Crude protein reduction and digestible methionine+cystine and threonine to digestible lysine ratios in diets for fingerlings of Nile tilapia / Redução de proteína bruta e relações de metionina+cistina e treonina digestíveis com lisina digestível em dietas para alevinos de tilápia do Nilo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The current study was aimed at investigating the crude protein reduction and the methionine+cystine and threonine to lysine ratios, based on the ideal protein concept in diets for reverted Nile tilapia fingerlings (Oreochromis niloticus), of the thailand line. Four hundred twenty Nile tilapia fingerlings with an average initial weight of 1.83 0.02 g, were allotted in a completely randomized design, with five treatments (seven replications per treatment and twelve fishes per experimental unit) in a 37-days trial. Treatment one consisted of a diet with 32.0% of crude protein (CP), methionine+ cystine:lysine ratio of 63.0% and threonine:lysine of 74.0%. In treatment two, the level of CP was reduced in four percentiles points and the amino acids ratios were the same of the treatment one, except the triptofan that was reduced in three percentiles points to ensure the minimum level of this amino acid. In treatment three the methionine+cystine:lysine ratio of 60.0% was used. In treatment four the methionine+ cystine:lysine ratio was 63.0% and the threonine:lysine ratio was 69.0%. The treatment five was similar to the treatment two, however was added 3.0% of glutamic acid, to verify a possible deficiency of nonessential amino acids. The fishes were maintained into 35 aquariums of 130 liters supplied with single-pass flow-through water, controlled temperature and indivudual aeration; and they were fed ad libitum six times per day. The fishes from treatment one had lower protein efficiency ratio and nitrogen efficiency ratio, whereas all the others parameters had no significant differences. The CP level of the diet is 28.0% since it is supplemented with limiting essential amino acids. The methionine+cystine and threonine to lysine ratios are 60.0% and 69.0%, respectively.

ASSUNTO(S)

nutricao e alimentacao animal proteins proteínas oreochromis niloticus tilápia (peixe) aminoácidos amino acids alevinos fingerlings oreochromis niloticus nile tilapia (fish)

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