SCARES ET AL.: CONDENSED FISH SOLUBLES 



MINERALS 



The ash content of condensed solubles aver- 

 ages about 99^ and occasionally is as high as 13% 

 of total weight (Scares et al. 1970). The major 

 inorganic elements (Table 5) are P, Na, and K. 



Table 5. — Inorganic elements content of menhaden fish 



solubles.' 



1 Scares, Miller, and Ambrose (1970) and Scares and Miller (1970). 



Chloride which is not included in Table 5 is also 

 present in amounts about equal to Na. Others 

 that are present in lower amounts include: Mg, 

 Ca, Fe, Al, Zn, and Mn. The trace elements that 

 are found at even lower levels include: Co, I, 

 Ag, B, Ba, Cr, Li, Ni, Rb, Sr, Si, Se, and perhaps 

 others not yet identified. Calcium and phosphor- 

 us analyses were determined by the method of 

 Kingsley and Robnett (1958) as adapted for the 

 Technicon. All other elements were determined 

 by emission spectographic analysis. 



These data show that the calcium and phos- 

 phorus levels are expectedly very low compared 

 to fish meal since the major portion of these two 

 elements are found in the bone which remains 

 with the meal. Most of the other minerals in 

 fish solubles also occur in lower concentrations 

 than in fish meal. Selenium, however, tends to 

 be found in concentrations that are equal to or 

 greater than fish meal. Three minerals — alumi- 

 num, copper, and iron — were detected in quite 

 variable concentrations. The average concen- 

 tration of auminum in all solubles samples is 



somewhat lower than that reported by Kif er and 

 Payne (1968) for fish meals from both the At- 

 lantic and the Gulf coasts. The aluminum con- 

 tent of solubles from Atlantic coast plants was, 

 however, considerably lower than that of men- 

 haden fish meals, whereas the aluminum content 

 of Gulf coast solubles was somewhat higher. 

 Similar diflferences in aluminum content (unpub- 

 lished data) were found in Gulf and Atlantic 

 menhaden fish protein concentrate (FPC) made 

 at the College Park Laboratory, starting with 

 raw fish and using stainless steel equipment 

 under aseptic conditions. Consequently, the 

 higher aluminum content appears to occur in the 

 Gulf species itself rather than as a contaminant 

 after they are caught. 



Selenium has become a focal point in trace 

 mineral research since Schwarz and Foltz (1957) 

 and Nesheim and Scott (1958) showed that it 

 is essential for the prevention of dietary liver 

 necrosis in rats and of encephalomalacia, exu- 

 dative diathesis, and muscular dystrophy in 

 chicks. Thompson and Scott (1968) have sug- 

 gested that the range of 0.15 to 0.2 ppm is the 

 desirable concentration for selenium in practical 

 poultry diets. As little as 0.05 ppm selenium 

 in the form of sodium selenite, however, has been 

 found to prevent the physiological abnormalities 

 mentioned above. 



So far, the Food and Drug Administration 

 has not permitted chemical compounds contain- 

 ing selenium to be added to the rations of live- 

 stock. For this reason, natural sources are cur- 

 rently the only available means of supplementing 

 selenium in the diet. Fish meal has been shown 

 to be a rich source of selenium by Kifer and 

 Payne (1968) and Kifer et al. (1969). 



A number of samples of fish solubles was ob- 

 tained from commercial menhaden plants 

 throughout the 1969 fishing season and analyzed 

 for selenium. A total of 38 samples were an- 

 alyzed — 20 from fish meal plants along the At- 

 lantic coast and 18 from plants along the Gulf 

 coast. 



Although neutron activation analysis was used 

 to determine the selenium content of the fish 

 meals reported in the above-mentioned papers, 

 we found that this method did not give reliable 

 results with fish solubles. Consequently, a wet 



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