Progress 09/01/23 to 08/31/24
Outputs
Target Audience:The target audience during this reporting period was fellow dairy researchers focusing on lactation and mammary gland growth and development along with veterinarians who study mastitis in lactating and non-lactating cattle.The audiences were reached during this reporting period via presentations at scientific meetings (e.g., American Dairy Science Association, National Mastitis Council, etc), publication of conference proceedings, and publication of journal articles. Publications are currently under preparation for submission for publication to the Journal of Dairy Science. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This research project has served as the basis for training 2 graduate students; 1 PhD, and 1 MS. The graduate students were/are being trained in research methodology, study design, experimental procedures, managing ongoing experiments, and summarizing research results and presenting them to research communities. The PhD student completed all the in vivo animal work and is currently mastering techniques of chemical- and immune-histochemical microscopy. The PhD student has also learned to troubleshoot assays and is summarizing data for publication. The undergraduate students included in this project are also being exposed to research practices and introduced to graduate education as a potential career pathway. How have the results been disseminated to communities of interest?Collected and analyzed data have been submitted for presentation at professional meetings (e.g., National Mastitis Council Annual Meeting) and presented at multistate research meetings (NE 1748) by the graduate students conducting the research. Two publications arein preparation for submission to the Journal of Dairy Science. What do you plan to do during the next reporting period to accomplish the goals?The PDs groups will continue working with the collected mammary tissues and analyzing the data. These efforts will be the primary focus for the final reporting period. These activities will result in several publications being submitted for publication and the PhD student graduating.
Impacts
What was accomplished under these goals?
Mastitis is primarily the result of an infection within the udder of the dairy cow and remains an extremely common and expensive disease for the US dairy industry. Mastitis not only afflicts milking cows, but also non-milking heifers, who's udders are growing and developing to produce milk for the first time. Infections in growing and developing udders are expected to impair mammary growth and development, and reduce an animal's lifetime milk production. The overall goal of this research is to determine how, and to what degree, mammary growth is affected by mastitis during rapid mammary growth and identify specific changes in udder growth processes that may be targeted for the development of future therapeutics. The results of this work will guide the development of management practices for producers to limit the impacts of these infections on mammary growth and development. Reducing the occurrence and impacts of mastitis on udder growth and development will increase dairy cow lifetime milk production, dairy cow health, the production efficiency of milk, and producer financial profitability. The progress and results for the specific objectives are listed below. 1. Define the structural changes in tissue architecture that result from infections within the udder when the mammary gland is growing and developing. A study was completed in the previous reporting period that utilized 21 pregnant dairy heifers. Overall, healthy, uninfected mammary gland tissues were collected from mammary glands rapidly growing and developing and compared against mammary tissues obtained from infected mammary glands that were also rapidly growing and developing. Tissues were collected and preserved for histological and molecular analyses. Morphometric histological analysis is completed, and the data have been summarized and are being prepared for publication. Additionally, the collected mammary tissues were used to quantify the number of dying and proliferating cells to determine how mastitis disrupts tissue and cell growth. 2. Localize and quantify connective tissue proteins in nonlactating but rapidly growing mammary glands that are changed in response to intramammary infections. This objective is in progress and we are testing antibodies against key connective tissue protein markers. We will also carry out a global collogen analysis to determine the degree of scar tissue deposited in infected mammary glands. 3. Determine the immune response initiated in non-lactating heifer mammary glands that are growing and developing in response to infections in the udder. Colostrum samples were collected from the infected and uninfected mammary glands to quantify the population of immune cells present. Neutrophils were predominantly recruited to the mammary gland during active infections but were not recruited to uninfected mammary glands. There was also a greater number of lymphocytes present in infected mammary gland tissues and milk samples. This aim is complete and the data are being summarized for publication with the data from aim 1. 4. Identify changes in the microbiome of non-lactating heifer mammary glands that result from establishment of infections in bovine mammary glands. Tissues have been collected and delivered to Co-PI McGuire. Sample processing, extraction, and analysis are underway in coordination with PD Enger.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
M. X. S. Oliveira, K. M. Enger, and B. D. Enger. 2024. Impact of Staphylococcus aureus intramammary infection on mammary cell proliferation in pregnant heifers. J. Dairy Sci. 107: (Suppl. 1):106-107.
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Progress 09/01/22 to 08/31/23
Outputs
Target Audience:The target audience during this reporting period is fellow dairy researchers focusing on lactation and mammary gland growth and development along with veterinarians that study mastitis. The audiences were reached during this reporting period via presentations at scientific meetings, publication of conference proceedings, and publication of journal articles. One of the journal articles published during this reporting period was selected as an editor's choice article, which further elevated this research's visibility. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This research project has served as the basis for training 2 graduate students; 1 PhD, and 1 MS. The graduate students were/are being trained in research methodology, study design, experimental procedures, managing ongoing experiments, and summarizing research results and presenting them to research communities. The PhD student completed all the in vivo animal work and is currently mastering techniques of immunohistochemistry. Undergraduate students are also being exposed to research practices and introduced to graduate education and professional career pathways. How have the results been disseminated to communities of interest?Collected and analyzed data have been submitted for presentation at professional meetings (e.g., National Mastitis Council Annual Meeting) and presented at multistate research meetings (NE 1748) by the graduate students conducting the research. Additionally, 2 publications were accepted for publication in the Journal of Dairy Science for dissemination to the larger scientific community. Another publication is in preparation for submission to the Journal of Dairy Science. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Mastitis is primarily the result of an infection within the udder of the dairy cow and remains an extremely common and expensive disease for the US dairy industry. Mastitis not only afflicts milking cows, but also non-milking heifers, who's udders are growing and developing to produce milk for the first time. Infections in growing and developing udders are expected to impact mammary growth and development, and consequently, reduce an animal's lifetime milk production and therefore producer profitability. The overall goal of this research is to determine how, and to what degree, mammary growth is affected by mastitis during rapid mammary growth and identify specific changes in udder growth processes that may be targeted for the development of future therapeutics. The results of this work will guide the development of management practices for producers to limit the impacts of these infections on mammary growth and development. Reducing the occurrence and impacts of mastitis on udder growth and development will increase dairy cow lifetime milk production, dairy cow health, the production efficiency of milk, and producer financial profitability. The progress and results for the specific objectives are listed below. 1. Define the structural changes in tissue architecture that result from infections within the udder when the mammary gland is growing and developing. A study was completed during this reporting period that utilized 21 pregnant dairy heifers. Overall, healthy, uninfected mammary gland tissues were collected from mammary glands rapidly growing and developing and compared against mammary tissues obtained from infected mammary glands that were also rapidly growing and developing. Tissues were collected and preserved for histological and molecular analyses. Morphometric histological analysis is ongoing and the data are being summarized and prepared for publication. Additionally, tissues are being examined to quantify the number of cells proliferating and dying to provide an indication of how mastitis disrupts tissue and cell growth. 2.Localize and quantify connective tissue proteins in nonlactating but rapidly growing mammary glands that are changed in response to intramammary infections. This objective is in progress and we are currently in the process of selecting and testing antibodies against key connective tissue protein markers. 3. Determine the immune response initiated in non-lactating heifer mammary glands that are growing and developing in response to infections in the udder. Colostrum samples were collected from the infected and uninfected mammary glands to quantify the population of immune cells present. Neutrophils were predominantly recruited to the mammary gland during active infections but were not recruited to uninfected mammary glands. There was also a greater number of lymphocytes present in infected mammary gland tissues and milk samples. We are continuing to determine how the immune cell population is changed during the recruitment to address the infection within the udder. 4. Identify changes in the microbiome of non-lactating heifer mammary glands that result from establishment of infections in bovine mammary glands. Tissues have been collected given the completion of the animal trial, and samples were delivered to Co-PI McGuire for analysis to begin.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Baker, P.H, K.M. Enger, S.K. Jacobi, R.M Akers, and B.D. Enger. 2023. Cellular proliferation and apoptosis in Staphylococcus aureus-infected heifer mammary glands experiencing rapid mammary gland growth. J. Dairy Sci. 106:2642-2650. doi.org/10.3168/jds.2022-22716.
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Baker, P.H, S.K. Jacobi, R.M Akers, and B.D. Enger. 2023. Histological tissue structure alterations resulting from Staphylococcus aureus intramammary infection in heifer mammary glands hormonally induced to rapidly grow and develop. J. Dairy Sci. 106:1370-1382. doi.org/10.3168/jds.2022-22463.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Oliveira, M.X.S., P.H. Baker, C.S. Gammariello, K.M. Enger, and, B.D. Enger. 2023. Tissue area variability of pregnant heifer mammary glands in response to Staphylococcus aureus challenge. Pages 153-154 in Natl. Mastitis Counc. Annu. Mtg. Proc., Atlanta, GA, Natl. Mastitis Council Inc., New Prague, MN.
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Progress 09/01/21 to 08/31/22
Outputs
Target Audience:The target audience during this reporting period is fellow dairy researchers focusing on lactation and mammary gland growth and development along with veterinarians that study mastitis. The audiences were reached during this reporting period via presentations at scientific meetings, publication of conference proceedings, and publication of journal aritcles. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This research project has served as the basis for training 2 graduate students; 1 PhD, and 1 MS. The graduate students were/are being trained in research methodology, study design, experimental procedures, managing ongoing experiments, and summarizing research results and presenting them to research communities. The MS student graduated this year and her manuscripts accepted for publication. She recently accepted a job at a premier research university as a research associate. Undergraduate students are also being exposed to research practices and introduced to graduate education and professional career pathways. How have the results been disseminated to communities of interest?Collected and analyzed data have been submitted for presentation at professional meetings (e.g., National Mastitis Council Annual Meeting) and presented at multistate research meetings (NE 1748) bythe graduate students conducting the research. Additionally, 2 publications have been prepared and submitted for publication in the Journal of Dairy Science for dissemination to the larger scientific community. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Mastitis is primarily the result of an infection within the udder of the dairy cow and remains an extremely common and expensive disease for the US dairy industry. Mastitis not only afflicts milking cows, but also non-milking heifers, who's udders are growing and developing to produce milk for the first time. Infections in growing and developing udders are expected to impact mammary growth and development, and consequently, reduce an animal's lifetime milk production and therefore producer profitability. The overall goal of this research is to determine how, and to what degree, mammary growth is affected by mastitis during rapid mammary growth and identify specific changes in udder growth processes that may be targeted for the development of future therapeutics. The results of this work will guide the development of management practices for producers to limit the impacts of these infections on mammary growth and development. Reducing the occurrence and impacts of mastitis on udder growth and development will increase dairy cow lifetime milk production, dairy cow health, the production efficiency of milk, and producer financial profitability. The progress and results for the specific objectives are listed below. 1. Define the structural changes in tissue architecture that result from infections within the udder when the mammary gland is growing and developing. A study was initiated during this reporting period where 9 out of a final total of 21 heifers were utilized in a second experiment. The remaining 12 heifers will be enrolled in the next reporting period to complete the study. Overall, healthy, uninfected mammary gland tissues were collected from mammary glands rapidly growing and developing and compared against mammary tissues obtained from infected mammary glands that were also rapidly growing and developing. Tissues were collected and preserved for histological and molecular analyses. Overall, formal analysis has been avoided due to the limited number of experimental units reducing the power to make definitive conclusions. Tissue areas are being quantified and the number of cells proliferating and dying are also being quantified. Formal analysis will be completed during the next reporting period. 2.Localize and quantify connective tissue proteins in nonlactating but rapidly growing mammary glands that are changed in response to intramammary infections. This objective is in progress using the tissues obtained the first and second heifer trials. 3. Determine the immune response initiated in non-lactating heifer mammary glands that are growing and developing in response to infections in the udder. Colostrum samples were collected from the infected and uninfected mammary glands to quantify the population of immune cells present. Neutrophils were predominantly recruited to the mammary gland during active infections but were not recruited to uninfected mammary glands. There was also a greater number of lymphocytes present in infected mammary gland tissues and milk samples. We are continuing to determine how the immune cell population is changed during the recruitment to address the infection within the udder. 4. Identify changes in the microbiome of non-lactating heifer mammary glands that result from establishment of infections in bovine mammary glands. Work concerning this objective will begin after completion of the second animal trail which is expected to occur next year.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2023
Citation:
Baker, P.H., F.K. Arnold, K.M. Enger, D.D. Clevenger, S.K. Jacobi, R.M Akers, and B.D. Enger. Histological evaluation of heifer mammary glands infected with Staphylococcus aureus that are growing and developing. Journal of Dairy Science.
- Type:
Journal Articles
Status:
Under Review
Year Published:
2023
Citation:
Baker, P.H., K.M. Enger, S.K. Jacobi, R.M. Akers, and B.D. Enger. Cellular proliferation and apoptosis in Staphylococcus aureus-infected heifer mammary glands experiencing rapid mammary gland growth. Journal of Dairy Science.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Baker, P.H., K.M. Enger, S.K. Jacobi, R.M. Akers, B.D. Enger. 2022. Effect of Staphylococcus aureus intramammary infection on heifer mammary gland growth and development. J. Dairy Sci. 105 (Suppl. 1):177.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Baker, P.H., F.K. Arnold, D.D. Clevenger, S.K. Jacobi, R.M Akers, and B.D. Enger. 2022. Histological response in hormonally stimulated mammary glands of non-pregnant dairy heifers to a Staphylococcus aureus intramammary infection. Pages 228-229 in Natl. Mastitis Counc. Annu. Mtg. Proc., San Diego, CA, Natl. Mastitis Council Inc., New Prague, MN.
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Progress 09/01/20 to 08/31/21
Outputs
Target Audience:The target audience during this reporting period is fellow dairy researchers focusing on lactation and mammary gland growth and development along with veterinarians that study mastitis. The audiences were reached during this reporting period via presentations at scientific meetings and publication of conference proceedings. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This research project has served as the basis for training 2 graduate students; 1 PhD, and 1 MS. The graduate students are being trained in research methodology, study design, experimental procedures, managing ongoing experiments, and summarizing research results and presenting them to research communities.Undergraduate students are also being exposed to research practices and introduced to graduate education and professional career pathways. How have the results been disseminated to communities of interest?Collected and analyzed data has been submitted for presentation at professional meetings (e.g., National Mastitis Council Annual Meeting) and multistate research meetings (NE 1748) to be presented by the graduate students conducting the research. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Mastitis is primarily the result of an infection within the udder of the dairy cow and remains an extremely common and expensive disease for the US dairy industry. Mastitis not only afflicts milking cows, but also non-milking heifers, who's udders are growing and developing in preparation to produce milk. Infections in growing and developing udders are expected to impact mammary growth and development, and consequently, reduce an animal's lifetime milk production and therefore producer profitability. The overall goal of this research is to determine how, and to what degree, mammary tissues growth is affected by mastitis during periods of mammary growth and identify specific changes in udder growth processes that may be targeted for the development of future therapeutics and define how the population of bacteria within the udder is changed. The results of this work will guide the development of management practices for producers to limit the impacts of these infections on mammary growth and development. Reducing the occurrence and impacts of mastitis on udder growth and development will increase dairy cow lifetime milk production, dairy cowhealth, the production efficiency of milk, and producer financial profitability. The progress and results for the specific objectives are listed below. 1. Define the structural changes in tissue architecture that result from infections within the udder when the mammary gland is growing and developing. A first study was conducted this year with 21 dairy heifers. We purposefully established an infection within mammary gland of each heifer's udder and compared these mammary tissues that were growing and developing in the presence of an infection to mammary tissue growing and developing without an infection present. Mammary tissues were collected at the end of the experiment and preserved and stored for microscopic and molecular examinations. In the first analysis of the collected tissues, infected mammary glands contained 13% less epithelium (cells that would later produce milk) than uninfected mammary glands, and also had more stromal tissue (non-milk producing tissue). This would indicate that infections impede growth of the tissue that would later produce milk and therefore reduce future milk production. Continued investigations are being conducted to determine how growth of this tissue by are impeded by the presence of an infection (either by more cells dying due to the infection or a reduced number of cells growing and multiplying). 2.Localize and quantify connective tissue proteins in nonlactating but rapidly growing mammary glands that are changed in response to intramammary infections. This objective is in progress using the tissues obtained from this year's first heifer animal trial. 3. Determine the immune response initiated in non-lactating heifer mammary glands that are growing and developing in response to infections in the udder. Milk like samples were collected from the infected and uninfected mammary glands to quantify the population of immune cells present. Additionally, the collected mammary tissues are being microscopically examined to quantify the immune cells present in the tissues to reflect the degree of information that the infections elicited. Neutrophils were predominantly recruited to the mammary gland during active infections but were not recruited to uninfected mammary glands. There was also a greater number of lymphocytes present in infected mammary gland tissues and milk samples. We are continuing to determine how the immune cell population is changed during the recruitment to address the infection within the udder. 4. Identify changes in the microbiome of non-lactating heifer mammary glands that result from establishment of infections in bovine mammary glands. Work concerning this objective will begin after completion of the second animal trail which is expected to occur next year.
Publications
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2022
Citation:
Enger, B.D., P.H. Baker, M.A. McGuire, R.M. Akers, S.K. Jacobi, K.M. Enger. 2021. Effect of intramammary infections on heifer mammary gland growth and development. Conference of Research Workers in Animal Disease Proceedings.
- Type:
Conference Papers and Presentations
Status:
Under Review
Year Published:
2022
Citation:
Baker, P.H., F.K. Arnold, D.D. Clevenger, S.K. Jacobi, R.M Akers, and B.D. Enger. 2022. Histological response in hormonally stimulated mammary glands of non-pregnant dairy heifers to a Staphylococcus aureus intramammary infection. Natl. Mastitis Counc. Annu. Mtg. Proc., San Diego, CA, Natl. Mastitis Council Inc., New Prague, MN.
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