The Milk You Consume

Greater Kashmir

Mastitis treatment and control is one of the largest costs to the dairy industry

Mastitis is the inflammation of the mammary gland and udder tissue, and is a major endemic disease of dairy cattle. It usually occurs as an immune response to bacterial invasion of the teat canal by variety of bacterial sources present on the farm, and can also occur as a result of chemical, mechanical, or thermal injury to the cow’s udder. Mastitis occurs when white blood cells (leucocytes), are released into the mammary gland, usually in response to an invasion of bacteria of the teat canal. Milk-secreting tissue, and various ducts throughout the mammary gland are damaged due to toxins by the bacteria. Mastitis can also occur as a result of chemical, mechanical, or thermal injury. Mastitis is most often transmitted by contact with the milking machine, and through contaminated hands or materials. 

Economic loss
Mastitis treatment and control is one of the largest costs to the dairy industry and is also a significant factor in dairy cow welfare. Losses arise from reduction in yields due to illness and any permanent damage to udder tissue, the cost of reduced longevity due to premature culling, milk thrown away due to contamination by medication or being unfit to drink, the extra labour required to tend to mastitic cows and the costs of veterinary care and medicines.

Effects of mastitis on milk
Mastitis can cause a decline in potassium and lactoferrin. It also results in decreased casein, the major protein in milk. As most calcium in milk is associated with casein, the disruption of casein synthesis contributes to lowered calcium in milk. Milk from cows with mastitis also has a higher somatic cell count (higher the somatic cell count, the lower the milk quality).     An overall effect of the chemical alterations in milk mean that the pH of milk, normally around 6.6, can increase to 6.8 or 6.9 in mastitic cows. The presence of certain blood enzymes in milk from mastitic cows can affect the taste of milk and its ability to be made into other dairy products.
Secondly, antibiotics are frequently used to control mastitis in dairy cattle. However, the presence of antibiotic residues in milk is very problematic, for at least three reasons. In the production of fermented milks, antibiotic residues can slow or destroy the growth of the fermentation bacteria. From a human health point of view, some people are allergic to specific antibiotics, and their presence in food consumed can have severe consequences. Also, frequent exposure to low level antibiotics can cause microorganisms to become resistant to them, through mutation, so that they are ineffective when needed to fight a human infection. For these reasons, it is extremely important that milk from cows being treated with antibiotics is withheld from the milk supply. 
The most obvious symptoms of clinical mastitis are abnormalities include swelling, hardness and redness of udder, watery appearance of milk, flakes, clots, or pus in milk, a reduction in milk yield, an increase in body temperature, signs of diarrhoea and dehydration and reduction in mobility due to the pain of a swollen udder or simply due to feeling unwell.

 Treatment and Control
Typically when clinical mastitis is detected, the cow is milked out and then given an intramammary infusion of antibiotic, i.e., infused directly into the infected gland. Intramammary infusions: Prior to intramammary infusion, the teat is cleaned well and the tip of the teat is swabbed with an alcohol swab and allowed to dry for a number of seconds. The antibiotic comes in a plastic tube with a plastic infusion cannula on the end.  After emptying the antibiotic tube, the teat is pinched off and the antibiotic fluid is palpated up into the gland.  Vaccinations for mastitis do exist, but as they only reduce the severity of the condition, and do not prevent new infection they should be used in conjunction with a mastitis prevention program. Awareness of the economic losses associated with mastitis is resulting in a desire for mastitis control programs. Control programs are focused on detection of mastitis by the identification of the causative agent and prevention of transmission by removing the source of the agent (milk contaminated fomites, bedding, persistently infected cows, etc.).  Practices such as good nutrition, proper milking hygiene, and the culling of chronically infected cows can also help. Ensuring that cows have clean, dry bedding decreases the risk of infection and transmission. Dairy workers should wear gloves while milking, and machines should be cleaned regularly to decrease the incidence of transmission. Application of teat dip or spray, such as iodine is vital before and after milking to remove the growth medium for bacteria. 

Author is PG scholar Division OF Veterinary Surgery and Radiology SKUAST-K. Feedback