Assessment of additive used to formulate molasses lick blocks to reduce beef cattle methane emissions

Maria NikoloricGamaliel SimanungkalitMalcolm PossellLuciano Adrian GonzalezAlex V Chaves^*

• School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney, Australia

Methane (CH₄) emissions from ruminants significantly contribute to agricultural greenhouse gases. Strategies to reduce these emissions without compromising productivity are urgently needed. This study evaluated the effectiveness of a novel product incorporated into molasses lick blocks and grain-based pellets to reduce methane emissions and improve productivity in grazing beef cattle. Four products were screened in vitro for their efficacy in reducing methane production. The most effective (Product 3) was then incorporated into grain-based pellets and offered to steers via GreenFeed units at target intakes of 0, 100, and 200 g/head per day. Dry matter intake (DMI), CH4 production, methane yield (g CH₄/kg DMI), methane intensity, water intake, and average daily gain (ADG) were measured. Product 3 reduced in vitro methane production by over 90% at a 6% inclusion rate (P < 0.05). In vivo, steers supplemented with product-containing pellets tended (P = 0.07) to reduce CH₄ production by 10.7% compared to the control. Methane yield was reduced (P < 0.01) by 11.7% and 7.5% for the 100 and 200 g/day supplementation levels, respectively. Methane intensity tended (P = 0.06) to be 16.8% lower in supplemented groups. Product intake was negatively correlated with CH₄ yield and intensity and positively associated with water intake and ADG (P < 0.05). The inclusion of Product 3 in supplements for grazing beef cattle significantly reduced methane yield and tended to reduce methane production and intensity, without negatively impacting performance. Product 3 shows potential as a viable methane mitigation strategy for grazing systems. However, further research is needed to assess the long-term effects and potential microbial adaptation associated with higher or prolonged dosing.