Ensiling salt-preserved shrimp waste with grass straw and molasses

Two experiments were conducted to evaluate the nutritional and fermentation characteristics of ensiled salt-preserved shrimp waste. In Experiment 1, 7.5% salt-preserved shrimp waste was stored for 6 days then mixed with molasses and perennial ryegrass straw. Treatments included three levels of shrimp waste (83, 65 and 47%, as mixed) within which there were three levels of dry molasses (0, 9, or 17%, as mixed). Mixtures were stored in 15-l mini-silos for 40 days. The resulting nine shrimp silages, which ranged from 33 to 52% DM and 11 to 21% CP, never reached a pH of <4.5, which is necessary for a stable grass silage. The silages that incorporated a high amount of shrimp waste (83%) and molasses (9 or 17%) with low levels of straw had high levels of lactic acid production but only a slight drop in pH. The high buffering capacity from the calcium carbonate in the shrimp waste may have diminished the effectiveness of the acids to change the pH of the final silage. When a lower level of shrimp waste (47%) and molasses were ensiled with high levels of grass straw, the pH remained high because of low lactic acid production. The use of low quality forages or, either the amount or source of carbohydrate substrates, may have limited bacterial growth and acid production. Without a pH of <4.5, the stability and the possible presence of bacterial pathogens in our shrimp waste silages make this a questionable feed to offer ruminants. In Experiment 2, two fistulated steers were used to evaluate the ruminal undegradable protein of fresh shrimp waste and shrimp silage (47% shrimp waste, 17% molasses). The samples were deposited into nylon bags and placed in the rumen at nine time points ranging from 0 to 96 h. Prior to insertion of the samples, steers were stuffed via the fistula with crustacean waste for a 2-week adjustment period. The ruminal undegradable protein was 57% for the fresh shrimp waste and 32% for the shrimp silage.