The use of bakery wastes as a nutritional source for fish

Abstract

The growth responses and food utilisation of mirror carp fed complete diets containing varying levels of waste bread and meat pie production waste were investigated under controlled conditions. Diets containing high levels of these wastes produced good growth with no deleterious effects. Diets containing high lipid levels with the fat supplied by the bakery waste were shown to spare protein. 17% fat in the diet allowed for a reduction in the protein level from 34% to 24% with similar growth responses. Hard fat as used in bakery products were found to require supplements of oils to produce the best growth responses. This was due to an apparent deficiency of some essential fatty acids. The growth responses of mirror carp grown in extensive ponds fed a supplemental diet of only bakery wastes were investigated. Protein sparing of natural protein from zooplankton in teh pond was seen to occur at all levels of feeding. This was supported by a simulation of the pond trial held under controlled conditions in the laboratory. Varying methids involved in the manufacture of a production pellet were investigated. Air drying of bread at room temperature was found to be an effective method of reducing excess moisture with a reduction of 40% by simple air drying, and 60% by blowing the sir with a fan. Preservation of bakery waste pellets was found to be practical with 5% salt or a mixture of 3% salt and 0.5% calcium propionate. pellets could be held at room temperature for a month without any adverse microbial growth. Binding of a bakery waste pellet was found to be effective without the addition of a binding agent. It was concluded that bakery wastes are a good nutritional source for fish, especially carp, with the most promising use being as an energy feedin xtensive pond culture.