Methane emissions in growing heifers while eating from a feed bin compared with 24-hour emissions and relationship...

The objective of the current study was to determine the relationship of daily CH₄ emissions estimated during mealtime compared with measured daily CH₄ emissions, and determine the relationship with feeding behavior, in growing heifers fed alfalfa silage in respiration chambers. Data from 8 growing cattle (Hereford × Holstein-Friesian) individually housed in 4 respiration chambers and fed ad libitum alfalfa silage delivered in Insentec feed-bins to record feeding behavior and intake were used. The 4 chambers are linked to 1 analyzer, which measures CH₄ in each chamber approximately every 3 min. Each 3-min measurement was expressed as grams per day and averaged per 24 h or per time during a meal. A strong correlation (r = 0.88; determined using Deming regression) was observed between CH₄ emissions (g/d) during mealtime (276 ± 22.7 g/d) and measured over 24 h (262 ± 24.0 g/d), without apparent systematic bias. Feeding behavior parameters that were correlated with CH₄ yield (g/kg dry matter intake) in the current study were a negative correlation with the number of visits to the feed bin (r = -0.45), average meal size (r = -0.57), and average daily eating rate (r = -0.48). In summary, CH₄ measured during meals was similar to 24-h measured CH₄ output in growing heifers fed ad libitum alfalfa silage in respiration chambers, and some feeding behavior parameters, based on feed bin visits, explained some of the variation in CH₄ yield between animals.