One thousand eight hundred and ninety male broilers of two strain crosses (fast and slow initial growth) were fed different ideal protein profiles in four-phase feed programs: 1 to 7, 8 to 21, 22 to 34 and 35 to 40 days of age. All vegetable, corn-soybean meal feeds were formulated to maintain the Met+Cys:Lys and Thr:Lys relationships at 75 and 65%, respectively, on true digestible basis. Three ideal protein profiles were used: low, medium and high. From 1 to 21 […]

The objective of this study was to evaluate different models in the adjustment of weight gain (WG) responses, obtained in an experiment carried out with ISA Label birds from 1 to 28 days of age. A total of 480 male and female chicks were distributed in a completely randomized design, in a 4 X 2 factorial arrangement (lysine levels X sex), with three replications of 20 birds each. The basal diet was formulated to meet the chick requirements, except for […]

The objective of the present study was to investigate crude protein reduction and the methionine+cystine and threonine to lysine ratios in diets for reversed Nile tilapia fingerlings (Oreochromis niloticus), Thai strain. Four hundred and twenty Nile tilapia fingerlings with an average initial weight of 1.83 ± 0.02 g were placed in a completely randomized design, with five treatments, seven replications per treatment and 12 fish per experimental unit, for 37-days. Two crude protein (CP) levels were evaluated (32 and 28%). […]

The effect of decreasing dietary crude protein (CP) with supplementation of amino acids, based on the ideal protein concept on Nile tilapia (Oreochromis niloticus) fingerlings performance was evaluated. A total of 396 fingerlings from Thai strain, with 0.80 ± 0.17 g of BW, was allotted to a randomized block design, with six levels of CP (32, 31, 30, 29, 28 and 27% of CP) in the diets, six replications with 11 fish each. The diets were formulated to be isocaloric […]

It was evaluated four crude protein (CP) levels in diets considered as commercial fed to barrows in the growing and finishing phases. A total of 48 barrows, from the same genetic strain, averaging initial weights of 30.8 ± 0.12 kg (growing phase) and 61.2 ± -0.89 kg (finishing phase), segregated in the production system, was used. The animals were allotted to randomized blocks design, composed of four treatment (level of CP) and six replications and two animals per experimental unit. […]

Two trials were conducted to evaluate the effects of increasing dietary digestible lysine levels, maintaining or not the amino acid relation, on performance of broilers from 22 to 42 days old on thermoneutral environment. Two hundred and ten male broilers (averaging initial weight of 662.5 g) and 168 broilers (averaging initial weight of 623.7 g) were assigned to a completely randomized experimental design in trials 1 and 2, respectively. In trial 1, the broilers were allotted to five treatments (digestible […]

Two trials were conducted to evaluate the requirements of increasing dietary digestible lysine levels, maintaining or not the amino acids relation, for broilers from 1 to 21 days old, on thermoneutral environment. A complete randomized experimental design was used in both trials. In trial 1, broilers were allotted to five treatments (0.92, 0.98, 1.04, 1.10, and 1.16% digestible lysine levels, conventional diet), with eight replicates of ten birds. In trial 2, chicks were allotted to four treatments (1.04, 1.10, 1.16, […]

Forty eight commercial hybrids, barrows and females with 5.47 ± 0.21 kg, were allotted to a randomized block design with four treatments and six replications, to determine the best lysine level until 11.9 ± .35 kg and subsequent effects at 19.0 kg. The chemical composition of body fractions and the carcass and empty body accretion rates were determined. The studied digestible lysine levels in the nursery phase were 1.16 at 1.46%. No effects were observed on the chemical composition of […]

Two trials were conducted to evaluate the effects of digestible lysine levels in diets maintaining or not the relationship of amino acids, on performance of broilers from 1 to 21 days, kept under heat stress. A completely randomized experimental design was used in both trials. In the trial 1, the broilers were allotted in five treatments (0.92; 0.98; 1.04; 1.10 and 1.16% of lysine in conventional diets), eight replicates and ten broilers per replicate. In the trial 2, the broilers […]

The objective of this work was to determine, through a digestibility assay, the nutritional requirement of true digestible lysine for broiler chickens, in the four growing phases. Four performance experiments, previously performed, allowed the determination of total lysine requirement of broiler chickens in the periods from 1 to 21, 15 to 40, 22 to 40 and 42 to 48 days of age. Thirty cecectomized adults Leghorn roosters were used, with an average weight of 2316±190 g, and individually caged in […]