Evaluation of agro-industrial by products as potential local feed for ruminant animals: volatile fatty acid and NH₃ concentration, gas production and methane emission

Due to high cost of conventional feed, the use of agro-industrial by products has been widely known as alternative for animal feed. The aims of this experiment is to get information about the potency of agro-industrial by product in Aceh that can be utilized as feed for ruminant animals based on volatile fatty acid concentration, gas production and methane emission. Eight kinds of agro-industrial by product in Aceh from three different location products (sago residues, coconut meal, soybean-ketchup by product, coffee pulp, cacao pod, sago tree, corncob, and rice brand) were used in this study. Prior to analyses, all samples were dehydrated at the temperature of 60°C for 24 h, then crushed to pass a 1 mm sieve. Crushed samples were analysed to determine volatile fatty acid concentration, gas production and methane emission. Incubation was carried out in water bath with three replicates for 48 h with the temperature of 39°C. The production of gas was collected and periodically documented at 2, 4, 6, 8, 12, 24, 36 and 48 h after incubation by using a syiringe. The VFA production from agro-industrial by products in this study was not significantly different (P>0.05) from one by-products and others from 83±2.26 mmol/l for cacao pod to 123 ±16.1 mmol/l for coffee pulp. The production of NH₃ was with the range of 5.72 mmol/l to 15.71 mmol/l for for sago trees and coconut meal respectively. Total gas production from agro-industrial by products was 69.90 ml g/DM to 210.40 ml g/DM with methane gas production in the range of 33,88 – 35.18 ml/g DM after agro-industrial by products were incubated for 48 h. In conclusion, based on the fermentation parameters in this study, local agro-industrial by products in Aceh Province can be utilized as sources of alternative animal feed as replacement of conventional. Based on fermentation parameters measured in this study (VFA, NH₃, gas production total) were still in optimal range for fermentation process in animal production