ABSTRACT. An experiment was carried out to evaluate the requirement of digestible methionine for growing pullets at growth phase (7 to 12 weeks of age). A completely randomized design was distributed in five treatments, six replicates, and 15 pullets per experimental unit. 450 Dekalb White pullets from the 7th weeks of age, with an average initial weight of 313.14 ± 12.49 g were used. Dietary treatments consisted in five diets supplemented with DL-Methionine which resulted in five levels of digestible methionine (0.266, 0.294, 0.322, 0.350, and 0.378 %). Performance, serological blood, histopathology and histomorphometry data were evaluated. Quadratic responses were observed for final live weight (p < 0.0143), weight gain (p < 0.0073), feed conversion ratio (p < 0.0058), glycogen deposition in the liver (p < 0.0001), gamma-glutamyl transferase enzyme activity (p < 0.0008), and villus height (p < 0.0024) with digestible dMet levels. In conclusion, the use of 0.343 % dMet, corresponding to a dMet:dLys ratio 55, is recommended for white-egg pullets from 7 to 12 weeks of age.

The objective of this study was to determine the chlorine nutritional requirement of Japanese Quails during the laying phase, based on performance and egg quality parameters. A total of 240 Japanese quails were distributed according to a randomized block design, with five treatments and six replicates, with 8 birds each. The experiment lasted 84 days, divided in four cycles of 21 days each. Treatments consisted of a basal diet formulated to meet the nutritional requirements, except for chlorine, and four supplementation levels with ammonium chloride, generating the levels 0.8; 1.6; 2.4; 3.2 and 4.0 g/kg. The parameters evaluated were: feed intake (g/bird/day), egg production (egg/bird/day), egg weight (g), egg mass (g), egg mass conversion (g/g), conversion per dozen eggs (kg/dz), weight of yolk (g/100 g of egg), albumen (g/100g of egg) and shell (g/100 g of egg), specific gravity (g/cm³) and shell thickness (mm). As a result of this study, feed intake, egg weight, weights of albumen, yolk, shell and specific gravity were not affected by treatments. There was a quadratic behavior for egg production, egg mass, egg mass conversion, conversion per dozen eggs and shell thickness according to the chlorine levels in the diets, with the requirements for those parameters established at 1.54; 1.37; 1.39 and 2.78 g/kg, respectively. The recommendation is 1.39 g/kg of chlorine and 244.22 mEq/kg of electrolyte balance in diets for Japanese quails.

The objective of this study was to evaluate the requirement of digestible tryptophan for white laying hens in the production stage fed diets of different digestible tryptophan:digestible lysine ratios, as well as animal performance and histological alterations in their reproductive and digestive systems. A total of 280 white laying hens at 29 weeks of age were distributed in a completely randomized design with five treatments and seven replications with eight birds in each. The treatments consisted of a base feed, formulated with corn, soybean meal and corn gluten meal, and supplemented with the synthetic amino acids L-lysine, DL-methionine, L-threonine, L-isoleucine, L-arginine, and L-valine, so as to meet the nutritional requirements for laying hens, except for digestible tryptophan. The basal diet was supplemented with 0.00; 0.017; 0.035; 0.052; and 0.069 g/kg of L-tryptophan in substitution for corn starch with the objective of reaching the levels of 0.151; 0.167; 0.183; 0.199; and 0.215 g/kg of digestible tryptophan in the feed. For the ratio between digestible amino acids and lysine, the recommendation of Brazilian Tables for Poultry and Swine was followed, except for the digestible tryptophan:digestible lysine ratios, which were 19, 21, 23, 25 and 27 for each treatment. The variation in the digestible tryptophan:digestible lysine ratio promoted changes in performance and in the histological characteristics, improving the results. The digestible tryptophan:digestible lysine ratio of 24.5% in the feed of white laying hens in production stage promotes better animal performance and histological results.

The objective of this study was to evaluate the reduction of protein, the formulation of diets and supplementation of an enzyme complex for laying hens. The layers were distributed in a completely randomized 2 × 2 × 2 factorial arrangement, with two levels of crude protein reduction (0.0 and 4.0 g/kg), two kinds of diet formulation (without and with reformulation, considering 75 kcal of metabolizable energy) and two enzyme supplementations (without and with enzyme complex supplementation), totalizing 8 treatments of 8 layers each, with 7 replications, in a total of 448 laying hens at 30 weeks of age. After data analysis, it was found that the enzyme complex supplementation in the diet of layers improves performance, promotes a similar egg quality and improves the bone and intestinal health of the layers.

Progressos significativos na área da produção animal devem-se ao desenvolvimento de pesquisas nos campos da genética, ambiência, sanidade, manejo e nutrição. A busca por melhores condições de manejo que beneficiassem o bem estar animal provocou modificações nas instalações. O melhoramento genético visando animais mais produtivos tem incentivado o numero de pesquisas para redução da incidência de doenças, principalmente as de origem metabólica. A incorporação na ração de produtos com maior biodisponibilidade como aminoácido industriais e minerais orgânicos, a inclusão de produtos moduladores da microflora entérica como probióticos, prebióticos, simbióticos e nucleotídeos como também, o uso de enzimas exógenas, tem beneficiado a utilização de nutrientes antes pouco absorvidos e muitas vezes indisponíveis na dieta. Biotecnologias mais recentes como a nutrição in ovo e a biologia molecular têm sido utilizadas para benefício da maior produtividade animal.

Significant progress in the area of animal production is due to the development of researches on genetics, environment, health, management and nutrition. The search for better management conditions that benefit animal welfare resulted in changes to the installation. The genetic improvement more productive animals has encouraged the number of searches to reduce the incidence of diseases, mainly of metabolic origin. The incorporation in products with higher bioavailability as industrial amino acid and organic minerals, the inclusion of products modifiers enteric of microflora as probiotic, prebiotic, symbiotic, nucleotides and exogenous enzymes, has benefited the use of nutrients are not well absorbed and often unavailable in the diet. Biotechnology latest as nutrition in egg and molecular biology has been used for the benefit of the increase animal productivity.