Aquatic feed

A large twin-screw extruder that is capable of making 6.3-15 MT of aquatic feeds and pet foods per hour and requires 450 kW (600 hp) is shown Figure 11. A process flow chart for making dry-expanded or semimoist pet foods and aquatic feeds is shown in Figure 12. 

Figure 12. Process flow sheet for making dry expanded or semimoist pet foods, and aquatic feeds. Courtesy of Wenger Manufacturing, inc., Sabetha, Kansas.

When treatment chemicals have to be employed, they may be iacorporated ia the food, used ia dips, flushes and baths, or allowed to remain ia the water for exteaded periods. Siace oae of the first respoases of aquatic animals to disease is reduction or cessation of feeding, treatments with medicated feeds must be initiated as soon as development of an outbreak is suspected. Antibiotics, such as terramycin, can be dissolved in the water, but may be less effective than when given orally. 

It appears that organisms at the top of aquatic food chains are not exposed to substantial levels of PAH in food because of the detoxifying capacity of organisms beneath them in the food chain. On the other hand, fish, birds, and aquatic mammals feeding on mollusks and other invertebrates are in a different position. Their food may contain substantial levels of PAH. Although they can achieve rapid metabolism of dietary PAH, it should be remembered that oxidative metabolism causes... 

Chlorella, aquatic plant, grass, hay, spruce twigs and needles, olive leaves, peach leaves, tobacco leaves Bovine muscle, bovine liver, pig kidney, milk powder, cereals, single cell protein, butterfat, fish oil, animal feed-stuffs, textiles... 

Burghardt G. (1980). Behavioral and stimulus correlates of vomeronasal functioning in reptiles feeding, grouping, sex and tongue use. In Chemical Signals Vertebrates and Aquatic Invertebrates 1 (Miiller-Schwarze D. and Silverstein R.M., eds.). Plenum, New York, pp. 275-302. 

The communities include in particular bacteria, lower aquatic plants (algae), higher aquatic plants, organisms fish feed on (e.g. water flea, amphipods etc.) and fish. They participate in the self purification of waters (reduction of residual pollution from effluent discharges like industrial drainage) and maintain the natural biological equilibrium. 

Pelgrom, S.M.G.J., L.P.M. Lamers, J.A.M. Garritsen, B.M. Pels, R.A.C. Lock, P.H.M. Balm, and S.E.W. Bonga. 1994. Interactions between copper and cadmium during single and combined exposure in juvenile tilapia Oreochromis mossambicus influence of feeding condition on whole body metal accumulation and the effect of the metals on tissue water and ion content. Aquat. Toxicol. 30 117-135. 

In aquatic environments, waterborne lead was the most toxic form. Adverse effects were noted on daphnid reproduction at 1.0 pg Pb+2/L, on rainbow trout survival at 3.5 pg tetraethyllead/L, and on growth of marine algae at 5.1 pg Pb+2/L. High bioconcentration factors were recorded for filter-feeding bivalve molluscs and freshwater algae at 5.0 pg Pb+2/L. 

Rooted aquatic plants, such as wild rice (Zizania aquatica), can accumulate up to 67 mg Pb/kg dry weight when cultured in tanks contaminated with high concentrations of powdered lead (equivalent to 7400 kg Pb/ha) however, this level is not considered hazardous to waterfowl feeding on wild rice (Behan et al. 1979). Lead content in plants collected from heavily hunted areas near refuges did not differ from those collected in the protected areas (Behan et al. 1979), which suggests that lead bioavailability to rooted aquatics is substantially lower from shot than from powdered lead. 

Weber, D.N., A. Russo, D.B. Seale, and R.E. Spieler. 1991. Waterborne lead affects feeding abilities and neurotransmitter levels of juvenile fathead minnows (Pimephales promelas). Aquat. Toxicol. 21 71-80. 

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