After effects of mastitis on milk
Mastitis resulting from major presence of pathogens causes considerable compositional changes in milk. The types of proteins present change dramatically. Casein, the major milk protein of high nutritional quality, declines and lower quality whey proteins increase which adversely impacts dairy product quality, such as cheese yield, flavour and quality. Serum albumin, immune-globulins, transferrin, and other serum proteins pass into milk because vascular permeability changes. Lactoferrin, the major antibacterial iron-binding protein in mammary secretions, increases in concentration.
Milk protein breakdown can occur in milk from cows with clinical or subclinical mastitis due to presence of proteolytic enzymes. Plasmin increases proteolytic activity by more than two fold during mastitis. Plasmin and enzymes derived from somatic cells can cause extensive damage to casein in the udder before milk removal. Deterioration of milk protein as a result of mastitis may continue during processing and storage. Mastitis increases the conductivity of milk and sodium and chloride concentrations are elevated. Potassium, normally the predominant mineral in milk, declines. Because most calcium in milk is associated with casein, the disruption of casein synthesis contributes to lowered calcium in milk.
Milk from cattle with mastitis also has a higher somatic cell count (higher the SCC, 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.
As antibiotics are frequently used to control mastitis in dairy cattle the presence of antibiotic residues in milk is very problematic, for at least three reasons. In the production of fermented milks, antibiotic residues can show 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 cattle 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, in reduction in milk yield, an increase in body temperature, signs of diarrhea and dehydration and reduction in mobility due to the pain of a swollen udder or simply due to feeling unwell.
Disease causing bacteria are often referred to as pathogens. The most common mastitis pathogens are found either in the udder (con- tagious pathogens) or the cow’s surroundings (environmental pathogens), such as bedding, manure, soil, etc.Read more →
Mastitis resulting from major presence of pathogens causes considerable compositional changes in milk. The types of proteins present change dramatically. Casein, the major milk protein of high nutritional quality, declines and lower quality whey proteins increase which adversely impacts dairy product quality, such as cheese yield, flavour and quality.Read more →
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, Read more →
Typically when clinical mastitis is detected, the cow is milked out and then given an intra-mammary infusion of antibiotic, i.e. infused directly into the infected gland. Prior to intra-mammary 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.Read more →
Somatic cell count (SCC) is the number of somatic cells found in a millilitre of milk. Somatic cells (or “body” cells) are a mixture of milk-producing cells shed from the udder tissue (about 2%) and cells from the immune system (the other 98%), known as leukocytes (also called white blood cells).Read more →