In vitro determination of ruminai dry matter and cell wall degradation, and production of fermentation end-products of various by-products

Abstract

The samples used in the experiment were nine types of by-products: giant pumpkin, red pepper, melon, broccoli, brewer's grains, fresh and boiled artichoke, lemon peel and orange peel. The dry matter degradability of each by-product was determined by in vitro fermentation with ruminal fluid of the goat. The materials were incubated at 39 °C for 12, 24, 48 and 72 h. At each time, pH, dry matter disappearance, neutral-detergent fibre disappearance, volatile fatty acids, lactic acid and ammonia productions were measured. Approximately 50% of the total dry matter loss of broccoli, melon and peels occurred at 12 h incubation. In addition, the total dry matter loss of the giant pumpkin, fresh and boiled artichoke, and brewer's grains was low (< 50% of dry matter loss) at 12 h. The molar proportion of acetate and propionate was influenced by the type of the feedstuff's. Thus, the acetate proportion was > 70% for all by-products, except for brewer's grains (63.8%), and the propionate proportion was < 20% for all by-products, except for the brewer's grains (21.3%). In conclusion, the ruminai dry matter and cell wall degradations, and production of fermentation end-products by in vitro determination offers a convenient method to compare the microbial digestion of the different byproducts.