Methane emissions intensity in grazing dairy cows fed graded levels of concentrate pellets

ABSTRACT

The current New Zealand greenhouse gas inventory predictions assume that dairy cows consume pasture only, but the use of supplemental feeds, including concentrates, on New Zealand dairy farms has increased greatly in recent decades. The objective of this study was to evaluate the effect of feeding graded levels of concentrates on methane (CH₄) emissions in lactating dairy cows within a pastoral system. Early lactation dairy cows (n = 72) were allocated (n = 18 per treatment) to receive 0, 2, 4 and 6 kg dry matter (DM) of treatment concentrates per day during milking. The cows grazed pasture ad libitum and CH₄ emissions were measured in the paddocks using automated emissions monitoring systems called ‘GreenFeed’. Gross CH₄ emissions (g/d) were similar for cows across the four dietary treatments, while CH₄ emissions intensity (g/kg fat and protein corrected milk production (FPCM) and milk solids production) linearly decreased with increasing concentrate inclusion in the diet (P < 0.02). The CH₄ intensity decreased linearly (r² = 0.42) and quadratically (r² = 0.53) with increasing FPCM production.

KEYWORDS:

• Enteric greenhouse gas emission
• pastoral
• cattle
• ruminant
• supplements

Acknowledgements

Troy Bosher received a scholarship from AgResearch Limited, New Zealand for his MSc degree at Massey University. The authors thank the staff of Massey University Dairy Farm 4 for their help with the husbandry of the dairy cows during the study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The dairy cow feeding study was funded by the Greenhouse Gas Inventory Research fund of the Ministry for Primary Industries (Wellington, New Zealand).