ABSTRACT This study aimed to examine the impact of levels of dietary supplementation with fat-soluble vitamins on the production performance and egg quality of laying hens. Three hundred Hy-Line White W-36 laying hens were evaluated from 28 to 44 weeks of age. The birds were allotted to one of six treatments in a randomized block design with 10 replicates with five birds each. Performance and egg quality parameters were evaluated in four 28-day periods. A corn and soybean meal-based basal diet was formulated so as to meet the nutritional requirements of the animals, with the exception of fat-soluble vitamins. The treatments consisted of dietary supplementation with 0%, 33.3%, 66.7%, 100.0%, 133.3% or 166.7% of fat-soluble vitamins (100% supplementation consisted of 7500 IU, 2000 IU, 10 IU and 1.8 mg of vitamins A, D3, E and K per kilogram of diet, respectively). Eggshell weight, shell thickness, shell strength, feed intake, egg weight, feed conversion per egg mass and feed conversion per dozen eggs showed a quadratic response (p≤0.05) to the treatments, whereas egg mass responded linearly. Optimal results were obtained at an average fat-soluble vitamin supplementation level of 109%, which corresponds to 8175 IU of vitamin A, 2180 IU of vitamin D3, 10.9 IU of vitamin E and 1.96 mg of vitamin K per kilogram of diet.

Modern broilers have been submitted to continuous genetic improvement, and therefore, their nutritional requirements must be constantly updated to ensure their performance. Two experiments were carried out to evaluate different digestible lysine levels for starter (1021 days) and grower (22-35 days) phases. The experiments were carried out with male and female Cobb 500 broilers, distributed according to a randomized block experimental design in a 5x2 factorial arrangement (5 increasing digestible lysine levels x 2 sexes), totaling 10 treatments, with 8 replicates of 22 and 20 birds during the starter and grower phase, respectively. Digestible lysine levels of 1.06, 1.12, 1.18, 1.24, and 1.30 were used in the starter diets (10-21 days) and 0.9, 0.98, 1.04, 1.10, and 1.16% in the grower diets (22-35 days). Based on the statistical analyses of the evaluated performance parameters, digestible lysine requirements for maximum performance were determined as 1.22% for males and 1.24% for females in the starter phase, and 1.16% for both sexes in the grower phase. Carcass and performance results indicate that digestible lysine requirements vary with sex and evaluated production parameter. Considering the most relevant broiler production parameters, in 22- to 35-d-old males, digestible lysine requirement for breast meat yield (1.16%) was higher than those for feed conversion ratio (1.07%) and weight gain (1.05%).

An experiment was carried out to evaluate the effects of different nutritional strategies on nitrogen (N), phosphorus (P) and calcium (Ca) balance and on copper (Cu), manganese (Mn) and zinc (Zn) excretion in broilers during the periods of 1 to 21 days and 1 to 46 days of age. Four hundred male Cobb-500 broilers were used. A randomized block experimental design was applied, including five treatments with eight replicates of 10 birds each. A five-phase feeding program was adopted (1-8, 9-21, 22-33, 34-40 and 41-46 days of age). Treatments consisted of a control diet (C) with typical protein level and low amino acid supplementation; a reduced-protein diet supplemented with synthetic amino acids formulated on ideal protein concept (IP); C with phytase (C+PHY) supplementation; C with inorganic-organic mineral supplementation (C+MIN); and a diet formulated on ideal protein (IP) basis, and supplemented with phytase and organic and inorganic minerals (IP+PHY+MIN). IP and IP+PHY+MIN diets reduced nitrogen excretion in 13.6 and 13.1% respectively, and promoted the same nitrogen retention (g/bird) and retention efficiency as compared to the diet with typical crude protein level. C+PHY and IP+PHY+MIN reduced phosphorus, calcium and manganese excretion, and improved phosphorus retention. C+MIN and IP+PHY+MIN reduced manganese excretion, but did not influence copper or zinc excretion.

Two experiments were carried out to evaluate the effects of the dietary inclusion of different dietary sunflower meal (SFM) levels (0% and 20%), with or without the supplementation of an enzyme complex (EC) (cellulase, β-glucanase, xylanase, and phytase) on broiler performance, carcass and cuts yields, economics, and dietary AMEn values. A randomized block experimental design, with a 2x2 factorial arrangement of eight replicates of 20 birds each, was used to test performance. A completely randomized experimental design with a 2x2 factorial arrangement of eight replicates of four birds each was used to test metabolism. No interaction effects between SFM and EC were observed on performance. Although SFM significantly reduced feed intake in the starter phase and total period, weight gain was not different in these phases. Feed: gain ratio improved with the use of SFM in all phases, probably due to the dietary inclusion of oil, which may have improved digestibility. There was a significant increase in weight gain with the use of EC in the starter phase, which is possibly explained by the immature digestive system of birds at this age. There were no SFM or EC significant effects on carcass or cuts yields. There was no significant effect of the addition of EC on dietary AMEn values; however, EC significantly improved the apparent metabolizability coefficients of phosphorus and calcium.