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The nutritive value of fish meal and condensed fish solubles as supplements in poultry rations March, Beryl Elizabeth

Abstract

Fish meals, particularly British Columbia herring meals, and condensed herring solubles have been studied for their nutritive properties as supplements in poultry rations. Both commercially and experimentally prepared herring meals were used in the study. Protein quality in fish meals was investigated to ascertain what degree of variability exists in commercial samples and to obtain information regarding the effects of raw material, processing temperature and storage. On the basis of the Protein Index Values commercial fish meals appeared to vary in the quality of their protein content. Much of the variability amongst different meals could be ascribed to the nature of the raw material. Experiments were carried out in which herring meals prepared under controlled conditions from material of known origin were compared. It was shown that the value as a protein source for the growing chick of meals produced under a considerable range of drying temperatures was similar. Differences in the vitamin content of fish meal were found to be responsible for differences in the rates of growth of chicks fed herring meals which had been dried at high and low temperatures. With the basal rations employed, folic acid was the limiting nutrient when herring meal was used as the sole source of supplementary protein. The folic acid content of meals prepared from similar raw material was found to be markedly affected by the temperature at which the meals were dried. Chicks and poults fed rations formulated to be complete in the known nutrients grew at a faster rate when 2.5 to 5.0 percent of herring meal was added to the rations. It was concluded that herring meal contains a factor(s) not identified with any of the known vitamins. Condensed herring solubles was shown to be an effective vitamin supplement to practical type poult rations whether or not the ration contained herring meal. Extraction of the oil from herring meals did not improve the growth response of chicks to the use of the meals as protein supplements. Normal and extracted commercial flame-dried meal and experimentally prepared low-temperature-dried meal were compared in this regard. Storage of herring meals for one year at -25°, 21° and 37°, respectively, did not appear to affect the nutritive value of the meals as protein supplements for chick rations. Chemical changes did occur in the fat present in herring meals during storage. The amount of ether-soluble material decreased with the length of the storage period and the iodine value of the ether extract decreased. The addition to the meal of 0.15 percent butylated hydroxytoluene before storage prevented any decrease in ether extractability of the fat during a 9-month storage period and considerably reduced the drop in iodine value of the extract.

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