Browsing by Author "Prestegaard-Wilson, Jacquelyn M."

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    Dairy Pipeline, June 2020
    Daubert, Jeremy; Hanigan, Mark D.; Hruby, Alexis; Prestegaard-Wilson, Jacquelyn M. (Virginia Cooperative Exension, 2020-06-18)
    This issue discusses how dairy farmers have been affected by COVID-19 and what the future opportunities are for farmers because of it. Included is information about government relief packages. Methane as a greenhouse gas and foraging habits are also discussed.
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    Dairy Pipeline, May 2019
    Martel, Cynthia; Prestegaard-Wilson, Jacquelyn M. (Virginia Cooperative Extension, 2019-04-29)
    There are two articles in this issue. The first discusses the potential use of industrial hemp as livestock feed. The second article discusses the potential use of essential oils as an alternative to ionophores such as monensin.
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    Improving nitrogen efficiency and profitability of dairy cattle in the United States
    Prestegaard-Wilson, Jacquelyn M. (Virginia Tech, 2022-09-08)
    The objectives of these studies were to assess U.S. dairy nutritionists' approaches toward balancing CP in lactating cow diets, and to leverage existing knowledge of postabsorptive AA metabolism through the application of a mathematical ration-balancing model to predict N efficiency through a more accurate postabsorptive amino acid (AA) delivery. In experiment 1, dairy nutritionists (n = 77) that fed a total of 521,000 lactating dairy cows responded to a questionnaire related to demographic information, feelings toward environmental nitrogen (N) excretion, and dietary CP balancing practices. Eighty-nine percent of nutritionists balanced diets based on one or more individual AA requirements of dairy cows. The primary concern with formulation of lower CP diets was the cost per unit of metabolizable protein (MP). In the second study, three treatments were fed to lactating Holstein cows (n = 48) to test proof of concept of NASEM 2021 and a nonlinear optimizer: a control balanced to fulfill all nutrient needs of lactating dairy cows producing 45 kg milk/d using the NRC (2001) dairy model (NRC01), and two diets balanced with a nonlinear optimizer that fulfilled requirements according to the updated NASEM (2021) dairy model and attempted to either: 1) maximize N efficiency through tailored post-ruminal AA supply (NEFF), or 2) maximize income over feed cost (IOFC). A simulation function was written in RStudio (version 2022.02.3) to predict daily animal performance with NASEM 2021. Dry matter intake, milk, and milk components from both the observed data and the simulation data matrices were analyzed as repeated measures (days) in a mixed model to test for both observed and predicted (simulated) differences in treatment means. Income over feed cost was $4.83, $4.77, and $5.12/cow/d for NRC01, IOFC, and NEFF, respectively (P = 0.96). Nitrogen efficiency (%) was greatest for NEFF (33.7), followed by NRC01 (28.9) and IOFC (23.4; P < 0.05 between all treatments). Based upon simulation data, NASEM 2021 predicted relative performance differences between animals that consumed treatments with differing absorbed EAA supplies, although residual analyses revealed that further progress could be made in milk protein (g/d), milk fat (g/d), milk yield (kg/d), and DMI (kg/d) predictions.
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    March 2021 Dairy Pipeline Newsletter
    Daubert, Jeremy; Hruby, Alexis; Prestegaard-Wilson, Jacquelyn M. (Virginia Cooperative Extension, 2021-03-10)
    In this issue: Your Greatest Resource - People; Enter Sandman - Do stall or bedding bype influence secondary measures of cow comfort; Upcoming Events. The Dairy Pipeline is published once per month by the Department of Dairy Science in the College of Agriculture and Life Sciences at Virginia Tech. This Dairy Pipeline contains timely, scientifically based, useful and applicable information that we seek to share with the dairy industry each month. We welcome use of this material in appropriate publications as well as for the formulation of recommendations. If you redistribute an article, we ask for a courtesy notification to be emailed to dascweb@vt.edu with the article title and the publication in which it will appear. Archived newsletters can be accessed from: http://www.sites.ext.vt.edu/newsletter-archive.
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    A survey of United States dairy cattle nutritionists' practices and perceptions of reducing crude protein in lactating dairy cow diets
    Prestegaard-Wilson, Jacquelyn M.; Daley, V. L.; Drape, Tiffany A.; Hanigan, Mark D. (Elsevier, 2021-12)
    Objective: The objective was to assess if US dairy nutritionists' approaches toward balancing CP in lactating cow diets are influenced by demographic information, feelings toward environmental nitrogen (N) excretion, and dietary CP cost. Materials and Methods: An electronic survey was sent to 886 US certified dairy nutritionists through the database of the American Registry of Professional Animal Scientists (ARPAS) via email. For survey data analysis, a nonparametric statistic was used to check whether the responses to each question were independent. Relationships among demographic data and responses to other questions were performed using Spearman's correlation. Poisson regression and least squares means were used to identify statistically meaningful differences between response counts within each respective question. Results and Discussion: A total of 77 nutritionists representing 1,065 herds from 28 states with a total of 521,000 total lactating dairy cows responded to the questionnaire. Eighty-nine percent of nutritionists balanced diets based on one or more individual AA requirements of dairy cows. Most respondents (72%) reported that they are currently formulating diets with lower dietary CP than they were 3 to 5 yr ago. The primary concern with formulating lower CP diets was the cost per unit of MP, likely due to the high and fluctuating cost of high-RUP feedstuffs. Implications and Applications: Currently, the impetus to reduce dietary CP in lactating cow diets is primarily financially, rather than environmentally, driven. Nutrition models that accurately predict individual AA requirements of dairy cows will allow nutritionists to develop even lower CP diets than is presently possible. Monitoring income over feed cost of low-CP diets supplemented with AA is critical to support the sustainability of the dairy industry.