Resumo

GUTIERREZ-CORONADO, Lourdes et al. Total, Digestible and Digestible Reactive Lysine Contents in Fishmeal.. Rev. Cient. (Maracaibo) [online]. 2008, vol.18, n.2, pp.218-224. ISSN 0798-2259.

The aim of the study was to determine and compare total, reactive, digestible and digestible reactive lysine contents in pelletized (PF) and extruded fishmeal (EF), the latest as an indicator of available lysine, which could be affected by prolonged storage or inadequate thermal processing. Twenty nine Sprague-Dawley male rats with an average initial weight of 100 ± 5 g divided into three groups were used, which were individually allocated under control conditions. Nine rats were fed with a diet based in enzymically hydrolyzed casein to determine endogenous ileal aminoacid flow. The another twenty rats were divided into two groups of ten rats and were fed with PF and EF base diets containing chromic oxide as indigestible marker for sixteen days. The rats were sacrificed to remove 20 cm of the terminal ileum. In PF and PE, diets and ileal digests, chromic oxide was determined by atomic absorption, total and reactive lysine after reaction of these materials with O-methylisourea to form homoarginine by high pressure liquid chromatography. True reactive lysine digestibility was determined after correcting for endogenous lysine loss at the terminal ileum of rats fed an enzyme hydrolyzed casein-based diet, followed by ultrafiltration of the digest (10,000 Da). Total and reactive lysine contents for PF and EF were 5.7 and 5.5%; 5.1 and 4.4% respectively. Digestible lysine and digestible reactive lysine were 5.5 and 5.1%; 4.5 and 3.8% respectively. Digestible lysine overestimates lysine contents in 22.2% for PF and 34.2% for EF. Digestible reactive lysine value for PF was similar to available lysine values reported in literature of 4.2 and 4.3%. Digestible reactive lysine could be considered as a good indicator of lysine availability.

Palavras-chave : Total lysine; digestible lysine; digestible reactive lysine; fishmeal; rats.