Fermentation characteristics of ensiled seafood wastes and low-quality roughages

Abstract

Experiments were conducted to investigate the chemical composition of seafood waste and the ensiling characteristics of seafood waste combined with low-quality roughages. Average crude protein of the fish and crab wastes was 60.4% and 44.1%, dry basis, respectively. Fish and crab processing wastes were ground and ensiled with corn stover or peanut hulls in proportions to result in dry matter (DM) levels of 40, 50 and 60% alone and with 5% dry molasses or 1% formic acid in 3.8 1 cardboard containers double-lined with polyethylene. The seafood wastes were also ensiled with wilted Johnsongrass (50:50, wet basis) with and without 5% dry molasses. All silages had desirable aroma except those with crab waste ensiled at 40 and 50% DM. After ensiling average pH for mixtures with fish waste was 6.5, compared with 8.0 for mixtures with crab waste. Addition of dry molasses decreased pH of the ensiled fish-waste mixtures, but had no effect on the crab-waste mixtures. Coliforms and fecal coliforms were decreased or eliminated by ensiling. Finfish wastes and crab processing wastes were mixed with wheat straw and ensiled in 210-1 metal drums, double-lined with polyethylene. Proportions of fish waste and straw were 70:30 and 51:49, wet basis, and those for the crab waste were 60:40 and 40:60, wet basis, respectively. Dry molasses (5%) was included in all mixtures and acetic acid was added to the crab-waste mixture to lower the initial pH to 4.5. Mixtures containing fish waste and straw decreased in pH after ensiling, the decrease being large for the mixture with the lower proportion of fish waste. Lactic acid concentrations were inversely related to pH. In the crab waste-straw mixtures, pH remained below 5, and essentially no lactic acid was present.