BAUERSFELD and SCARES: FISH SOLUBLES 



fish meals must be improved to develop a product 

 that will remain in suspension. 



Fifth, fish proteins must be odorless, relatively 

 free from a fishy taste, have a light color, and 

 be stable. Many manufacturers of milk replac- 

 ers feel that the fat content of the fish product 

 must be kept as low as possible (less than I'^r ) 

 to maintain the stability of fish protein. Some 

 manufacturers suggest additions of antioxidant 

 since they have experienced a deterioration of 

 autolysates after storage. However, it has been 

 reported by Ronning (1970) that hydrogenated 

 fish oils with an iodine number of 80 are of value 

 in high-energy milk replacers. Through the ad- 

 dition of higher levels of a-tocopherol (Vitamin 

 E) and by reducing the levels of unsaturated 

 fatty acids by hydrogenation, he was able to feed 

 calves up to 26.2 5f fish oil with no detrimental 

 effects. 



Sixth, the bone content of the fish protein 

 product must be relatively low. Producers of 

 milk replacers indicate they want a final product 

 with less than a 10% mineral content. More 

 importantly, they want this concentration of 

 minerals to remain constant from one batch of 

 milk replacers to another. Therefore, the major 

 individual ingredients in the milk replacer must 

 have a constant mineral composition. In addi- 

 tion, if a milk replacer containing fish protein 

 is to be fed for the production of veal calves, 

 it must be low in iron (less than 50 ppm) . The 

 preferred paleness of veal muscle tissue results 

 from a state of anemia due to the low iron con- 

 tent of the rations fed to veal calves. At present, 

 the iron content of FPC made by isopropyl al- 

 cohol extraction may vary between 147 and 770 

 ppm (Finch, 1970). However, a large part of 

 this iron comes from mechanical contamination 

 (i.e., grinding) and may be of a type that is 

 poorly available to animals. If the iron content 

 can be made unavailable by adding an iron- 

 chelating agent, as suggested by Saheb and 

 Charpentier (1970), a high-quality veal meat 

 may be produced. Inasmuch as the major mar- 

 ket in the United States is for replacement ani- 

 mals, iron should not be a problem. 



Seventh, the moisture content of the fish pro- 

 tein must be kept low to prevent lumping of the 

 milk replacer and other texture changes during 



storage. Most milk replacers contain 5% mois- 

 ture or less. 



Eighth, fish protein to be used in milk replac- 

 ers would have to have a reasonably low bacter- 

 ial plate count because neonatal animals are quite 

 susceptible to digestive upsets. A low moisture 

 content would help to keep bacterial growth to 

 a minimum. 



EXPERIMENTAL RESULTS 



Our research at the National Marine Fisheries 

 Service, College Park Laboratory was conduct- 

 ed to determine the feasibility of using fish sol- 

 ubles in milk replacer rations. 



EXPERIMENT I 



The objective of the first study was to deter- 

 mine the eff"ect of partially substituting con- 

 densed menhaden fish solubles in a commercial 

 ration for veal calves. Four Holstein bull calves 

 were placed individually in stalls at 3 days of 

 age. Two of the calves were fed a commercial 

 veal ration, containing 24% protein and 20 Sr 

 fat. The remaining two calves received the same 

 commercial ration with low-fat (3% ) menhaden 

 fish solubles replacing 5^r of the ration on an 

 equal weight basis. The calves were full-fed 

 twice daily. Table 1 shows the results of this 

 experiment. At 75 days of age, the milk replacer 

 plus fish solubles group had average daily weight 

 gains (0.93 kg) and feed conversions (1.41) 

 comparable to those of the all-milk products re- 

 placer. However, due to the small number of 



Table 1. — Experiment I. Weight gains and feed con- 

 sumptions of calves fed either control milk replacers 

 or milk replacers containing 5% fish solubles. 



1277 



