Mastitis in Dairy Cows: Milk Production and Farm Profitability Silent Killer
Dr. Pophale Krushnakant Subhash1, Dr. Rokade Prashant Prakash2, Dr. Solapure Vaibhav Marotirao3 and Dr. Kodulkar Kshitij Shashikant4
1 (M.V. Sc Livestock Products Technology), 2 (M.V. Sc Pathology), 3 (M.V. Sc Poultry Science), 4 (M.V. Sc Veterinary Gynaecology and obstetrics)
Corresponding author: Dr. Pophale Krushnakant Subhash1, krushnakantpophale16.sp@gmail.com
Abstract
Mastitis is one of the most prevalent and economically significant infectious diseases affecting dairy cattle worldwide. Yet, even as major studies have been made in recent years in dairy management and milking technology, mastitis continues to compromise milk yield, quality and animal welfare, along with farm profitability. The disease is a consequence of interactions between infectious agents, host defence mechanisms and environmental or managerial factors. The intention of this popular article is to present a clear and easily understandable overview of mastitis in dairy cows, focusing on its causes, types, pathogenesis, economic importance, diagnosis, cure and prevention. It is vital to understand mastitis as a management-driven disease rather than a strictly infectious disease for effective control, coupled with sustainable dairy production (Radostits et al., 2010; IDF, 2011).
Key Words: Mastitis, dairy cows, udder health, milk quality, somatic cell count.
- Introduction
Mastitis, generally defined as inflammation of the mammary gland, continues to be one of the major constraints to profitable dairy farming in most parts of the world. It is prevalent in a wide range of dairy herd production systems, varying from small-scale holders to intensive commercial systems. The overall detrimental impact brought forth by this condition generally causes a reduction in milk yield, deterioration in milk quality, increased treatment costs, and often causes the loss of valuable animals through premature culling (Radostits et al., 2010).
Despite much research on it, mastitis remains one of the prevalent diseases due to not being a single causative factor. Poor milking hygiene, filthy housing, malfunctioning milking machines, nutritional deficiency and late detection are some of the reasons for the disease to occur. Thus, mastitis should not be considered simply an infection in the udder but an indication of failure in the management of the herd as a whole (National Mastitis Council, 2017).
- Etiology and Causative Agents
Mastitis is primarily caused by bacterial pathogens, although fungi and algae, mycoplasma species, are occasionally implicated. Mastitis pathogens, based on source and mode of transmission, are classified as contagious or environmental Quinn et al., 2011.
These contagious mastitis pathogens like Staphylococcus aureus, Streptococcus agalactiae and Mycoplasma spp. usually reside within the mammary gland and are transmitted among cows during milking. Poor teat sanitation, dirty milking equipment and also incorrect order in milking favour their transmission.
The environment in which a dairy cow lives harbours pathogens, such as Escherichia coli, Streptococcus uberis, and Streptococcus dysgalactiae from manure, soil, bedding material and water. Poor housing hygiene and wet dirty conditions greatly increase exposure of teats to these organisms, especially between milkings.
- Types of Mastitis
3.1 Clinical Mastitis
Clinical mastitis is a condition where signs include a visible abnormality of milk, such as flakes, clots, watery appearance or blood; along with the swelling, heat, pain and redness of the udder. Systemic signs may include fever, reduced appetite and depression. Severe cases occur, especially when coliform infections are concerned.
The ability of severe coliform mastitis to swiftly escalate to toxaemia and be potentially lethal highlights the importance of early detection and immediate care.
3.2 Subclinical Mastitis
It is characterized by elevated SCC (somatic cell count) and a reduction in milk production, though it has no visible clinical signs. This form is responsible for the majority of economic losses as cows affected often go untreated and continue to shed their pathogens.
Screening routinely by SCC estimation and CMT (California mastitis test) will help in the identification of subclinical cases and prevent long-term losses in production.
- Pathogenesis
The mammary gland is protected by physical barriers such as the teat canal and keratin lining, as well as innate and adaptive immune mechanisms. When pathogens succeed in breaking through these defences, often during or shortly after milking when the teat sphincter remains open, mastitis develops.
Once inside the gland, bacteria proliferate and induce an inflammatory response characterized by leukocyte infiltration and elevated SCC. While inflammation promotes clearance of pathogens, it also destroys milk-producing epithelial cells, ultimately contributing to decreased milk production and if left unchecked, irreparable loss of glandular function in chronic instances.
- Economic Impact
Generally, mastitis has been considered the costliest disease in dairy herds. The economic losses arise from decreased milk yield, discarded milk during treatment, veterinary expenses and increased labor, reduced milk quality premiums and premature culling.
Subclinical mastitis alone can bring significant hidden losses since the reduction in milk yield is mostly not recognized by farmers until the cumulative losses become quite high.
- Diagnosis
Besides the clinical examination of udder and milk, cow-side tests like CMT, laboratory estimation of SCC, and bacteriological culture of milk samples are involved in the diagnosis of mastitis. The identification of the causative organism by milk culture is of paramount importance for the selection of appropriate therapy and designing herd-level control programs.
Routine blind treatment is not recommended, especially in chronic or recurrent cases, since cure rates are low and there is a growing risk of resistance to antimicrobials.
- Treatment
Treatment strategies depend on the severity of infection, causative organism and stage of lactation. Intramammary antibiotics are commonly used for mild to moderate cases, whereas severe infections require systemic antibiotics, anti-inflammatory drugs and supportive therapy (Radostits et al., 2010).
Often, chronic infections caused by Staphylococcus aureus respond poorly to the treatment; culling may, therefore, represent the most economically feasible option to prevent further spread within the herd. National Mastitis Council (2017)
- Prevention and Control
Mastitis control effectively depends on prevention management practices rather than treatment. The major measures involve proper milking hygiene, pre- and post-milking teat disinfection, clean and dry housing, periodic milking machine maintenance, dry cow therapy, balanced nutrition and regular monitoring of SCCs.
A well-implemented mastitis control program has been demonstrated to greatly reduce incidence and enhance overall productivity in the herd.
Conclusion
Mastitis is a highly preventable disease in dairy cattle, driven principally by management practices. Where infectious agents may trigger the condition, it is human decisions that determine the condition’s persistence within herds. Sustainable dairy farming demands a proactive approach to udder health, with hygiene, monitoring and prevention preferred to repeated therapeutic interventions. Effective mastitis control is not optional; it is a cornerstone to profitable and responsible milk production. Radostits et al., 2010
References
Radostits O M, Gay C C, Hinchcliff K W and Constable P D. 2010. Veterinary Medicine: A Textbook of the Diseases of Cattle, Horses, Sheep, Pigs and Goats. 10th Ed., Saunders Elsevier, London, pp. 673–748.
Quinn P J, Markey B K, Leonard F C, FitzPatrick E S, Fanning S and Hartigan P J. 2011. Veterinary Microbiology and Microbial Disease. 2nd Ed., Wiley-Blackwell, Oxford, pp. 465–475.
National Mastitis Council. 2017. Laboratory Handbook on Bovine Mastitis. National Mastitis Council Inc., Madison, Wisconsin, USA.
IDF. 2011. The Global Standard for Quality Raw Milk. Bulletin of the IDF No. 444. International Dairy Federation, Brussels.
