There is no question that the ongoing narrative concerning climate change and various “man-induced” gas emissions (including ammonia, carbon dioxide, methane and nitrous oxide) includes dairy production.

While many producers (and others involved in agriculture) may not agree with the significance or level of gas contributions of agriculture to the total production, that disagreement may be somewhat irrelevant. The discussion, social media uproar, political activism and governmental regulations are, seemingly, hard and fast.

A 2013 study sponsored by the California Air Resources Board showed that the dairy industry contributed a total of 4% of the greenhouse gases (GHGs) emitted in California. Similar results may also be seen across the U.S. Other estimates have shown ag’s GHG contribution as low as 2.5% of the total.

Despite what some might consider relatively low contributions, this issue involves and targets the dairy industry. It involves everything from gases cows produce in the rumen and release via eructation (burping), to those produced from normal lagoon functions and those produced by microbial activity on the pen surface. To clarify a point made erroneously by poorly informed media, politicians and many of your favorite Hollywood entertainers, emissions from the backend of the animal are insignificant. Most gas production by dairy cattle is related to rumen-based microbial activity in the breakdown of nutrients, particularly fiber and other carbohydrates provided to the animal through the feeding program.

Much of this issue is a concern in intensive dairy production states like California. Given California’s political and environmental regulatory positions, dairies there have been the target of scrutiny for years and subsequently have led the way for the entire dairy industry in GHG mitigation. Over recent years, U.S. dairies, in general, have accomplished a great deal, including a 63% reduction in GHG emissions per gallon of milk. This accomplishment is not related to a push for lower emissions. It is the result of ever-increasing improvements in efficiency of milk production related to improved management, nutrition and genetics.

There has been an increase in uses of alternative energy sources, including the establishment and growth of the digester industry. This has helped reduce the handling of manure and provided an alternative on-farm energy source.

Keep in mind that the production of these various gases is simply a normal byproduct of rumen function. The rumen is a fermentation vat. As rumen microbia break down various feed particles and nutrients, various gases are produced as a waste product. So as dairy producers take management steps to reduce gas emissions, questions arise. How does basic nutrition and feeding of cows affect GHG emissions on the farm? Can we further reduce production of gases like ammonia and methane by altering feed ingredients?

One thing we should remember is that earlier research has shown that feeding programs, products and additives that reduce production of these waste gases also serve to improve feed efficiency in the cow, at some level. In other words, this results in an increase in energy retention that serves to meet maintenance and production energy requirements.

Recent research has shown that GHG production can be related to diet or ration type as well as level of dry matter intake. An example: Dry matter intake for dairy cows is higher than that of beef cattle. Secondly, dairy diets are largely forage- or fiber-based, whereas feedlot cattle consume a predominantly starch-based diet. Research has shown that on a total amount of GHG produced per head, dairy cattle with higher dry matter intake and higher fiber intake produce more GHG. So diet type has a direct effect. It also has been shown that diet GHG potential can be modified. This has also resulted in some of ration modeling and formulation systems to now include a GHG potential estimation component.

Additionally, revised formulation and diet development research has shown that improved ration/diets combined with better forage quality can work to not only improve animal performance by increasing nutrient yields absorbed by the animal, but it also increases nutrient retention in the rumen. This results in less waste and GHG output. So reduced emissions can be a byproduct of an improved nutrition program.

Feed additives

Several feed additives have been identified and are being developed to reduce GHG. Recent research has shown a growing number of additives that may reduce GHG emissions and potentially improve rumen function. Some additives include enzyme sources (especially fibrolytic enzymes), yeasts and other direct- fed microbials and plant extracts. Many of these have been initially identified as a means of improving diet digestibility and increasing feed efficiency as it affects milk and component production. Feeding of ionophores such as Rumensin have long been known to improve feed efficiency in beef and dairy diets. Rumensin has been known for quite some time for its ability to reduce the production of methane, ammonia and other gases.

More recently, specific additives have been identified and developed as a means of specifically reducing methane production.

3-Nitrooxypropanol (trade name Bovaer, Royal DSM) is a product researched around the world for the last 10 years as a methane mitigant in both beef and dairy cattle. Extensive research has been conducted at Penn State University on this and other additives to examine not only the effect the product has on methane reduction but, importantly, any effects on milk production and components. This same product has been researched in feedyard cattle in Alberta, Canada in conjunction with Agriculture and Agri-Food Canada and other groups. The Penn State research showed reductions in methane production of 16% to 36%, depending on various nutrition and production parameters, while having minimal overall effect (positive or negative) on milk and component production. Ag Canada feedlot trials showed reductions as well. These, similarly, had minimal effects on gains or feed efficiency. In the U.S., DSM Nutritional Products is seeking approval through the FDA to use this product as a medicated feed item.

Other research, such as that conducted at the University of California-Davis, has focused on the effects of a seaweed-based product. Some data reports methane output reductions as large as 90%.

Furthermore, a Swiss-based company, Mootral, is researching and developing a plant extract product that is also showing positive responses in reducing methane output in dairy cattle. Studies have shown a potential reduction of as much as 40%.

Cost effective?

For the dairy producer, additives such as these show promise for reducing methane and other GHG particularly in markets, such as California, where legislation is in place to require methane and GHG reductions. However, the question becomes, can the inclusion of these additives or other GHG mitigating practices be done in a cost-effective manner? Or will this simply be another cost of production? Limited cost information is available at this time, and until wider-spread research is available on-farm, the industry lacks practical knowledge of true effects or costs to the producer. For an industry that struggles with profitable production, the inclusion of yet another expense that may or may not have any performance enhancement is troubling.

One potential bright spot may be that some retail food-marketing companies, to create a larger environmental conscious picture for their consumers, may require producers to include such products or practices in the production of milk or meat and possibly, in some form, pay the producer accordingly. This is referred to as pull-through marketing and is becoming commonplace as retailers such as Walmart or McDonalds work to appease their environmentally sensitive customers. So the possibility may exist that the pull-through from these retailers could result in better commodity (milk or meat) price for producers. Conversely, it could also serve as a requirement for purchase where no incentives are offered to the producer.

Conclusions

Issues raised concerning methane and GHG production by the dairy industry are apparently here to stay. The positive side of this argument is the effect of improving management to comply with growing regulations. With existing and developing tools (additives) emerging, opportunities for compliance to the regulatory environment is improving. However, at this point, the industry still does not have a clear picture of the cost and implications to the producer. Only time will tell.

References omitted but are available upon request by sending an email to the editor.