What Causes SCC Fluctuations?
Proper management of your cows and strict hygiene procedures are certainly the most significant means of keeping the incidence of mastitis and your somatic cell count (SCC) low. However, certain periodic factors also come into play which increases the susceptibility to infection.
Depending on where a cow is in her lactation, her SCC may be either naturally elevated or depressed. At the start of the dry period, SCC rises due to the increased pressure in the udder causing the teat canal to dilate. This allows bacteria to enter the teat where the milk becomes an excellent growth medium.
Cows have the greatest resistance to mastitis during mid-lactation, which is reflected by a drop in SCC. At this point, the teats are sealed and the small volume of fluid that is in the glands has a composition that inhibits bacterial growth. SCC rises again in the late dry period as fluid once again accumulates in the udder and the teats start leaking, providing the perfect opportunity for bacteria to migrate up the teat canal.
SCC remains elevated for approximately 5 days after calving to transfer antibodies to the calf in colostrum and transition milk.
SCC is also affected by season. Higher temperatures increase bacterial activity and the summer months contain more cases of elevated SCC and mastitis compared to the winter. Heat stress caused by high temperatures and humidity can also cause an increase in SCC.
Tracking the periodic fluctuations of SCC can help you manage your bulk tank SCC and anticipate periods of high infection rate, enabling you to treat more effectively and achieve the best price for your milk.
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