Grape marc reduces methane emissions when fed to dairy cows

Area of Science:

• Animal Science
• Agricultural Science
• Environmental Science

Background:

• Grape marc, a winemaking byproduct, contains condensed tannins and crude fat, which can mitigate enteric methane (CH4) production in ruminants.
• Current utilization of grape marc as a feed supplement presents an opportunity to reduce methane emissions from livestock.

Purpose of the Study:

• To investigate the impact of dried, pelleted grape marc (DGM) and ensiled grape marc (EGM) as dietary supplements on dairy cow milk yield and composition.
• To quantify the effects of DGM and EGM on enteric CH4 emissions and ruminal microbial communities in Holstein dairy cows.

Main Methods:

• Thirty-two late-lactation Holstein dairy cows were assigned to three dietary groups: control (CON), DGM, or EGM for 18 days.
• Feed intake, milk yield, and milk composition were monitored. Enteric CH4 emissions were measured using the SF6 tracer technique.
• Ruminal bacterial, archaeal, fungal, and protozoan communities were quantified via microbial community analysis.

Main Results:

• Milk yield was lower in the EGM group compared to CON and DGM groups. Both DGM and EGM diets decreased milk fat yield and saturated fatty acids while increasing beneficial unsaturated fatty acids.
• Enteric CH4 emissions and yield decreased by approximately 20% in cows fed DGM and EGM diets compared to the CON diet.
• Grape marc supplementation altered ruminal bacterial and archaeal communities, but not fungal or protozoan communities.

Conclusions:

• Dietary supplementation with dried or ensiled grape marc can significantly reduce enteric CH4 emissions in dairy cows.
• Grape marc can improve milk fatty acid profiles, offering nutritional benefits.
• The use of grape marc as a feed supplement presents a viable strategy for CH4 abatement in ruminant agriculture.