Fermentation characteristics, nutritional value and palatability of ensiled seafood wastes and low quality roughages

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Virginia Polytechnic Institute and State University


Fish and crab processing wastes were ground and ensiled with corn stover or peanut hulls alone and with 5% dry molasses or 1% formic acid in 3.8 liter cardboard containers double lined with polyethylene. The wastes and roughages were ensiled in proportion to give dry matter levels of 40, 50 and 60%. The seafood wastes were also ensiled with wilted Johnsongrass with and without molasses. After ensiling, average pH for mixtures with fish waste was 6.5, compared to 8.0 for mixtures with crab waste. Addition of dry molasses resulted in a decrease (P <.01) of pH to 5.6 for the ensiled fish mixture but had no effect on the crab waste mixtures. Lactic acid was higher (P< .01) for ensiled mixtures containing fish waste than for those containing crab waste. Substantial levels of acetic acid were present in the silages. Butyric acid levels were higher in silages containing crab waste and decreased linearly (P< .01) with increased dry matter levels. Desirable ensiling was observed for the mixture of fish waste and Johnsongrass. Coliforms and fecal coliforms were decreased or elIminated by ensiling. In a large silo study, mixtures of finfish and crab processing wastes were mixed with wheat straw and ensiled in 210 liter metal drums, double lined with polyethylene bags. Proportions of the fish and straw were 70:30 and 51:49, wet basis, while that of the crab was 60:40 and 40:60. Acetic acid was added to the crab waste mixtures to lower the initial pH to 4.5. After ensiling all mixtures containing fish and straw showed a decrease in pH. Addition of acetic acid to mixtures containing crab waste inhibited fermentation, but resulted in a very stable product. In a sheep digestion trial, dry matter digestibility was higher (P <.01) for the 70:30 diet than for the 51:49 fish diet. There was no difference in dry matter digestibility between the crab silages. Crude protein digestibility was higher (P <.01) for diets containing ensiled fish, compared to diets containing ensiled crab. Nitrogen retention was positive for sheep receiving all diets. Nitrogen retention was higher (P <.01) for animals fed the crab silage diets, compared to those receiving diets containing fish silage. There was a trend for P absorption to be higher in animals fed crab silage. In the sheep palatability trial, intake of dry matter was higher (P < .01) for sheep consuming the crab silage diet and lowest (P <.01) for sheep fed the 70:30 fish silage diet.