Quantification of enteric methane according to physiological state in high producing dairy cows in Costa Rica

Abstract

This research quantifies the enteric methane emission in highly productive Holstein cows in a commercial dairy farm, by using the SF6 technique. The objective was to determine enteric methane emission in Holstein cows in different physiological states in an intensive grazing milk production system. Nine Holstein cows were selected which represented the typical conformation of the herd in age (5.7±0.6 years), number of lactations (3.6±0.4 births), average milk production (7924±280 kg) and live weight (672±36 kg), in different physiological states: dry (D), pre-partum (PP), early lactation (EL), and in medium/final (M/F) lactation state. Forages and supplements provided prior to milking were weighed and sampled in order to determine dry matter intake and digestibility (67.8±1.9%). In each methane measurement period, samples were collected from pastures to determine crude protein (15.9±0.3%), neutral detergent fiber This research quantifies the enteric methane emission in highly productive Holstein cows in a commercial dairy farm, by using the SF6 technique. The objective was to determine enteric methane emission in Holstein cows in different physiological states in an intensive grazing milk production system. Nine Holstein cows were selected which represented the typical conformation of the herd in age (5.7±0.6 years), number of lactations (3.6±0.4 births), average milk production (7924±280 kg) and live weight (672±36 kg), in different physiological states: dry (D), pre-partum (PP), early lactation (EL), and in medium/final (M/F) lactation state. Forages and supplements provided prior to milking were weighed and sampled in order to determine dry matter intake and digestibility (67.8±1.9%). In each methane measurement period, samples were collected from pastures to determine crude protein (15.9±0.3%), neutral detergent fiber This research quantifies the enteric methane emission in highly productive Holstein cows in a commercial dairy farm, by using the SF6 technique. The objective was to determine enteric methane emission in Holstein cows in different physiological states in an intensive grazing milk production system. Nine Holstein cows were selected which represented the typical conformation of the herd in age (5.7±0.6 years), number of lactations (3.6±0.4 births), average milk production (7924±280 kg) and live weight (672±36 kg), in different physiological states: dry (D), pre-partum (PP), early lactation (EL), and in medium/final (M/F) lactation state. Forages and supplements provided prior to milking were weighed and sampled in order to determine dry matter intake and digestibility (67.8±1.9%). In each methane measurement period, samples were collected from pastures to determine crude protein (15.9±0.3%), neutral detergent fiber (63.0±0.9%) and in vitro dry matter digestibility. Daily methane emission per cow was similar (p>0.05) in D, PP and in M/F, and higher (p<0.05) in EL, with ranges (g.c^-1.d^-1) between 240 and 443 in D, from 238 to 483 in PP, from 277 to 506 in EL, and from 281 to 470 in M/F. A linear relationship was determined between total dry matter intake and methane emission (r² varied between 0.42 and 0.78 depending on physiological state), as well as between methane produced and milk production per day (r²=0.71). High producing cows emit more methane but are less methane emitters per liter of milk produced. The Ym varied depending on physiological state of the cows, and the annual value was similar to that suggested by IPCC. 

Keywords: Enteric methane; dairy cows; grazing; tropics; SF6; greenhouse gases.