The net contributions dairy cows make to the food system in the U.S. are not necessarily well understood by consumers, Juan Tricarico of the Innovation Center for U.S. Dairy, explained at the 2015 JAM.

Tricarico noted that while nutrient conversion efficiency are sometimes used to describe these contributions they are often poorly documented or based on dubious assumptions. As result, a study was conducted to 1) define coefficients to calculate human-edible fractions of major dairy feed ingredients used in the United States, and 2) estimate the share of the dairy ration that is human-edible on a national level using these coefficients. The analysis was performed on a national average dairy ration computed from 350 farm surveys used in the carbon footprint life cycle assessment for fluid milk (available at http://www.lcacommons.gov ).

The national average ration includes weighed rations for calves, open heifers, bred heifers, first calf heifers, springers, lactating cows and dry cows, and accounts for forage grazed during the year. The national average ration includes 33 ingredients and contains 53% forage and 47% concentrate (DM basis). Food, fuel, and fiber industry byproducts (14 ingredients) account for 19% of dairy feed dry matter. Eight major crops account for 80% of dairy feed dry matter (corn 42%, alfalfa 22%, wheat 3.1%, soybean 3.0%, canola 1.8%, sorghum 1.7%, barley 1.4%, and cottonseed 1.4%).

Two coefficients were calculated to estimate human-edible fractions of each ingredient. The first coefficient was calculated as 1 minus NDF content. The non-NDF fraction was considered human-edible if it does not contain toxic compounds, and ingredients containing more than 30% NDF were excluded, Tricarico said. The second coefficient was calculated by multiplying the first coefficient by the proportion of total ingredient production currently demanded by the U.S. food industry. This coefficient incorporates current consumer demand, preferences and eating habits.

The research showed the amount of human-edible dairy feed is either 20 or 0.9% of ration DM when using coefficients 1 or 2, respectively.

Dairy cows make a net positive contribution to food supply in the U.S. by converting significant amounts of otherwise unusable plant matter in feed into food, Tricarico concluded.

 Global livestock production is projected to double by 2050 and the majority of this growth will be occurring in the developing world.

Much of the growth in the global livestock sector will occur in areas that are currently forested (i.e., parts of South America and South East Asia), it has been well established that significant reductions of carbon sequestering forests will have large effects on global climate change, Dr. Frank Mitloehner of the University of California-Davis explained at the 2015 JAM.

Mitloehner said livestock production in most countries of the developed world (e.g., U.S. and Europe) have a relatively small greenhouse gas (GHG) contribution within the countries' overall carbon portfolios, dwarfed by large transportation, energy and other industry sectors.

In contrast, livestock production in the developing world, he said, can be a dominant contributor to a country's GHG portfolio, due to the developing world's significantly smaller transportation and energy sectors. The fact that land-use changes associated with livestock (i.e., forested land converted to pasture or cropland used for feed production) are a significant source of anthropogenic GHGs in Latin America and other parts of the developing world is apparent.

The Food & Agriculture Organization attributes almost half of the climate-change impact associated with livestock to the change of land-use patterns but the U.S. and most other developed countries have not experienced significant land-use change practices around livestock production within the last few decades, sometimes centuries, Mitloehner said.

Intensification of livestock production provides large opportunities for climate change mitigation and can reduce greenhouse gas emissions from deforestation, thus becoming a long-term solution to a more sustainable livestock production, noted Mitloehner.  He explained that overall, growing demands for animal protein could strongly increase GHG emissions from agriculture but that knowledge exists to improve efficiencies in livestock production, which dramatically reduces GHG per unit of production.

What is called for is a sustainable intensification in animal agriculture, coupled with technology transfers from developed to developing countries, to supply a growing demand for animal protein using sustainable and modern production practices, Mitloehner said.