Managing Dairy Cattle Rations to Reduce Nutrient Loss & Optimize Milk Production
Dairy cows produce methane 24 hours a day, 365 days a year due to their unique digestive tract that allows them to break down plants and turn them into meat and milk.
- For cows to produce lots of milk, they need to eat a diversity of nutrients such as proteins, minerals, and fats.
- Any excess nutrients they receive can subsequently end up in their waste which can impact local air and water quality.
So, what can we do about greenhouse gases and water quality issues from dairy production? Research in nutrition through optimizing animal health and milk production has allowed farmers to implement these practices and significantly decrease the environmental footprint of milk.
There are three ways we can manage dairy rations to improve nutrient losses and decrease greenhouse gas emissions.
1. Reducing excreted N and P through feed management.
Cow nutritionists are trained dietitians that create recipes to support cows’ health and milk production.
- Nutritionists utilize practices known as amino acid balancing where they make a recipe that includes all 10 essential amino acids that a cow needs to maintain health and milk production.
- Farmers feed the exact amount of dietary protein, which can subsequently decrease farm production of ammonia and nitrous oxide, a local air pollutant and a greenhouse gas respectively.
The same goes for phosphorus. Nutritionists can optimize the amount of phosphorus included in the diet so that cows receive the exact amount of nutrients necessary in their feed and nothing extra.
- This goes back to ensuring the phosphorus source can be digested by the cows, quantifying how much phosphorus is brought onto the farm in feed and fertilizer, and subsequently managing how much manure is applied to fields.
- Farmers are required to manage their nutrients through Confined Animal Feeding Operating (CAFO) planning, which only allows nutrients to be applied to fields depending on how much phosphorus the crop planted needs to grow.
- Researchers have made significant progress on properly managing nitrogen on farms and ongoing work is determining how to effectively manage phosphorus.
2. Reducing methane emissions through feed management.
Fiber—typically from forages—is one of the main feed sources for cow methane production. Conversely, dietary fats and grains soak up the molecules that would become methane, allowing cows to utilize that carbon for energy. While most dairy farmers are feeding a small amount of grain already, dairy producers can look to incorporate around 6-7 pounds per cow per day to help reduce emissions.
- Dairy cow methane emissions can be reduced by 10-15% with the right combination of feedstuffs.
- Many grains require nitrogen fertilizer to be utilized to achieve optimum performance, which results in the production of nitrous oxide, which is more potent warmer than methane.
- Careful consideration must account for the climate impact of growing those feeds and utilize management strategies that can minimize the carbon intensity.
Rumen modifiers include plant compounds and essential oils.
- These molecules adhere to the methane producing microbes in the cow’s stomach or capture the free hydrogen to prevent methane formation.
- Utilizing these modifiers can yield a net 10% reduction in methane emissions with varying levels of success.
- Most of these modifiers are currently fed for reasons such as improving animal health, nutrient utilization, or milk production and the methane reduction benefits are seen as a secondary benefit.
By formulating a climate friendly ration, it may be possible to reduce methane emissions as much as 15-20% in the short term.
3. Optimizing milk production to minimize GHG emissions per gallon of milk (intensity).
While we want to reduce livestock methane emissions, we don’t want to do so at the expense of reducing milk production. Therefore, diet formulation must include an appropriate number of amino acids, energy, and fiber intake to maintain happy and healthy cows. The U.S. dairy industry has had incomparable success in reducing the environmental impact per gallon of milk produced by increasing the milk productivity per cow.
- Healthy animals produce more milk. Reducing disease on farms as well as treating sick cows as early as possible helps minimize the impact of sickness on milk production.
- Utilize genetics for high milk producing cows. Cows that produce more milk utilize a smaller percentage of what they eat to sustain their own health. In a sense they dilute out the feed they eat to sustain health and use a greater percentage for milk production.
- Most rumen modifiers are currently fed for reasons such as improving animal health, nutrient utilization, or milk production and the methane reductions are seen as a secondary benefit.
While the methane reducing feed additives that can achieve 30+% methane reductions are still a couple of years away from implementation, dairy farmers can keep maximizing efficiency and drive down the carbon footprint per pound of milk produced. Additionally, producers can bridge the gap before methane inhibiting additives arrive by constructing a diet for cow and planetary health.