Suplementação de glutamina em dietas elaboradas com ingredientes de origem vegetal e animal para pintos de corte

The potential of glutamine supplementation in reduced-crude protein diets for chicken-meat production

This review explores the potential of including glutamine, a so-called non-essential amino acid, in the formulation of reduced-crude protein (CP) diets for broiler chickens. There is a precedent for benefits when including glycine and serine in reduced-CP diets. Fundamentally this is due to decreases in non-essential amino acid concentrations in reduced-CP diets - an unavoidable consequence of reducing CP without amino acid supplementation. The situation for glutamine is complicated because analysed dietary concentrations are very rarely provided as standard assays do not differentiate between glutamine and glutamate and are reported on a combined basis as glutamic acid. The dietary requirement for glutamic acid is approximately 36.3 g/kg but it is increasingly unlikely that this requirement will be met as dietary CP levels are progressively reduced. Glutamine is an abundant and versatile amino acid and constitutes 50.5 mg/g of whole-body chicken protein and is the dominant free amino acid in systemic plasma where it has been shown to provide 22.6% (139.9 of 620.3 μg/mL) of the total in birds offered 215 g/kg CP, wheat-based diets. In addition to dietary intakes, glutamine biosynthesis is derived mainly from the condensation of glutamate and ammonia (NH3) catalysed by glutamine synthetase, a reaction that is pivotal to NH3 detoxification. Glutamate and NH3 are converted to glutamine by phosphate-dependent glutaminase in the reciprocal reaction; thus, glutamine and glutamate are interchangeable amino acids. However, the rate of glutamine biosynthesis may not be adequate in rapidly growing broiler chickens and exogenous and endogenous glutamine levels are probably insufficient in birds offered reduced-CP diets. The many functional roles of glutamine, including NH3 detoxification and maintenance of acid-base homeostasis, then become relevant. Twenty feeding studies were identified where dietary glutamine supplementation, usually 10 g/kg, was evaluated in birds kept under thermoneutral conditions. On balance, the outcomes were positive, but the average dietary CP was 213 g/kg across the twenty feeding studies, which indicates that CP and, in turn, glutamine concentrations would have been adequate. This suggests that glutamine inclusions in reduced-CP diets hold potential and consideration is given to how this may be best confirmed.

Dietas pós-eclosão suplementadas com fontes de gordura e acrescidas de taurina e glicina sobre a morfometria intestinal e o desempenho de frangos de corte de um a 21 dias

RESUMO O objetivo deste estudo foi avaliar o efeito do fornecimento de dietas pós-eclosão suplementadas com diferentes fontes de gordura insaturada e adicionadas ou não de taurina e glicina sobre o desempenho produtivo, a biometria e a morfometria do intestino delgado de pintos de corte de um a 21 dias de idade. Foram utilizados 480 pintos de corte machos de um dia de idade da linhagem Cobb. O delineamento foi inteiramente ao acaso, em esquema fatorial 2 x 4, com e sem suplementação de taurina e glicina e quatro dietas (controle, óleo de peixe, de soja e de girassol), totalizando oito tratamentos com seis repetições de 10 aves cada. As rações experimentais foram fornecidas de zero a quatro dias de idade. O desempenho zootécnico foi avaliado ao alojamento e aos quatro, sete e 21 dias de idade. Nestas mesmas datas, foram sacrificadas duas aves por unidade experimental para biometria do intestino e histomorfometria da mucosa do intestino. A adição de diferentes fontes de gordura e a suplementação de glicina e taurina às dietas de transição não influenciaram o desempenho produtivo de um a 21 dias. A suplementação das dietas com glicina e taurina alterou a morfologia da mucosa intestinal, principalmente do duodeno, resultando em maior comprimento do vilo e relação vilo:cripta. Entretanto, parte dos efeitos positivos depende do tipo de óleo adicionado, mostrando que dietas pós-eclosão acrescidas de fontes de lipídios podem ser benéficas no desenvolvimento da capacidade funcional do intestino de frangos de corte.