FISHERY BULLETIN: VOL. 70, NO. 4 



Huber and Slade (1967) substituted varying 

 levels of fish protein (defatted fish meal) for 

 skim milk protein in calf milk replacers in 

 growth and balance studies. They also investi- 

 gated the effect of varying levels of dietary fat 

 in combination with fish protein on growth re- 

 sponse. Their data showed that average daily 

 gains and feed efficiencies were not significantly 

 different when fish protein replaced up to 40 Sf 

 of the dietary protein. However, when fish pro- 

 tein replaced from 60 to 67*^^ of the dietary pro- 

 tein, significant decreases (P<0.01) occurred. 

 Increasing fat in the rations from a 10 to 20 Sf 

 level caused a linear increase (P<0.05) in gains. 

 However, no interaction between protein source 

 and fat level was detected. Furthermore, as the 

 amount of fish protein in the milk replacer in- 

 creased, digestibilities of dry matter, crude pro- 

 tein, fat, and ash decreased. Only when fish pro- 

 tein furnished 100 "^r of the dietary protein was 

 there a significant depression (P<0.05) in the 

 percent of digested nitrogen retained. Crude 

 protein in the fish concentrate was reported to 

 be 80 ''r digestible compared to 90 "^f for skim 

 milk protein. 



Williams and Rust (1968) reported a study 

 with four different formulations of experimental 

 milk replacers, and their results supported the 

 findings of Huber and Slade (1967). Defatted 

 fish flour provided from 14 to 42 '^r of the total 

 protein in these experimental rations. Total pro- 

 tein, fat, and digestible nutrients were equal in 

 all experimental rations and were similar to 

 those of the standard milk replacer ration. At 

 the termination of the 42-day experiment, they 

 reported that calves fed the various experimental 

 milk replacers gained similar amounts of weight 

 and they were comparable to calves on the con- 

 ventional milk replacer. These results indicated 

 that fish protein could be effectively utilized and 

 provide up to 42 Ty of the protein in the ration. 



Gorrill (1970) conducted similar studies on 

 the use of fish protein in milk rei:)lacers. Fish 

 protein concentrate (FPC), which was in this 

 case isopropanol extracted fresh whole herring, 

 accounted for bO^/r of the protein in the fish 

 containing milk replacer. He also fed a dry 

 starter on a restricted basis and hay ad lib. with 

 the liquid diet and found that at least 50^/f of 



the milk replacer protein could be supplied by 

 FPC with no significant difference in weight 

 gains from those of whole milk or an all-milk 

 product replacer ration. 



In European countries there has been increas- 

 ing interest in developing fish products which 

 could be utilized in milk replacer rations. France 

 is currently producing 550,000 to 600,000 tons 

 of milk replacer per year which includes the use 

 of fish protein in veal diets. In particular, two 

 French feed manufacturers began marketing 

 milk replacers containing fish protein in the form 

 of FPC or autolyzed fish concentrate in an effort 

 to use a lower priced animal protein. 



CRITERIA FOR PROTEINS 

 IN MILK REPLACERS 



Generally, there are eight criteria that will 

 have to be met by the producers of fish protein 

 before feed manufacturers will consider using 

 such protein in milk replacer formulas. 



First, the fish protein must be highly available 

 to the animal. At present, a wide range of val- 

 ues has been reported on fish protein in milk re- 

 placer rations. Reports of from 50 to 80 Sr di- 

 gestible protein can be found in the literature. 

 Since skim milk has a digestible protein value 

 of about 90 '^r , it is imperative that fish products 

 have a protein digestibility as close to this as 

 possible. 



Second, the product must be of uniform qual- 

 ity and be available throughout the year in quan- 

 tities large enough to meet demands. 



Third, fish protein must be lower in cost than 

 milk protein or equal if DSM is scarce. Manu- 

 facturers will be willing to use fish protein only 

 if its substitution for milk products gives a re- 

 duction in price of the milk replacer. There is 

 always risk involved when changing formulas, 

 and the manufacturers must be shown an eco- 

 nomic advantage before they will take that risk. 



Fourth, the fish protein must be suspendable 

 in water when used in the formulation. With 

 the increased application of automatic feeding 

 devices in the rearing of neonatal animals, a com- 

 pletely suspendable milk replacer is important. 

 The functional properties of current FPC and 



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