ANSC 460.3 Lecture Notes - Lecture 11: Antibody, Pregnancy, Cell Division
27 Jun 2018
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Dry period and mammary involution
- dry period
onon-lactating period prior to an impending parturition
ooptimizes milk production in subsequent lactation
- dry period at least 45-50 days
o20-25% reduction in milk yield with no dry period
- drying-off cows
owithdrawal of grain, reduce water supply several days before initiation
odrastically reduces milk production (fewer nutrients available)
omilking halted 45-60 day prior to expected date of calving
- lack of withdrawal of milk
oincreases intra-mammary pressure and FIL levels
oapoptosis follows
oirreversible
- abruptly drying off high producing cows
ocongestion of mammary gland
ouncomfortable for animal
omay have to milk after dried off
oanimal welfare issue
- 3 phases of mammary involution
oactive involution
initial 21-30 day of dry period
milk accumulates 2-4 days and then rapid decline due to apoptosis
this is irreversible once initiated
lactose level declines rapidly
helpful because no build up of osmotic pressure so less water
drawn from blood
lactoferrin level increases markedly
removing iron so less nutrients available for pathogens (required
for microbial proliferation)
Ig levels increase because milk accumulates and is a good environment
for microbes to proliferate
High susceptibility to new IMI in early dry period
Lack of milk removal promotes bacterial growth
Teat-end disinfection is stopped
Keratin plug not fully developed
oIntra-mammary dry cow therapy critical
Protects mammary gland for 3-4 weeks during early involution period
Long acting Ab infusing into each quarter
Kill existing infections and protect from new infections
Dry cow therapy and teat dipping= two most important practices to
prevent infection
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Document Summary
3 phases of mammary involution: active involution initial 21-30 day of dry period. Ig levels increase because milk accumulates and is a good environment for microbes to proliferate. High susceptibility to new imi in early dry period. Keratin plug not fully developed: intra-mammary dry cow therapy critical. Protects mammary gland for 3-4 weeks during early involution period. Kill existing infections and protect from new infections. Dry cow therapy and teat dipping= two most important practices to prevent infection. Can use a paste that forms physical barrier used in addition to dry cow therapy: steady-state involution (mid-dry period) Length depends on total length of dry period (may not have it at all of dry period to short) High producing cows: takes longer to establish the plug: redevelopment and colostrogenesis (late dry period) Concentrations of major milk constituents increase ~2-week pre-partum. Ig (antibodies) increase as colostrum is being formed. High susceptibility to new imi in late dry period.
