Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/10/2016
Publication Date: N/A
Technical Abstract: Two experiments were conducted to evaluate the effect of bait delivery rate on methane emission estimates measured by a GreenFeed system (GFS; C-Lock, Inc., Rapid City, SD). The manufacture recommends that cattle have a minimum visit time of 3 minutes so that at least 3 eructations are captured to effectively measure methane emission. Hence, the total time that an animal spends in the GFS can impact the methane emission estimates. Because cattle voluntarily place their heads in the GFS, they are encouraged to extend their visit by the small amounts of bait (32 grams) the GFS delivers at discreet intervals. Data were collected from cattle grazing a native mixed-grass prairie range site in northwest Oklahoma. These 2 experiments were conducted to evaluate the effect of time interval between bait deliveries (alfalfa pellets) on methane emission estimates. Thirteen heifers were used and the GFS was programmed to provide 8 portions of bait each visit with up to 4 visits/day. In Experiment 1, delivery intervals were 18, 21, 24, and 27 s over a 57-day sampling period. In Experiment 2, the delivery intervals were 19, 27, 35, and 43 s for 53 days. Data were analyzed by ANOVA for the effect of delivery intervals on daily methane gas (grams) and sampling length (seconds) with a linear and quadratic contrast. In Experiment 1, methane emission linearly decreased (P < 0.01) 7 grams/day, but in Experiment 2 there was no effect (P > 0.63) of delivery interval on methane emission. Sampling length was linearly increased (P < 0.01) by increasing the delivery interval in both Experiments 1 and 2. With these cattle that had been trained to use the GFS, baiting delivery interval had no constant effect on methane emission estimates. Further, lengthening the bait delivery intervals increased the total sampling time per day. Hence, baiting delivery interval has little effect on methane emission estimates as long as total sampling time is sufficient.