Methane emission as determined in contrasting dairy cattle breeds over the reproduction cycle

Abstract

In order to be able to quantify potential dairy breed differences in methane production, measurements of gaseous exchange were made in respiratory chambers at six different time-points within the reproduction cycle (4 weeks before calving and lactation weeks 8, 15, 23, 33 and 41). Ten cows each of Holstein (large framed, pure dairy breed), Jersey (small framed, pure dairy breed), and Simmental (large framed, dual-purpose breed) were employed. No breed differences were found in methane emission per kg of dry matter (DM) intake (25–26 g) except in the dry period. However, Simmental cattle emitted more methane per kg of energy-corrected milk (24 g) than the other two breeds (20 g) throughout the entire lactation. This was resulting from the consistently lower ratio of milk production to body weight affecting the proportion of feed required for maintenance purpose. The same relationship occurred with progressing stage of lactation, while methane emission per unit of DM intake again remained unaffected, except in the dry period where they were higher. Coefficients of variation of methane per unit of DM intake did not differ between breeds both across stages of the reproduction cycle and across individual cows. Therefore, it seems unlikely that there are major differences among cows of different dairy breeds in the proportionate methanogenic activity of the rumen and its microbes. Any differences might be explained by associated changes in feed intake and conversion ratio.