pathogens, and by a dramatic increase in somatic cells. These are comprised of leukocytes (white blood cells)and epithelial cells from the udder lining. Increased somatic cell counts are therefore indicative of the presence of mastitis. Once the infection reaches the level known as"clinical" mastitis, pus can be observed in the teat canal just prior to milking, but at sub-clinical levels, the presence of mastitis is not obvious Somatic Cell Count(000s/ml) Daily Milk Yield (kg) I st lactation Older 23.1 18-34 23.0 35-70 28.0 71-140 224 274 141-282 27.0 282-565 21.9 26.3 566-1130 214 25.4 1131-2262 20.7 24.6 2263-4525 20.0 19.0 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 destry the growth of the fermentation bacteria. From a human health point of view, some people are allergic to ific 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 withdrawal time after final treatment for various antibiotics is shown below Amoxcillin 60 hrs Cloxacillin 48 hrs Erythromycin 36 hrs Novobiocin 72 hi Penicillin 84 hrs Sulfad imethozine 60 hrs Sulfabromomethozine 96 hrs Sulfaethoxypyridozine 72 hrs Anti-Microbial Systems in Raw milk There exists in milk a number of natural anti-microbial defense mechanisms These include lysozyme- an enzyme that hydrolyses glycosid ic bonds in gram positive cell walls 77 pathogens, and by a dramatic increase in somatic cells. These are comprised of leukocytes (white blood cells) and epithelial cells from the udder lining. Increased somatic cell counts are therefore indicative of the presence of mastitis. Once the infection reaches the level known as "clinical' mastitis, pus can be observed in the teat canal just prior to milking, but at sub-clinical levels, the presence of mastitis is not obvious. Somatic Cell Count (000's/ml) Daily Milk Yield (kg): 1st Lactation Older Lactations 0-17 23.1 29.3 18-34 23.0 28.7 35-70 22.6 28.0 71-140 22.4 27.4 141-282 22.1 27.0 282-565 21.9 26.3 566-1130 21.4 25.4 1131-2262 20.7 24.6 2263-4525 20.0 23.6 >4526 19.0 22.5 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 destry 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 withdrawal time after final treatment for various antibiotics is shown below: Amoxcillin 60 hrs. Cloxacillin 48 hrs. Erythromicin 36 hrs. Novobiocin 72 hrs. Penicillin 84 hrs. Sulfadimethozine 60 hrs. Sulfabromomethozine 96 hrs. Sulfaethoxypyridozine 72 hrs. Anti-Microbial Systems in Raw Milk There exists in milk a number of natural anti-microbial defense mechanisms. These include: • lysozyme - an enzyme that hydrolyses glycosidic bonds in gram positive cell walls