Cow Behavior, Herd Dynamics & Mastitis
Every farmer knows that mastitis is the most costly disease in the dairy industry. Just a single infected quarter can decrease a cow’s production by 10-12% (Akers & Nickerson, 2011). The environmental risk factors for the disease and effective control measures are widely known. Less discussed—perhaps to some degree less understood—is the relationship between herd dynamics or individual cow behavior and mastitis.
Like most mammals, cows often exhibit behavioral changes in response to illness several days before any clinical signs are apparent. Being aware of these early warning signs can help determine which cows should receive extra monitoring, be segregated and/or begin an early treatment plan.
Also, certain behaviors themselves (usually in response to stress) may increase the risk of mastitis. Stress triggers the release of cortisol which alters the metabolism and causes the immune system to be suppressed, making infection by harmful microorganisms easier.
As a herd animal, cows naturally try to establish a social hierarchy. When this hierarchy changes or is unclear such as during calving periods or in certain parlor styles, stress levels increase and so too does the risk of disease. While it is next to impossible to control cows’ behavior, high-risk periods can be anticipated and steps taken to ensure stress levels are minimized.
Behavioral Changes in Response to Infection
A two-year study in early lactation cows by faculty from the University of British Columbia and the Southern University of Chile identified several changes in behavior that precede the appearance of clinical signs of mastitis.
Feed intake decreased by an average of 1.2 kg a day 5 days before clinical symptoms were seen. Cows spent less time feeding and had decreased competitive behavior for resources such as food and water. Less time was spent self-grooming and more time was spent standing, likely to relieve pain or pressure on the udder.
These behaviors are encompassed by the term “Energy Conserving Sickness Behavior”. The study found that these the greatest improvement of these behaviors occurred 2 days after treatment began, with feeding behavior (intake and duration) improving faster than competitive behaviors.
Although it is impossible to monitor each cow’s behavior for these early warning signs, seeing them in a large portion of the herd may be more obvious and allow early action to be taken to minimize severity, spread and duration of infection.
Behaviors Increasing the Risk of Infection
While dairy cows exhibit many behaviors that have the potential to increase the risk of infection, the two most prominent are calving related behaviors and social behaviors. Their significance is largely due to the stress associated with these factors.
Literature from McGill University implicates calving related behavior as a stress factor that may contribute to mastitis. The frequency of natural calf suckling is usually more frequent than that of milking, so invading microorganisms have little time to develop since their growth medium (milk) is removed more often.
An older study (Tsolov, Dimitrov, Koleva, & Burzilov, 1989) cited found that in the first two months post-partum, duration and frequency of mastitis infections were lower in cows that were allowed to be suckled by calves for 6-10 days than cows that were only allowed several hours to 4 days.
Since optimizing milk production is also a goal along with mastitis prevention, a possible solution might be to milk fresh cows more frequently. This is supported by reports in The Journal (Blakemore, 2014) from some farmers in the United States and Britain that fresh cows choose to go through robotic parlors 4-5 times a day compared with an average of 2.3 times a day for the rest of the herd.
Some cows may also experience difficult calf separations which increases stress levels, as well as the tension of being reintroduced into the lactating herd where the social hierarchy shifts every time a cow enters or leaves the herd.
In addition to the stress associated with calving, cows that are recumbent for long periods of time after giving birth have an increased risk of developing mastitis due to increased exposure to environmental pathogens.
As previously mentioned, social hierarchy has a significant influence on dairy cow behavior and may be associated with stress factors than can increase the risk of mastitis. Every time a cow is introduced to the herd or leaves the herd, the hierarchy is re-established. Lower rank cows engage in more competitive behaviors either through trying to gain rank or being bullied into submission by a stronger herd mate. This contact with other herd members increases the risk of transmission of contagious pathogens from infected to uninfected cows, resulting in lower ranking cows being more susceptible to mastitis.
Parlor type also has an influence on the social hierarchy of a dairy herd. Herds housed in tie stalls have less freedom for social interactions, therefore herd relationships and social hierarchies are often unclear. This results in higher stress levels than might be seen in herds kept on pack or housed in free stalls. Allowing time for pasture turn out might be one method to alleviate social stress experienced by tie stall herds.
Although effective herd management and mastitis control programs are the primary means of reducing infection, being aware of behavioral changes and stress factors related to the disease is beneficial. Early warning signs enable action to be taken quickly to treat and segregate potentially infected cows and minimize the spread of infection throughout the herd. Addressing stress factors as a complementary measure to standard management and control practices can keep the herd happy and healthy, boosting production and quality.
With recent advancements in robotics and tracking technology, it may be possible in the future to monitor individual cow behavioral and stress data to pinpoint at risk individuals sooner and more effectively. There is no substitute for good hygiene and management when it comes to mastitis control, but behavior and herd dynamics are important factors to be aware of to maintain happy, healthy cows.
If you're having difficulty recognizing the signs of early infection or controlling the spread of mastitis through your herd, visit our herd health product page to determine which somatic cell count testing device is right for you. You can also contact our Quality Milk Specialist to answer your questions or request a demo.
Akers, M. R., & Nickerson, S. C. (2011). Mastitis and its Impact on Structure and Function in the Ruminant Mammary Gland. Mammary Gland Biol Neoplasia, 275-289.
Blakemore, J. (2014, January 20). Robots help to transform the future at Northumberland dairy farm. Retrieved from The Journal: http://www.thejournal.co.uk/business/robots-help-transform-future-northumberland-6530355
Tsolov, S., Dimitrov, M., Koleva, M., & Burzilov, G. (1989). Effect of suckling a calf on the frequency of mastitis. Veterninarna Sbirka, 6-11.
Sepúlveda-Varas, P., Proudfoot, K. L., Weary, D. M., & von Keyserlingk, M. A. G. (2016). Changes in behaviour of dairy cows with clinical mastitis. Applied Animal Behaviour Science, 8-13.
About the Author
Anna Schwanke is an undergraduate student at the University of Guelph, Ontario. She is responsible for researching and writing about a wide variety of topics related to dairy cow welfare and management for Dairy Quality Inc. The 10 years she spent living in Australia, as well as her love of travelling, give her a firsthand viewpoint of issues facing the international dairy community. She plans to graduate from the University’s College of Physical & Engineering Science in 2019 and pursue a career in the Life Sciences or Agriculture industry.
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