Source: UNIVERSITY OF GEORGIA submitted to NRP
REDUCING ANTIBIOTIC USAGE: ALTERNATIVE PRACTICES FOR DRY COW ANTIBIOTIC THERAPY AND A PROGRAM TO GARNER PRODUCERS’ PERCEPTIONS AND ADOPTION
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
ACTIVE
Funding Source
AFRI COMPETITIVE GRANT
Reporting Frequency
Annual
Accession No.
1032260
Grant No.
2024-68008-42644
Cumulative Award Amt.
$300,000.00
Proposal No.
2023-09582
Multistate No.
(N/A)
Project Start Date
Jul 1, 2024
Project End Date
Jun 30, 2027
Grant Year
2024
Program Code
[A1701]- Critical Agricultural Research and Extension: CARE
Recipient Organization
UNIVERSITY OF GEORGIA
200 D.W. BROOKS DR
ATHENS,GA 30602-5016
Performing Department
(N/A)
Non Technical Summary
Alternative approaches to reduce antibiotic use on dairy farms are needed to address industry and consumer concerns. Blanket dry cow therap, or intramammary infusion of high concentration and long-lasting antibiotics into every quarter to prevent intramammary infection at milking cessation, accounts for a large portion of the antibiotic usage on dairy farms. Thus, practices that reduce intramammary infection and simultaneously decrease antibiotic usage are critically needed. Our overall objectives are to 1) determine the effect of alterative dry-off management practices on stress, inflammation, immunity, and intramammary infection occurrence of dairy cows in order to replace blanket dry cow therapy on dairy herds, and 2) develop an Extension program to share the current knowledge in mastitis control, judicious antibiotic usage and research findings with dairy producers, veterinarians, and industry practitioners. We hypothesize that less frequent milking and administrating dry cow vaccines prior to dry-off will minimize stress and inflammation, improve immunity and prevent intramammary infection, and prove viable alternatives for blanket dry cow therapy. We will perform two applied research projects in multiple dairy farms to test our hypothesis, and build a robust Extension program focusing on educating dairy producers, veterinarians, and industry practitioners for judicious antibiotic usage by adopting management practices that improve mammary health with less reliance on antibiotics. These integrated efforts will eventually improve not only the health and welfare of dairy cattle, but also profitability of dairy producers and sustainability of dairy farms.
Animal Health Component
70%
Research Effort Categories
Basic
30%
Applied
70%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
3073410310060%
3113410109040%
Knowledge Area
311 - Animal Diseases; 307 - Animal Management Systems;

Subject Of Investigation
3410 - Dairy cattle, live animal;

Field Of Science
1090 - Immunology; 3100 - Management;
Goals / Objectives
Our long-term goal is to use practical and scientifically tested approaches to improve production and health of dairy cattle, thereby reducing the usage of antibiotics. Our overall objectives are to 1) determine the effect of alterative dry-off management practices on stress, inflammation, immunity, and IMI occurrence of dairy cows in order to replace BDCT on dairy herds, and 2) develop an Extension program to share current knowledge in mastitis control, judicious antibiotic usage and research findings with dairy producers, veterinarians and industry practitioners.
Project Methods
In the extension projects, we will develop an initial survey to collect data on current industry practices related to dry-off protocol, antibiotic usage and the attitudes and comfort with antibiotic usage and alternative dry-off protocols of the producers. The survey will be synthesized using the Qualtrics XM online platform and data will be analyzed utilizing SPSS. We will distribute this survey in year 1. Through this survey, we will fully understand management practices of all facets across our diverse dairy industry in Georgia and allow for development of programs tailored to the needs of specific producers or producer groups.Based on the initial survey, we will develop a follow up extension program to incorporate educational programs on best-management practices related to antibiotic use and dry-off protocols into our current Extension programming efforts which ultimately results in changes in management practices and reduction in antibiotic usage on GA dairy operations. We will utilize multiple channels to develop Extension media. Workshops and farm field days will be hosted to discuss current, relevant management practices as well as share the findings from research trials. Video recording of these events or similar content will be adapted to create informative videos to be posted through departmental and industry media outlets. We will publish additional Extension bulletins regarding milk quality, mastitis, antibiotic resistance, judicious antibiotic usage, outcomes obtained from producer survey, and results from research trials of this proposal. These Extension bulletins are available through UGA Extension system to reach and educate county agents. Written publication will also be produced for inclusion in the DairyFax newsletter managed by our Extension team. The outcomes from this project will also be summarized and submitted to magazines to obtain a broader impact nationally and internationally.Upon delivery of educational programs and materials, the follow-up survey will be given at the end of year 3 to evaluate whether participants implemented practices according to the information provided through Extension media and to collect farm productivity data to quantitively evaluate impact of programmatic efforts. Data from our surveys could be shared to the Journal of Extension as a Research in Brief publication. This would also allow for us to share our survey development and program evaluation procedures and create a model for Extension programs across the country to utilize.In the research project, we will conduct two experiments to identify the effects of different dry cow vaccination schedules (prior to vs. on the day of dry-off), and milking frequency in the late lactation on inflammation, immunity, and incidence of IMI of dairy cows compared with blanket dry cow therapy (BDCT) and selective dry cow therapy (SDCT).These studies will be conducted in three commercial dairy farms located in Georgia with good mammary health record. We will collect milk yield data, diseases including clinical mastitis, reproductive parameters, and culling. For each cow, the usage of antibiotics administered at dry-off, and for treating mastitis in the subsequent lactation will be recorded. The total usage for each antibiotic will be calculated according to the number of tubes used and the amount of antibiotic per tube. The total usage of each antibiotic will be compared between treatments. Blood samples will be drawn from a subset of cows to measure stress and inflammation markers. An immune function assay will also be performed. We will identify acquisition of mammary infection by examining the bacterial profile in milk prior to treatment before dry-off and after calving.We expect to observe that administering vaccines earlier and reduced milking frequency in late lactation will improve immune functions of cows in the early dry period, maintain a similar or lower incidence of IMI compared with those received dry cow vaccines and BDCT/SDCT, but the amount of antibiotics will be lower than cows with BDCT. Upon completion of these projects, we will provide feasible and scientifically proven management strategies to reduce antibiotic usage at milking cessation without negative impacts on intramammary infection occurrence.Research findings will also be presented at the Georgia Dairy Conference where over 500 dairy producers, industry personnel, veterinarians, and students are presented with current research practices and management techniques. Results from the producer survey and research trials will also be presented in the Annual Meetings of National Mastitis Council, and American Dairy Science Association. These results will also be published in well recognized peer-reviewed journals such as Journal of Dairy Science.

Progress 07/01/24 to 06/30/25

Outputs
Target Audience:On the extension side, target audience, including dairy producers, nutritionists and extension specialists and county agents, will have a further understanding of how different management approaches at the time of milking cessation can affect cow immunity and subsequent health and performance. These audiences will be reached through the dairy extension newsletters, popular express articles, regional workshops and conferences, and surveys. On the research side, the audiences include dairy scientists and students. The knowledge obtained from this study will be delivered via presentations and posters at national and international meetings, and peer-reviewed publications. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The projects supported by this grant have provided many opportunities for training and professional development for undergraduate and graduate students, extension agents, and other industry professionals. During our experiments, at least 6 undergrad research assistants or intern students were involved. They actively participated in animal trials and lab analysis. This provided opportunities for these students to train their professional skills and gain experience in farm management and animal care and dairy cattle research. Further, this grant supports one graduate student who oversees animal studies. This student has gained experience in experimental design and conducting animal trials and has opportunities to communicate with producers to understand the current trend and development of the dairy industry. Further, many other graduate students have participated in this experiment as well to gain experience in dairy management on commercial dairy farms. We have also provided opportunities to county extension agents for professional development. We collaborated with county extension agents in different workshops which not only intended to educate the dairy producers but also provide an excellent opportunity for extension agents to learn the newest technologies in the dairy industry. Further, in our workshops, in addition to dairy producers, we have invited many industry professionals. We also present results in different meetings for industry professionals. These all provide opportunities for them to receive further professional training in the latest technology in dairy cattle management. How have the results been disseminated to communities of interest?We have disseminated the results to communities of interests in several approaches: Department seminar presented by the graduate student Presentations and posters in the annual meeting of American Dairy Science Associations Presentation presented by the graduate student in the Sixth International Lactation Biology Symposium. Publication in UGA DairyFax newsletter. DairyFax newsletter is published quarterly by the UGA dairy Extension team. The subscribers include not only ALL dairy producers in GA but also industry personnel, veterinarians, Extension agents, and agriculture teachers in GA and nationwide. A producer workshop has been hosted during which the UGA dairy extension team disseminated the results to dairy producers, extension agents, and other industry professionals. Face-to-Face meetings with producers have been hosted to deliver the results. What do you plan to do during the next reporting period to accomplish the goals?In the next reporting period, we will: Continue to analyze the data collected from experiments conducted in this current reporting period to have a full understanding how reduced milking frequency and advancing dry cow vaccination affect mammary health and their potential to replace the antibiotics treatment at milking cessation. Perform additional animal experiments to explore additionalstrategies to minimize stress and inflammation of the cow in her early dry period, e.g., administration of nonsteroidal anti-inflammatory drugs, and their impacts on intramammary infection and the antibiotic usage at the time of milking cessation. Research results will be published in peer-reviewed journals and presented in the annual meeting of American Dairy Science Association and/or National Mastitis Council, and the GA dairy conference. The producer survey will be completed, and data will be analyzed. More producer workshops and face-to-face producer meetings will be hosted in different areas of Georgia. More articles will be published in the DairyFax newsletter, UGA extension bulletin, and other popular express journals. The results from these projects will also be posted online through our website and social media to reach a broader impact.

Impacts
What was accomplished under these goals? Dry period, the two-month non-lactating interval between two consecutive lactations, is a stressful period for a dairy cow. Cows transitioning from the late lactation to the early dry period undergo major shifts in management and nutrition, including udder engorgement from abrupt milking cessation, social disruptions due to regrouping, dietary change from energy-dense lactating cow diet to a low-energy dry cow ration, and dry cow vaccination. These events trigger stress and induce systemic inflammation of cows in the early dry period. The upregulated stress and inflammatory responses may contribute to the increased intramammary infections by impairing the immune function of cows in the early dry period. A common approach to prevent intramammary infections in the dry period is the intramammary administration of antibiotics at the time of milking cessation. It is effective but raises concerns over antibiotics resistance. In contrast, strategies that minimize stress and inflammation may improve the immune functions of cows in the early dry period, reducing the intramammary infection rate during the dry period and alleviating the need for antibiotics treatment at the time of milking cessation. Thus, two novel management approaches have been studied in this reporting period, namely reduced milking frequency in the late lactation and advancing dry cow vaccination. Reduced the milking frequency lowers the milk production of cows prior to dry-off, minimizing stress and inflammation following milking cessation. And performing dry cow vaccination earlier will minimize inflammation in the early dry period. We hypothesize that these two approaches will enhance the cow immunity and reduce the intramammary infection rate and mastitis incidence in the subsequent lactation. In the first study, a total of 324 late lactating cows were enrolled. Cows received dry cow vaccines either at 11 d prior to scheduled dry-off, or at 2 d prior to dry-off according to the standard operating procedure of the farm. The circulating inflammation and stress markers and peripheral immunity were examined in the early dry period and the disease incidences, reproduction and lactational performance in the subsequent lactation were recorded. Preliminary data suggest that multiparous cows (more than one birth prior to dry-off) who received vaccines earlier had similar intramammary infections in early lactation but produce more milk in the subsequent lactation compared with multiparous cows who receive vaccines closer to dry-off. In the second study, late lactating Holstein cows (n = 996) were milked either 3 times a day (n = 480) or 2 times a day (n = 516) in the last 13 d of the lactation. The circulating concentration of inflammation and stress markers, and immune functions were examined around dry-off. And pooled milk samples were collected within 3 d post-calving from each cow and cultured to detect common mastitis pathogens. Preliminary data suggest that reduced milking frequency in late lactation did not affect systemic inflammation in the early dry period but increased the milk culture positive incidence in early lactation. The preliminary results from these experiments were presented in GA dairy conferences, and at different producer workshop and face-to-face meetings during this reporting period. Multiple presentations or posters will be presented in the annual meeting of the American Dairy Science Association at the end of June 2025. The other objective is to develop and distribute a survey to capture current management practices and challenges that dairy producers, veterinarians, and other industry members face, specifically as it relates to antibiotic use and dry-off protocol. This information will drive future Extension programming toward meeting the needs specified by the respondents. To address this objective, the UGA dairy team has developed and initiated three targeted surveys designed to capture the perspectives and practices of Georgia's dairy industry stakeholders. The producer survey aims to (1) summarize current dry-off management practices, (2) assess attitudes toward antibiotic use and alternative protocols, (3) identify perceived barriers to adopting non-antibiotic approaches, (4) gather herd productivity and health data related to mammary health, and (5) evaluate preferred communication and education methods. The survey created for veterinarians is designed to gauge their views on antibiotic stewardship and how they view their role in communication about antibiotics with producers. The survey for extension agents differs in that it focuses on their understanding of and confidence in addressing antibiotic use in the dairy industry. While survey distribution was delayed due to an overlapping data collection timeline and heightened biosecurity concerns related to HPAI, we are now in the active data collection phase. Informal producer feedback has also been gathered through two recent forums involving both small- and large-scale operations. Finally, we have assembled a producer panel that is reflective of Georgia's diverse dairy industry. We also intended to develop an Extension program to educate on the best management dry-off practices and judicious antibiotic usage and evaluate its impact. During this reporting period, we have hosted one producer workshop in one dairy concentrated area of Georgia to discuss the strategies to minimize stress and inflammation in the early dry period and visit different dairies for face-to-face meetings with dairy producers. We also attended GA dairy conference to showcase our research and progress with dairy producers and industry professionals. We have also published results in GA dairy newsletters to achieve broader impacts. Although we are at the beginning of this grant, we have already received positive feedback from dairy producers. We have learned that several producers are starting to consider a change in management to minimize inflammation and stress in the early dry period. We expect more positive behavioral changes of the dairy producers as our project continues.

Publications

  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2025 Citation: Gao, J., C. G. Savegnago, N. L. P. Kant, A. M. Roper, T. N. Marins, and S. Tao. 2025. Effect of milking frequency before dry-off on milk yield and mammary health in dairy cows. J. Dairy Sci. (accepted).
  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2025 Citation: Gao, J., Y. B. Amancio, N. Andriotti, C. G. Savegnago, T. N. Marins, A. M. Roper, and S. Tao. 2025. Effect of intramammary infusion of chitosan on immune cell infiltration and mammary health in dairy cows. J. Dairy Sci. (accepted)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2025 Citation: J. Gao, G. Guzi Savegnago, T. Nogueira Marins, A. M. Roper, and S. Tao. 2025. Effect of chitosan on viability of bovine immune and mammary epithelial cells and neutrophil chemotaxis. Poster in GA Dairy Conference; Savannah, GA.
  • Type: Other Status: Published Year Published: 2025 Citation: Gao, J., Tao, S. Managing inflammation around dry-off. Heat Stress Producer Workshop 2025. 03/04/2025. Greenville, GA
  • Type: Other Status: Published Year Published: 2025 Citation: Gao, J., S. Tao. 2024. Advancing dry cow vaccination: Insights from UGA research. Oct Nov Dec, Georgia DairyFax newsletter.