Title: DETERMINATION OF GIZZEROSINE ACTIVITY IN FISH MEAL WITH A HOMOLOGOUS RADIOIMMUNOASSAY (PEER REVIEWED AT INSTITUTO DE NUTRICION Y TECNOLOGIA DE LOS ALIMENTOS, UNIVERSITY OF CHILE, MACUL, SANTIAGO, CHILE)
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 12, 1995
Publication Date: N/A
Interpretive Summary: Gizzerosine is known to be the causative agent of "black vomit", a serious poultry disease. Gizzerosine is formed by the reaction of lysine with histidine during the heating process of fish meal manufacturing. Fish meal is a major source of protein in poultry diets and to a lesser extent in swine and farm-reared fish. Gizzard erosion results in economical loss due to deaths and poor productive performance. At present, fish meals are certified with respect to the presence of gizzerosine, using a bioassay in which chicks are fed the test meals and subjective scores are assigned according to the degree of erosion in the gizzards following the test period. This certification represents a significant cost for the fish meal exporters. The bioassay lacks the efficiency, accuracy, reproducibility and cost-efficiency of modern analytical methods for the detection of toxic substances. We have developed a homologous radioimmunoassay for the quantification of trace amounts of gizzerosine-like material present in fish meals. The assay is highly sensitivity and reproducible. This method should be a useful tool for the certification of low-toxicity fish meals and the prevention of black vomit. Additionally, the possibility of quantifying gizzerosine activity will also be of great importance for the elucidation of the mechanisms of action by which this toxin produces the pathological conditions associated with the disease. This research will be of interest to the poultry industry, feed manufacturers and other scientists.
A homologous radioimmunoassay (RIA) for the determination of toxic gizzerosine activity in commercial fish meals has been developed. Three polyclonal antibodies (GR316, GR415, and GR418) were produced in female rabbits, and extensively characterized for their potential use in individual RIAs. The RIAs had lower detection limits of 0.048, 0.78, and 0.39 ng/mg using the three respective antibodies. The antibodies crossreacted with histamine from 21 to 100%. No crossreactivity with histidine or lysine was observed for any of the three antibodies. Antibody GR415 was chosen for determination of gizzerosine in extracted fish meal samples. A mild buffer extraction procedure was used resulting in 98% gizzerosine recovery. Displacement curves from extracted and serially diluted fish meal samples were parallel with gizzerosine standard. Inter and intra-assay coefficients of variation were 11 and 15% respectively. We used the RIA for determination of gizzerosine activity in a pool of 23 fish meal samples of known gizzerosine scores (determined with a chick bioassay), and histamine content. The partial correlation coefficient between gizzerosine content determined by the RIA and gizzerosine scores from the bioassay was high (0.83), and statistically significant (p<0.01). There were also significant correlations between gizzerosine scores and histamine content of the fish meals (0.63, p<0.01), and between histamine content and gizzerosine levels determined by the RIA (0.59, p<0.01). The application of the homologous RIA for the determination of gizzerosine activity in commercial fish meals could be of significant importance for the prevention of gizzard erosions in the poultry industry, and for studying gizzerosine-induced pathology and metabolism.