RESUMO O objetivo deste trabalho foi determinar a composição química e os valores de energia metabolizável aparente (EMA) e metabolizável aparente corrigida pelo balanço de nitrogênio, EMAn, de alguns alimentos para frangos de corte. Foram utilizados 432 pintos de corte macho, de 14 a 24 dias de idade, distribuídos em delineamento inteiramente casualizado com 12 tratamentos (11 alimentos e uma dieta referência), seis repetições e seis aves por unidade experimental. A metodologia utilizada foi da coleta total de excretas. Foram objetos de estudo: Duas farinhas de vísceras (FV), duas farinhas de penas e sangue (FPS), duas farinhas de carnes e ossos (FCO), soja integral tostada (SIT), farelo de soja (FS), quirera de milho (QM), farelo de trigo (FT) e milheto (M). Os valores de proteína bruta e extrato etéreo (%), EMA e EMAn (kcal/kg) foram, respectivamente: 58,84; 12,64; 3705 e 3340 para a FV 1; 57,64; 11,66; 3565 e 3241 para a FV 2; 80,58; 6,79; 3070 e 2740 para a FPS 1; 82,27; 6,38; 3060 e 2703 para a FPS 2; 48,06; 9,60; 1574 e 1283 para a FCO 1; 41,21; 9,08; 1353 e 1088 para a FCO 2; 36,45; 20,78; 3192 e 2989 para a SIT; 46,22; 1,72; 2648 e 2336 para o FS; 8,51; 3,61; 3354 e 3265 para a QM; 17,11; 3,14; 1948 e 1788 para o FT e 12,01; 4,09; 3072 e 2948 para o M. As diferenças observadas na composição química e energética evidenciam a necessidade de pesquisas para atualizar os valores nutricionais dos alimentos.

ABSTRACT The aim of this work was to determine the chemical composition and values for apparent metabolisable energy (AME), and apparent metabolizable energy corrected for nitrogen (AMEn), in broiler feeds. In the experiment, 432 male broiler chicks, 14 to 24 days old were used, distributed in a completely randomised design with 12 treatments (11 feeds and a reference diet), six replications and six birds per experimental unit. The method employed was the total collection of excreta. The feeds under study were: Two of viscera meal (VM), two feather and blood meal (FBM), two meat and bone meal (MBM), roasted whole soybean (RWS), soybean meal (SM), ground corn (GC), wheat bran (WB) and millet (M). The values for crude protein and ether extract (%), AME and AMEn (kcal/kg) were respectively: 58.84, 12.64, 3705 and 3340 for VM1; 57.64, 11.66, 3565 and 3241 for VM 2; 80.58, 6.79, 3070 2740 for FBM 1; 82.27, 6.38, 3060 2703 for FBM 2; 48.06, 9.60, 1574 and 1283 for MBM 1; 41.21, 9.08, 1353 and 1088 for MBM 2; 36.45, 20.78, 3192 and 2989 for RWS; 46.22, 1.72, 2648 and 2336 for SM; 8.51, 3.61, 3354 and 3265 for GC; 17.11, 3.14, 1948 and 1788 and for WB; and 12.01, 4.09, 3072 and 2948 for M. The differences found in chemical and energy composition highlight the need for research to revise the nutritional values of feed.

Two-hundred sixteen white laying hens were used to assess the ideal ratio of digestible threonine:lysine in diets for laying hens at 24 to 40 weeks of age. Birds were assigned to a randomized block design, with six treatments, six replicates per treatment and six birds per experimental unit. The cage was used as the blocking criterion. Experimental diets contained different digestible threonine:digestible lysine ratios (65, 70, 75, 80, 85 and 90%) with 142 g/kg of crude protein. Experimental diets were formulated to be isonitrogenous and isocaloric with different contents of L-glutamic acid. Feed intake (g/hen/d), egg production (%), egg weight (g), egg mass (g/hen/d), feed conversion ratio (kg/dozen and kg/kg egg), eggshell weight (g), albumen weight (g), yolk weight (g) and body weight gain (g) were assessed. The maximum egg production was observed at 78% digestible threonine:digestible lysine ratio, while the best values of feed conversion ratio (kg/dozen egg) and feed conversion ratio (kg/kg of egg) were observed at 77.6% and 75%, respectively. Feed intake, egg mass and egg contents (yolk, albumen and eggshell) were not affected by treatments. The estimated digestible threonine:digestible lysine ratio of Hy-Line W36 laying hens at 24 to 40 weeks of age is 78%, corresponding to 5.70 g/kg of dietary digestible threonine.

Two hundred fifty-two Hy-Line W36 laying hens were allotted in a randomized block design with 6 treatments, 7 replicates and 6 hens per experimental unit in order to determine the ideal digestible isoleucine: digestible lysine (Ile:Lys) ratio for laying hens aged 24-40 weeks. Experimental diets contained 5.92, 6.33, 6.73, 7.14, 7.54 and 7.95 g/kg of digestible isoleucine, resulting in different Ile:Lys ratios (0.73:1, 0.78:1, 0.83:1, 0.88:1, 0.93:1 and 0.98:1). Experimental diets were isonitrogenous, with different dietary contents of glutamic acid, and made isocaloric by adjusting the levels of cornstarch. All essential amino acids were provided proportionally to digestible lysine. Feed intake, egg production, egg weight, egg mass, feed conversion ratio per egg mass, feed conversion ratio per dozen eggs, albumen, yolk and eggshell content were assessed. Feed intake, egg production, egg mass and feed conversion ratio were influenced by Ile: Lys ratios quadratically. The egg weight was not affected by Ile: Lys ratio. No differences were observed in the egg quality according to Ile: Lys ratios. The data indicates that the optimum digestible isoleucine: digestible lysine ratio for laying hens aged 24-40 week is 0.84:1, corresponding to the consumption of 681 mg of isoleucine and 811 mg of lysine/hen day-1.

Two hundred and fifty-two Hy-Line W36 laying hens were allotted in a completely randomized design with 6 treatments, 7 replicates and 6 hens per experimental unit in order to determine the ideal ratio of isoleucine (Ile) in relation to lysine (Lys) to laying hens aged 42-58 weeks. Experimental diets contained digestible Ile at different levels, resulting in different Ile:Lys ratios (0.73:1; 0.78:1; 0.83:1; 0.88:1; 0.93:1 and 0.98:1). A basal diet was formulated to provide Isoleucine in levels below recommendations. This diet was supplemented with L-isoleucine to make up the 6 diets. Each diet was made isonitrogenous by varying the dietary contents of glutamic acid and isocaloric by adjusting the contents of cornstarch. All essential amino acids were provided proportionally to lysine. Egg production, egg weight, egg mass, feed conversion ratio, albumen, yolk and eggshell contents were recorded and compiled at every 28-day period. No differences were observed in the performance over a wide range of dietary isoleucine concentrations from 5.76 to 7.73 g/kg corresponding to 0.73:1 to 0.98:1 Ile:Lys ratios. The lowest Ile:Lys ratio (0.73:1) was sufficient to ensure satisfactory performance of birds, corresponding to the consumption of 534 mg of isoleucine and 731 mg of lysine/day.