Utilization of crab processing waste and chitin associated with the waste as feed for ruminants
Ayangbile, Gbemiga A.
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Four experiments were conducted with crab processing waste. Addition of 1.5% propionic/formic acid prevented degradation up to 14 d. Desirable fermentation was achieved when 32% of the treated crab waste was ensiled with 32% straw, 16% molasses, and 20% water with or without .1% microbial inoculant. The pH of the silage was lowered and high concentration of lactic acid was observed. Use of .2% NaOCl or .4% H₂O₂ retarded spoilage of crab processing waste up to 7 d. Ensiling of the treated waste (32%), straw (32%), molasses (16%), and H₂0 (20%) indicated that the chemical used in preservation enhanced fermentation. Addition of .4% NaOCl and 1.5% acetic acid to the crab processing waste retarded degradation up to d 4. The trimethylamine (TMA) concentration and NH₃ evolution were highest for the untreated waste while the lowest concentration for TMA and NH₃ evolution were observed for the NaOH-treated waste. Addition of 1% NaNO₂ or combination of .4% NaOCl/CaOCl (1:1, w/w) preserved the waste for up to 10 d. The evolution of NH₃ and H2₂S, and TMA concentration were lowest for the waste treated with 1% NaNO₂. Apparent digestibility of DM, organic matter, CP, energy, NDF, ADF, cellulose and hemicellulose decreased linearly (P<.01) with level of crab waste-straw silage in diets containing 0, 50, and 100% crab waste-straw silage. Nitrogen retention increased linearly (P<.05) with level of crab waste-straw silage. The apparent absorption was higher (P<.01) and retention was positive (P<.05) for Ca, Mg, Na, K, Cu and Fe with sheep fed the highest level of crab waste-straw silage. Daily gain, feed efficiency and carcass characteristics tended to be higher for steers fed 30% crab waste-straw silage, dry basis. The flavor and overall desirability of cooked meat were not adversely affected by feeding up to 30% crab waste-straw silage, dry basis. Modifying the existing methods of quantifying chitin showed that initial decalcification or deprotinization of the samples with chemicals are not necessary. Similar values were obtained for chitin when ADF/ashing method was compared to the ADF/deacetylation method. These methods prevented loss of chitin during preparation. Digestibility of chitin was higher (58%) for sheep fed 100% crab waste-straw silage compared to the value of 37% in sheep fed 50% crab waste-straw silage. When ADF/ashing method was used in quantifying chitin, higher disappearances were obtained for samples containing 100% crab meal kept in the rumen or incubated in vitro for 72 h.
- Doctoral Dissertations