Researchers at University of California, Davis, added fresh grape pomace left over from winemaking operations to alfalfa-based feed for dairy cows and found that methane emissions were reduced by 10% to 11%. The preliminary findings could offer a low-cost sustainable pathway for vineyards to reduce waste while helping dairy operations maintain quality while cutting back on emissions of methane, which is a powerful greenhouse gas.

“We found that the feed with the additive of grape pomace changed the fatty acid composition of the milk and, in particular, increased the polyunsaturated fats, which are the main fats in grape pomace,” said Selina Wang, head of research. “This suggests that supplementing the feed with an optimal fatty acid profile may have positive impact on the fatty acid profile of the milk and increase their health benefits.”

Wine grapes are high in fats and tannin, which is known to reduce methane emissions, so the research sought to test if adding grape pomace to feed could have a positive effect while not adversely affecting production. “It’s a byproduct that’s not being used much,” he said. “This is something that can be included in our efforts to try to reduce emissions.”

To do the research, scientists worked with Holstein dairy cows and gave the animals feed consisting of alfalfa, wheat, almond hulls, cottonseed and grain. After two weeks, the cows were split into three groups: A control group with no change in diet, another where the feed combination included 10% grape pomace and a third that received 15% grape pomace. Every four weeks, the cow groups would change feed combinations.

They were fed twice daily by postdoctoral students and interns, and emissions were monitored daily. Milk production was documented in the morning and evening and milk samples were collected weekly to analyze for fat, protein, lactose and other measurements, which showed no differences between the control and other groups.

Methane and hydrogen emissions were reduced compared with the control group, suggesting that grape pomace reduced enteric emissions without affecting production.

After 5 months of intense negotiations the Danish government is introducing an agricultural carbon tax payable by farmers, the first of its kind worldwide.

From 2030, this climate tax on agriculture will be charged at 300 Danish krone (€40; US$43) per ton of CO2e produced, increasing to 750 Danish krone (€100; US$107) by 2035.

However, a basic deduction, or tax break, of 60% will be applied to the average emissions from different types of livestock, providing an economic advantage to climate-efficient farmers. Following this reduction, farmers will pay 120 Danish krone (€16; US$17) per ton of CO2e in 2030, and 300 Danish krone in 2035.

Denmark is a big exporter of dairy and pork produce and agriculture emissions make up 22.4% of the country’s total carbon emissions, compared with 15.6% ten years ago.

In terms of numbers, Denmark has 547,000 dairy cows, on 2,300 farms, producing 5.87 billion kg of milk per year. It has around 900,000 beef and other cattle as well as 11.5 million pigs.

Experts believe the carbon tax will slash 1.8 million tonnes of carbon production in its first year of operation, enabling Denmark to meet its target of cutting 70% of its total emissions by that year.

This bold move comes with the agreement between the coalition government and a number of Danish farming bodies and is likely to set a precedent for other countries to follow. Sanctioning the tax with the Danish government were the Danish Agriculture and Food Council, the Danish Society for Nature Conservation, the Confederation of Danish Industry, the Trade Union NNF, and the Danish Local Government Association.

The money raised by this carbon tax is said to be going back into the agricultural sector to enhance green initiatives and climate technology. Calls have been made to ensure this tax collection is regulated and that it should possible align with an emissions trading system at EU level.

Meanwhile, farmers around the world took to social media to comment on the tax. Some called it “a real breakthrough moment for agriculture” whilst others said: “Take note, this nonsense is coming our way too.”

A new Cornell University study provides evidence that a spillover of avian influenza from birds to dairy cattle across several US states has now led to mammal-to-mammal transmission.

“This is one of the first times that we are seeing evidence of efficient and sustained mammalian-to-mammalian transmission of highly pathogenic avian influenza H5N1,” said Diego Diel, associate professor of virology and director of the Virology Laboratory at the Animal Health Diagnostic Center (AHDC) in the College of Veterinary Medicine.

Whole genome sequencing of the virus did not reveal any mutations in the virus that would lead to enhanced transmissibility of H5N1 in humans, although the data clearly shows mammal-to-mammal transmission, which is concerning as the virus may adapt in mammals, Diel said.

As of July 24, 11 human cases have been reported in the U.S., with the first dating back to April 2022, each with mild symptoms: four were linked to cattle farms and seven have been linked to poultry farms, including an outbreak reported in the past few weeks in Colorado. These recent patients fell ill with the same strain identified in the study as circulating in dairy cows, leading the researchers to suspect that the virus likely originated from dairy farms in the same county.

While the virus has the ability to infect and replicate in people, the efficiency of those infections is low.

“The concern is that potential mutations could arise that could lead adaptation to mammals, spillover into humans and potential efficient transmission in humans in the future,” Diel said.

It is therefore critical to continue to monitor the virus in affected animals and also in any potential infected humans, Diel said. The U.S. Department of Agriculture (USDA) has funded programs for H5N1 testing, at no cost to producers. Early testing, enhanced biosecurity and quarantines in the event of positive results would be necessary to contain any further spread of the virus, according to Diel.