Milk Quality and Mastitis Control Flashcards
True or False: pathogens are able to move easily between the quarters of the udder
false; these are separated by connective tissue
What type of cells synthesize and secrete milk?
alveolar cells; 60% milk storage
Milk letdown is induced by what?
oxytocin-induced contraction of myoepithelial cells
Following milk letdown, the milk is transported to where?
gland cistern via ducts (ducts = 20% milk storage)
Milk is accumulated in where?
the gland cistern (cistern = 20% milk storage)
What is the physiology of milk letdown?
suckling stimulates release of oxytocin > induces milk letdown; this “suckling” is more commonly stimulated by workers
- oxytocin has a very short half life: 2-3 minutes
- milk letdown is inhibited by stress
If milk letdown does not occur, what is the issue with this?
60% of the milk is stored in the alveolar cells, so only 40% of the milk produced will be readily accessible without milk letdown
What are the various methods of teat protection?
- skin
- inner and outer sphincters
- keratin plug
- physical barrier
- bacteriostatic properties
What makes up the innate immunity of the bovine udder?
- macrophages
- neutrophils
- NK cells
- complement
What are somatic cells and what levels of somatic cells are diagnostic for disease.
- immune cells that move from blood into the mammary gland
- Healthy and non-infected glands: SCC < 100,000 cells/mL of milk
- mostly macrophages, neutrophils, lymphocytes, and epithelial cells
- Infected glands: SCC > 200,000 cells/mL of milk
- mostly neutrophils
What is mastitis and what are signs of peracute mastitis?
= inflammation within the mammary gland
- Peracute
- 5 cardinal signs (redness, heat, swelling, pain, loss of function)
- Systemic signs (fever, anorexia, dehydration, depression, muscle tremors, “down cow”)
- Fast progression (4-12 hrs) and death
What are the signs of acute mastitis?
- 5 cardinal signs: redness, heat, swelling, pain, loss of function
- mild depression and fever
What are the signs of subacute mastitis?
- subdued signs of inflammation
- most common presentation of clinical mastitis
What are signs of subclinical mastitis?
- inflammation in the absence of gross signs (incr SCC)
- most common presentation of mastitis
What are signs of chronic mastitis?
- persistence of inflammation for weeks/months
- continuous process or periodic flare-up cases
What pathogens are most commonly associated with mastitis?
most commonly caused by bacterial intramammary infection (IMI); fungi/yeast = least common
- Contagious pathogens:
- cow-to-cow trasmission via fomites
- Strep agalactiae
- Staph aureus
- Mycoplasma sp.
- cow-to-cow trasmission via fomites
- Environmental:
- Strep uberis
- Strep dysgalactia
- Coagulase neg. Staph. (CNS)
- Trueperella pyogenes
- Coliforms
- E. coli, Klebsiela sp., Serratia sp., Pseudomonas sp.
Describe the MOA of Staph aureus in causing mastitis
- causes moderate incr in SCC
- small shedding in milk
- inflammation mediated by coagulases, alpha, beta, and epsilon-hemolysins
- beta-lactamase and deep penetration into tissue: poor response to tx
- consider segregation and culling
What is the MOA of Strep agalactiae in causing mastitis?
- does not actively invade parenchymal tissue
- inflammation is mostly subclinical w/ acute flare-ups
- blockage of collecting ducts
- leads to involution of mammary tissue
- replacement of secretory cells w/ scar tissue
- decr milk production
- marked incr in SCC
- Abx susceptibility
- ampicillin, cephapirin, pirlimycin
What is the MOA of Mycoplasma sp. in causing mastitis?
- inflammation is often subclinical w/ acute flare-ups
- clinical cases often progress from 1 to mult quarters b/t 1-3 d
- coffee-grounds appearance to milk
- intro via purchase of diary animals or intro of outside rearing heifers
- biosecurity
-
non-responsive to antimicrobial tx
- ID and culling
- segregation challenge
- need for specialized culture (4-7d for lab results)
What is the MOA of Strep uberis in causing mastitis?
- acute and chronic mastitis (similar to Strep agalactiae)
What is the MOA of Strep dysgalactiae in causing mastitis?
- infections assoc. w/ teat injury (viral, mechanical, chemical, etc.)
What is the MOA of coliforms in causing mastitis?
- peracute to acute mastitis
- sudden and marked swelling of affected quarter
- fever, mm tremors, rumen stasis, dehydration
- serous milk (early) w/ fibrin or pus (late)
-
incr incidence of death and agalactia compared w/ other pathogens
- px particularly guarded for Klebsiella sp.
- Fast recovery if inflamma contains pathogen proliferation
- milk production recovered in 1-2 weeks
Why is early lactation a high risk period for developing mastitis?
- immunosuppression occurs during early lactation (3-4 wks postpartum)
- stress and cortisol concentrations around parturition
- negative nutrient balance
- oxidative stress
What is the impact of elevated milk production around peak lactation?
loss of teat canal integrity and milk leakage
What are some reasons that first 21 days of the dry off period (i.e. involution) is a time of increased susceptibiltiy to new IMIs?
- pressure from milk buildup (production declines and cows are not milked)
- potential milk leakage w/o constant teat end disinfection
- death of secretory cells and active tissue remodeling
- failure to form keratin plug
What are some reasons that last 7-14 days of the dry off period (i.e. involution) is a time of increased susceptibiltiy to new IMIs?
- pressure from colostrogenesis
- decr lactoferrin and resident leukocytes
- colostrum components impair function of immune cells
- rapid tissue differentiation and oxidative stress
What are the best ways to prevent IMIs during the dry off period?
- health management - biosecurity
- segregation and culling of chronically infected cows
- nutrition
- cow comfort - clean and dry environment
- vaccination
- teat skin condition
- excellent milking procedures
- improve immunity peripartum
What are the goal and objectives of milk parlors and machine milking?
Goal: milk cows quickly, gently, and completely
- incr milk harvested
- decr discomfort of cows
- decr risk of injury and mastitis
What steps are a part of the cleaning and stimulation process in milk parlors?
- apply disinfectant (pre-dip)
- remove foremilk (cistern)
- 2-3 strings from each quarter
- 15 sec per cow
- check for mastitis
- clean/black floor
- mastitic milk cannot go to bulk tank
- dip-strip vs. strip-dip vs. dip-strip-dip
What steps are a part of the contact time for disinfection process in milk parlors?
- 30 seconds
- proper udder preparation removes 75% of bacteria present on teat skin to attachment
- bacteria left on teat will end up in milk
- past 30 seconds:
- strip and wipe teats with a single-use towel (teat and teat end)
What is the purpose of the lag time in milk parlor procedings and how long should this be?
- allows cow to respond to manual stimulation
- 70-80 sec
What steps are a part of attaching the cow’s udder to the milking machine?
- 90-120 sec after onset of manual stimulation
- goal is to attach unti to clean/dry teats
- prevents liner slips
- attention to placement of claw
- folded teats
- dry quarters
Describe the process of milking the cow with the milking machine
- 4-6 min
- machine maintenance
- proper pulstor fxn
- adequate vaccum presure
- fix liner slips
- backflow of milk, potential for contamination
- avoid over-milking
- residual milk (50-100 mL/quarter)
What are the steps in detaching the cow from the milking machine and the post-dip?
- cut-off vaccum
- avoid teat injury
- automatic based on milk flow
After milking, cows will return to a …
- clean and dry pen
- fresh food and water
- proper heat abatement
What are the various severity scoring levels for mastitis?
- Mild = abnormal milk (clots, flakes, watery)
- Moderate = abnormal milk + signs of udder inflammation (heat, swelling, pain)
- Severe = systemic illness (fever, dehydration, wekaness, inappetence)
*tx based on severity: intramammary abx, +/- anti-inflammatory, +/- systemic and supprortive tx
What are your treatment considerations and diagnostics for chronic cases of mastitis?
- “three strikes rule” - do not tx quarter > 3x within a lactation
- > 2 monthly tests with SCC > 200,000 cells/mL
- consider non-tx options:
- older cows
- other dz
- mult quarters
- culling cow
- early dry-off
What are your options for diagnosing specific mastitis pathogens?
- lab tests: 24-48hrs, except Mycoplasma = 7d
- on-farm culture: improve timing
- UMN bi- and tri-plate
- chromogenic selective media
How do you decide to treat based off your culture results?
- no growth - do not tx
- gram - cleared by time of culture
- Mycoplasma
- gram - = do not tx
- robust immune response
- incr spontaneous cure
-
gram + = treat
- less robust immune response (decr spontaneous cure)
What are the cure rates for various IMI pathogens?
- Strep agalactiae - 90-95%
- CNS - 60-80%
- Environmental Strep - 40-50%
- Staph aureus - 20-30%
What are your monitoring parameters for herds and mastitis?
- bulk milk SCC and bacterial counts
- rate of clinical mastitis
- prevalence of subclinical mastitis
- presence of contagious mastitis pathogens
What is the protocol for dry cow therapy?
- treat all quarters from all cows with long-acting intramammary abx at dry off
- +/- teat sealants
- particularly important for S. agalactiae and S. aureus
- Goal: minimize new infections and promote cure during dry period
- Vaccination:
- coliform mastitis (E. coli): reduces CS
- Klebsiella sp. mastitis: under dev.
What are the 6 keys to a mastitis control program?
- Proper milking management
- Environmental control
- Dry cow therapy
- Milking machine maintenance
- Treatment protocols
- Vaccination
