Progress 11/01/07 to 10/30/12
Outputs
OUTPUTS: A successful Streptococcus uberis experimental intramammary challenge model was developed, which will be used to determine the effect of vaccination against environmental streptococci in breeding age and pregnant dairy heifers. Culture-based therapy and a vaccination program to control staphylococcal mastitis in does were used to reduce the prevalence of this disease and improve animal health and milk quality in a dairy goat herd. The daily feeding of a dietary immunostimulant supplement to dairy heifers prepartum resulted in less mastitis, lower somatic cell counts, and greater production in early lactation compared with unsupplemented animals. Thus milk yield as well as quality were improved. Results have been presented at annual meetings of professional societies, regional dairy conferences, as well as to local dairy producer meetings, and have been published as abstracts, proceedings papers, and journal articles. PARTICIPANTS: S. Nickerson PI, W. Gilson Co-PI, and L. Ely Co-PI are professors who collaborated on the project. K. Jackson and V. Eubanks are graduate students who contributed to the project. F. Kautz is a technician who assisted with the project TARGET AUDIENCES: PIs of other institutions were targeted to share our knowledge in promoting further research. Veterinarians were targeted to communicate research findings with dairymen, and producers were targeted to directly apply results to on-farm conditions. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Streptococcus uberis mastitis is very difficult to control. Experimental vaccines against this disease need to tested for efficacy, and results of the experimental intramammary challenge model demonstrate a means for efficacy testing. Culture-based therapy and vaccination to control mastitis in goat herds will improve milk production and quality, as well as producer profits. Use of a dietary immunostimulant supplement in dairy heifers will lower prevalence of mastitis, improve milk quality, and increase yield for producers.
Publications
- Jackson, K.A., D.J. Hurley, F.M. Kautz, L.O. Ely, and S.C. Nickerson. 2012. Development of Streptococcus uberis mastitis in bred dairy heifers using an experimental challenge model. Journal of Dairy Science. 95:7210-72-13.
- Nickerson, S. C. 2012. Invited review. Managing mastitis in heifers: An initial step in improving dairy herd health. 2012. Chapter 16 in Milk Production - An Up-to-Date Overview of Animal Nutrition, Management and Health. Pp. 333-358. (ISBN 979-953-307-116-8), InTech, Rijeka, Croatia.
- Eubanks V., S. Nickerson. D. Hurley, F. Kautz, J. Graham, N. Forsberg, Y. Wang, K. Zanzalari, and J. Chapman. 2012. Dietary supplementation to enhance immunity against mastitis in dairy heifers vaccinated against Staphylococcus aureus: An update. Pages 155-156 in Proceedings of the 51st Annual Meeting, National Mastitis Council, Inc. St. Petersburg, FL, 2012.
- Nickerson, S. C. 2012. Invited paper. Mastitis management for the future milking herd. In Proceedings of the High Plains Dairy Conference 2012, Amarillo, TX. March 7-8, 2012.
- Nickerson, S.C. and W.E. Owens. 2012. Mastitis detection, prevention, control in replacement heifers. Pages 4-6 in Progressive Dairyman, Issue 2, January 21, 2012.
- Eubanks, V.J., D.J. Hurley, L. O. Ely, F.M. Kautz, S.C. Nickerson, N.E. Forsberg, Y.Q. Wang, K. Zanzalari, and J. Chapman. 2012. Pre- and postpartum mmunomodulatory effects of a dietary supplement on the immune system of dairy heifers. J. Anim. Sci. Vol. 90, Suppl. 3/J. Dairy Sci. Vol. 95, Suppl. 2. Pg 222. Abstr # 220.
- Eubanks*, V.J., S.C. Nickerson, D.J. Hurley, L.O. Ely, F.M. Kautz, J. Graham, N.E. Forsberg, Y.Q. Wang, J.D. Chapman, and K.P. Zanzalari. 2012. Enhancing immunity against mastitis in dairy heifers through vaccination and use of a dietary immunostimulant. Poster Session sponsored by PrinceAgri, ADSA-AMPA-ASAS-CSAS-WSASAS Joint Annual Meeting, Phoenix, AZ.
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: 1) No standard practices currently exist to control caprine mastitis, and a collaborative study was completed by researchers at UGA and a local registered commercial goat herd. Culture-based therapy was employed to reduce the duration of existing cases of mastitis in does as well as a vaccination program to prevent staphylococcal mastitis in doelings and mature does to reduce the prevalence of this disease and improve animal health and milk quality. 2) UGA researchers are working with the pharmaceutical company Boeringer-Ingelheim to develop techniques to combine vaccination with antibiotic therapy to prevent the establishment of staphylococcal mastitis in dairy heifers and increase cure rates of quarters with existing infections. 3) We are also working with PrinceAgri and Omnigen to combine vaccination with an immunostimulant feed additive to improve the efficacy realized with vaccination and further reduce prevalence of mastitis and improve subsequent milk yield, product safety, and milk quality. 4) Lastly, we were funded by Merial to develop a vaccine efficacy evaluation trial against Streptococcus uberis mastitis in dairy heifers. PARTICIPANTS: Individual: S. C. Nickerson: Principle Investigator. W. D. Gilson: Collaborated in sample collection and laboratory analysis. L. O. Ely: Collaborated in data analysis. Partner Organizations: Prince Agri, and Merial: Provided funding and partial laboratory analyses. TARGET AUDIENCES: Target audience: Dairy producers who can use the results generated by these trials to improve the efficiency of their operations for enhanced income. Bovine practitioners who can use results to recommend mastitis treatment products or prevention tools such as immunization. Graduate students: Those working on theses and dissertation research. Undergraduate students: Those working part-time on these projects enhanced their knowledge of animal health. Efforts: The inclusion of technicians, dairy producers, extension agents, and college students in these scientific trials increased their knowledge of dairy cow health and management. PROJECT MODIFICATIONS: None
Impacts
1) A collaborative study of the prevalence of mastitis in goats in a commercial dairy herd demonstrated that this disease was present in >80% of lactating does. The presence of mastitis in dairy does decreased milk production by reducing milk synthesis and secretion by milk producing tissues, and also decreased milk quality by increasing the number of white blood cells (somatic cells) in milk as well as bacteria counts. Methods that are being developed to control mastitis in dairy goats will 1) improve milk quality by decreasing the leukocyte count as well as bacterial counts in milk, thereby providing a safer more wholesome product for consumers; 2) improve milk quantity by eliminating the infections and returning the gland to full milk production; and 3) improve health and welfare of does and of suckling kids and increase their weaning weights. 2)Prevention is the key to controlling bovine mastitis in adult lactating and dry cows, and this should be the focus of preventing this disease in heifers. Initial work with vaccination (Boeringer-Ingelheim) showed that immunization of heifers can reduce the incidence of Staphylococcus aureus mastitis by 45 to 61%. Successfully treated heifers produce 10% more milk during their first lactation, which translates to approximately 2,000 pounds of milk for a heifer with an average lactation yield of 20,000 pounds of milk. This translates to $500 more per animal per year at a current milk price of $25/cwt. In a milking string of 100 first calf heifers in the typical Georgia dairy herd, this figure becomes $50,000 per year. By enhancing the efficacy realized by vaccination, we can return even greater income to dairy producers and maximize milk quality and safety to the consuming public. Results of the PrinceAgri and Omnigen project have demonstrated that use of vaccination in combination with an oral immunostimulant in dairy heifers increases blood L-selectin and interleukin-8, as well as leukocyte phagocytic activity, which boosts heifers' immune system against diseases such as mastitis. Results of the Merial project demonstrated that a successful Streptococcus uberis experimental intramammary challenge model was developed, which will be used to determine the effect of vaccination against environmental streptococci in breeding age and pregnant dairy heifers.
Publications
- 1. Eubanks, V.J., N.E. Forsberg, Y.Q. Wang, K.P. Zanzalari, J.D. Chapman, D.J. Hurley, F.M. Kautz, L.O. Ely, and S.C. Nickerson. 2011. Effects of OmniGen-AF on enhancing immunity in dairy heifers vaccinated with a Staphylococcus aureus bacterin. Abstract. ADSA Annual Meeting. New Orleans, LA. Journal of Dairy Science 94, E-supplement 1: 702-703.
- 2. Eubanks V., N. Forsberg, Y. Wang, K. Zanzalari, J. Chapman, L. Ely, and S.C. Nickerson. 2011. Immunostimulating effects of OmniGen-AF on vaccinating dairy heifers with a Staphylococcus aureus bacterin: Preliminary report. Exhibit/Poster Session. Georgia Farm Bureau Commodity Conference Tour, Athens, GA.
- 3. Eubanks V., N. Forsberg, Y. Wang, K. Zanzalari, J. Chapman, L. Ely, and S.C. Nickerson. 2011. Immunostimulating effects of OmniGen-AF on vaccinating dairy heifers with a Staphylococcus aureus bacterin: Preliminary report. Exhibit/Poster Session. Graduate Students and Postdocs in Science (GSPS). Third Annual Interdisciplinary Scientific Research Day. Paul D. Coverdell Center. May 20, 2011.
- 4. Eubanks V., N. Forsberg, Y. Wang, K. Zanzalari, J. Chapman, L. Ely, and S.C. Nickerson. 2011. Immunostimulating effects of OmniGen-AF on vaccinating dairy heifers with a Staphylococcus aureus bacterin: Preliminary report. Poster Session. Southern Dairy Conference, Atlanta, GA.
- 5. Jackson, K.A.*, S.C. Nickerson, F.M. Kautz, and D.J. Hurley. 2011. Experimentally induced Streptococcus uberis mastitis in dairy heifers. Page 164 in Proceedings of the 3rd International Symposium on Mastitis and Milk Quality and American Association of Bovine Practitioners 44th Annual Conference, September 22-24, 2011, St. Louis, MO.
- 6. Jackson, K.A., S.C. Nickerson, F.M. Kautz, and D.J. Hurley. 2011. Experimentally induced Streptococcus uberis mastitis in dairy heifers: A challenge model incident to a vaccine trial. Abstract. ADSA Annual Meeting. New Orleans, LA. Journal of Dairy Science 94, E-supplement 1: 701.
- 7. Jackson, K. A., D. J. Hurley, F. M. Kautz, and S. C. Nickerson. 2011. Development of a challenge model to experimentally induce Streptococcus uberis mastitis in bred dairy heifers. Poster Session. Southern Dairy Conference, Atlanta, GA.
- 8. Upchurch, M., F. Kautz, and S.C. Nickerson. 2011. Local leukocyte response of the heifer mammary gland to mastitis-causing bacterial pathogens. Poster Session. CAES Young Scholars Program. July 6, 2011.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: 1) Currently, no standard practices exist to control caprine mastitis, and a collaborative study is underway by researchers at UGA and a local registered commercial goat herd. We are using culture-based therapy to reduce the duration of existing cases of mastitis in does as well as a vaccination program to prevent staphylococcal mastitis in doelings and mature does to reduce the prevalence of this disease and improve animal health and milk quality. 2)We are working with the pharmaceutical company Boeringer-Ingelheim to develop techniques to combine vaccination with therapy to prevent the establishment of staphylococcal mastitis and increase cure rates of quarters with existing staphylococcal infections in dairy heifers. We are also working with PrinceAgri and Omnigen to combine vaccination with an immunostimulant feed additive to improve the efficacy realized with vaccination and further reduce prevalence of mastitis and improve subsequent milk yield, safety, and quality. Lastly, we have been funded by Merial to develop a vaccine against Streptococcus uberis mastitis in heifers. PARTICIPANTS: Individual: S. C. Nickerson: Principle Investigator. W. D. Gilson: Collaborated in sample collection and laboratory analysis. L. O. Ely: Collaborated in data analysis. Partner Organizations: ImmuCell Corporation, Prince Agri, and Merial: Provided funding and partial laboratory analyses. TARGET AUDIENCES: Target audience: Dairy producers who can use the results generated by these trials to improve the efficiency of their operations for enhanced income. Bovine practitioners who can use results to recommend mastitis treatment products or prevention tools such as immunization. Graduate students: Those working on theses and disseration research. Undergraduate students: Thise working part-time on these projest enhanced theri knowledge of animal health. Efforts: The inclusion of technicians, dairy producers, extension agents, and college students in these scientific trials increased their knowledge of dairy cow health and management. PROJECT MODIFICATIONS: None
Impacts
1) An ongoing collaborative study of the prevalence of mastitis in goats in the commercial dairy herd demonstrated that this disease was present in >80% of lactating does. The presence of mastitis in dairy does decreases milk production by reducing milk synthesis and secretion by milk producing tissues, and also decreases milk quality by increasing the number of white blood cells (somatic cells) in milk as well as bacteria counts. Methods that are being developed to control mastitis in dairy goats will 1) improve milk quality by decreasing the leukocyte count as well as bacterial counts in milk, thereby providing a safer more wholesome product for consumers; 2) improve milk quantity by eliminating the infections and returning the gland to full milk production; and 3) improve health and welfare of does and of suckling kids and increase their weaning weights. 2)Prevention is the key to controlling this disease in adult lactating and dry cows, and this should be the focus of preventing this disease in heifers. Our initial work with vaccination (Boeringer-Ingelheim) has shown that the immunization of heifers as early as 6 mo of age can reduce the incidence of Staphylococcus aureus mastitis by 45 to 61%, and the coagulase-negative staphylococci by 8 to 30%. Successfully treated heifers produce 10% more milk during their first lactation, which translates to approximately 2,000 pounds of milk for a heifer with an average lactation yield of 20,000 pounds of milk. This translates to $500 more per animal per year at a current milk price of $25/cwt. In a milking string of 100 first calf heifers in the typical Georgia dairy herd, this figure becomes $50,000 per year. We expect that by enhancing the efficacy already realized by vaccination, we can return even greater income to dairy producers and maximize milk quality and safety to the consuming public. Results of the PrinceAgri and Omnigen project have demonstrated that use of vaccination in combination with an oral immunostimulant in dairy calves increases blood L-selectin and interleukin-8, which boost the calves' immune system against calfhood diseases. Results of the Merial project have demonstrated that a successful Streptococcus uberis experimental intramammary challenge model was developed, which will be used to determine the effect of vaccination against environmental streptococci in breeding age and pregnant dairy heifers.
Publications
- 2. Nickerson, S. C. 2010. Managing mastitis in dairy heifers maximizes producer profits. Animal and Dairy Science Departmental Report. http://www.ads.uga.edu/ADS2008DepartmentalReports.html
- 3. Raymond, R., C. W. Bales, D.E. Bauman, D. Clemmons, R. Kleinman, D. Lann, S. C. Nickerson, and K. Sejrsen. 2010. Recombinant bovine somatotropin (rbst): a safety assessment. Animal and Dairy Science Departmental Report. http://www.ads.uga.edu/ADS2008DepartmentalReports.html
- 4. McClary, D. M. and S. C. Nickerson. 2010. Relationship between the use of recombinant bovine somatotropin (Posilac) in dairy cows and the incidence of clinical mastitis. in Dairy Cattle. Mastitis and Milking Management. DAIReXNET. http://www.extension.org/pages/Dairy_Cattle_Mastitis_and_Milking_Mana gement
- 5. Nickerson, S. C., L. O. Ely, E. P. Hovingh, and P. W. Widel. 2010. Immunizing dairy heifers can reduce prevalence of Staphylococcus aureus and reduce herd somatic cell counts. in Dairy Cattle Mastitis and Milking Management. DAIReXNET. http://www.extension.org/pages/Dairy_Cattle_Mastitis_and_Milking_Mana gement
- 1. Nickerson, S. C. 2010. Maximizing producer profits through managing mastitis in dairy heifers. in Proceedings of the 2010 Florida Ruminant Nutrition Symposium Pre-Conference Symposium. 11 pp. Gainesville, FL.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: OBJECTIVE 1) Characterization of host mechanisms associated with mastitis susceptibility and resistance: The immune response of dairy cows and dairy goats to vaccination against Staphylococcus aureus mastitis is being evaluated at 2 state universities in Georgia. Effects of immunization on new infection rate and somatic cell counts are being assessed. OBJECTIVE 3) Assessment and application of new technologies that advance mastitis control, milk quality and dairy food safety: The evaluation of a novel antimicrobial intramammary infusion product against subclinical mastitis caused by staphylococci and streptococci is being conducted in two local Georgia dairies. Cure rates and effects on somatic cell counts are being monitored. PARTICIPANTS: Individual: S. C. Nickerson: Principle Investigator. W. D. Gilson: Collaborated in sample collection and laboratory analyses. L. O. Ely: Collaborated in data analyses. Partner organization: Immucell Corporation: Provided funding and partial laboratory analysis for the evaluation of a novel antimicrobial intramamamry product. TARGET AUDIENCES: Target audience: Dairy producers who can use the results generated by these trials to improve the efficiency of their operations for enhanced income. Bovine practitioners who can use results to recommend mastitis treatment products or prevention tools (immunization). Undergraduate students: Those working part-time on the projects enhanced their knowledge of animal health. Efforts: The inclusion of technicians, dairy producers, extension agents, and college students in these scientific trials increased their knowledge of daiy cow health and management. PROJECT MODIFICATIONS: Nothing significant to report during this period.
Impacts
OBJECTIVE 1) Characterization of host mechanisms associated with mastitis susceptibility and resistance: Results to date indicate that vaccination reduces new S. aureus infection rate, somatic cell counts, and culling rate while increasing milk yield, milk protein, milk fat, and days in milk. Thus, immunization improved milk production as well as milk quality, probably as a result of improved udder health. OBJECTIVE 3) Assessment and application of new technologies that advance mastitis control, milk quality, and dairy food safety: The active ingredient in a novel intramammary infusion product, nisin, is generally regarded as safe for human consumption (GRAS), and may be marketed with a minimal no withdrawal period as long as milk from treated quarters is visibly normal. Thus, dairymen can market and be paid for milk from cows treated for mastitis much sooner rather than waiting the 36- to 96-hour withdrawal (milk discard) time.
Publications
- Nickerson, S. C. and W. E. Owens. Mastitis detection, prevention, and control in dairy replacement heifers. Pages 45-54 in 2009 Louisiana Dairy Report. LSUAC. Baton Rouge, LA. 2009.
- Nickerson, S. C. A comprehensive plan to control mastitis and milk quality. Animal and Dairy Science Departmental Report. 2009. http://www.ads.uga.edu/ADS2008DepartmentalReports.html
- Nickerson, S. C. A review of mastitis detection, prevention, and control in dairy replacement heifers. Animal and Dairy Science Departmental Report. 2009. http://www.ads.uga.edu/ADS2008DepartmentalReports.html
- Nickerson, S. C. Importance of dry cow management in the control of mastitis. in Dairy Cattle Mastitis and Milking Management. DAIReXNET. 2009. http://www.extension.org/pages/Dairy_Cattle_Mastitis_and_Milking_Mana gement
- Nickerson, S. C. Future trends in mastitis research. Pages 5-21 in Proceedings of the Annual Scientific Meeting of the Canadian Bovine Mastitis Research Network. Montreal, Quebec, Canada. 2009.
- Nickerson, S. C. and W. E. Owens. Mastitis detection, prevention, and control in dairy replacement heifers. in Dairy Cattle Mastitis and Milking Management. DAIReXNET. 2009. http://www.extension.org/pages/Dairy_Cattle_Mastitis_and_Milking_Mana gement
- Nickerson, S. C., E. P. Hovingh, C. Peterson, S. Brannock, E. Schaffer, and P. W. Widel. Efficacy of a Staphylococcus aureus bacterin in reducing the new infection rate and somatic cell count in a commercial dairy. Animal and Dairy Science Departmental Report. 2009. http://www.ads.uga.edu/ADS2008DepartmentalReports.html
- Owens, W. E. and S. C. Nickerson. Medical therapy options for control of bovine mastitis. Pages 55-62 in 2009 Louisiana Dairy Report. LSUAC. Baton Rouge, LA. 2009.
- Reeve-Johnson, L., and S. C. Nickerson. Self-cure rates in American dairy cows infected with Staphylococcus aureus at drying off. Animal and Dairy Science Departmental Report. 2009. http://www.ads.uga.edu/ADS2008DepartmentalReports.html
- Nickerson, S. C. New frontiers in mastitis research. Page 348 in Proceedings of the 2009 Annual Meeting of the American Dairy Science Association, Montreal, Quebec. Journal of Animal Science, Vol. 87, E-Suppl. 2/Journal of Dairy Science, Vol. 92, E-Suppl. 1. Paper 389. 2009.
- Nickerson, S. C. Mastitis in beef bulls caused by Arcanobacterium pyogenes. Page 582 in Proceedings of the 2009 Annual Meeting of the American Dairy Science Association, Montreal, Quebec. Journal of Animal Science, Vol. 87, E-Suppl. 2/Journal of Dairy Science, Vol. 92, E-Suppl. 1. Paper 788. 2009.
- Raymond, R., C. W. Bales, D.E. Bauman, D. Clemmons, R. Kleinman, D. Lann, S. C. Nickerson, and K. Sejrsen. Recombinant bovine somatotropin (rbST): A safety assessment Presented at the 2009 Annual Meeting of the American Dairy Science Association, Montreal, Quebec. 2009.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: OBJECTIVE 1) Characterization of host mechanisms associated with mastitis susceptibility and resistance: The immune response of dairy cows and dairy goats to vaccination against Staphylococcus aureus mastitis is being evaluated at 2 state universities in Georgia. Effects of immunization on new infection rate and somatic cell counts are being assessed. OBJECTIVE 3) Assessment and application of new technologies that advance mastitis control, milk quality and dairy food safety: The evaluation of a novel antimicrobial intramammary infusion product against subclinical mastitis caused by staphylococci and streptococci is being conducted in two local Georgia dairies. Cure rates and effects on somatic cell counts are being monitored. PARTICIPANTS: Individuals: S. C. Nickerson: Principle Investigator. W. D. Gilson: Collaborated in sample collection and laboratory analyses. L. O. Ely: Collaborated in data analysis. Partner Organization: Immucell Corporation: Provided funding and partial laboratory analyses for the evaluation of a novel antimicrobial intramammary infusion product. TARGET AUDIENCES: Target audience: Dairy producers who can use the results generated by these trials to improve the efficiency of their operations for enhance income. Bovine practioners who can use results to recommend mastitis treatment products or prevention tools (immunization). Undergraduate students: Those working part-time on the projects enhanced their knowledge of animal health. Efforts: Including technicans, dairy producers, extension agents, and college students in these scientific trials increased their knowledge of dairy cow health and management. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
OBJECTIVE 1) Characterization of host mechanisms associated with mastitis susceptibility and resistance: Results to date indicate that vaccination reduces new S. aureus infection rate, somatic cell counts, and culling rate while increasing milk yield, milk protein, milk fat, and days in milk. Thus, immunization improved milk production as well as milk quality, probably as a result of improved udder health. OBJECTIVE 3) Assessment and application of new technologies that advance mastitis control, milk quality, and dairy food safety: The active ingredient in this intramammary infusion product, nisin, is generally regarded as safe for human consumption (GRAS), and may be marketed with a minimal no withdrawal period as long as milk from treated quarters is visibly normal. Thus, dairymen can market and be paid for milk from cows treated for mastitis much sooner rather than waiting the 36- to 96-hour withdrawal (milk discard) time.
Publications
- Fain, J. L., W. M. Graves, J. M. Haslett, S. C. Nickerson, and J. K. Bernard. Effect of combining GnRH and ECP with a CIDR-prostaglandin protocol on pregnancy rates in Holstein heifers submitted to timed artificial insemination. Professional Animal Scientist. 2008. In Review.
- Gilson, W. D., and S. C. Nickerson. The Georgia mastitis situation: Cell counts and microbiology. Pages 30-34 in Proceedings of the Southeast Dairy Herd Management Conference. November 12-13, Macon, GA. 2008.
- Gilson, W. D., S. C. Nickerson, and L. O. Ely. Evaluating somatic cell counts in frozen milk samples using the DeLaval DCC. Pages 196-197 in Proceedings of the 47th Annual Meeting of the National Mastitis Council, National Mastitis Council, Inc. Madison, WI. 2008.
- Nickerson, S. C. Control of heifer mastitis: Antimicrobial treatment: An overview. Veterinary Microbiology. 134:248-259. 2008.
- Nickerson, S. C., E. P. Hovingh, C. Peterson, S. Brannock, E. Schaffer, and P. W. Widel. Efficacy of a Staphylococcus aureus bacterin in reducing the new infection rate and somatic cell count in a commercial dairy. Pages 234-235 in Proceedings of the 47th Annual Meeting of the National Mastitis Council, National Mastitis Council, Inc. Madison, WI. 2008.
- Rollin, E., S. C. Nickerson, D. T. Ensley, and R .D. Berghaus. Mastitis outbreak in beef bulls on a feeding test. American Association of Bovine Practitioners. Sept 25-27, Charlotte, NC. 2008.
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