Thermal processing of corn and physical form of broiler diets.

This study aimed to assess the effect of preprocessing of corn and of physical form of diets on growth performance, carcass yield, and nutrient digestibility in broilers and also the influence of corn processing on pellet quality. A total of 1,080 male Cobb chicks from 1 to 35 D were evaluated. Birds were distributed according to a completely randomized design in a 3 × 2 factorial arrangement, with 3 types of corn processing (unprocessed, pelleted, or expanded), and 2 diet physical forms (mash or pelleted), totaling 6 treatments and 9 replicates with 20 birds. The data were submitted to ANOVA, and means were compared by Tukey's test (P < 0.05). There was no interaction between the physical form and preprocessing of corn for any of the studied variables (P > 0.05). The use of expanded corn in the diets before pelleting resulted in higher pellet durability index and lower amount of fines (P < 0.05) when compared with unprocessed corn. Broilers fed pelleted diets had higher feed intake (FI) and weight gain (WG; P < 0.001), higher amounts of abdominal fat (P < 0.05), and lower ileal digestible energy (IDE, P = 0.05) than those fed mash. There was no effect of the feed form on nutrient digestibility (P > 0.05). Broilers fed diets with unprocessed corn had higher FI when compared to those fed diets with expanded or pelleted corn (P < 0.001). The use of pelleted corn resulted in lower WG than the other processing methods (P < 0.01). The corn expansion process improved feed conversion ratio and adjusted feed conversion ratio (P < 0.001). Inclusion of expanded corn improved the coefficient of apparent ileal digestibility of DM, CP, starch, and IDE (P < 0.05) in comparison with unprocessed corn. It is concluded that pelleted diets improve broiler performance. The corn expansion can be used to improve physical quality of the diets and broilers growth performance and nutrient digestibility.

Effect of pelleting and different feeding programs on growth performance, carcass yield, and nutrient digestibility in broiler chickens.

This experiment was conducted to study the effect of different feeding programs and pelleting on performance, nutrient digestibility, ileal digestible energy (IDE); and carcass yield of broilers from 21 to 35 d of age. In total, 768 male broilers were distributed according to a completely randomized design with 6 treatments and 8 replicates of 16 birds each. The treatments were mash and pelleted diets provided ad libitum, or pelleted and supplied at the same rate (100%) or restricted at 95, 90, and 85% (P100, P95, P90, and P85) of the amount consumed by the birds fed mash diet ad libitum. When supplied ad libitum, the pelleted diet had the highest feed intake and weight gain (WG), better feed conversion ratio (FCR), better feed conversion adjusted for 2.3 kg (AdjFCR, P < 0.001) and caloric conversion (P < 0.001); and higher amount of abdominal fat (P < 0.001) when compared to the control (mash ad libitum). However, there were no effects on nutrient digestibility (P > 0.05). When the pelleted feed was provided in the same amount as in the control group, there were no differences in any of the evaluated parameters (P > 0.05). Limiting pelleted diet to 95, 90, and 85% of free choice mash diet resulted in lower WG (P < 0.001). P90 and P95 treatments resulted in higher dry matter and crude protein digestibility and IDE in relation to the others (P < 0.001). Carcass yield was reduced (P < 0.05) in the birds fed P85 diet. The regression analysis between P100, P95, P90, and P85 showed a linear reduction in WG when restriction was increased (P < 0.01); however, there was a linear increase in the nutrient digestibility (P < 0.001). It is concluded that pelleting improves broiler performance, but these results depend on feed intake. The higher intake provided by pelleting can increase the amount of abdominal fat. Feed intake reduction can result in lower performance and lower carcass and cuts yield in broilers.