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Saving the earth with fiber digestibility

Michael Miller

August 24, 2021

In increased frequency, we see headlines in the news about greenhouse gas emissions and animal agriculture. Methane is one of the main greenhouse gases of concern. Cows produce methane from fermentation in the rumen, also called enteric methane. There is a push to reduce methane production from cows to help with climate change.

Another benefit of reducing enteric methane production is increasing rumen efficiency, as energy is lost when methane is produced in the rumen. There is a lot of information about additives that help reduce methane from ruminal fermentation, which is an exciting field to study. However, we can reduce methane using forages, in particular, highly digestible forages.

Forages are the main component of the dairy cow diet, and to achieve high milk production, the quality of the forages needs to be high. Fiber is the main constituent of forages and is quantified by neutral detergent fiber (NDF). This can be further broken down into potentially digestible (pdNDF) and indigestible NDF (iNDF). Some forages have gene mutations that allow for greater fiber digestibility and lower iNDF, such as brown midrib (BMR) corn silage and low-lignin alfalfa. An article from the Journal of Dairy Science investigated the effects of feeding conventional (CONV) corn silage or BMR corn silage to dairy cows on intake, milk yield and enteric methane emissions. They reported that cows fed BMR corn silage consumed more dry matter and produced more energy-corrected milk (ECM) than cows fed CONV corn silage. Cows fed BMR corn silage also produced less methane when expressed as gram per kilogram of dry matter intake (DMI) compared to cows fed CONV corn silage. Cows were able to utilize more of the corn silage and produce less methane.

This study focused on corn silage, which leads one to question whether this fiber digestibility effect would also occur in grass silage. In an article from the Journal of Animal Feed Science and Technology, they reported that cows fed an early-cut grass silage (high fiber digestibility) had greater intakes and milk yields while also producing less methane, when expressed as liters per kilogram of DMI compared to cows fed a late-cut grass silage (lower fiber digestibility). So, forages with higher fiber digestibility and lower indigestible fiber allow the cow to better reach her genetic potential with greater intakes and milk production and less methane production.

Dairy farmers have been and will continue being stewards of the land to help conserve soil, as this gives them the ability to grow their own feed. As the fiber digestibility of those forages increases, cows will respond with greater intakes and milk yield while producing less methane. Another benefit of highly digestible forages is the ability to feed a high-forage diet that can support high production with less purchased feed cost. So, with these considerations, we can create a forage system for your dairy that can help save the dairy money while also saving the planet by reducing methane emissions from your cows.



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