Effect of dietary inclusions of types of Acacia mearnsii on enteric methane and other gases production in dairy cows

Abstract

Methane (CH4) poses a greenhouse effect and research is focusing on the use of tannins to control this gas. This study investigated the effect of dietary inclusions of A. mearnsii De Wild. forage (AMF) in maize (Zea mays L.) silage diets or tannin extract (ATE) this forage in pellets on ruminal enteric CH4 in dairy cows. For each of two experiments, 24 crossbred Holstein-Friesian and Jersey dairy cows that had ⁓200 d in milk were selected. Cows were grouped into four groups of six cows each. The experiments were done in a completely randomized design. In experiment 1, cows were fed pellets containing 0.75% (0.75ATE), 1.5% (1.5ATE) and 3.0% (3ATE) A. mearnsii tannin extract (ATE) and a commercial concentrate as a control (0ATE). In experiment 2, cows were fed 0% (AMF), 5% (AMF), 15% (AMF) or 25% (AMF) A. mearnsii forage (AMF) in maize silage diets. For both experiments, cows were adapted to diets for 14 d followed by 21 d of weekly data collection. Sampling of ruminal CH4 and other gases (N2, CO2and H2) was conducted weekly during the data collection period by pricking the rumen. The multiple gas analyser device (SKZ Industrial, Jinan, China) was used to measure enteric CH4 (% vol) and other gases (N2, H2 and CO2, % vol). The inclusions of ATE in pellets did not affect CH4 (P > 0.05), while the inclusions of AMF in maize silage diets affected (P 0.05). The CH4expressed in intakes of dry matter (DM), organic matter (OM), crude protein (CP), acid detergent fibre (ADF) and neutral detergent fibre (NDF) (kg d-1) decreased at 25AMF (P < 0.0001). The linear and quadratic effects of AMF affected the enteric CH4 per intake of DM, NDF, ADF and OM (P < 0.05). Inclusion of tannin extract in pellets did not affect CH4 while AMF inclusions in maize silage diets of dairy cows can potentially decrease enteric CH4.

Keywords

• Greenhouse gas, methane, rumen-headspace gases