soy hulls] in the diet on the gizzard pH and digestibility of nutrients in broilers at different ages. It is concluded that rice is a cereal of choice in prestarter diets for broilers. The reduction in gizzard pH and the improvement of digestibility of nutrients observed with additional fiber suggests that young broilers might need a minimal amount of fiber in the diet for optimal performance.
In Exp. 2 was designed to study the influence of fiber source (3% OH; and 3% sugar beet pulp, SBP) and dietary fat (5% soybean oil, SO; and 5% yellow grease, YG) on digestive traits and productive performance was studied in broilers from 1 to 21 d of age. Therefore, the inclusion of moderate amounts of fiber in the diet might improve performance and nutrient digestibility in young chicks, especially when saturated fats are used.
In Exp. 3, the effects of type [3% OH, 3% SBP, and 3% cellulose microcrystalline (CEL)] and particle size of OH and SBP ground through a 0.5- or a 2.0-mm screen on growth performance and digestive traits were studied in broilers from 1 to 21 d of age. It is concluded that additional OH and SBP improves gizzard weight and growth performance in young chicks fed low-fiber diets and that the effects are more pronounced with OH than with CEL. Particle size of OH and SBP does not affect broiler performance, but coarse grinding increases gizzard development and reduces nutrient digestibility in young birds.
In Exp. 4, the effects of different sources of dietary fiber (3% OH, 3% SBP and 3% CEL) on gastrointestinal tract development and digesta pH were studied in 25-d-old broilers. We concluded that dietary fibre affects the development and pH value of the different segments of GIT and that the effects differ according to the physico-chemical characteristics of the source of fibre used.
In Exp. 5, the effects of inclusion of pea hulls (PH) in the diet on growth performance, digestive traits and nutrient retention were studied in broilers from 1 to 18 d of age. We conclude that the size of the digestive organs increases with increasing levels of PH in the diet. In general, the best performance and nutrient digestibility values were observed with levels of PH within the range of 2.5 and 5.0%. Therefore, young broilers have a requirement for a minimum amount of dietary fiber. When pea hulls are used as a source of fiber, the level of crude fiber (CF) required for optimal performance is within the range of 2.56 to 3.50 g/kg diet. An excess of CF (above 3.50%) might hinder nutrient digestibility and growth performance.
In Exp. 6, the effects of increasing the level of OH and SBP in the diet on growth performance, digestive traits and nutrient retention were studied in broilers from 0 to 18 d of age. We conclude that the inclusion of moderate amounts of a source of fiber (2.5 to 5%) improved digestibility of nutrients and feed efficiency. However, a further increase to 7.5% has negative effects on these traits. Young chicks have a requirement of CF ranging from 1.61% to 2.42-2.94% with higher levels when OH are used. An excess of dietary fiber (> 2.94% CF) hinder nutrient digestibility and growth performance.
