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ANS 1 > Chapter 17: Dairy Cattle > Flashcards

Chapter 17: Dairy Cattle Flashcards

1
Q

Dairy Species and Breeds

A
  • usually Bos taurus for high milk output, but also hybrids in places like SE Asia for heat/parasite tolerance and milk output
  • Holsteins (worldwide predominance because of high yield) and Jerseys
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2
Q

Domestication

A
  • originally thought to be about ~2000 BC (later than sheep and beef)
  • now thought to be ~5000 BC based on pottery in Europe that had traces of milk (possibly to make cheese)
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3
Q

Dairy Cattle Distribution

A
  • India has 18% of dairy animals, but not the largest amount of milk production
  • US has 12% of dairy animals
  • dairy cattle fairly evenly distributed worldwide bcs fluid milk is highly perishable
  • majority of milk produced is exported around the world as non-fluid milk
  • these other products have longer shelf life than fluid milk (esp cheese and milk powder)
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4
Q

Milk Powder

A
  • majority of milk is water
  • when water is extracted from milk, you get milk powder
  • milk powder is the DM of milk
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5
Q

Dairy Industry in the US

A
  • 9M dairy cows in US
  • CA #1 producer, with 1.7M cows
  • then Wisconsin, NY, Idaho
  • dairy practices differ by region, state, and country
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6
Q

Herd Sizes/Stocking Density

A
  • over time, dairy herds have increased
  • smallest ones might be in NE (100s)
  • CA: avg is 2500, but could be as much as 5-10,000
  • consolidation of different types of inputs (largest being feed) determines herd size
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7
Q

High Quality Forage

A
  • determines herd size and operation type
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8
Q

Pasture

A
  • smaller herds
  • need a lot of rainfall
  • NorCal has pasture-based dairies on the coast
  • can’t do pasture all year in the Midwest because of snow
  • Central Valley: corn plant silage (more close in nutritive value to actual plant), hay (loses some nutritive value), grains
  • total mixed rations
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9
Q

High-Quality Forage

A
  • high nutritive density
  • high digestibility
  • need nutrients in the feed to be readily available/easily accessible to the microbes
  • milk production is the most energy-demanding process and is very nutrient-demanding on the animal
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10
Q

Breeds

A
  • genetics determine how much milk is produced
  • Holsteins: 23,000 lbs (11,000 L) of milk per lactation
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11
Q

Lactation

A
  • period between calving/birth to dry-off period (often corresponds to weaning, but not w/ dairy cattle bcs calves are taken from dairy cows
  • lactation length: 300-305 days
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12
Q

Dry Period

A
  • 60 days
  • 2 months before calving
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13
Q

Timeline

A
  • cow impregnated
  • 281 days later, she gives birth and starts producing milk
  • 2 mo after birth: she comes back into heat and is bred again
  • 2 mo before birth: she stops getting milked and gets dry period
  • calving once a year, lactating for 10 mo, dry for 2 mo
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14
Q

Milk

A
  • 90% water
  • lactose
  • fat
  • protein (also Ca)
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15
Q

Lactose

A
  • carbohydrate/sugar
  • disaccharide (12-C)
  • one molecule of glucose and one molecule of galactose
  • only produced in the mammary glands (udder for cows)
  • lactose can be used by the baby, but also brings water into milk
  • water from cow’s blood supply is moved into lactose-making cells in the udder
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16
Q

Monosaccharide

A
  • 6-C sugar (hexose)
  • like glucose
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17
Q

Disaccharide

A
  • 2 hexose sugar molecules (12-C)
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18
Q

Fat

A
  • milk has cream in it that floats to the top
  • those droplets make up the fat in milk
  • liquid is homogenized to remove the fat
  • 3 fatty acid chains attached to one glycerol backbone make up triglycerides
  • fatty acid chains come from VFAs and the food that the cow is eating
  • lactose made from glucose consumed by cow, fatty acids made from VFAs and diet
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19
Q

Homogenized

A
  • milk is blended/frothed, and fat that floats up to the top is mashed up to remove fat skin on top of milk
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20
Q

Proteins

A
  • AA building blocks
  • several proteins in milk are only produced by the udder
  • cheese: protein groups in curdled milk are separated and clotted together
  • also how calcium gets in milk
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21
Q

Perfect Foods

A
  • honey and milk
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22
Q

Udder

A
  • one udder
  • 4 quarters, none of them connected to each other
  • 4 glands
  • 4 teats
  • milk cows 2-3 times per day (the more you milk them, the more the cells are stimulated to make milk)
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23
Q

Blood Supply to the Udder

A
  • every second, liters and liters of blood pump through udder tissue to deliver nutrients
  • deliver water, glucose, VFAs, other fatty acids, AAs
  • diet of lactating cow has to be exceptional
24
Q

Epithelial Cells

A
  • cells that are involved with secreting liquids and fluids, as well as nutrient and/or gas exchange
  • in lungs (gas exchange), small intestine (nutrient absorption into blood), large intestine (water absorption into blood supply), kidneys (take water out of digestive tract, circulation, and remove it from the body), salivary glands, reproductive organs, and udder (to extract nutrients from blood and bring to udder)
25
Q

Udder Epithelial Cells

A
  • take nutrients from the circulation and create lactose, specific milk proteins, and new types of triglycerides to make milk
  • milk can then be removed from alveolus
26
Q

Alveolus

A
  • 0.1 mm
  • each alveolus is filled with microdroplets of milk
  • alveoli contains myoepithelial cells, epithelial cells and milk
  • alveoli acts like sponge
  • when squeezed, milk comes out
27
Q

Myoepithelial Cells

A
  • contract in response to stimuli
  • surround epithelial cells making milk
  • alveolus is this whole complex
28
Q

Milking Cows

A
  • teat-dipping and stripping (testing milk quality)
  • sends nerve signals from teats to brain to pituitary gland, which releases oxytocin into the blood that activates myoepithelial cells
  • myoepithelial cells contract –> milk letdown
29
Q

Oxytocin

A
  • hormone for milk letdown
  • want it to act naturally
  • peaceful and calming hormone
  • also in humans
30
Q

Colostrum

A
  • when female was pregnant, her udder/epithelial cells prepared for calving as it approached
  • epithelial cells take antibodies from mum’s blood supply and store them in the alveoli so that newborn calf can get antibodies from that first milk and get passive immunity
  • those antibodies go away, so it’s not always colostrum being produced
31
Q

Lactation to Dry Period

A
  • lactation: 300-305 days
  • to get to dry period, just stop milking them
  • corresponds to natural process of weaning the calf
  • udder shrivels up, milk is removed back into circulation
  • udder redevelops for next lactation
32
Q

Weaning

A
  • process of young animal being removed from/stopping consumption of milk
  • weaning = dry off period of dairy cow
33
Q

Calving

A
  • calves are 30-35 kg at birth and fed milk
  • taken to hutches and fed for 8 weeks solely on milk
  • at 50 kg, weaned and moved to roughage and forage
  • heifers reach puberty, then are mated/bred at around 15 mo through AI or natural breeding
  • 9 mo pregnancy (no estrous cycles)
  • you don’t get any milk out of your calves until they’re 2 years old
  • calving
  • lactation begins
  • breed 2 mo after calving
  • dry period 7 mo after calving
34
Q

Milk Production

A
  • lactation starts at about 40 L (Holsteins)
  • peak production 3-4 mo into lactation
  • dry period 7 mo into pregnancy (10 mo into lactation)
  • with each successive pregnancy, she makes more milk as the udder grows bigger
35
Q

Milking Management

A
  • we are producing food, so need to be aware of hygiene and protection of udder
  • high risk of pathogens and microbes entering teat hole and infecting the udder
  • udder has warm environment and nutritious milk, so microbes would love to get in there and multiply
36
Q

Mastitis

A
  • infection of the udder
  • treat by squirting antibiotics into teat and into the udder
  • no milk produced by an antibiotic-treated cow doesn’t get into human food supply
  • infection in one teat can be isolated to one quarter of the udder because the quarters are not connected
  • want to keep infections isolated to single teat (why you dip and strip)
  • can still drink milk from the other teats (unless undergoing antibiotic treatment)
37
Q

Synchronization of Cycles

A
  • not always easy to detect heat
  • use series of hormone injections to induce ovulation
  • treat them with LH and FSH to bring her into heat for insemination
  • greater likelihood of conception
38
Q

Deciding What Bull to Breed (with a Holstein, for example)

A
  • could use beef bull to get into beef production as well
  • could use sexed semen to get more heifers from the best milk producers
  • could use sexed semen from beef bull to get steers to sell as beef
39
Q

Jersey x Holstein Cross

A
  • you get Jerseys’ high fat and protein content in milk
  • you get Holsteins’ higher volume
  • example of hybrid vigor
40
Q

Hybrid vigor

A
  • when we mix genetic potentials of different breeds and their offspring is better than each individual parent
  • Bos taurus x Bos indicus
  • Jersey x Holstein
41
Q

Dry Matter to Milk Ratio

A
  • 90% to 10%
42
Q

Mammary Epithelial Cells

A
  • cells that form single layer structure of an alveolus in a mammary gland
43
Q

Dairy Production Advances

A
  • number of cows has decr dramatically
  • productivity per animal has incr dramatically (on avg)
  • 1944: 25 M cows, 2000 L milk/cow
  • went from 22 L of methane/1 lb milk to 8 L of methane/1 lb milk
  • reduced carbon footprint of milk production
  • come a long way in managing animal byproducts
44
Q

Technology

A
  • milk harvesting thru robotics
  • milking 3x a day bcs cows make more milk the more they’re milked
45
Q

Nutrition

A
  • improved by balancing rations and identifying limiting nutrients (AAs - lysine, types of fats)
46
Q

Hormonal Tech

A
  • bovine somatotropin (bST)
  • intro’d in 90s to incr milk production
47
Q

Selective Breeding/Genetics

A
  • DNA testing of calves to determine her milk production compared to sisters’, helps in decisions of who to use as replacement heifers
48
Q

Management

A
  • confinement systems have advantage of monitoring animals and improving feeding management
  • manure management to decr environmental impact
49
Q

Improved Animal Health

A
  • reduced incidence of disease, vaccinations, better treatments, etc.
50
Q

Reproductive Management

A
  • getting cows in calf using AI
  • better heat detection
  • synching estrous cycles
  • sexed semen
51
Q

Overall Welfare

A
  • wellbeing in terms of management, feed, etc.
  • all comes together and translates into more efficient and productive animal
  • improved milk production, beef production, horses’ performance
52
Q

rbST

A
  • synthetic growth hormone somatotropin that scientists in the 80s and 90s used to improve milk production (lactation curve incr, would reduce greenhouse gas emissions)
  • was tested to ensure animal welfare and that milk quality was same between non- and rbST-treated cows
  • Monsanto invested money to bring tech to market in order to make more milk
53
Q

Public and rbST

A
  • rbST became very common, but spurious claims provoked ppl into thinking that drinking milk from hormone-treated cows caused cancer
  • grocery stores stopped selling hormone-treated milk, even though that milk was cheaper (bcs more available) and farmers could produce more
  • tech that was used on 30-40% of the dairy industry reduced to almost 0% now
  • tech of the past
  • consumer perception took over and became powerful voice
  • public opinion does matter in terms of raising food and selling products
54
Q

Where to Get Facts From?

A
  • scientific publications, rather than social media flooded w/ fake news
  • peer-reviewed publications and lit
55
Q

Peer-Reviewed Literature

A
  • scientific studies that are critically evaluated by peer scientists/experts and need to pass peer review to be published by scientific publications
  • peer review process can take months to years
56
Q

Scientific Publications

A
  • the accepted venue where scientists and academics publish their findings, views, interpretations, and opinions

ANS 1 (21 decks)

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