We studied the influence of cereal, heat processing of the cereal, and inclusion of additional fiber in the diet on the productive performance and digestive traits of broilers from 1 to 21 d of age. Twelve treatments were arranged factorially, with 2 cereals (corn and rice), 2 heat-processing treatments of the cereals (raw and cooked), and 3 sources of fiber (none, 3% oat hulls, and 3% soy hulls). Each treatment was replicated 6 (trial 1) or 3 (trial 2) times. Growth traits were recorded in both trials; digestive traits were measured in trial 1, and total tract apparent retention (TTAR) of nutrients was determined in trial 2. Feeding rice improved TTAR of all nutrients and feed conversion from 1 to 21 d of age (P

We studied the influence of the cereal (corn and rice), heat processing (HP) of the cereal (raw and steam cooking), and fiber inclusion (none; 3% oat hulls, OH; and 3% soy hulls, SH) in low-fiber diets on the development and pH of the digestive tract in broilers. There were 12 treatments arranged factorially and 3 replicates (a cage with 12 chicks) per treatment. Digestive traits were measured at 1, 5, 9, 15, and 22 d of age, and digesta pH was determined at 22 d of age. The relative weight (% BW) of proventriculus and gizzard was greater in chicks fed corn than in chicks fed rice (P < or = 0.01). Heat processing had little effect on relative weight (RW) of the digestive organs. An interaction between cereal and HP of the cereal was detected for the gizzard and the liver; HP of corn reduced RW of the gizzard and increased that of the liver, but no effect was observed with HP of rice. The RW of the proventriculus was increased by SH inclusion (P < or = 0.05), whereas the RW of the gizzard was increased by OH inclusion (P < or = 0.001). Also, SH inclusion increased gizzard digesta (P < or = 0.01) and moisture (P < or = 0.001) content. Dietary treatment did not affect relative length (cm/kg of empty BW) of the intestines. Feeding rice tended to increase gizzard digesta pH (P = 0.081) but reduced that of the intestines (P < or = 0.001). Neither HP of the cereal nor hull inclusion affected pH of the digestive tract. We conclude that the RW of the proventriculus and gizzard is reduced by feeding rice and increased by hull inclusion. Dietary treatment had little effect on the weight and relative length of the intestines. Chicks might require a minimal amount of fiber in the diet to stimulate the development of the upper gastrointestinal tract.

A trial was conducted to study the effects of type and particle size of dietary fiber on growth performance and digestive traits of broilers from 1 to 21 d of age. There was a negative control diet with 1.54% crude fiber, a positive control diet that included 3% cellulose (CEL), and 4 additional diets arranged factorially that included 3% oat hulls (OH) or sugar beet pulp (SBP) ground through a 0.5- or a 2.0-mm screen. For the entire experimental period, fiber inclusion improved BW gain (P≤0.01) and feed conversion ratio (P≤0.001), but particle size of the fiber source did not affect performance. The relative weight of the gizzard was higher (P≤0.001) with OH and SBP than with CEL or the control diet. Also, gizzard weight decreased (P≤0.001) with a reduction in particle size of the fiber source. Fiber inclusion increased HCl concentration and reduced gizzard pH (P≤0.01), and the effects were more noticeable with OH and SBP than with CEL. Fiber inclusion increased total tract apparent retention of nitrogen (P≤0.001) and soluble ash (P≤0.001) as well as the AMEn of the diet (P≤0.001). All of these effects were in general more pronounced with OH than with CEL, with SBP being intermediate. A reduction in particle size of the OH and SBP improved total tract apparent retention of DM (P≤0.001), nitrogen (P≤0.05), and soluble ash (P≤0.01) as well as the AMEn of the diet (P≤0.05). 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.

No abstract

The influence of fiber source and dietary fat level on digestive traits and productive performance was studied in broilers from 1 to 21 d of age. There were 6 treatments arranged factorially with 3 sources of fiber (none; 3% oat hulls, OH; and 3% sugar beet pulp, SBP) and 2 fat sources (5% soybean oil, SO; and 5% yellow grease, YG). Each treatment was replicated 6 times and the experimental unit was a cage with 18 broilers. Fiber inclusion improved BW gain (P < or = 0.05) and feed:gain ratio (P < or = 0.001) and increased total tract apparent retention (TTAR) of all nutrients measured (P < or = 0.001). The increases observed in TTAR of nitrogen and ether extract and on AME(n) of the diet were more pronounced with OH than with SBP. The increases in nutrient digestibility with OH inclusion were higher at excreta than at ileal level and in fact, SBP inclusion reduced the apparent ileal digestibility of most nutrients. The relative weight (%) of the gizzard was increased (P < or = 0.001) and the pH of its contents was reduced (P < or = 0.001) when additional fiber was included in the diet. The TTAR of nutrients was higher for the SO than for the YG diets (P < or = 0.001). Also, the increases in ether extract digestibility (P < or = 0.05) and AME(n) (P < or = 0.05) of the diet with fiber inclusion were more pronounced with the YG than with the SO. 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.