Evaluasi Gas Rumah Kaca (CH4, CO2 dan N2O) dari Feses Sapi FH Laktasi yang Diberi Pakan Rumput Gajah dan Jerami Padi

Abstract

Livestock sector is one of potential sector to produces greenhouses gases from feces. FH (Frisien Holstein) is one of the dairy cows mostly raised in Indonesia. Feces production of FH approximately 18.45-36.9 kg per day. Dairy cows feces produces the main greenhouse gases such as CH4, CO2 and N2O. Dairy cows feces either solid or liquid has the potential to emit CH4, CO2 and N2O. The aim of this experiment was evaluate the production of greenhouse gases from lactating dairy cow feces that fed with elephant grass (EG) and rice straw (RS). This experiment was conducted from September to December 2014 in KUNAK, Animal Waste Processing and PAU Laboratory of Bogor Agriculture University, and Greenhouse Gases Laboratory of BALINGTAN. BALINGTAN method in measuring greenhouse gases was used in this research. Feces were collected as much as 1 kg in 24 hours and incubated for 8 weeks to measure greenhouse gases. CRD (complete random design) repeated measurements was used with 3 treatments : RS (100% rice straw), EG (100% elephant grass) and RSEG (50% rice straw+50% elephant grass). Measured variables were greenhouse gases (CH4, CO2, N2O), proximate feed analysis, feces proximate analysis, total of feces organic matter, C organic feces, N feces, ammonia (NH3) concentration, feces weight in 24 hours, dairy cows body weights, and feed consumption. The result showed that CH4 gas production from lactating dairy cow feces had no significant effect in each treatment (P>0.05). There was no differences on the CO2 production (P>0.05) between RS, EG, and RSEG but N2O production was higher in RS (P<0.05) than EG and RSEG. Different feeding significantly affected CH4 gas production in the first week (P<0.05), while for the second week until the last week of the study was not significant effect (P>0.05). The first week of CH4 measurement, generated the highest production on dairy cows in RS treatment and followed by RSEG, while EG treatment produces CH4 lower than RS and RSEG. Furthermore, CO2 production in the first week to the third week showed an increase volume in all treatments. In the third week until the sixth week showed a decline in CO2 gas production and increased back on the last week of incubation. Peak production of CO2 gas in all treatments occurred in the third week, it demonstrated the high content of digestible organic matter such as energy and protein and the declined of CO2 production caused by decreasing of digestible substrate. Production of greenhouse gases associated with the substrate that used by the bacteria which is the fiber has longer degradation process so CO2 gas produced slower. Furthermore, the highest production of N2O gas was produced from RS treatment (P<0.05). Fluctuation of N2O gas production was influenced by the concentration of NH3, N content of feces and the role of microbes during the feces incubation process. Generally, the production of CH4 and CO2 produced from dairy cows lactating feces was higher than N2O. The greenhouse gases produced from feces was associated with organic matter content, easily digestible substrate, and length of fermentation. Lactating dairy cow feces with elephant grass and rice straw diet potential in produces greenhouse gases. It can be concluded that greenhouse gases production from lactating dairy cow feces from RS, EG and RSEG produces CH4 and CO2 equally but N2O was produced higher in RS treatment. The incubation process for 8 weeks showed a decreased of CH4 and N2O, feces’s substrate and organic matters, C organic, N and NH3.