This page provides an archive of presentations made by USDFRC scientists and staff. Most of these presentations are as part of the Center’s Webinar Series, which is livestreamed at 3 p.m. CT on the first and third Wednesday of each month. Contact us to receive notification about upcoming seminars.
Using snapshots to create the bigger picture
Dr. Jen McClure, Feb. 17, 2021
The rumen microbiome is a unique habitat filled with complex microbes working in collaboration to turn forage into meat and milk. These microbes influence feed efficiency, methane emissions, animal health, and milk components. Much of this research has been done on a small scale using canulated cows or collecting samples via stomach tubing. These procedures limit the number of animals that can be collected from and are invasive and thus not ideal for commercial application. Recently we investigated the possibility of using buccal swabs as a proxy for exploring the cattle microbiome and have found that this method allows for more animals to be sampled and has potential to act as diagnostic tool in the future.
Alfalfa and corn silage are often grown in rotation to provide forage for dairy cattle and other livestock, but the performance of this system is hampered by low establishment year yields of alfalfa and excessive loss of soil and nutrients during corn silage production. This presentation will describe how establishment of alfalfa by interseeding into corn has the potential to double first year yields of alfalfa, increase overall forage production and profitability of corn silage-alfalfa rotations, and decrease soil and nutrient loss from cropland. Key management practices for successfully establishing alfalfa in corn silage will be reviewed. Ongoing needs for research to further refine this production system for on farm use will also be discussed.
Baled silage has increased substantially in popularity over the last quarter-century, and is especially popular among small and/or mid-sized forage and livestock producers. There are many reasons for this popularity, but the primary reasons include the ability to utilize much of the same equipment needed to conserve dry hay, as well as a reduced risk of rain damage to valuable forage crops. Most management principles for baled silages are similar to those often recommended for precision-chopped silages, but the fermentation of baled silages is inherently restricted compared to chopped silages. Fermentation is restricted by reduced moisture concentrations, less accessibility of sugars to bacteria responsible for fermentation, and generally less dry matter density within the silage. Specific research updates within this presentation include: i) moisture management - dry silages; ii) moisture management - wet silages; iii) effects of manure application on silage fermentation; iv) bale cutting/slicing mechanisms; v) effects of delayed wrapping; vi) fermentation in cold weather; and vii) aerobic stability. Baled silage techniques are applicable in many production situations, and this form of forage conservation will likely remain popular indefinitely.
Historically, the U. S. had a diverse population of dairy breeds, but market and other factors have led to a consolidation around Holstein genetics. Recently, the national Jersey herd has been expanding as farmers look for advantages in reproduction, milk components, and feed efficiency. Due to readily observable differences in traits such as body size and milk components, Jersey cows are perceived to be more efficient that Holstein cows. However, the experimental evidence for this perception is currently equivocal. Research evaluating nutritional and efficiency responses in Holstein and Jersey cows will be summarized and some underexplored areas for future research will be highlighted.
Wells that supply drinking water to rural households are subject to the principle of “tragedy of an open access resource”. A household owns and maintains the well infrastructure, but they do not own the groundwater or control its quality as this resource has “open access”. This problem and the tensions it can bring are apparent in several regions of Wisconsin where agricultural production and exurban development are juxtaposed. Our research team investigated well water quality of rural households in two studies, one in the northeast and the other in southwest Wisconsin (aka the SWIGG Study). We assessed the extent of well contamination by nitrate and conventional microbial indicators of water sanitary quality. Detection of specific microbes found only in human wastewater or livestock manure allowed us to determine sources of fecal contamination. Lastly, we combined Geographic Information System (GIS) data with statistical modeling to identify risk factors for well contamination, for example, the proximity of manure storage. Understanding the “what, where, and how” of rural well contamination in Wisconsin presents opportunities for improving groundwater quality to the benefit of farmers and rural households alike.
Selecting appropriate cover crop varieties can maximize benefits to growers and the environment. However, little is known about cover crop variety performance across the United States. At dozens of environments nationwide, we evaluated varieties of hairy vetch, crimson clover, and winter pea. Results show differences in variety performance for winter survival, forage quality, fall and spring vigor, biomass, and flowering time. Top-performing varieties differed by region and year. Varieties that excelled in warm winter conditions underperformed when exposed to cold winters.
The famous dairyman, W.D. Hoard, was paraphrased in a 1918 edition of “Hoard’s Dairyman” as saying that the inside of a dairy cow was the darkest place on earth. Over one hundred years since that quote, the microbial populations of the ruminant gastrointestinal tract remain largely unclassified and functionally mysterious. We have made many critical discoveries in the microbiology of these systems that are relevant to dairy and beef production; however, these systems are incredibly complex. To pierce this complexity and discover useful insights, we used the latest in DNA sequencing technologies to create genetic maps of microbes in the ruminant gut. These new maps grant us insights into the biology of the ruminant gut that were nearly impossible to identify previously. They also provide us the means to develop cost effective techniques to rapidly assess the rumen microbes of an individual cow. By taking advantage of the fact that they “ruminate” and chew the contents of their stomachs, we can assess a cow’s current microbial profile by taking an oral swab prior to feeding. At a cost of less than $5 per sample, it will soon be possible for us to analyze the microbial contents of an entire herd of cows in a cost-effective way. Ultimately, we hope that these discoveries will result in diagnostic tools that can be used on commercial dairies to identify poor performing or sick cows and to inform the farmer as to which treatment will be most effective for those animals. By sifting through big data from these small microbial cells, it may be possible to improve the production efficiency of cattle beyond their genetic predisposition.
Dairy production has changed dramatically in the past 30 years, with a shift from many small farms to fewer large farms. This increase in production intensity mirrors similar trends throughout the livestock industry, and it potentially changes the nature of infectious disease transmission from herd to humans, particularly via environmental routes like groundwater and surface water. However, the significance of this change to human health has not been fully explored. This presentation will describe how quantitative microbial risk assessment (QMRA) can be a useful tool in studying infectious disease transmission on a changing dairy landscape, provide recent examples of QMRAs relevant to the Wisconsin dairy industry, and propose a QMRA-based research agenda for proactively addressing future challenges.
Higher forage diets often decrease intake resulting in lower milk production, however, new varieties of alfalfa may potentially result in greater overall nutrient digestibility resulting in similar milk production to a control diet formulated with lower forage concentrations. The goal is to formulate diets with forages that are produced locally at lower cost and improve the overall sustainability of dairy production systems. Information on nutrient composition and digestibility of high quality alfalfa and how it can replace more expensive feedstuffs will help nutritionists formulate diets at high forage concentration without negatively affecting milk production.