RESUMO: O experimento foi realizado para avaliar o desempenho de frangos de corte nas idades de 1-7 e 8-21 dias de idade, utilizando valores de energia metabolizável do milho, farelo de soja e óleo de soja determinados anteriormente em outro ensaio de metabolismo. Dois estudos foram realizados, divididos em fases de acordo com as idades: pré-inicial (1-7 dias) e inicial (8-21 dias). Em cada estudo, foram utilizados 924 pintos de corte distribuídos aleatoriamente em 42 unidades experimentais, em um delineamento inteiramente casualizado consistindo de cinco dietas utilizando os valores de energia metabolizável aparente corrigida para o balanço de nitrogênio do milho, farelo de soja, e óleo de soja, determinados nos ensaios de metabolismo, e uma dieta com os valores de energia metabolizável dos mesmos alimentos publicados na literatura. No final de cada fase, os animais e as sobras de ração foram pesadas para determinar o consumo de alimento, ganho de peso e conversão alimentar. As dietas com maiores inclusões de óleo de soja mostraram desempenho superior nas diferentes idades. Na fase pré-inicial, apenas a conversão alimentar foi significativa. Na fase inicial, houve diferença significativa para a conversão alimentar e ganho de peso médio e diário.

ABSTRACT: The experiment was carried out to evaluate the performance of broilers in 1-7 and 8-21 days of age, using metabolizable energy values of corn, soybean meal and soybean oil previously determined for each phase in another metabolism trial. Two trails were conducted, divided into phases according to ages: pre-starter (1-7 days) and starter (8-21 days). At each trial were used 924 broiler chicken randomly distributed into 42 experimental units in a completely randomized design with six treatments and seven replications. Treatments consisted of five diets using the values of apparent metabolizable energy corrected for nitrogen balance of corn, soybean meal and soybean oil determined in different metabolism trials, and one diet with the metabolizable energy values of these same ingredients, published on the literature. At the end of each stage, the animals and feed leftover were weighted to determine feed intake, weight gain and feed conversion ratio. Diets with higher soybean oil inclusion, showed superior performance at different stages. At pre-starter only feed conversion ratio was significant (P<0.05). In the initial phase, there was a significant difference (P<0.05) for feed conversion ratio, daily and average weight gain.

The objective of this trial was to evaluate the bioavailability of DL-2-hydroxy-4-(methyl) butanoic acid (DL-HMBA) and a polyherbal ingredient (PHI) in relation to DL-methionine (DLM) on broilers. Nine hundred male broiler chickens of the Cobb 500 strain were fed from 22 to 42 days of age either a basal diet without industrial methionine supplementation or the basal diet supplemented with DL-HMBA at one of three levels (0.143, 0.286 and 0.429%) or DLM at one of three levels (0.093, 0.186 and 0.279%, each of which is 65% of the respective DL-HMBA level by weight) or PHI at one of the same three levels used for DLM (0.093, 0.186 and 0.279%). The weight gain, feed conversion ratio and relative weights of breast and abdominal fat were improved over that of basal diet-fed broilers by the addition of DL-HMBA and DLM to the diet. A simultaneous exponential regression analysis revealed that the relative bioavailability values for DL-HMBA and PHI were 52% and 5% of that of DLM, respectively, for weight gain, and 57% and 4%, respectively, for feed conversion ratio. Concerning breast meat yield, a simultaneous linear regression analysis (slope ratio) showed that the relative bioavailability for DL-HMBA was 65% of that of DLM. Considering all studied parameters together, the relative bioavailability values for DL-HMBA and PHI are 58% and 4.5% of that of DLM on a product basis.