Evaluation of enteric methane production in dairy cows fed Acacia mearnsii

We investigated the effect of different incorporations of Acacia mearnsii forage (AM) in maize silage or A. mearnsii tannin extract (AME) in pellets on dairy rumen CH₄.

Using a completely randomized design per experiment, 24 crossbred Holstein-Friesian and Jersey dairy cows per experiment were divided into groups (n = 6 cows per experiment). Dairy cows were fed pellets with 0% (0PEL), 0.75% (0.75PEL), 1.5% (1.5PEL), or 3.0% (3PEL) of AME (Experiment 1). Furthermore, dairy cows were fed 0% (0AM), 5% (5AM), 15% (15AM), or 25% (25AM) of AM in maize silage (Experiment 2). Data sampling period (21 days) of ruminal CH₄ and nitrogen (N₂), carbon dioxide (CO₂), and hydrogen (H₂) gases (% vol) was conducted after the adaptation period (14 days) for each experiment.

Enteric CH₄ was not affected by AME inclusion, but AM inclusions affected CH_4, except for CH₄ (% vol per cow per day). The inclusions of 25AM decreased CH₄ per nutrient intake (kg/day), such as dry matter (DM), organic matter (OM), crude protein, acid detergent fiber (ADF), and neutral detergent fiber (NDF). In addition, there was a linear and quadratic AM inclusion effect on CH₄ per intake of nutrients, including DM, NDF, ADF, and OM.

Enteric CH₄ was not affected by AME but was decreased by AM in dairy cows.