Lactation- Exam 3

what is the distinguishable feature of mammals?

lactation

What two functions does the mammary gland serve?

-provides nutrition to offspring

-source of passive immunity to offspring

In the U.S. where does milk primarily come from?

dairy cows

Besides dairy cows, what other animals does milk primarily comes from in the U.S?

goats and sheep

What makes a mammal?

-most have hair

• all have mammary glands

critical part of repro strategy in mammals?

lactation

True or false, yield and composition of milk vary's considerably between and with species?

true

How many glands and teats does a cow udder have?

4 glands, terminate in 4 teats

How many glands and teats does a mare udder have?

4 glands served by 2 teats

How many glands and teats does a sheep and goat udder have?

2 glands and 2 teats

How many glands and teats does sow udder have?

6-20 glands and each gland has a teat

What is a gland?

a secreting organ

What kind of glands are mammary glands?

exocrine glands; gland that secretes fluid into a duct

What is secreted by mammary glands?

milk

What kind of cells is milk synthesized and secreted from?

from epithelial cells in a tissue consisting of alveoli

what kind of system is alveoli connected to?

duct system

What are the two protective factors in milk?

antimicrobial proteins and proper intestinal flora

Lactoferrin

binds iron (Fe) required for bacterial growth

Lysozyme

enzyme that hydrolyzes bacterial cell walls

Proper intestinal flora

factors in milk contribute to their establishment

What is milk composed of?

water

lactose

fat

protein

minerals

vitamins

What cow breed has the greatest milk fat percentage?

Holstein

First-drawn milk is higher or lower in fat?

lower; "fat leaves last"

Is milk fat higher or lower in the fall and winter?

higher

Is milk fat high or lower in the spring and summer?

lower

What temperatures s milk accentuated with?

greater than 85 degrees Fahrenheit

What factors affect milk production?

inheritance

feed and management

multiple births

age of animal

Male offspring cause greater or lower milk production?

greater

At with lactation are sows at peak milk yield?

during 3rd or 4th lactation

Beef cows produce most milk at what age range?

5-9 years of age

Dairy cows produce highest amount of milk at what age range?

5-8 years of age

Are nutritional needs greater during lactation or gestation?

lactation

Mastitis

Inflammation of the udder

What is the most costly disease of dairy cattle?

Mastitis

What is mastitis causes by?

chronic infection of streptococcus & staphylococcus bacteria

What are the three main causes of mastitis?

Dirty or poorly adjusted milking equipment

Poor milking practices (dirty animals)

Injuries to cows because of their surroundings

What are the symptoms of Mastitis?

Detection of clots or flakes in milk

Quarter of udder is sensitive to tough

Swollen or hot to tough

tested for via California mastitis test

Treatment for Mastitis

• Specific organisms should be identified by milk cultures

• Treated by intramammary injection of antibiotics

• More frequent milking to reduction pathogen load

and reduce growth medium (milk)

Where is mother's milk important for young?

important for survival, development, and growth

Colostrum

first milk

Why is colostrum important?

-offspring has low (or none) immunity, this provides some immunity

-transfer of immunoglobins via this

-intestinal absorption of immunoglobins lasts 24 hours

-newborn must receive this early to acquire disease resistance

-should have frozen available on hand

Transition from producing colostrum to producing normal milk takes how long?

3-5 days

What is the composition of colostrum?

Contains antibodies, vitamin A and D, fat, protein, and most minerals

Mammogenesis

structural development or growth of mammary gland

Lactogenesis

associated with the end of pregnancy & parturition; tissues change

from nonlactating to lactating state

Milk secretion

synthesis of milk by epithelial cells

Milk removal

passive removal from cisterns and ejection of milk from alveolar

lumen

Galactopoesis

maintenance of lactation

Suspension

maintain attachment to body (cow udder structure)

Median suspensory ligament

Separates left and right halves of udder (structure of cow udder)

Lateral suspensory ligament

outer wall of udder (structure of cow udder)

Four glands or quarters

Separate from each other -- milk cannot move between quarters (structure of cow udder)

Alveolus

Sac-like structure with hollow center and basic milk-producing structure in udder

Lumen lined with single layer what kind of cells?

epithelial cells

myoepithelial cells

surround epithelial cells and are involved in milk ejection

Neural system of udder

Sensory nerves found in teats and skin

Circulatory system of udder

All of milk precursors come from blood

Estrogen

responsible for duct and cistern growth

Progesterone

stimulates growth of alveoli

What is responsible for initiation of lactation?

Growth hormone, adrenal corticosteroids, and prolactin

Prior to milking, milk is stored where?

milk cavity of the alveoli (lumen)

Milk letdown occurs when

after about 45 seconds

What happens during milk secretion?

Oxytocin, hormone released by posterior pituitary, causes contractions of myoepithelial cells surrounding each alveolus

Negative pressure

with the milking machine

Positive pressure

with hand milking

Positive and negative pressure

both occur during suckling

What mist be opened to remove milk?

streak canal

Epinephrine (adrenalin)

released into blood and can override action of oxytocin

When does lactation curve peak

around 4-6 weeks and then decreases

Dry period

Milk secretion is not occurring; 2 months is ideal in dairy