RESUMO
Feed form is well recognized to improve broiler performance, specially by increasing feed intake (FI). However, when different diet energy levels are used, the results differ in the literature. Therefore, this experiment was conducted to evaluate the influence of feed form and dietary metabolizable energy (ME) levels on broiler performance, carcass yield and on the digestibility of DM, CP, starch and gross energy. In total, 1152 male Cobb 500 broilers were evaluated between 35 and 47 days. The birds were distributed according to a completely randomized design in a 2 × 4 factorial arrangement, consisting of two feed forms (mash or pellet) and four ME levels (12.73, 13.06, 13.40 or 13.73 MJ/kg), totaling eight treatments with eight replicates of 18 birds. Broilers fed the lowest ME level presented the lowest weight gain (WG) and worst feed per unit gain (P < 0.01). Metabolizable energy intake increased (P < 0.01) with progressive increments of ME, which, however, did not affect caloric conversion (CC, P > 0.05). Pelleted diets promoted higher FI, WG, ME intake (P < 0.01) and better feed per unit gain and CC (P < 0.05) compared with mash. In mash diets, increasing dietary ME levels promoted a linear increase in WG (P < 0.01) and reduced feed per unit gain (P ≤ 0.05), but did not affect FI (P > 0.05). In pelleted diets, on the other hand, increasing ME levels linearly reduced FI (P < 0.05) and feed per unit gain (P < 0.01). Broilers fed pelleted diets presented higher abdominal fat deposition than those fed mash (P < 0.05). Increasing ME levels reduced the coefficients of ileal apparent digestibility of DM (P < 0.01) and total starch (P < 0.05) but did not affect the digestibility of other evaluated nutrients. The digestibility of all nutrients was lower when pelleted diets were fed compared with mash. Increasing inert material inclusion in the diets at the expense of soybean oil to reduce dietary ME levels promoted higher pellet durability index values (P < 0.05) and the percentage of fines (P < 0.01). Overall, the results suggest that pelleted diets promote better broiler performance because they increase FI, since the digestibility of dietary fractions is reduced. Chickens consuming low-energy pelleted diets may increase FI to compensate for energy deficit. In contrast, broilers fed mash diets may have reached their maximum intake capacity and did not regulate FI by changing feed energy density. When feeding pelleted diets, dietary energy reduction should be considered to reduce feed costs and to improve the carcass quality of broilers.
Assuntos
Ração Animal/análise , Galinhas/fisiologia , Metabolismo Energético , Óleo de Soja/administração & dosagem , Animais , Galinhas/crescimento & desenvolvimento , Dieta/veterinária , Digestão/efeitos dos fármacos , Masculino , Nutrientes/metabolismo , Amido/administração & dosagem , Aumento de PesoRESUMO
The objective of the study was to evaluate the deposition of selenium in the breast muscle of broilers fed different selenium sources during different periods. Two experiments were carried out with broilers fed 45% sodium selenite (SS) or 2% hydroxy-selenomethionine (HSM) to determine the selenium deposition rate in the muscle tissue. In Experiment 1, 48 broilers were distributed in a completely randomized design with six treatments with eight replicates each, consisting of diets containing 0 Se (0), 200 or 400 µgSS/kg (200 SS, 400 SS), or 100, 200, or 300 µgHSM/kg (100 HSM, 200 HSM, 300 HSM) for 10 days. The highest Se breast content was obtained with 300 HSM diet, followed by 200 SS diet compared to the other treatments. Experiment 2 had a completely randomized design following a plot scheme subdivided in time, and consisted of a basal diet supplemented with 300 µg SS/kg (300 SS), basal diet with 200 µg HSM/kg (200 HSM) or basal diet supplemented with 100 µgSS/kg and 100 µgHSM/kg (100 SS+100 HSM). Dietary Se sources did not influence Se breast content measured on days 3 and 6. However, on days 9 and 12, higher Se breast contents were measured in broilers fed 200 HSM and 100 SS+100 HSM diets compared with those fed 300 SS diet. In conclusion, the supplementation of broiler diets with HSM at 2% for a short period is more efficient to increase selenium deposition in the breast muscle than sodium selenite.(AU)
Assuntos
Animais , Carne/análise , Galinhas/metabolismo , Galinhas/fisiologia , Selênio/análise , Ração Animal/análiseRESUMO
The objective of the study was to evaluate the deposition of selenium in the breast muscle of broilers fed different selenium sources during different periods. Two experiments were carried out with broilers fed 45% sodium selenite (SS) or 2% hydroxy-selenomethionine (HSM) to determine the selenium deposition rate in the muscle tissue. In Experiment 1, 48 broilers were distributed in a completely randomized design with six treatments with eight replicates each, consisting of diets containing 0 Se (0), 200 or 400 µgSS/kg (200 SS, 400 SS), or 100, 200, or 300 µgHSM/kg (100 HSM, 200 HSM, 300 HSM) for 10 days. The highest Se breast content was obtained with 300 HSM diet, followed by 200 SS diet compared to the other treatments. Experiment 2 had a completely randomized design following a plot scheme subdivided in time, and consisted of a basal diet supplemented with 300 µg SS/kg (300 SS), basal diet with 200 µg HSM/kg (200 HSM) or basal diet supplemented with 100 µgSS/kg and 100 µgHSM/kg (100 SS+100 HSM). Dietary Se sources did not influence Se breast content measured on days 3 and 6. However, on days 9 and 12, higher Se breast contents were measured in broilers fed 200 HSM and 100 SS+100 HSM diets compared with those fed 300 SS diet. In conclusion, the supplementation of broiler diets with HSM at 2% for a short period is more efficient to increase selenium deposition in the breast muscle than sodium selenite.
Assuntos
Animais , Carne/análise , Galinhas/fisiologia , Galinhas/metabolismo , Ração Animal/análise , Selênio/análiseRESUMO
An experiment was carried out to evaluate the digestibility and metabolizability of corn and a corn/soy-based diet with the inclusion or not of xylanase and/or phytase in broilers. In the trial, 1,120 broiler chicks were distributed according to a completely randomized experimental design, consisting of 16 treatments, with 10 replicates of 7 birds each. Treatments were evaluated following a factorial arrangement (4 × 2 × 2), with 4 xylanase levels (zero, 50, 100, or 150 fungal ß-xylanase units/kg; FXU), 2 phytase levels (zero or 1,000 phytase units/kg; FTU), and 2 diets (corn/soy or pure corn). The same basal diets were fed from one to 14 d post hatch for all birds, after which the experimental diets were provided until d 25. All birds were euthanized on d 25 for collection of ileal contents. Samples of feed, excreta, and ileal digesta were analyzed for determination of apparent ileal digestibility. The effect of xylanase on the coefficient of apparent dry matter metabolizability and apparent metabolizable energy was increased by the presence of phytase in the complete diet but not in the diet based on pure corn resulting in a diet*phytase*xylanase interaction (P < 0.01; P < 0.001, respectivaly). Equivalent effects were observed for the apparent coefficient of ileal protein digestibility in which xylanase effects were potentiated by the presence of phytase only in the complete diet, resulting in a significant 3-way interaction. In corn there was a limitation in improving digestibility when we added increasing levels of xylanase with phytase. Otherwise in the corn/soy-based diets, the enzymes were potencialized when they were added together. The fact that the effect of xylanase was enhanced by the presence of phytase in complete diets but not in pure corn may be associated with differences in substrate (arabinoxylan and/or phytate) concentration and presentation, diet nutrient balance, or other factors. It can be concluded that the interactive effects of xylanase and phytase can be substantial but may depend on the characteristics of the diet fed.
Assuntos
6-Fitase/farmacologia , Galinhas/metabolismo , Dieta/veterinária , Endo-1,4-beta-Xilanases/farmacologia , Glycine max , Zea mays , 6-Fitase/administração & dosagem , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Suplementos Nutricionais , Digestão/efeitos dos fármacos , Endo-1,4-beta-Xilanases/administração & dosagem , Metabolismo Energético , Fezes/química , Íleo/metabolismoRESUMO
An experiment was conducted to test the hypothesis that a coarse limestone diet improves productivity, reproductive performance and the calcium utilization of molted broiler breeders. In total, 640 broiler breeder females, 73-week-old and sixty-four 27-week-old cockerels, Cobb 500, were evaluated during 10 weeks, according to a randomized block design composed of 4 treatments with 8 replicates each. Treatments consisted of diets with the inclusion of 100% fine limestone-fine PS (0.2 mm GMD-geometric mean diameter); PS1: 30% fine limestone+70% limestone with 1.0 mm GMD; PS2: 30% fine limestone+70% limestone with 2.0 mm GMD; and PS3: 30% fine limestone+70% limestone with 3.0 mm GMD. Calcium retention in the gizzard of the breeders, bone characteristics, and breeder performance, egg characteristics, eggshell quality, incubation performance, chick quality and yield, chick pre-starter live performance, and chick bone characteristics were determined. There was no significant difference (P>0.05) in the rate of lay, percentage of non-settable eggs, egg weight, egg shape index, egg specific gravity, eggshell weight, thickness, and percentage hatchability and egg weight loss of broiler breeders fed with diets with different limestone particle sizes. The chick quality and yield, chick pre-starter live performance, and chick bone characteristics were not affected (P>0.05) by any of the limestone particle sizes. It was concluded that live and reproductive performance parameters of broiler breeders post molting is not affected by limestone particle size in the feed.