Posts Tagged: milk
Got milk? Got a question about tsetse flies? Yes? Then you'll want to attend the Science Café presentation on Wednesday, June 7, when medical entomologist and tsetse expert Geoffrey Attardo of the UC Davis Department of Entomology and Nematology will discuss “Got Milk? The Evolution...
Medical entomologist Geoffrey Attardo with some of his images he displayed at the UC Davis Picnic Day. (Photo by Kathy Keatley Garvey)
When it comes to nursing moms and their babies, an elegant web of cause and effect connects climate, breast milk, gut microbes and infant health.
That web was clearly illustrated by a recently published study involving 33 women and their babies in the West African nation of The Gambia. The research team, including scientists from UC Davis and UC Agriculture and Natural Resources, found that complex breast milk sugars called oligosaccharides helped protect nursing babies from illness and also influenced the mixture of microbes in the infants' guts.
The researchers also showed that changes in food availability from season to season could affect the composition of the women's breast milk and the protective quality of the babies' gut microbiota. And those changes, in turn, impacted the health and growth of the breastfed infants.
Composition of breast-milk sugars and infant health
Oligosaccharides occur abundantly as more than 200 different chemical structures in human breast milk. It's been known for some time that these complex sugars contribute to infant health by supporting the growth of beneficial bacteria in the baby's gut. And these gut bacteria have been shown to play a key role in fending off infectious illnesses.
But little has been known about how changes in the composition of the breast milk sugars might affect the health and growth of infants, especially those living in areas where infection rates are high.
To explore that relationship, the researchers monitored the composition of the oligosaccharides in the mothers' milk and examined the infants' gut microbiota at 4 weeks, 16 weeks and 20 weeks after the babies were born. Then they analyzed the data, looking for possible relationships to the health and growth of the babies and the status of their gut microbes.
They found that two of the oligosaccharides, lacto-N-fucopentaose and 3′-sialyllactose, had a direct relationship to the babies' health and growth. High levels of the former were associated with a decrease in infant illness and with improved growth, measured as height for age, while the latter proved to be a good indicator of infant growth, measured by weight per age.
“Our findings provide evidence that specific human milk oligosaccharides can alter the composition of breast milk, making it more protective against infection and allowing the infant to invest energy in growth rather than fending off disease,” said the study's corresponding author Angela Zivkovic, an assistant professor of nutrition at UC Davis.
Influence of wet and dry seasons
The researchers also were curious how seasonal shifts in food availability, which significantly impact the mothers' diets, might be reflected in breast milk composition and infant health.
The Gambia has two distinct seasons, the wet season from July to October and the dry season from November to June.
The wet season is also known as the “hungry” season because it is the time of year when food supplies tend to be depleted, infection rates rise and the farming workload is highest. In contrast, the dry, or “harvest,” season is characterized by plentiful food supplies as well as significantly higher energy stores and less illness among the local people.
The researchers found that mothers who were nursing during the wet or “hungry” season produced significantly less oligosaccharide in their milk than did those nursing during the dry season.
In examining the makeup of the babies' gut microbiota, the researchers noted that most of the bacteria belonged to the Bifidobacteria genus. They also discovered that higher levels of Dialister and Prevotella bacteria were accompanied by lower levels of infection.
In addition, higher levels of Bacteroides bacteria were present in the infants' guts that had abnormal “calprotectin” – a biomarker associated with intestinal infections.
“We are very interested in which specific dietary factors influence the oligosaccharide composition of mother's milk,” Zivkovic said. “If we can find the mechanisms that change the composition of breast milk sugars, we may have a new approach for modifying the infant microbiota and ultimately influencing the health and vigor of the nursing baby.”
The study by Zivkovic and colleagues appears online in the journal Scientific Reports. The research is part of a long-running, cross-disciplinary project at UC Davis examining milk and its role in nutrition.
Funding for the study was provided by the National Institutes of Health, UK Medical Research Council, Bill and Melinda Gates Foundation, Alfred P. Sloan Foundation, and Peter J. Shields Endowed Chair in Dairy Food Science at UC Davis.
Robert Lustig, professor of pediatric medicine at UC San Francisco, said he believes drinking whole milk can lead to lower calorie intake overall because it is more filling than low-fat and non-fat alternatives.
A UC Agriculture and Natural Resources (UC ANR) expert shared a different viewpoint. Lorrene Ritchie, director of the UC ANR Nutrition Policy Institute, said low-fat or skim milk products are still preferable to whole milk because liquid calories are not as filling as equivalent calories from solid food. Nationwide, the goal for most people should be to reduce calorie intake.
"Until we decrease calorie intake on a population level, we are unlikely to see much reversal in the obesity epidemic," Ritchie said.
Before the end of 2015, the federal government is expected to release its revised Dietary Guidelines for Americans. According to the Guardian article, the guidelines are expected to tout vegetables, fruits, whole grains, legumes, nuts, seafood and "low- or non-fat dairy." The guidelines inform the USDA's dietary infographic, which at the moment takes the form of a plate half filled with vegetables and fruit, and the other half with a small portion of protein food and whole grains.
The Nutrition Policy Institute has been advocating for the addition of water on the MyPlate icon to reinforce its position that plain tap water is the best choice for quenching thirst.
Cementing its place as California's most important agricultural commodity by farm revenue, California farms sold about $9.4 billion worth of milk while the dairy industry contributed approximately $21 billion in value added to the gross state product in 2014, according to a California Milk Advisory Board (CMAB) study conducted by the Agricultural Issues Center, a statewide program of UC Agriculture and Natural Resources. Including sales of inputs to dairy farms and milk processors along with raw milk and wholesale milk product sales, the dairy industry contributed $65 billion in total sales to the California economy in 2014. The growing demand for dairy products like cheese and yogurt as well as strong dairy exports accounted for 189,000 jobs that are dependent on the state's milk production and processing.
“The dairy industry's contributions are vital to California's economy, from creating jobs to stimulating local and regional economies to providing nutritious and enjoyable products to consumers everywhere,” said John Talbot, CEO of the California Milk Advisory Board. “A large number of California residents depend on the dairy industry for employment and these jobs would not exist without it.”
The $21 billion to California's gross state product included $7.4 billion as income to industry workers and owners and $13.4 billion through related, outside industries such as feed, veterinary and accounting services used for dairy production and electricity, packaging, equipment and trucking services used by processors. The tax revenue generated from these jobs supported important statewide initiatives to improve education, healthcare, roads, community services and the environment.
Overall, 189,000 jobs in California are associated with the dairy industry. Of this amount, approximately 30,000 jobs are on the farm and 20,000 jobs represent dairy processing. For every dairy farm job, there are several more jobs that are tied to the business and create a linked chain of economic impacts.
Additionally, the induced effect of the dairy industry also creates jobs in the community to support the area's dairy workers and their families, such as school teachers and local bus drivers.
California Holds Rank as Nation's Dairy Leader
California leads the nation in dairy production and dairy continues as the top commodity in the country's top agricultural state. It has been the nation's largest milk producer since 1993 and is also the country's leading producer of butter, ice cream, nonfat dry milk and whey protein concentrate. California is also the second largest producer of cheese and yogurt.
Farm milk sales generated $9.4 billion gross revenue in 2014. Wholesale dairy product (cheese, fluid milk, ice cream, butter and other dairy) sales hit $25 billion in 2014.
Dairy Farmers Improve Business Performance
As an essential part of California's farming heritage, dairy farmers understand the importance of protecting the land, water and air for their families, their communities and future generations. In 2014, California dairy farmers produced more milk with fewer resources. Talbot credits “improved dairy practices and management adopted by farmers” for the increased business efficiencies. The pounds of milk produced per cow increased to 24,000 pounds in 2014 from 15,000 in 1984. Farmers are applying 23 percent less water to their fields than they did in the early 1980s and have seen their average crop yields increase by more than 40 percent despite using less water.
Beyond the economic impacts calculated in the report, California dairy farmers and employees are active participants in their communities and contribute to social, environmental and other broad public goals.
Study Leaders and Methodology
The study was conducted by a team of researchers at the UC ANR Agricultural Issues Center (AIC). Daniel A. Sumner, the director of AIC who holds the Frank H. Buck, Jr. Chair Professorship in the Department of Agricultural and Resource Economics at UC Davis, led the study. Josué Medellín-Azuara, a project scientist at the UC Davis Center for Watershed Sciences, and Eric Coughlin, a junior research specialist at AIC, were part of the research team. They measured myriad impacts using dairy-specific data for 2012 and projections for 2014 and a database and model of economic linkages (IMPLAN).
About the California Milk Advisory Board
The California Milk Advisory Board (CMAB), an instrumentality of the California Department of Food and Agriculture, is funded by the state's more than 1,450 dairy families. With headquarters in South San Francisco and Modesto, the CMAB is one of the largest U.S. commodity boards. It executes advertising, public relations, research and promotions on behalf of California dairy products, including Real California Milk and Real California Cheese. For more, visit RealCaliforniaMilk.com.
Frank Mitloehner once called this village home. Now a professor and air quality UC Cooperative Extension specialist in the Department of Animal Science at UC Davis, Mitloehner thinks that if this village can do it, so can California.
It is easy to see how Mitloehner was inspired to study ways that California can take advantage of its plentiful supplies of animal methane. In eight bovine bio-bubbles that function as airtight barns, he captures and measures every emission from his resident livestock in order to understand how methane emissions vary with feed and herd management.
At Davis, a commercialized version of a similar methane bio-reactor has been patented and licensed by Ruihong Zhang, professor in the Department of Biological and Agricultural Engineering at UC Davis. It has been constructed at the local landfill and will be used to demonstrate a sustainable village on the UC Davis campus.
Mitloehner recently hosted a seminar for the Western Center for Agricultural Health and Safety at Davis. Since the Food and Agriculture Organization of the United Nations (FAO) committee released their 2006 report entitled, “Livestock’s Long Shadow,” he has challenged two key misleading sentences in their report. The phrase compared the contribution of livestock emissions to that of transportation. By saying the contributions to climate change were similar, the report led many environmental advocates to the conclusion that eating less meat was the equivalent of taking cars off the road, setting up a meat vs. miles tradeoff that exaggerated the methane contributions of livestock everywhere.
Mitloehner’s response was the publication Clearing the Air, Livestock’s Contribution to Climate Change. After his paper was released, BBC, CNN and other media published his science-based estimate that the livestock contribution in the U.S. is 3.4 percent of U.S. emissions. Globally, 18 percent of warming was estimated to be livestock related. This estimate included livestock in the broadest sense - changes in land use, deforestation and desertification in developing countries.
Nonetheless, Mitloehner showed that U.S. methane emissions remain flat, while developing countries are increasing animal production to meet the demand for eggs, meat and dairy, especially Asia. But why is the U.S. so low?
Mitloehner shared a few facts that help explain the phenomena:
- The U.S. has fewer dairy cows. Today’s 9 million dairy cows supply 60 percent more milk than the 16 million cows in production in 1950. That means there is increased efficiency per cow for the same methane produced.
- Thirty percent of the methane in dairy production is from manure in ponds. There is the potential for recovery on the approximately 1,500 California farms, where the average herd size is 1,100 head.
- Methane has 20 times the warming potential of carbon dioxide, but when burned to heat water or to generate power, its warming potential is reduced by a factor of 20.
- The more fiber in the feed, the more methane is released by the rumen of the animal. One dairy cow in the U.S. produces an average of 20,000 lbs of milk per cow annually, the same amount of milk as five cows in Mexico, or up to 100 cows in India for the same, or less methane per cow. Reasons: low fiber diet, less parasites and less disease result in large differences in production per cow.
Mitloehner occupies that middle space between the economically driven farmers who survived years of falling milk prices and the sustainable advocates that want dairy to either disappear entirely or retreat into historical practices. When he is not serving on the President’s Council of Advisors on Science and Technology (PCAST) or the National Academies Institute of Medicine, he keeps company with local farmers and students and answers to science.
Dairy addicts like myself, whose ancestors have evolved on milk for over 10,000 years, are likely to continue to frequent the organic dairy cases, hopeful that there are mutual benefits to paying higher prices for local labels in returnable glass bottles as a way to sustain the farms.
In reality, California has been exporting surplus dairy products to growing populations since the 1890s and that won’t change soon. Those markets do more to keep dairies profitable than my weekly milk and yogurt purchase. Lactose for pharmaceuticals and whey proteins for infant formulas are shipped internationally from several of California’s mammoth cheese factories, sometimes worth more the cheese itself.
Mitloehner believes that “sustainable intensification” is the solution to keeping local dairies viable. He believes that science will provide the path to better regulation. The dairy nations that seem determined to get at the truth - New Zealand, France, Ireland and the Netherlands - have formed an international partnership at FAO entitled LEAP to address the issues. Mitloehner's leadership a chair of the partnership will keep methane bioreactors on the agenda.
Mitloehner tells the story of how he neutralized errors in the FAO report “Livestock’s Long Shadow” (YOUtube).
LEAP site at the FAO. NGOs include World Wildlife Federation and Greenpeace. Mitloehner said that Greenpeace is also a partner although not listed on the site. Workshop materials available for download.
July 2012 opinion post by Robert Goodland at New York Times food blog. This is an example of criticism of Mitloehner’s role as head of the FAO partnership LEAP (Livestock Environmental Assessment and Performance).