A concern facing dairy farmers as the long, hot days of summer approach is the threat of heat stress in their cows. Experienced at temperatures above 80°F, heat stress affects growth and development as well as milk composition and volume. Heat stress is a major cause of low fertility in dairy cattle. It also increases susceptibility to metabolic disorders, mammary gland pathogens and mastitis. Compared with other livestock, cattle are unable to dissipate their heat load efficiently. Additional heat generated by the fermentation of food in the rumen compounds this problem. Cows’ sweating response is not highly effective, and the animals rely on respiration to cool themselves. Because of their inefficient response, cattle accumulate a heat load during the day that must be dissipated in cooler nighttime temperatures. In extreme weather conditions with overnight temperatures above 70°F, however, this doesn’t happen. Cattle experiencing increasing heat stress will stop feeding and become restless. They will then begin drooling and breathing more rapidly and with increased effort. They will also begin to group together, further exacerbating the problem. If not controlled, severe cases of heat stress will result in death. Economically, decreased milk yield and reproductive losses through hot summer months seriously affect the dairy industry. Increased occurrences of extreme weather conditions caused by ongoing global warming will only worsen these losses.
Maternal antibodies play an important role in protecting newborns from harmful pathogens. Antibodies known as immunoglobulins (Igs) are transferred from the mother’s placenta into the fetus, where they protect the infant while the infant’s immune system is still developing, Human milk also contains many different Igs, such as IgA, IgM, IgG, and secretory forms of IgA and IgM. Consuming human milk provides additional immune protection to infants and has been shown to reduce the risk of infectious diseases.
Some recipes are meant to be top secret—Colonel Sanders’ fried chicken; Big Mac’s special sauce; your great aunt Ingrid’s sherry cake. But the ingredients in cow milk shouldn’t be private and confidential. The advent of targeted metabolomics approaches, which characterize large numbers of small molecules in milk, offers the opportunity to produce a detailed and comprehensive picture of cow milk’s chemical composition. And yet, many studies employing these new techniques have not publicly reported their findings, or report the components they have found but not their concentrations. Rather than having scientists continuing to re-invent the analytical milk wheel, a team of Canadian researchers has just published a “centralized, comprehensive, and electronically accessible database” of all detectable metabolites in cow milk. We may never know what Colonel Sanders uses to season his fried chicken batter, but the (detectable) chemicals that make up cow milk—all 2,355 of them—are now on the record.
How do mammary cells change and gain the ability to make milk at each birth? Scientists, at present, only have fragmentary information and little detail about the hierarchy of mammary cells contributing to the lactation cycle beginning at each pregnancy. A cellular hierarchy is like a family tree. It shows the relationships between different types of cells i.e., who begat whom. Knowledge of cellular hierarchies in mammary tissue could help answer many difficult questions. Which cells (progenitor cells) give rise to the cells that make milk or cells that form part of the mammary tissue structure supporting lactation? How do mammary epithelial cells cease producing milk after weaning? Which mammary cells develop into breast cancer and why? Recently, a group of investigators produced a massive molecular resource that may help answer these and many other questions relating to mammary tissue function. Importantly, the investigators made the resource available to all scientists to maximize its potential for additional discoveries.
Human milk is known to provide a variety of nutrients that aid infants’ growth and development and are beneficial to their health. But as children grow a little older, they often don’t meet recommended dietary guidelines, particularly when it comes to eating enough fruits and vegetables.
New parents use baby books to record the dates of all of their child’s firsts—when they first eat solid foods, take their first steps, cut their first tooth, and say their first words. These books tell part of the child’s life story, allowing parents to reminisce years later about when all of these exciting milestones happened in the life of their child. Researchers that study the evolutionary history of humans are similarly interested in knowing the dates of these developmental milestones in order to recreate life stories for fossil skeletons (albeit for the less sentimental reason of comparing to living humans). Amazingly, teeth—even those from individuals that died hundreds of thousands of years ago—act much like doting parents, capturing every day of childhood as they grow.
Infectious diseases are not conquered, but sometimes that’s our perception. The infectious microbial agents patiently await the right opportunity occurring at the intersection of multiple circumstances. Their unpredictability is their modus operandi, which often amplifies their adverse impacts.
Native Americans are about twice as likely as white people in the United States to develop diabetes, and more likely to do so than any other ethnic group in the country. The reasons for this are complex, but post-reservation lifestyles and diets packed with processed sugar and saturated fats are big contributors. Given the extent of the problem, any research that identifies cheap interventions to which many people are likely to be amenable has the potential to reap substantial public health benefits. In a recent issue of the Journal of Nutrition, Kim Kummer of the University of Washington in Seattle, and colleagues report that encouraging the consumption of full-fat dairy products, such as full-fat milk and cheese, could be a useful tool in efforts to cut the disease burden.
Babies born in resource-poor rural and semi-rural communities have a high risk of stunting, that is, being born short for their gestational age. Rates as high as 60% have been documented in one indigenous population in Guatemala. Stunting at birth predicts increased infant and child mortality as well as ongoing growth retardation. Growth retardation in turn carries a higher risk for impaired brain function and loss of economic productivity. In female infants, growth failure presents a greater reproductive risk for themselves and their eventual children due to intrauterine growth restriction. The issue is primarily a consequence of inadequate nutrition, and is considered to be a major public health challenge in developing nations. However, nutrition interventions carried out during the infant and toddler stages have had only limited success in either treating or preventing growth failure. Those aimed at maternal nutrition during pregnancy, primarily focusing on micronutrients, have produced positive, albeit modest, effects on newborn size. Interventions prior to conception have not been well studied in humans, but animal studies have shown promise.
A current trend in the marketing of healthy foods and drinks is highlighting a product’s short ingredient list; the less “stuff” in a food, the healthier it must be, right? This may be true for energy bars or fruit juices, but when it comes to human milk, a long list of ingredients is precisely what makes it optimal for infant health. Over the last decade, as the health food aisle has increased in so-called simple and clean foods, human milk’s ingredient list just keeps getting more complicated. Innovations in analytical tools have led to more in-depth studies detailing the specific types of fats, amino acids, sugars, and other metabolites present in human milk. Creating milk “–omes”—specifically, the milk metabolome, glycome, and lipidome—complicates human milk research in the best possible way, opening the door to identifying specific milk components that influence infant growth and development.