Dairy Metabolism Group
Dairy cattle are amazing animals, relying on many feeds that are useless to people to support metabolic rates that exceed those of marathon runners. Dairy products account for 17% of the protein in the American diet, and how we feed and manage cows has a big impact on the sustainability of dairy production. Our research investigates the biology underpinning the incredible feats performed by the humble dairy cow while also asking practical questions of relevance to the dairy industry. Our aims are to better understand the metabolic physiology of dairy cattle to identify strategies that will improve the economic and environmental sustainability of dairy production.
Key ongoing projects
- Mechanisms underlying sustained milk production responses to anti-inflammatory treatment in early lactation dairy cows. (USDA-NIFA AFRI grant)
Inflammation has recently been recognized as a key factor not only in severe illness, but also in less obvious, chronic health problems. Inflammation is now known to have a dramatic impact at the start of lactation, with numerous studies demonstrating that elevated blood markers of inflammation are associated with more illness and decreased milk production in dairy cows. Our overall hypothesis is that inflammation in early lactation limits milk production capacity by decreasing mammary cell number, activity, or both. To evaluate this hypothesis, we will first monitor disease incidence, milk production, and production efficiency in dairy cows treated with the anti-inflammatory agent sodium salicylate or placebo for the first week of lactation. In a second group of cows, we will repeat this treatment but focus on mammary gland responses, including gene activation, cell growth and death, and production of milk nutrients. Based on preliminary work, we anticipate that salicylate treatment will enhance milk production throughout the 10-month lactation, likely due to increased numbers of milk-producing cells in the mammary gland. We expect the long-term outcome of this work to be the development of an anti-inflammatory treatment strategy for early lactation cows that improves mammary function, increases milk yield, and promotes production efficiency. This would improve the economic and environmental sustainability of the dairy industry, thus contributing to an abundant food supply with minimal impact on the natural environment.
- Making milk from human-inedible feedstuffs (Support from Kansas Dairy Association)
There seems to be great interest in sustainability and sources of food among consumers today. The message about the importance of producing enough food for 9 billion people by 2050, without additional inputs, has been attracting attention. This is good thing, but some analyses of inefficiencies in the current food system overlook important factors when comparing different approaches to feeding the world. One of the most glaring oversights is the assessment of ruminant agriculture as the inefficient sector based on the fact that a relatively smaller proportion of their feed is turned into meat and milk. This sort of logic ignores the fact that diets consumed by ruminants are often of substantially lower quality (from a human perspective) than what is fed to monogastric animals. In fact, it is very common for dairy farms in the U.S. to feed diets that contain 20 – 40% products that are waste streams from human food, fuel, and fiber production; such products include cottonseed, soybean hulls, and corn gluten feed, none of which are consumed by humans. We continue to seek ways to push the limits in utilizing these waste streams in diets for high-producing dairy cattle.
- Inflammation as a key component of the metabolic adaptations to the lactating state (NSF grant)
The immune system is responsible for defending the body against pathogens and mediating the responses to some injuries through inflammatory processes. Inflammation can also impact metabolism and energy use. We will test whether the non-defensive roles of the immune system are necessary for the metabolic transitions that occur with the onset of lactation, a period when energy use in an animal undergoes extreme changes. The question will be assessed through the use of non-steroidal anti-inflammatory drug administration at the start of lactation in cattle because they are well suited for these studies and are very tractable experimental systems. The objective of this research is to assess whether endogenous inflammation in early lactation is necessary to induce insulin resistance and conserve glucose as nutrient demands for the mammary gland increase. Basal and insulin-stimulated glucose kinetics, as well as liver, muscle, and adipose tissue markers of inflammation and insulin signaling will be measured in cows at high and low milking frequency. Milking frequency will alter milk yield, allowing for the assessment of whether inflammation-mediated homeorhetic processes are particularly important for supporting extreme milk yields. By blocking endogenous low-grade inflammation in early lactation, anti-inflammatory treatment is expected to increase insulin sensitivity, resulting in increased muscle and adipose tissue utilization of glucose, suppressed liver gluconeogenesis, and impaired regulation of plasma glucose concentration in early lactation. Results from the studies will be disseminated through peer-reviewed journals and through presentations at scientific meetings.
- Is orosomucoid a mechanistic link between inflammation and impaired intake during the transition period? (USDA-AFRI grant in collaboration with U. Tennessee and Berry College colleagues)
Among the most significant challenges in the dairy industry is the complex of health disorders that commonly occur in the week after cows give birth. Cows that become ill as they are beginning lactation have impaired welfare, reduced milk production, and have greater difficulty becoming pregnant again. Both inflammation and poor feed intake are known risk factors for these disorders, but so far there has been little evidence to tie these problems together in early lactation cows. Our overall hypothesis is that an inflammation-induced protein in the bloodstream, orosomucoid, suppresses appetite and promotes disease in early lactation dairy cows. To evaluate this hypothesis, we will use sheep as a model organism and test whether infusion of orosomucoid into the brain decreases feed intake. Secondly, we will assess whether signaling pathways used by leptin, the appetite-suppressing hormone, are involved. Finally, we will use blood samples from 450 dairy cows that were closely monitored before and after giving birth to determine whether orosomucoid concentrations can be used to predict which cows will have poor feed intake and/or which will have health disorders in early lactation.These concepts could allow dairy producers and veterinarians to identify cows at greatest risk for early lactation disorders by measuring blood orosomucoid concentrations and providing additional preventative care for cows with elevated concentrations. It is also possible that scientists could develop a treatment to prevent orosomucoid from having its negative effect on appetite. Any progress made to decrease the prevalance of early lactation health disorders would have a positive impact on the social, economic, and environmental sustainability of the dairy industry.
- Linking cattle nutrition to human nutrition: a value chain approach to improving the production, handling, and consumption of animal source foods in Ethiopia (USAID project in collaboration with SIIL and Project Mercy colleagues)
The overall research objective of this project is to create a systems-based research approach that strengthens linkages between improved animal-source food production and consumption practices and human nutrition outcomes in Ethiopia. The goal is to identify, in a qualitative and quantitative manner, the pathways between agriculture interventions and nutritional outcomes. The project implements a systems-based research approach that will define and quantify linkages between the various activity domains, including the creation of a conceptual framework, based on quantifiable data collected from each research domain. Focus of the research will be on highland crop-livestock systems and smallholder commercial dairies, which prevail in urban and peri-urban areas. Forage on-station research will be conducted at Melkassa, and on-farm trial locations will be chosen based on input from collaborators. Cattle nutrition trials will be held in Hawassa and ChaCha. Collaboration with on-farm research will focus on the areas of influence of Africa RISING.