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72 Cards in this Set

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  • Back
What are the components of a milking system?
A vacuum system
Pulsation elements
an arrangement for transporting and collecting milk
a milking cluster that brings vacuum and pulsation to the cow
Typically, what is milk milked into?
directly into a bucket or can
recorder jars which discharge to a pipeline directly into a pipeline.
How does a calf suckle?
The calf compresses the neck of the teat between its tongue and the hard palate and squeezes milk trapped in the teat cistern into its mouth by compressing the teat between the tongue and palate from base of teat to teat opening. The calf then lowers its jaws and tongue to allow teat cistern to fill again and process is repeated.
Describe pulsation rate?
The pulsation rate is the number of times the air in the pulsation chamber of the teat cup is evaluated and returned to atmospheric pressure each minute. 50/50 60/40 70/30
What is a machine stripping and why should this NOT be practiced?
The act of pulling downward on the milk cluster along with hand massage of the udder. Increased incidence of mastitis and overmilking.
How much milk remains in the udder after milking and how can it be removed?
After milking about 10 to 15 percent of the total remains in the udder. This can only be removed by injecting oxytocin.
What is the most common sign of mastitis?
increased bacterial count. Appearance of flakes, clots,watery secretions, hard quarters,swelling or redness
Why shouldn't you wash the udder?
it is important for the udder to be dry because when the udder is wet water will run down the flank and udder and accumulate at the top of teat cups. This contaminated water can leak into teat cup and promote bacterial growth in milk or increased incidence of mastitis.
How is mastitis determined in the milking facility?
a few streams of foremilk from each quarter are examined on the black surface of a strip cup
When should the milking units be attached and why?
about 1min after udder stimulation has begun.
What is mastitis?
mastitis refers to any inflammation of the mammary tissue, the effects of microorganisms that invade the mammary gland cause most problems
When are cows prone to new intramammary infections?
cows are most prone to aquiring new intrammammary (IMIs) in the period just after drying off and just before parturition.
lactoferrin increases during dry period
Why do IMI occur primarily at this time
Soon after the mammary gland dries off, some of the mammary cells regress and die. If during this period bacterial cells gain access to the mammary gland; these immune cells may be preoccupied with tissue remodeling so that microorganisms avoid destruction, thereby gaining an opportunity for colony formation.
List the factors that are involved with new IMIs
Immune responses generally are supressed by treatment with steroid hormones. During the periparturient period and estrogens and glucocorticoids are high.
Secretions accumulated on the teat end could provide nutrients for bacteria
Streak canal is at least temporarily open and suseptible
calving into dirty environment
dry cow treatments-long acting antibiotic treatment and barrier dip w/ latex seal. Internal barrier tip orbisil
Describe the proper technique for antibiotic treatment of a cow
It is recommended that the teat ends be carefully cleaned and disinfected and that the treatment syringe cannula only be minimally inserted into the teat opening to infuse the product.
Define MSCC. What kind of cells are they?
The somatic cell count of raw milk is the most common producer-related method to evaluate milk quality and udder health status of the lactating cow. Leukocytes and a small percentage of epithileal cells normally occur in milk. This combination of cells is referred to as the milk somatic cell count.
What is the MSCC of an infected cow and an infected cow?
Milk from uninfected cows typically contains less than 200,000 cells per milliliter. It is not uncommon to find uninfected cows with MSCC of 50,000 cells or less. 400,000+ from an infected.
What is the primary cause of primary mastitis?
Bacterial mastitis results when bacteria traverse the teat opening, overcome the defenses in milk and begin to multiply. The likelihood for invasion is greatly increased of bacteria reside in or colonize the teat duct

Defense: lactoferrin, keratin, feed anions if you have low blood calcium that falls out
Why does swelling occur in a mastitic mammary gland?
bacteria produced toxins can cause swelling.
What is the function of PMNs?
Neutrophils sometimes called polymorphonuclear leukocytes. These cells act to engulf the bacterial cells and destroy them. There massive migration can disrupt the secretory epithelium and dead and dying PMN's mcan also damage the PMN
Describe the leukocyte response to bacteria
After the PMNs cross the capillary wall, they move through the connective tissue toward the sites of bacterial invasion. They accumulate around the alveoli or ducts before entering the milk. The cells traverse the epithileum by either squeezing between the epithelial cells or by passing through areas where the epithileal cells have been killed once the PMN's enter the milk they depend on essentially random collisions to detect bacteria in milk for engulfment.
Why will milk production be reduced after a bout of mastitis?
it is generally believed that few damaged or destroyed secretory cells are replaced during a current lactation. Accumulation of cell debris or clots or milk component (likely caused by acute local changes in pH or ion concentrations) can block drainage of milk from groups of alveoli and effectively induce local involution and loss of milk production capacity of these cells.
define subclinical
is the most prevalent- the milk is usually visibly normal, but the concentraiton of MSCC is increased or pathogens are identified from milk samples processed for bacteriological testing. Normally occurs before the other forms and often leads to clinical
define acute mastitis
characterized by hot, painful, and swollen quarters or mammary glands and is frequently accompanied by fever and loss of appetite. On physical inspection the milk may contain flakes, clots, shreds, or blood. Milk yield is often severely depressed.
define Gangrenous mastitis
the affected quarter may have a bluish discoloration and be noticeably cold to the touch. The discoloration often leads from the teat upward
define chronic mastitis
repeated by clinical attack. The milk contains clots or flakes, and the quarter may be swollen. This can cause the glands to become hard and less pliable than normal. Chronically infected gland often fail to respond to treatment. although clinical symptoms may disappear temporarily.
What change occurs in milk protein from a mastitic cow?
Protein composition is altered as the level of mammary specific proteins declines and level of serum- derived proteins increases. The milk proteins also are more likely to be degraded b/c of the action of protocolytic enzmes.
Decribe the compositional changes that occur in mastitis milk?
The content of casein, phosphorus, and potassium decrease while sodium, chloride, and free fatty acids increase-whey proteins, lactoferrin, alphalactalbumin
conductivity measures for mastitis
What happens to milk yield as MSCC increases?
it decreases
What is linear score and why is it important?
The linear score helps identify cows affected by subclinical mastitis and allows the producer to evaluate easily the effects of subclinical mastitis on milk production in the herd
The linear score is an exponential number
What causes the cells to influx into the mammary gland?
Bacterial products can be potent chemotactic (send a chemical signal for cells to come) agents
what are the primary bacterial species that cause mastitis?
streptococci, staphylococci (contagious) or the coliforms (environment) cause ~95 percent of cases
Define contagious mastitis, define environmental mastitis.
common mastitis pathogens found either on or in the udder are referred to as contagious since many of these do not survive in the environment. ex: humans, milk machine

Environmental mastitis is caused by pathogens routinely found in bedding, soil, and manure
how is contagious mastitis spread?
often during the milking procedure or by human contamination
How is environmental mastitis spread?
between milking times
how is a milk sample taken for culture?
udders must be washed with a sanitizing solution and then dried because water droplets on teat ends may contain bacteria. Samples may be collected immediately after preparation for milking. The teat must be disinfected with alcohol, and milk collected into sterilized tubes. Samples of milk are usually streaked onto blood agar culture plates and incubated at 37 degrees celcius. Read at 24 and 48 hours.
Describe strep. ag mastitis
most often infects mammary ducts in the lower regions of the udder but if unchecked can spread and cause tissue damage throughout the udder. This bacteria is the most common, contagious, chronic mastitis.

Actinomyces pyogene-mastitis caused by flies
describe staph aureus mastitis?
more damaging to secretory tissue because of the potent complement of toxins produced by these organisms. Furthermore, these organisms are prone to establish deep-seated areas of infection with the connective tissue of the alveoli. Produce walled off areas of abcess
describe coliform mastitis
coliforms are considered environmental pathogens and are associated with factors such as dirty calving facilities, wet and dirty bedding, poor pre-milking practices, or even contamination during application of intramammary treatments. It is estimated that 75 percent of coliform infections result in clinical mastitis (abnormal milk, udder swelling, and frequent systemic symptoms such as fever and loss of appetite)
What other organisms cause mastitis?
coagulase-negative staphylococci (CNStaph) Staphylococcus chromogenes, stapylococcum hyicus, staphlococcus epidermis, staphylococcus hominis and staphylococcus xylosus. Mycoplasma bovis, psuedomonis aeruginosa, serratia spp., actinomyces pyogenes, prototheca spp., bacilla cereus, nocardia spp. and some yeasts and molds. mycoplasma.
What does mastitis cost the U.S. industry annually? What are the costs/cow/year?
~2 billion dollars annually or about 11 percent of the value of the total milk produced in the U.S. each year. 172 per cow per year
What system plays the most important role in milk production?
the endocrine system
define-endocrine system
A system of glands which secretes hormones into the bloodstream to regulate the body
Describe the experiment of Asimov and Krouse
They showed that injections of pituitary (GH) extracts consistently increased milk production in lactating cows.
Describe how hormones were determined to be essential for milk secretion and production.
Ablation(removal) replacement experiments.
triply operated(adrenal, ovari-, and hypophys-ectomized animals were given injections of hormones)
What technique vastly improved our ability to understand the hormonal relationship as it pertains to mammary development and milk production?
radioimmunoassay (RIA) techniques allow accurate measurement of circulating blood or tissue concentrations of many hormones. Became possible to determine correspondance between the secretion rate and pattern of secretion of a particular hormone and a specific physiological process.

Why is the measurement of total hormone concentrations not acceptable for determining endocrine status?
RIA method depends on antibody-antigen bindings that it is possible with highly specific antibodies that fragments of hormones might be detected in addition to intact molecules.

Doesn't distinguish between free and bound
Compare and contrast steroid hormone concentrations in cows and humans
estradiol 50pg/ml to 300 pg/ml
women concentrations of estradiol-17, B can be 1000xhigher than for cows

2 pg/ml to 15pg/ml
What is the effect of ovariectomy on mammary development
it markedly impaired mammary development and showed that without the ovary,exogenous GH had no effect on mammary development.
small effect on estradiol and GH concentration
reduction in total mammary gland weight and volume in heifers
parenchymal tissue was reduced
slows mammogenesis
what is the effect of GH on mammary gland development?
significantly increased parenchymal tissue protein and averages for all other measures of mammary parenchymal tissues were higher
GH stimulates IGF-1 has receptors in mammary gland.
What is the effect of estradiol on mammary gland development in heifers?
Stimulates proliferation of the mammary epithelial cells.
What is BrdU and why is it used?
Bromodeoxyuridine labeling-analog of thymidine that can be detected in cells that incorporate the nucleotide using immunohistochemistry
describe the estromedin hypotheisi
effects of estrogen might actually be induced by secretion of other mediators locally within the mammary gland result of an estrogen-induced effect on another organ or tissue to secrete a growth factor.
What is a mitogen?
a substance that triggers mitosis
describe the interaction between IGF-1 and estrogen
Heifers treated with estradiol have increased production of IGF-1 in their mammary stromal tissue
Why do we think that estrogen is so important in mammary development?
Estrogen is believed to be responsible for much of the mammary growth during gestation. It is also important for final duct growth and lobulo(group of alveoli(bunch of grapes)-alveolar development
is PRL required for mammogenesis and lactogenesis?
for sheeps and goats-not cattle
(likely a permissive agent for the mammogenic effect of steroids and other growth factors)
change in prl blood [prl]
1) photopenol
2) environmental temp
These are UV light
prolactin stimulates milk production
Is it only adequate to measure blood concentrations of hormones? What else needs to be measured?
No, because biological effects of circulating hormones.
Describe the relationship between estradiol concentration and day of gestation
concentrations of estradiol are higher(relative to estrous cycle) with a further gradial increase during gestation and with a more dramatic increase during the final few weeks before calving
How is PRL thought to work in pregnancy? what inactivates PRL?
Rodents PRL is needed for both mammary growth and functional differentiation of the alveolar cells during pregnancy. PRL secretion is markedly inhibited in cold weather and during short photoperiods
lactation failure.
Why is PRL thought to be less important in mammary development in cattle?
There are no specific changes in secretion of PRL in cattle associated with mammogenesis and lobulo-alveolar formation during pregnancy
Where is the PRL gene transcribed?
In the lactotropes of the anterior pituitary gland but also by cells in the placenta, hypothalamus, and mammary gland and by lymphocytes
what happens to the PRL receptor in the ewe and the cow as parturition approaches
expression of the PRL receptor in the bovine or ovine mammary gland increases dramatically near the time of parturition in concert with lactogenesis, and this level of expression is generally maintained during lactation
describe the types of PRL receptors
single chain membrane-spanning proteins are arranged into three domains:
1) an extracellular region where PRL binding occurs on the extracellular surface
2) a hydrophobic portion that spans the plasma membrane
3) An intracellular cytoplasmic domain
These three are all apart of second messanger
What is placental lactogen?
a prolactin-like hormone with similar biological effects.
Implicated in preparation for the mammary gland for lactation, stimulation of steriodogenesis, fetal growth, and alteration of maternal metabolism and lactogen
describe the effect PL has on cattle, sheep, goats, rats and mice
Rats and mice-produce 2 forms of PL. Pl-1 appears early in gestation, peaks, and remains stable for most of gestation. PL-2 is produced initially at about mid gestation but then peaks near parturition supporting the idea it is involved in lactogenesis.
Goats and sheep-correlated w/mammary development and subsequent milk production
bovine-most of the PL is secreted into the fetal circulation
What is the function of adrenal steroids in regards to mammaogenesis?
adrenal steroids are essentially for physiological homeostasis, but it is unlikely that these hormones are directly critical for mammogenesis
How do we know this?
Adrenal ectomy does not consistently reduce mammary development
What about thyroxine(T4) and triiodothyronine (T3)?
The thyroid gland is important metabolically but thyroidectomized animals can conceive and lactate, so this means thyroid hormones
Describe PTHrP
parathyroid hormone-related protein, produced by the alveolar cells of lactating animals, seems to play a significant role in stimulation of mammary uptake of calcium.
Calcium increases right@parturition
Describe the function of TGF-beta
Implants containing TGF-B act locally and reversibly to inhibit ductal growth when placed near actively growing end buds in mice
Describe the effects of GH on udder development?
A positive effect of GH on udder growth in heifers has been confirmed in several studies.
Prepubertal mammary gland grows in response to exogenous