|Fsih and fishery products in poultry rations|
Baelum, J. (1962). Fsih and fishery products in poultry rations, in: Heen, E. et al. Fish in nutrition. pp. 356-363
In: Heen, E.; Kreuzer, R. (1962). Fish in nutrition. Fishing News (Books): London. XXIII, 447 pp., more
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VLIZ: Biological Resources 
Fish meal and condensed fish solubles are by far the most important feedingstuffs of fish origin. Commercial fish meals are manufactured from various fish or waste products from the fish industry; the type of the raw material and the method of manufacture greatly influences the value of the product as feed for poultry. The chemical composition of the fish meal depends on the raw material employed whilst the factory treatment influences its protein value. It has been reported that drying fish meal at relatively low temperatures gives a better product than results from high temperature drying. With these reservations, fish meal may be considered as the best source of high quality protein, containing considerable amounts of all the essential amino acids, though not particularly high in methionine. Fish meal has been a common ingredient in poultry rations as long as rational feeding of laying birds and chicks has been practised. Although the protein requirements of poultry can be largely satisfied by vegetable protein, experience has shown that higher egg production from laying birds and better growth rates with chicks are obtained when feeds of animal origin, especially fish meal, are included in the ration. A partial explanation of the special nutritive value of fish meal was obtained with the discovery of the "animal protein factor", of which vitamin B12 was later found to be an effective part. Numerous investigations have shown, however, that the specific effect of fish meal is not due to its content of vitamin B12 alone. Other unidentified growth factors appear to exist in fish meal and other fish products, although a specific effect of this type has not been found in all cases. Even though fish meal protein is considered to be of superior feeding value and is difficult to replace, it is used in relatively small amounts of 3-5 per cent, since vegetable protein is cheaper. Fish meal does, however, have some undesirable properties. If fed in large amounts, it may induce a fishy flavour in poultry meat, and to a lesser extent in eggs. White fish meal has been reported occasionally to cause a significant depression in the hatchability of fertile eggs. Furthermore, fish meal from some countries has been shown to be infected with salmonella bacteria, and thus to spread this disease in the poultry flocks. Owing to the high content of vitamin B12 condensed fish solubles are used as a supplement in many vegetable chicken diets. Various tests have shown that the supplementation of a vegetable diet ( corn and soybean meal ration) with condensed fish solubles increases the growth rate of chicks. No less remarkable are the results of American trials which show a similar, but smaller, effect when supplementing feedingstuffs with the ash of fish solubles and dry whey. These inorganic constituents produced a highly significant increase in growth. In Scandinavian countries condensed fish solubles are not used as a special ingredient in the ration, but are included in the fish meal, whereby it becomes rich in vitamin B12. Herring meal, supplemented with condensed fish solubles, is known under the name of "whole meal" and is considered to be the best fish meal on the market. No doubt it would be in the interest of the poultry producers and the feed manufacturers (and probably stimulate the demand for fish meal) if the commercial meals were standardized to some extent, showing less variability in the chemical composition and the nutritive value; fish meal may be expected to be absolutely free of pathogenic bacteria. The salt content of the product must be low; if it exceeds a certain low limit, the content must be stated. If the substances which produce the fishy flavour in poultry meat and eggs could be economically extracted, the amount of fish meal in poultry rations could be increased without risk of off-flavour in meat and eggs; but it is not likely that fish meal will ever be able to compete in price with soybean meal.