Dairy cattle Flashcards
free stall
barn-loose housing systems
cows are able to move anywhere throughout the pen
includes resting areas
cleaner environment
fewer teat/udder injuries
tie stall
harder on milker, more walking/kneeling
can be harder on cows: decreased exercise; poor design can result in lameness, broken tails, swollen hocks, neck lesions, and decreased cleanliness
older buildings may have poor ventilation
dry lot
economical
cows are able to move freely, good ventilation
only for milder climates since cattle can be prone to heat stress during summer
what is important to allow with feeding when housing cattle?
allow free-grazing when weather allows
we can’t control exact forage nutrients, harder to manage individual cows and in extreme climates lead to cattle being housed indoors for part of the year
but pasture is more economical for feeding costs, more natural environment, and environmentally sustainable
dairy parlor
separate area in farm where cows are milked
rotary or carousel dairy parlor
arranged so that cows enter onto a turning platform that rotates slowly
grade A milk
fluid grade milk
milk produced under sufficiently sanitary conditions to qualify for fluid consumption
used in manufactured dairy products
grade B milk
used in cheese, butter, nonfat dairy milk
how long do dairy farms milk a cow for before culling?
the cow produces milk for about 5-6 years before being culled and used for beef
cow gestation
~280 days
what is important for cows to do in order to continue producing milk?
they need to give birth to 1 calf per year to continue producing milk
usually artificially inseminated within 3 months of giving birth
udder/teat anatomy
have 4 mammary teats
each teat in the udder has separate glands/ducts/quarters
mastitis
infection of mammary gland
doesn’t directly spread to the other ducts because of the separation it would have to spread down 1 quarter through the teat and duct and then up through another quarter
signs of calving
increased udder size (aka “bag-up”), tail head muscles slacken, will seek isolation
how long is labor?
3-8 hours if no complications
how much weight can a cow lose after giving birth?
~60 kg
40 kg calf, 20 kg fluids and tissue
dry period
part of the lactation cycle
nutrient intake is directed toward developing a fetus rather than milk (aka “drying up” or “dry cow”)
cow will rest and prepare for birth
when does lactation start?
toward the end of pregnancy
starts with prolactin and growth hormone
key for good milking
oxytocin: released in blood in response to contraction of udder’s muscle cells
milk available for removal from udder because of udder contractions
what is important to ensure oxytocin is released?
providing the cows with a clean, low stress environment
stress = adrenaline which inhibits oxytocin release
how to prepare a cow for milking
- if udder needs to be cleaned use a disinfectant to wash and dry udder/teats thoroughly
- once teats are visibly clean we apply a pre-dip halfway up teat ensuring a drop is observed hanging from teat end
- leave pre-dip on for amount of time specified by manufacturer (usually ~30 sec)
- remove pre-dip by drying teat and paying attention to cleaning/drying teat end
- “strip the teat”: milk 3 or 4 squirts of milk into a strip cup (container with a strainer that helps identify animals with abnormal milk)
types of pre-dips
can be sprayed or applied with a dip cup
sprays are more sanitary but dip cups are more effective
make sure to clean and disinfect dip cup after use
pre-dips
commercial preparations proven to be effective germicides
why do we remove the first few squirts of milk from each teat?
these squirts tend to contain the highest number of inflammatory cells if they’re present
when should you start milking after preparing the cow?
milking should begin 60-90 sec after pre-dip removal from teats
this has been shown to be optimal for oxytocin to cause milk letdown
machine milking vs hand milking
machine milking easier on hands but can result in overmilking and teat-end trauma if done improperly
ways machine milking can increase risk of mastitis: excessive vacuum pressure, leaving milk units on too long, not disinfecting units between animals, detaching unit with vacuum still present
post milking
teats should be dipped with another germicide (called post-dip) which decreases the risk of bacteria entering the teat opening until teat sphincter closes
post-dip is left on until next milking
in very cold weather leave post-dip on for 30 sec, then dry teats or they may get frostbitten
have fresh feed available to cows when they return to pen after milking
mastitis causing bacteria
streptococci (or similar gram-positive cocci), staphylococci, gram-negative rods (enteric coliforms)
most common: staph aureus, strep agalactiae, coliforms such as E. coli and mycoplasma
staph aureus
most common bacterial cause of mastitis
can produce toxins and abscesses
can resist phagocytes and immune response, some mutations have antibiotic resistance
staphylococci
cause of chronic infections
what is streptococci associated with?
associated with sub-clinical and acute infections
what is E. coli and staph aureus associated with?
acute gangrenous mastitis
mastitis CS
inflammation signs: redness, swollen, tender, hard
can progress to severe disease in cows: fever, depression, off-feed, death
milk will be abnormal: off color, watery, flakes/clots, bloody
mastitis sub-clinical infections
no evidence of abnormality but milk is positive on special tests
how is mastitis caused?
bacteria entering teat canal
bacteria in 1 quarter of an infected cow can also spread to other quarters
somatic cells
consists of mainly immune cells that enter the milk compartment of the udder
always have small amounts which protect the udder against bacterial infection
older animal = more somatic cells
SCC levels will be high after calving and towards end of each lactation period
how do bacterial infections affect somatic cell counts?
the number of immune cells will rapidly increase when bacteria enters the udder
after the infection is cleared the SCC levels will gradually drop to normal which can take weeks
normal somatic cell count (SCC)
cows without infections usually have SCC < 142,000 cells/mL
SCC of subclinical mastitis cow
milk and mammary glands appear normal but SCC > 200,000 cells/mL
how do you determine antibiotic to use after determining that an infection is present?
culture and identify the organism and perform antibiotic sensitivity testing
California Mastitis test (CMT)
4-compartment paddle with 1 compartment used per quarter of udder
1 or 2 squirts of milk are collected per quarter in each paddle compartment
paddle is tilted to allow most milk to run out leaving 1-2 tsp (5-10 mL) in each compartment
CMT reagent is added in each compartment in a volume equal to retained milk and mixed in circular swirling motions
see if each compartment turns jelly-like or stays milky
results read as negative, trace, +1, +2, +3
why would a compartment of a CMT test turn jelly-like?
the CMT reagent is reacting with the DNA of the leukocytes that produces measurable response
mastitis treatment
non-antibiotic teat sealants provide protection against new infections
most cases respond well to an intra-mammary infusion of antibiotic using lactating mastitis tubes
each tube is labeled as milk withdrawal time and all milk is discarded until this period is complete
some cases require parenteral drugs
how are mastitis infusion tubes designed?
so the user can’t insert the tip too far into the teat
if it is inserted too far then the tip would be pushing bacteria further up into the teat cistern
parturient paresis
“milk fever”
caused by low blood calcium close to and after calving with 80% of cases occurring within 1 day of calving
right before calving there’s a sudden increase in calcium demand and a delay in calcium metabolism since calcium is redirected from fetus to the udder which results in rapid increase in calcium clearance which results in majority of cows experiencing hypocalcemia
calcium feedback loop
parathyroid hormone stimulates physiologically active form of vitamin D —> increased calcium absorption
body will also pull calcium from bone and other organs
colostrum calcium
calcium in colostrum may be 8-10x greater then in blood supply
milk fever stages
stage 1: < 1 hr; CS: loss of appetite, hypersensitivity, weakness, weight shifting, shuffling hind feet, bellowing
stage 2: 1-12 hrs; CS: extended head, depression, cold skin, dry muzzle, staggering, trembling, difficulty standing, GI stasis, tachycardia
stage 3: won’t survive more than a few hrs without treatment; CS: bloat, “downer cow”, weak pulse, coma, death
milk fever treatment
goal is to restore normal serum calcium levels as soon as possible
recommended to give IV injection of calcium gluconate salt (administer slow while auscultating heart since calcium is cardiotoxic) (can also give oral calcium bolus: avoids cardiotoxic risks but not recommended unless it’s a mild case)
preventing some of the clinical signs in treating milk fever
effective nutritional management during the dry period/early lactation has reduced clinical signs to rates less than 1%
milk fever preventatives
maintaining low blood calcium levels before calving to stimulate an increase in the proportion of calcium that is absorbed from the diet during pre-calving period
magnesium supplemented for 2-3 weeks pre-calving and during early lactation also helps
what causes ketosis?
insufficient feed intake
feed intake doesn’t meet nutritional demand —> insufficient ruminal production of propionic acid (precursor of glucose) —> hypoglycemic —> metabolizes fatty acids and glycerol supplies —> fatty acids and glycerol are oxidized to form acetyl-co-a —> excess of acetyl-co-a so it’s converted to ketone bodies —> ketosis
feed intake not meeting energy demand —> lack of energy: liver can’t cope —> excess of acetyl-co-a so converted to ketone bodies —> ketosis
ketosis
ketone bodies accumulate and are excreted in milk and urine
cows go through energy depletion period after calving when the cow can’t consume enough to meet body maintenance requirements along with nutritional demands of udder
common in fresh dairy cows (post partum) and in early lactation (first 6 weeks); can also see in cows carrying twins/ewes carrying twins/triplets
primary ketosis
animal not fed appropriately
secondary ketosis
animal stops eating
ketosis CS
anorexia, depression, sweet smelling breath, nervous dysfunction signs, pica (ingestion of non-nutrients like plaster), abnormal licking/biting, incoordination, abnormal gait, bellowing, aggression
is ketosis self-limiting?
post-partum ketosis is self limiting because anorexia causes animal to stop producing milk which will stop excess demand for glucose
LDA/RDA
left or right abomasal displacement
most common abomasal disorders occur during first 3 months of lactation and usually in high production cows
abomasum is suspended by a loose attachment to the body wall which could move out of position and fill up with gas and prevent normal flow of feed through GIT
abomasal volvulus
abomasum can twist on itself
this cuts off blood supply to the abomasum which can lead to necrosis
CS: depressed, loss of appetite, decreased manure and milk, tachycardia, auscultation and percussion of abdomen (pinging sound in the abdomen)
tx: surgical replacement of abomasum to correct position, usually need to remove fluid/gas buildup too
LDA tx
“rolling” the cow: cast the cow and roll the animal onto its back so the abomasum “floats” back to its normal position
calves and immunity
during gestation the placenta of the cow separates the blood of the fetus from the dam which prevents transfer of protective immunity while in the uterus
calf is born completely dependent on absorption of maternal antibodies from colostrum
calf’s GIT is designed to temporarily allow absorption of large molecules including antibodies (immunoglobulins) from small intestine
immunoglobulins in colostrum
contains different types of immunoglobulins but IgG accounts for ~85% of the total volume
IgG absorption is most efficient in the first 24 hours of life and declines rapidly after 12 hours of age (at 24 hours gut is completely closed and there is no immunoglobulin absorption into circulation
colostrum most efficient within 4 hours of age
what happens if there is a failure of passive transfer through colostrum?
the calf has an increased risk of morbidity, mortality, and will have decreased calf growth rate and feed efficiency
separating the calf from the dam
routine practice: separate within a few hours following birth and house them in a separate location which prevents the cow and calf from forming a strong bond (less stressful when done earlier)
after removal from dam calf is fed colostrum through bottle or esophageal feeder
McGrath feeder
kinks off automatically when you let it hang down and you can administer with 1 hand while you hold the calf with the other
used for hand feeding colostrum to calves
calf scours
enteritis causing diarrhea
usually < 1month (3-16 days for most cases)
caused by: Bovine Viral Diarrhea (BVD), Infectious Bovine Rhinotracheitis (IBR), cryptosporidia, coccidia, Escherichia coli, salmonella, clostridium perfingens
causes of pneumonia
infectious bovine rhinotracheitis (IBR) + bovine respiratory syncytial virus (BRSV) cause pneumonia in stressed calves
when should you start vaccinating a young animal?
vaxxing of young animals doesn’t yield adequate protective immunity until they’re 1-2 months old
clostridium perfingens normals
normally inhabits digestive tract in small numbers without causing disease and if a toxin is produced it passes through animal without problems
exposure to sudden increased carbohydrates –> resident bacteria may multiply rapidly –> large amount of toxins –> damage to intestines –> absorption of toxins into bloodstream –> rapid death
enterotoxemia CS
usually absent with animals that were healthy several hours prior and then are suddenly found dead
can see CNS signs (excitement, incoordination, circling, head-pressing, convulsions) before coma and death
recently dead/near death: usually on their side with head and neck bent backwards
clostridium vaccines
most are inactivated and contain 2,4,7, or 8-way combos of multiple clostridial organisms/toxoids
common reactions: tissue reactions and swelling so we administer in neck SQ
IBR
highly contagious infectious disease caused by a herpes virus (can see abortions because of this)
CS: respiratory signs; in milder cases conjunctivitis, occasional coughing, poor milk yield
some strains cause high fever, depression, drooling due to ruminal stasis, halitosis from pus in larynx/trachea, varying degrees of dyspnea
generalized systemic infection can persist in clinically recovered animals for years, virus inactive until triggered by stress
BVD CS
CS: depends on immunity status and strain of infecting virus
non-vaxxed animals + virulent strain: severe sickness, bloody diarrhea, high fever, off-feed, mouth ulcers, pneumonia; some infected die, some recover within 1-2 weeks, pregnant animals that recover may abort 2-4 weeks after exposure if in 2nd trimester
vaxxed + non stressed: less severe, usually only visible sign is sporadic abortions
PI3
common respiratory illness similar to common cold that weakens immune system
while immune system is suppressed other diseases/infections are more likely to develop
usually included in the vaxx program even though not 100% effective
BRSV
likely similar to RSV in humans except causes significant epithelial destruction including emphysema
RSV
one of the common cold viruses in older human kids, adolescents, and adults
“summer pneumonia”
association between newborn calves that are losing maternal antibodies and outbreaks of BRSV
venipuncture
restraint: squeeze chute
usually use jugular or coccygeal veins
dairy cows less fractious so can usually halter and tie for procedures
coccygeal blood draw: tail up cow, clean manure from ventral side of tail, wipe with alcohol, palpate vertebral prominences and groove that runs directly along ventral midline of tail, use 3 or 6 cc syringe with 1in needle, insert perpendicular directly on midline groove ~3in from base of tail avoiding insertion directly over bony prominence, apply direct pressure after removal to avoid hematoma
tail-up
stand caudal to cow and use both hands to grasp base of tail and push it straight over dorsum without letting it curl or shift
tail twisting
restraint method that is performed by bending the tail to make the cow stay in place
