Relação lisina digestível: proteína bruta em dietas para frangos de corte no período de 1 a 21 dias de idade. Desempenho e metabolismo

Abstract

e efeito quadrático sobre a EMAn (15,5 e 18,5% de PB) e o coeficiente de retenção de N (15,5% de PB). Considerando os resultados de ganho de peso, a relação ideal de lisina digestível:proteína bruta na fase inicial foi de 6,8% (18,5% de PB) e 5,9% (21,5% de PB) ou 1,26 e 1,27% de lisina digestível. Os teores de PB das rações para frangos de corte na fase inicial podem ser reduzidos para 18,5%, sem afetar o desempenho das aves, mas reduzindo a excreção de nitrogênio em 24%, desde que as rações sejam suplementadas com aminoácidos sintéticos.Palavras-chave: aminoácidos digestíveis, excreção, aves, nitrogênio, proteína ideal Digestible lysine:crude protein ratios on initial broiler diets -performance and metabolism ABSTRACT -The experiment aimed to test different ratios digestible lysine:crude protein (CP) in diets for broiler until 21 days. One thousand and eight hundred 1-d birds of Cobb strain were allotted to a completely randomized design with a hierarchical rank model with three levels of CP and four ratios digestible lysine:CP was used. In the performance trial, the diets were fed to 30 birds in each of the five replicates. At 21 days of age, feed intake, weight gain and feed conversion were evaluated. A linear increase on weight gain was observed in the 18.5 and 21.5% of CP levels. Feed conversion improved linearly according to the ratios of lysine within the three levels of CP studied. Carcass yield increased linearly with increasing rations at the level of 15.5% of CP, it not being significant at the other levels of CP studied. In the metabolism trial, the ratios digestible lysine:CP showed linear effect on EMAn (21.5% of CP) and nitrogen excretion (18.5% of CP), quadratic effect on EMAn (15.5 and 18.5% of CP) and N retention coefficient (15.5% of CP). Based on the results of weight gain, the ideal digestible lysine:CP ratio in the initial phase was of 6.8% (18.5% of CP) and 5.9%(21.5% of CP), or 1.26 and 1.27% of digestible lysine. The dietary CP contents fed to broilers in the initial phase can be reduced to 18.5%, with no effect on bird performance, but by decreasing nitrogen excretion to 24%, since the diets are supplemented with synthetic aminoacids.

Protease Supplementation under Amino Acid Reduction in Diets Formulated with Different Nutritional Requirements for Broilers

“…Carcass yield results found in this trial are in agreement with findings of several other authors, as they also did not find any influence of reducing crude protein levels of the diet on these parameters, when followed by amino acid or exogenous enzyme supplementation (Kamram et al, 2008;Rodrigues et al, 2008;Vasconcellos et al, 2010). Yuan et al (2017) reported an increase in the gene expression of pancreas enzymes when a protease supplement was added to the diet for broilers.…”

“…Thus, when there is an unbalance of a certain digestible amino acid, namely lysine, there are deamination and transamination reactions with donation and/or degradation of its respective amino groups, moving the amino acid function to other functions such as excretion of its metabolism products (Dalólio et al 2016). Rodrigues et al (2008) claim that the digestible lysine:crude protein ratio in the diet is very important and should be maintained around 5.90% until 42 days. In the present study this ratio was 5.77% and 5.31% in the Rostagno et al (2005) and Cobb-Vantress Guidelines (2008), respectively.…”

“…In the present trial no effect of amino acid reduction and protease supplementation of the diet were found on the weight of pancreas of broilers at 42 days. Rodrigues et al (2008) evaluated different digestible lysine:crude protein ratios and did not find differences in broilers carcass yield. Vasconcellos et al (2010) studied different levels of crude protein in broiler diets and found no effect on carcass yield.…”

Efeito de diferentes níveis de proteína bruta sobre o desempenho e composição de carcaça de frangos de corte machos de 21 a 42 dias de idade

“…De maneira semelhante, Gomide et al (2007) concluíram que o nível de PB da dieta pode ser reduzido para 16% sem que haja prejuízo sobre as variáveis de desempenho, desde que a dieta inicial seja de acordo com as recomendações da literatura; porém diferentemente do presente trabalho essas dietas foram suplementadas com fitase. Rodrigues et al (2008a) verificaram que aves alimentadas com dietas contendo 17% de PB e relação lisina digestível:proteína bruta de 5,9% apresentam desempenho semelhante à dieta controle. Da mesma forma, Costa et al (2001) Leeson & Summers (2005), aves que recebem dietas deficientes nutricionalmente tendem a aumentar o consumo de ração para suprir as deficiências dietéticas.…”

Statistical modelling of data from performance of broiler chickens

“…The broilers can be kept in batches separated by sex or mixed, for each batch there are different specifications for handling. Generally, mixed-batch experiments are performed according to the recommended specifications, but the statistical analyzes are done as if there was no mixing of the sexes, since the models used do not take into account the variability between the sexes, see for example Kalmendal et al (2011), Korver et al (2004, Rodrigues et al (2008), Teixeira et al (2007) and Qureshi (1996).…”