Mammary Flashcards
Waht is the heritability of medial suspensory ligament conformation?
0.33
How many litres of milk can an East Friesian goat give per lactation?
450l
How many litres of milk can a Lacaune sheep give per lactation?
290l
What is the record annual milk production for a Californian dairy goat?
> 1200l
List 7 physiological factors that affect SCC
DIM, parity, oestrus, nutrition, stress, genetics, daylight
What is the heritability of SCC in sheep and goats?
0.1-0.15 in sheep. 0.2-0.25 in goats
How is the balance of cells in the milk altered in mastitis?
More neutrophils relative to normal macrophages
Which bacteria are the most common agents of subclinical mastitis in small ruminants? Name two species from the group
Coagulase negative staphylococci. E.g. epidermidis, caprae
What is the cure rate for subclinical mastitis during the dry period on sheep and goats?
Sheep: 35-67%
Goats: 20-60%
Which period of lactation is associated with most new cases of mastitis? Why?
First thrid. Start of machine milking and suckle-to-machine transition.
List four main areas of focus for mastitis control programmes
Milking routine, hygeine, drying-off, culling
Name the two main reservoirs for mastitis-causing staph. and strep.
Mastitic udders and skin
What is the frequency of environmental mastitis compared to cattle? What implications does this have for teat dipping?
Much less frequent. Pre-dipping is less important and has less evidence supporting it, but is still recommended
What evidence is there to support the use of post-milking teat dipping?
It reduces SCCs and reduces new infections by 30-40%
Which animals should be milked first?
Clean, young and recently in milk animals
List three milking routine risk factors for hyperkeratosis
Overmilking, vigorous stripping, claw removal under vacuum
Is there any evidence for/against abrupt vs gradual dry off?
No evidence either way.
What effect do intramammary antibitoics have on the dry period sub-clinical mastitis cure rate?
Sheep: increases from 65% to 96%
Goats: increases from 50% to 93%
What threshold has been proposed for culling goats based on SCC (in mycoplasam free herds)
more than one SCC >2 million
In what circumstances are teat sealants valuable?
Where environmental mastitis is common
What is the Vimco mastitis vaccine targetted against?
Staphylococcus aureus expressing biofilm components
One study in Greece showed what reduction in mastitis cases with Vimco
44% reduction in clincial cases
33% reduction in subclinical cases
What are the EU limits on bulk milk tank bacterial counts for small ruminants?
1.5million cfu/ml if heat treated
500,000 cfu/ml if not heat treated
List 4 sources of high bulk milk tank bacteria counts
mastitis, dirty udders, dirty equipment, poor milk cooling
What does a high preincubation bulk milk count suggest?
Equipment or milk cooling problems
What does a high lab-pasteurised bulk milk count suggest?
Biofilm formation in equipment, or dirty udders
What do high coliform counts suggest?
Very dirty udders or dirty equipment
What prevalence of intramammary infections is suggested for sheep’s milk bulk tank SCCs of:
1million
500,000
250,000
35%
23%
16%
What prevalence of intramammary infections has been suggested for goat’s milk bulk tank SCCs of:
1.5million
750,000
50%
30%
What iSCC thresholds have been proposed for one-off iSCCs in sheep?
> 1mil = infected
500k-1mil = suspicious
<500k = clean
What thresholds have been suggested for serial iSCCs in sheep and goats?
Lower threshold: 250k in sheep, 750k in goats
Upper threshold: 800k in sheep, 1.5mil in goats
Two+ values over upper threshold = mastitis
All under lower threshold = clean
Anything else = intermediate
Describe how to perform a Caliofornia Mastitis test
Add one teaspoon of reagaent and one of milk to each paddle. Swirl for 10-30s and then tip out.
Score 1: starts to climb the sides when swirling but does not gel
Score 2: Starts to gel but still purs out
Score 3: Single mass of gel tips out together
Describe one way to perform a milk quality crisis intervention.
Calculate individual animal SCC and bacterial controbutions to the bulk tnak by multiplying concentration by yield. Removing the worst 10% offenders from contributing to the tank can reduce bulk SCC by 99%
List the range of syndromes seen with contagious agalactia (6)
Agalactia, fever, arthritis, keratoconjunctivitis, pneumonia, septicaemia
List the 4 (sub)species potentially responsible for contagious agalactia.
M. agalactiae
M. mycoides capri (Mmc)
M. capricolum capricolum (Mcc)
M. putrefasciens
By what routes is contagious agalactia shed and for how long?
Shed in all bodily fluids for months post infection
What is the incubation period of contagious agalactia?
5-7 days
Describe the clinical course of contagious agalactia mastitis
Over the course of three days milk will progress from watery, to thick and lumpy, to completely absent.
What mortality rates are assocaited with contagious agalactia
Up to 100% in youngstock
0-50% in adults depending on strain, host and endemicity
What is the sensitivity and specificity for Mycoplasma agalactiae serology in unvaccinated animals?
Se: 75-85%, Sp: 99%
Describe the mammary histopathology in contagious agalactiae
Interstitial inflammation with mononuclear leukocytes around acini and ducts, and within ducts alongside desquamated epithelial cells.
Is antibiotic treatment fo contagious agalactia successful?
Rarely and can induce carrier status. (Range of tissues infected, plus biofilm formation, makes antibiotic choice and interpretation of resistance tests impossible)
How can contagious agalactia be controlled?
Test and separate/cull or endemic management with partially effective inactivated vaccines.
Name two factors associated with precocious udder
Selection for high mlk yield. Production of PTHrP
List 9 zoonotic pathogens of raw milk
C. jejuni
STEC
Listeria
Salmonella
Staph aureus
Coxiella
Brucella
Tuberculosis
TBEV
By what cellular mechanism is small ruminant milk produced?
Apocrine secretion
Which stain is used for direct microscopy of milk somatic cells?
Pyronin Y-methyl green
Deficiencies of which micronutrients are associated with mastitis?
Vitamins A & E, Selenium
List the four methods of somatic cell counting. What is counted in each?
Direct micrsocopy: Cells
Coulter counter: Particles
Fossomatic and DeLaval: DNA
