Mammary Physiology Flashcards by Mariah Casaday

Variation in location, number, and nipple openings of mamamry glands correlate to:

Litter size

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The mammary gland is an _____ gland that functions to:

Exocrine
Nourish the neonate

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Explain how the mammary gland functions as a food source and as protection:

Food Source: Fat, protein, sugar (CHO), vitamins, minerals, water
Protection: Immunoglobulins (colostrum), first antibody protection

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Components of bovine milk include:

Water
Fat
Solids (Protein, Lactose, Minerals)

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Proteins included in milk include:

Casein and whey

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Definition of milk solids:

Dried powder left after all the water is removed from liquid milk

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Why does the amount of milk solids matter in real life?

Too much water and/or too few solids can lead to diarrhea and malnutrition

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Milk replacer is typically what percent solids?

12-15%

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The less total solids in a species’ milk, the _____ suckling occurs

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Fat in bovine milk is made from:

Half from Acetate and Butyrate production in rumen
Half is pooled fatty acids from blood (body fat, diet, synthesized in liver)

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____ have the most fat in milk, followed by ____ and finally _____ (least).

Sheep
Cows
Goats

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Protein is formed in the mammary glands by:

Lactational epithelial cells

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Milk protein is synthesized by:

Amino acids in blood
Glucose required (Propionate from rumen, breakdown of AA)

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Casein is the ___ portion of the milk, and _____ is used to separate casein from whey

Curd
Acid treatment (Rennin)

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Whey is the ______ portion of the milk and is mainly made of:

Liquid (by-product of cheese production)
Alpha-lactalbumin and beta-lactoglobulin

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Lactose is a _________ composed of _____ and ______

Disaccharide; glucose/galactose

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What is the rate limiting step for milk production in cattle? Why?

Lactose production
Based upon how much glucose is available from propionate

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What are the inorganic components of milk?

High in: Ca, P, K, I, and vitamins
Low in: Na/Cl (less than blood)
Lower in: Fe, Se, & other micro minerals

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Nonstructural carbohydrates include _________ and form _______ (VFA)

Concentrates (Sugar/Starch), Propionate

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Structural carbohydrates include:

Lignin
Cellulose
Hemicellulose
Pectin

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Cellulose produces _____ (VFAs), Hemicellulose produces ________, and Pectin produces _________.

Cellulose: Acetate, Butyrate
Hemicellulose: Acetate, propionate
Pectin: Acetate, propionate

VFAs provide how much of the energy requirement for the ruminant?

60-80%

Which VFA is most essential for milk production?

Propionate
More propionate = more lactose = more milk

Why don’t we feed mostly grains to increase milk production?

Leads to subacute rumen acidosis

What is colostrum?

The first secretion from the mammary glands after giving birth; rich in antibodies (but contains more than antibodies)

Which species get immunoglobulins from the placenta only?

Rabbits, guinea pigs, mice, primates

Which species get immunoglobulins in utero and from colostrum?

Dogs and cats

Which species get immunoglobulins from colostrum only?

Ruminants, horses, pigs

Embryogenesis/ Mammogenesis:

Development of the mammary gland tissue and growth

Lactogenesis:

Synthesis and initiation of milk secretion from the alveoli

Galactopoeisis:

Biosynthesis of milk

Lactation:

Full milk secretion and maintenance of lactation

Galactokinesis:

Ejection of milk

Involution:

Regression and atrophy of the mammary gland

Mammogenesis occurs from ______ to _______ and is known as ______________

Birth to puberty; allometric growth

During puberty, what parts of the mammary gland develop?

Ducts, alveoli, mammary epithelium (last trimester, "bagging up")

Lactogenesis process:

Initiation of lactation Stimulation at teat Nerves carry message to pituitary Release of prolactin and oxytocin Bloodstream to udder Milk letdown

Galactopoiesis process:

Alveolar secretory cells Lactose: pumped into alveolus and fluids follow osmotic gradient Proteins: excreted by golgi apparatus; casein forms micelles as it is insoluble in water (milky appearance) Fat: droplets form in cell and extruded with a surface membrane

Galactokinesis process:

Reflex action: stimulation, auditory stimulus, conditioned reflex Oxytocin (posterior pituitary) Contraction of myoepithelial cells & relaxation of large alveolar ducts Milk ejection

Milk ejection lasts:

5-20 min

Exogenous administration of oxytocin causes:

Will cause milk letdown in: Heifers, cows with udder edema, removal of "residual" milk

Lactation length by species?

Swine: 21-28 days, 24 avg Equine: 4-7 months Canine: 6-10 weeks Goats: 2-4 months, 8-10 months (Dairy) Sheep: 2-5 months, 4-8 months (Dairy) Beef: 6-8 months Dairy: 10-12 months

What is the main way we start to "dry off" cattle?

Decrease feed intake, remove concentrates/forage

What is the benefit of dry cow treatment?

Reduces persistent mammary infections Decreases infection during dry period

When do we start dry cow treatments?

45-60 days before calving

Methods of drying off cattle?

Teat sealant Vacciantions Move to a different group, go on vacation

Factors that affect milk production?

Nutrition Length of dry period Frequency of milking BCS at parturition

Describe Agalactia in mares?

Prolactin inhibited by dopamine Fescue hay (Neotyphodium coenophialum)

Treatment/control of fescue toxicosis (agalactia) in mares?

Remove from fescue 30-60 days prepartum Administer domperidone

What things cause involution of the mammary gland?

Decreased milking/nursing Massive decline in metabolic activity of the mammary tissue Degeneration of alveolar tissue