VTI2011

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Lactation PhysiologyMammary Gland
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Prevention

• Healthy cows with good immune systems will be
  able to fight off mastitis infections. Many
  mastitis pathogens are eliminated by the cow's
  own defense system.
• Assure that the diets are balanced for Vitamin E
  and Selenium.
• Immunization with J5 vaccine will not prevent
  infection but will decrease the severity of
  clinical signs.

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The mammary gland nourishes the neonate

• Exocrine gland common to all mammals
• Function nourish the neonate
• Food source fat, protein, sugar (CHO), vitamins,
  minerals, water
• Protection immunoglobulins (first Ab protection
  absorbed via intestinal tract)

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The mammary gland is part the reproductive system

• The mammary gland is loosely considered part of
  the reproductive system
• Serves a reproductive function nourishment of
  the neonate survival of species.
• Relies on same endocrine (hormonal) support for
  development and function.
• Example gonadal steroids, prolactin, etc.

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Endocrine Glands Affect Mammary Function
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Mammary Gland Structure

• Udder consists of four separate glands
• A teat hangs from each quarter
• Bottom of teat closed by sphincter muscle known
  as streak canal
• Can have extra nonfunctional teats
• Called supernumerary teats
• Removed when calf is young

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Mammary Gland Structure

• Conformation of teats
• Vary in shape from cylindrical to conical
• Rear teats are usually shorter
• Each teat has one streak canal
• Teats should be moderately sized and located
  centrally on each quarter
• Sphincter in each teat should be tight enough to
  prevent leakage
• Teats are hairless

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Mammary Gland Structure

• Support system Stroma (connective tissue)
• Glandular secreting tissue Parenchyma
• Alveoli- secreting epithelial cells
• Duct system- lined by epithelial cells
• Lobules lobes- clusters of alveolar tissue
  supported by connective tissue

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Separate Mammary Glands-Quarters
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60
Front quarter is smaller
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Mammary Gland Structure/Suspension

• Intermammary groove separates left and right
  halves of the udder
• Udder can weigh anywhere from 7 to 165 pounds
• May support up to 80 pounds of milk
• Rear quarters secrete 60 of the milk
• Udder continues to grow in size until cow is 6
  years of age
• Well attached udder fits snugly against the
  abdominal wall in front and on the sides
• Extends high between thighs in rear
• 3 major supporting structures
• Skin
• Median suspensory ligament
• Lateral suspensory ligament

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Mammary Gland Suspension

• Skin
• Minor role in support
• Median suspensory ligament
• Separates right and left halves of udder
• Connects udder to abdominal wall
• Lamellae
• Elastic tissue which responds to weight of milk
  in udder
• Lateral suspensory ligament
• Inflexible
• Surround the outer wall of udder
• Attached to prepubic and subpubic tendons
• Intermammary groove formed where lateral
  suspensory ligament and median suspensory
  ligament meets

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Fig 29-3. An illustrated view of the ligaments
that permit udder suspension (Courtesy of Iowa
State University)
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Mammary Gland Support
Medial suspensory ligament
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Internal Anatomy

• Streak canal
• Functions to keep milk in udder and bacteria out
  of udder
• Teat cistern
• Duct in teat with capacity of 30-45 milliliters
• Separated from streak canal by folds of tissue
  called Furstenbergs rosettes
• Gland cistern
• Separated from teat cistern by the cricoid fold
• Holds up to 400 milliliters of milk
• Collecting area for the mammary ducts
• From this branches the mammary ducts

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Fig 29-4. A dissected mammary gland showing the
gland cistern, teat cistern and streak canal
(Courtesy of Mark Kirkpatrick)
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Alveoli and Duct System

• Alveoli is the basic milk producing unit
• Small bulb-shaped structure with hollow center
• Lined with epithelial cells that secrete milk
• Each cubic inch of udder tissue contains 1
  million alveoli
• Each alveoli surrounded by network of capillaries
  and myoepithelial cell
• Contraction of myoepithelial cell stimulates milk
  ejection
• Groups of alveoli empty into a duct forming a
  unit called a lobule
• Several lobules create a lobe
• Ducts of lobe empty into a galatophore, which
  empties into the gland cistern
• Ducts provide storage area for milk and a means
  for transporting it outside
• Lined by two layers of epithelium

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Alveoli and Duct System
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Alveolar Products

• Alveolus
• basic secretory unit lined by epithelial cells
  which synthesize and/or secrete
• lipid - triglycerides free fatty acids (FFA)
• protein - caseins
• lactose - disaccharide osmoreactive molecule
  (draws water)
• minerals vitamins - Ca, P, K Vits. A, B, C, D
• water

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Circulation

• One gallon of milk requires 400 gallons of blood
  being passed through udder
• Ratio may increase in low producing cows
• Blood enters the udder through external pudic
  arteries
• Blood exiting udder from veins at the base of
  udder blood can travel through two routes
• Via external pudic veins
• Via subcutaneous abdominal veins

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Fig 29-6. Blood flow to and from the mammary
gland determines milk producing capability of the
cow (Courtesy of Iowa State University)
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Mammary Venous Circle
Cranial Mammary Vein
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Mammary Vessels
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Mammary gland defense system

• Smooth muscle sphincter surrounding the teat
  canal inhibits bacterial closure. Because the
  teat canal lumen remains dilated for up to 2
  hours after milking, feed cows after milking to
  keep them on their feet.
• Keratin, a waxy substance derived from the teat
  canal lining partially occludes the lumen of the
  teat canal and inhibits bacterial penetration.
  Only infuse the tip of intramammary infusion
  cannulas into the teat canal.
• Somatic Cells are the most important natural
  defense mechanism to infection. Leukocytes
  (mostly PMN, polymorphonuclear neutrophils)
  function by phagocytosing and killing bacteria.
  They may reach in the millions.
• Antibodies and other soluble factors in milk.
  They coat bacteria and enhance PMN engulfment.
  They also interfere with bacterial adhesion to
  tissues, reducing multiplication and neutralizing
  toxins.

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Lymphatic System

• Helps regulate proper fluid balance within udder
  and combat infection
• Fluid drained from tissue only travels away from
  udder
• Blood capillary pressure
• Contraction of muscles surrounding the lymph
  vessels
• Valves that prevent backflow of lymph
• Mechanical action of breathing
• Lymph travels from udder to the thoracic duct and
  empties into blood system
• Flow rates of lymph depend on physiological
  status of the cow

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Lymphatic System

• Fluid enters the lymph system through open-ended
  vessels called lacteals

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Function of the Lymphatic System
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Lymphatic System- Edema

• Edema
• low pressure, passive system fed by a high
  pressure vascular system!
• this situation results in pooling of interstitial
  fluid if evacuation of lymph is impaired
• Example tissue trauma increased mammary blood
  flow at parturition

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Alleviating Mammary Edema

• Preparturient milking may be helpful
• store colostrum from healthy cows to feed calves
• Frequent milkout to reduce mammary pressure
• Diuretics, corticoids to reduce swelling

• Mammary massage, icing
• work fluid towards supramammary lymph nodes
• Reduce salt intake
• Dont feed too much, too early before calving

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• Foul smell and necrotic odor
• Arcanobacterium pyogenes
• (another)anaerobe
• Watery milk, swollen udder
• Coliforms
• Watery and red, sick cow
• Staph aureus poor prognosis

• Subclinical mastitis contagious
  organismsStaphylococcus aureus,
• Streptococcus agalactia, Mycoplasma bovis
• Clinical mastitis
• Environmental organisms Strep. nonag. Group50
• Coliform organisms (Eschericia coli, Klebsiella,
  Enterobacter sp., etc.)
• 90 of the time

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Cows Reproductive Cycle
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Uterus
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Reproductive hormones
Estrogen positive feedback
Progesterone negative feedback
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Reproductive Physiology
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Day 0 is considered to be estrus. Days 1-5 are
metestrus. Days 6-17 are diestrus. Days 18-20
are proestrus.
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Metestrus
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Ovaries
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Insemination Timeline
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KaMar/ Bovine Beacon
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Tail Paint
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Tail Paint
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Heat Watch
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Ovsynch

• Ovsynch uses two hormones
• PGF2a and GnRH
• Ovsynch occurs in three stages
• Day 0 - Stage 1 GnRH injection to create a new
  follicle
• Day 7 - Stage 2 PGF2a injection to end the
  currnet estrus cycle and regress the corpus
  luteum
• Day 9 Stage 3 Second GnRH injection to cause
  the new follicle to ovulate and release the egg
• All cows will ovulate 24-32 hours after the
  second GnRH injection
• Day 10 Insemination

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CIDR - Source ansci.wisc.edu

• CIDRs (Controlled Internal Drug Release) are an
  intravaginal progesterone insert used in the beef
  cattle, dairy cattle, goat and sheep industries.
• The progesterone is released at a controlled rate
  into the bloodstream after insertion.
• In all species, CIDRs are used for the
  synchronization of estrus.
• This can be highly beneficial in large herds
  because with the synchronization of estrus,
  groups of cows and heifers can be bred at the
  same time in a narrow window.  

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Lutalyse

• Lutalyse is a veterinary pharmaceutical brand
  name
• Lutalyse is a PGF2a therapy treatment
• If an animal is known to be open (i.e. her
  ovulated egg was not inseminated), a shot of
  Lutalyse will end the cycle and start a new one.
• Lutalyse/ PGF2a will cause the death of the
  corpus luteum, resulting in reduced progesterone
  production.
• Pregnant women SHOULD NOT administer shots of
  Lutalyse it can cause their bodies to terminate
  the pregnancy!

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Rectal Pregnancy

• Easiest, fastest, cheapest
• status 25 - 30 days post breeding
• US 12 days (18 days in small ruminants)
• Radiograph 90 days
• Positive signs of pregnancy
• Fetus
• cotyledons/caruncles
• amniotic vesicle
• fetal membrane slip
• Suggestive signs
• Ipsilateral corpus luteum
• Ipsilateral middle uterine artery in the broad
  ligament

US 40 day pregnancy
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Fetal Membrane Slip (be gentle, as you can damage
a pregnancy by rough palpation) 32 days thread
1 horn45 small string 1horn60 string 2
hornsgt70 large string
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Pregnancy

• Placentomes
• cotyledon/caruncle unit)
• You must rule out that you a not palpating an
  ovary by feeling at least 3.

The fetus descends out of reach from 3-7
months.You can first feel the fetus at 55-60
daysTo estimate an aborted fetus they are2
months mouse3 months rat4 months small cat5
months large cat6 months beagle dog
75 days pea size100 dime115 nickel125
quarter150 half dollargt 150 variable
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• Gestation Avg. 283 days
• 1 2 days before parturition elevated tail head
• Stage I Preparatory stage
• 6 hours
• Inappetance, restlessness, kicking belly
• Stage II Delivery
• 30 min 4 hours (Avg. 75 minutes)
• Heifers take longer
• Head diving posture
• Stage III
• Expel placenta
• 4 12 hours
• KNOW pg 375 normal PE calf

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Calf care

• Oxygen
• fetal membranes and fluids
• 1st breath 30 secs 90 110 breaths/min
• Temperature
• Draft free, deep bedding, heat source
• 100 102 degrees F
• Umbilical cord and umbilicus
• Usually naturally or rupture
• 3 provodine iodine or chlorehexidine (14)
• Nutrition
• Stand 1 4 hrs
• Bond
• Pass meconium 1st feces in 24 hrs.
• Colostrum IgG, dairy 4L and beef 1-2 L
• 10 15 BW in first 12 24 hours, After 24 hrs
  IV plasma
• Milk replacer 5 6 BW . BID
• PE Table 17 -1

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Dystocia

• Common cattle and sheep
• 1st time (primiparous) mums
• 1st calf heifer, fat, torsion,
• milk fever (no contractions)
• 3 approaches
• Mutation and traction
• Obstetrical chains, calf jacks
• Fetotomy in cattle
• C section
• Fetus too large, small pelvis, cervix does not
  dilate, vaginal prolapse, dead fetus, malformed
  fetus

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Post partum problems

• Retained placenta
• Prolapse vagina or uterus "cast her wethers" and
  "lost her calf bed

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References

• Slides courtesy of Dr. H.D. Tyler, Iowa State
  University
• References Dr. M. A. Barnes, Virginia Tech and
  Dairy Cattle Science. 4th Ed. 2005.
• http//www.vet.k-state.edu/studentorgs/bovine/pdf/
  Reproductive_Physiology.pdf
• http//cal.vet.upenn.edu/projects/repropath/FNorma
  l/ovaries/template.htm