The effect of amylase supplementation on individual variation, growth performance, and starch digestibility in broiler chickens.

The objective of this study was to evaluate the variance of starch digestibility in broilers individually fed diets without or with supplemental exogenous amylase. A total of 120 d-of-hatch male chicks were individually reared from 5 to 42 d in metallic cages and fed maize-based basal diets or diets containing 80 kilo-novo-α-amylase units/kg (60 birds or replicates per treatment). Beginning on d 7, feed intake, body weight gain, and feed conversion ratio were recorded; partial excreta collection was conducted every Monday, Wednesday, and Friday until 42 d, when all birds were sacrificed for individual collection of duodenal and ileal digesta. Lower feed intake (4,675 vs. 4,815 g) and feed conversion ratio (1.470 vs. 1.508) were observed in amylase-fed broilers during the overall period (7-43 d; P < 0.01), whereas body weight gain was not affected. Amylase supplementation improved total tract starch (TTS) digestibility (P < 0.05) on each day of excreta collection (except for d 28, where no difference was found), averaging 0.982 vs. 0.973 compared to basal-fed broilers from d 7 to 42. Both apparent ileal starch (AIS) digestibility and apparent metabolizable energy (AMEN) were increased (P <0.05) from 0.968 to 0.976 and from 3,119 to 3,198 kcal/kg, respectively, with enzyme supplementation. Activity of amylase in the duodenum was higher (18.6 vs. 50.1 IU/g of digesta) in supplemented birds. Amylase supplementation led to a reduced coefficient of variation for both TTS (averaged 2.41 vs. 0.92% from 7 to 42 d) and AIS digestibilities (1.96 vs. 1.03%), as well as AMEN (0.49 vs. 0.35%), when compared to the nonsupplemented group, indicating lower individual heterogenity. An age effect was detected for TTS digestibility, as both groups saw an increase during the first weeks (slightly more pronounced in the supplemented group); older birds (d 30 onwards) presented a lower TTS digestibility compared to ages between 7 and 25 d. In conclusion, amylase supplementation in maize diets for broilers can attenuate individual bird variation for starch and energy utilization by increasing amylase activity and enhancing starch digestibility.

Effect of age and different doses of dietary vitamin E on breast meat qualitative characteristics of finishing broilers.

The supplementation of vitamin E on broiler chicken diets is essential to the prevention of lipid oxidation reactions in the meat and improvement of meat quality. The objective of this study was to assess the effect of different doses of dietary vitamin E on breast meat quality of broiler chickens in the finishing period. Five doses of vitamin E were used (30, 90, 150, 210, and 270 mg/kg feed) in broilers' diets from 42 to 54 d of age. A completely randomized design was conducted, followed by a split-plot, where the vitamin E dose was considered as the whole plot, and broilers' age at slaughter was the subplot. Breast meat quality was assessed at 4 different ages (45, 48, 51, and 54 d old), using 50 birds per age, totaling 200 birds. Meat quality characteristics evaluated were: pH at 24 h post mortem, color (brightness, redness, and yellowness), water holding capacity, cooking loss, shear force, and lipid peroxidation. There was no interaction between age and dose of vitamin E for meat quality characteristics (P > 0.05). The age at slaughter had a quadratic effect (P < 0.05) on pH, brightness, redness, and water holding capacity. Although pH values were higher in the breast meat of older birds (51 and 52 d old), breast meat of younger birds (48 d) had a more reddish aspect. Shear force value was higher in breast meat of birds slaughtered at later ages (P < 0.01), as a linear age-effect was observed. Brightness increased linearly (P < 0.05) with higher vitamin doses, whereas treatments did not alter yellowness, cooking loss, and lipid peroxidation. In this study, increasing vitamin E doses in the finishing period increased the brightness of broiler breast meat, whereas slaughtering at later ages resulted in greater meat pH and shear force value.

Effect of different doses of phytase and protein content of soybean meal on growth performance, nutrient digestibility, and bone characteristics of broilers.

This study evaluated the effects of high phytase doses and soybean meal (SBM) with different CP content on growth performance, ileal nutrient digestibility, digestible energy, plasmatic myo-inositol, phosphate release in vitro, and bone composition of broiler chickens. One thousand two hundred 1-day-old broilers were distributed in a 2 × 2 completely randomized factorial arrangement, with 2 phytase doses (1,000 and 2,500 phytase units [FYT]/kg of feed) and 2 SBM with different CP concentrations (45 and 47%), totaling 4 treatments with 12 replicates of 25 birds each. The chickens received feed and water ad libitum. Diets were based on corn and SBM, with different inclusions of soybean hull used to dilute the CP content of SBM according to each treatment. The inclusion of 2,500 FYT increased weight gain from 0 to 21 d (P < 0.05), whereas growth performance from 22 to 42 d was not affected, and SBM had no effect on growth performance. At day 21, ileal digestibility of dry matter, ash, and P, and digestible energy were greater in diets with 2,500 FYT/kg (P < 0.05), as well as phosphate in vitro release (P < 0.01) compared to the lower dose. At day 42, diets with SBM 47% CP and 2,500 FYT/kg promoted greater digestibility of dry matter, ash, CP, Ca, P, and digestible energy (P < 0.001), and greater phosphate release (P < 0.05) in comparison to other treatments. myo-inositol level in the plasma at 21 and 42 d was higher with the use of 2,500 FYT compared to 1,000 FYT (P < 0.05). The higher phytase dose increased tibia ash, toe ash, and Seedor Index (P < 0.05) at day 21, and the Ca content in tibia was higher with 2,500 FYT and SBM 47% CP at day 42. In conclusion, higher phytase doses for broilers improve weight gain, myo-inositol provision, and bone mineral composition. Nutrient ileal digestibility can be enhanced by higher phytase doses when in combination with SBM of greater nutritional quality.

High doses of phytase on growth performance, bone mineralization, diet utilization, and plasmatic myo-inositol of turkey poults.

An experiment was conducted to evaluate the growth performance, bone mineral composition, diet utilization, and plasmatic concentration of myo-inositol (MYO) in turkeys fed different phytase doses from 1 to 28 d. A total of three hundred and twenty 1-day-old turkeys were distributed in a completely randomized design with 4 treatments and 8 replicates of 10 birds each. Treatments included a basal diet without phytase; reduced diet (reduced -0.15% available P and -0.18% Ca) without phytase; reduced diet + 2,000 units of phytase (FYT)/kg; and reduced diet + 4,000 FYT/kg. From day 26 to 28, partial excreta collection was conducted, and on day 28, 7 birds per replicate were euthanized for collection of ileal content and left tibia bones were removed from 2 of the same euthanized birds. Feed, excreta, and ileal digesta samples were analyzed to determine nutrient digestibility and metabolizability, ileal digestible energy, and AME. Tibia bones were analyzed for ash, Ca, and P content, and calculation of Seedor index. On day 28, blood samples were collected from 2 turkeys per replicate to analyze plasmatic MYO concentration. Feed conversion ratio was not affected, but phytase supplementation resulted in higher feed intake and body weight gain compared to turkeys fed the reduced diet (P < 0.05), and both doses were similar to the basal diet. Increasing the phytase dose had a linear effect (P < 0.05) on ileal digestibility of P and metabolizability of DM, CP, Ca, and Na, and also on AME. P content in the tibia bone increased linearly (P < 0.05) with phytase supplementation, and the same linear increase (P < 0.05) was observed for plasmatic MYO. In conclusion, the supplementation of turkey poult's diets with high levels of phytase up to 4,000 FYT/kg improves diet utilization by increasing P digestibility and dietary metabolizability, leading to higher P content in the bone and enhancing MYO provision and absorption.