The joint venture between the state farm at Bikal, which has a fish processing plant producing nearly 10 t/day of fish waste, and the Haki to operate a large commercial sheat-fish production unit using the thermal waters available at Bikal, involves formulating a semi-moist diet which will satisfy the requirements of the sheatfish and utilize the fish waste available. The most logical solution is for Haki to manufacture a dry commodity mix containing all the necessary premixes of vitamins and minerals, and to ship this dry material to Bikal for incorporation there as the dry mix component in the finished feed. Only mixers and extruders will be necessary at Bikal, and the simple final formulation will be 40 parts dry mix to 60 parts pasteurized fish waste. This mix can be blended and extruded for immediate feeding or can be slightly dried to form a feed particle pericle and then frozen for future use. Using the logical assumptions that the nutritional requirements of the sheatfish would be approximately those of the channel catfish, Ictalurus punctatus, an appropriate dry mix formulation was calculated which would contain sufficient vitamins and minerals to satisfy the needs of the growing sheatfish. Assuming that sheatfish can digest and utilize the same type of commodities and feedstuffs used in the catfish industry in the USA, the gross nutrient balance, the digestible energy values, and the micro nutrient supplements were formulated to be mixed 40/60 with the wet ground pasteurized fish waste from the carp processing plant at Bikal. This formulation, which will be tested first in the recycle system at Haki before release to the production unit, is shown in Appendix 2. The premix for the mineral component is shown in Appendix 3.
Using the assumptions that the European catfish or sheatfish, Silurus glanis, would have about the same digestive ability and about the same nutritional requirements, several other formulae for catfish production using commodities available in Hungary were discussed. Dr F. Majoros, leader of the experimental feed mill, was briefed on the advantages and disadvantages of the feed formulations for catfish listed in the NAS/NRC bulletin on Nutrient Requirements of Trout, Salmon and Catfish1, and in the bulletin on Nutrient Requirements of Warmwater Fishes2. The same principles applied to the use of slaughterhouse wastes. A dry mix of low protein content, available energy, and good binding characteristics could be compiled from available commodities and then blended with the moist slaughterhouse wastes to form a semi-most extruded pellet of appropriate size for use with the fish and system available. The proportions of each in the final mix will be dependent upon the moisture content of the slaughterhouse waste, and the desired protein content of the ration for the size and species of fish reared. New formulations manufactured in the feed mill will be reviewed in standard tables of nutrient content for the levels of gross nutrients present, and for balance of amino acids in the protein component of the ration.
