PSII-1 Determining Appropriate Numbers and Times of Daily Measurements to Estimate Ruminal Methane Emission of Meat Goats Using a Greenfeed System

Abstract

Abstract The study was conducted to determine appropriate numbers and times of daily measurements to estimate methane production by meat goats using a GreenFeed (GF) system. Sixteen Boer wethers with an initial age of 7.4 ± 0.08 months and BW of 20.02 ± 0.71 kg were situated in a 12.4 × 12.4 pen. Oat hay, which was the major dietary constituent, was offered twice daily in individual Calan Gate feeders. Concentrate-based pellets were used as bait feed to attract animals to visit the GF regularly. The system was programed using C-Lock Inc. software to automatically dispense a small amount of pellets (120 g/day) and to measure methane production using sensors in the system. Each animal had a unique RFID tag identified by RFID reader in the system. There were 3, 4, and 6 equally spaced 1-h feeding and measurement periods (i.e., 0600-0700, 1400-1500, and 2200-2300 h for GF-3T, 0700-0800, 1300-1400, 1900-2000, and 0100-0200 h for GF-4T, and 0800-0900, 1200-1300, 1600-1700, 2000-2100, 0000-0100, and 0400-0500 h for GF-6T, respectively). The study was a Latin square with each feeding period assigned to each animal for a 2-wk period. Data were analyzed with mixed model procedures of SAS. Methane emission in g/day and g/kg dry matter intake (DMI) were not impacted by feeding period (P > 0.05). When expressed in g/min, g/visit, and g·visit-1·min-1, differences in CH4 production between feeding schedule were significant (P < 0.02). The GF-6T treatment resulted in greatest emission of CH4 in g/min (5.7, 5.9, and 6.6 for GF-3T, GF-4T, and GF-6T, respectively; P < 0.04). On the other hand, CH4 emission in g/visit ranked (P < 0.05) GF-3T > GF-4T > GF-6T (12.8, 10.9, and 7.3, respectively). Regarding CH4 intensity (g/kg BW), the differences between treatments were not significant (1.10, 1.17, and 1.16 for GF-3T, GF-4T, and GF-6T, respectively; P = 0.24). Heat production (MJ/day), which was calculated from CH4, CO2, and O2 production, was greater (P < 0.05) for GF-3T (8.1) than for GF-6T (7.6), with that for GF-4T intermediate (7.6; P > 0.05). Animals of GF-3T, GF-4T, and GF-6T visited the GF 2.1, 2.8, and 3.8 times per day, which significantly (P < 0.001) differed from each other. Average visit length was similar for GF-3T and GF-4T (P > 0.05) and greater (P < 0.05) than for GF-6T (4.6, 4.6, and 4.1 min for GF-3T, GF-4T, and GF-6T, respectively). In conclusion, results of the study indicate that at least 3 daily feeding or measurement periods should occur between 0600 and 0700, 1400 and 1500, and 2200 and 2300 h to accurately estimate methane production using a GF system in a confinement setting.