3 – Feeding Dairy Cattle

Question 1

Feeding costs

Answer 1

• Single HIGHEST production cost
  o AB study: 30-35% total production costs

Question 2

What are the components of a dairy cow diet?

Answer 2

• Fiber sources: milk fat production (acetate)
  o Ex. alfalfa silage, pea silage, grass silage
• Grains: gluconeogenesis (propionate)
  o Ex. barley, corn
• *some feed provide both grain and fiber
  o Ex. corn silage, barley silage

Question 3

Alfalfa

Answer 3

• *leaves
  o Margin less than ½ serrate

Question 4

Pea silage

Answer 4

• Can be difficult to grow alfalfa in some areas
• *tend to see higher milk fat, but lower milk protein (balance each other out in the end)

Question 5

Barley

Answer 5

• Feed more in Canada compared to the states
  o Grown better here due to temperature
  o requires less heat and water compared to corn

Question 6

Making a balanced ration

Answer 6

• determine content of available feedstuffs
  o near infrared (NIR) + wet chemistry
• determine animal requirements

Question 7

DMI vs. milk production rules of thumb

Answer 7

• *DMI=critical for milk production
  o Diet is usually 50% DM
• 6kg ‘tax’ (4.5kg for jerseys)
• Multiple the remaining intake by 2=milk yield

Question 8

If Holstein eating 25kg/day what would the milk yield be?

Answer 8

• Take away 6kg ‘tax’=19kg for milk production
• *38kg/day

Question 9

What ‘drives’ DMI?

Answer 9

• Bodyweight
• Milk production (producing more=need more DMI)
• Body condition
• Implants

Question 10

What limits DMI?

Answer 10

• Ration NDF: fiber
  o Too much fiber=sits longer
• Ration net energy
  o Will get full before having enough to produce milk
• Forage mass/allowance
• Ration protein (CP/TDN)

Question 11

What are the environmental factors that change DMI?

Answer 11

• Air temperature
• Plant toxins
• Water requirement and intake

Question 12

What is the 3 diets concept?

Answer 12

• Formulated
• Delivered
  o Loading the mixer: first input of error
• Consumed
  o Can’t control as well

Question 13

Spanish herds all on same ration

Answer 13

• All herds feed the same thing
• *if ration alone was what determined milk production=would assume all the yields would be the same

Question 14

What does increasing age at 1st calving do to production?

Answer 14

• Decreases production
  o Get more adipose tissue laid in the udder=reduced ability to produce milk

Question 15

What does increasing stalls/cow do to production?

Answer 15

• Increases production

Question 16

What does pushing up feed do to milk yield?

Answer 16

• 3.8kg more milk

Question 17

What is feed refusals?

Answer 17

• when you feed the next time, there is still feed in the feed bunks
• *continually having food in front of them

Question 18

What does feed refusals to milk yield?

Answer 18

• 1.6 kg more milk

Question 19

What are the 2 different feeding systems?

Answer 19

• Component feeding
• Total mixed ration

Question 20

Component feeding

Answer 20

• Ad-lib feeding of forage
• Concentrates fed separately
  o Milking parlour
  o Computer feeders
  o Individual feeding ‘station’

Question 21

What are the disadvantages with component feeding system?

Answer 21

• Concentrates may be taken in during short timeframe
• Rumen pH fluctuations
• Competition leading to grain overload

Question 22

What is partial mixed ration?

Answer 22

• Some grain is fed in parlor
• *most of grain is mixed with forage

Question 23

Total mixed ration systems

Answer 23

• All feed components mixed to form TMR
• Composition of diet tightly regulated
• *appropriate mixing is critical

Question 24

What happens with inadequate mixing in TMR?

Answer 24

• Sorting and rumen pH fluctuations

Question 25

What happens with overmixing in TMR?

Answer 25

• Put it into a powder
• Small particles leading to grain overload and/or frothy bloat

Question 26

What are the 7 steps for problem solving a dairy ration?

Answer 26

1. Characterize low production
2. Evaluate Average days in milk
3. Evaluate trends in herd size
4. Evaluate herd nutritional management
5. Evaluate the cows
6. Evaluate cow environment
7. Additional testing
   - *rarely do them all at once

Question 27

Characterize low production (1)

Answer 27

• Evaluate milk by time and parity
• If low production in heifers:
  o Overcrowding, pen moves?
  o Small size at calving?
  o Over conditioned at calving?
• If low production in cows:
  o Underfeeding?
  o Ketosis, lameness?

Question 28

Evaluate average days in milk (2)

Answer 28

• Where in lactation is the ‘average’ cow
• Indicator of reproductive efficiency
  o If conceives later=longer lactation
  o Longer lactations=average cow further in lactation (ex. 200DIM vs. 155DIM)
• Increased DIM=decreased milk

Question 29

Herd investigation example

Answer 29

• Average DIM=240 with 29kg/cow/day
• *addressed reproductive efficiency issue (ex. one bull had a hurt leg)
  o New average DIM=180 with 33kg/cow/day
• NO ration changes

Question 30

Evaluate trends in herd size (3)

Answer 30

• Herd expansions decrease milk yield for up to one year
  o Hierarchy is diminished at 150-200 cows (before that would have 2 hierarchy groups)
• Long vs. short term LOW production

Question 31

How do health problems effect herd size?

Answer 31

• Death loss
• Reduced herd size
• Reduced milk yield

Question 32

What is happening with long term LOW production?

Answer 32

• Nutrition problems
• Health problems
• Increased DIM

Question 33

What is happening with short term LOW production?

Answer 33

• Expansions
• Health problems
• Nutrition problems

Question 34

Evaluate herd nutritional management (4)

Answer 34

• Determine which cows are eating
• This takes time
• NEVER assume
• Evaluate feed ingredients
• Determine amount fed
• Check mixer scales
• Reconstruct diet
• Evaluate TMR: CAREFUL SAMPLING

Question 35

Evaluate feed ingredients

Answer 35

• See all feeds
• Understand system
• Analyse dry matter, forage, and grain particles, ensiled feed pH

Question 36

Determine amount fed

Answer 36

• Interview feeder
• Determine amounts offered and refused
• Weigh everything

Question 37

Evaluate the cows (5)

Answer 37

• Body condition
• Cud chewing
• Manure evaluation
  o ‘if soap you could lather up’
• Lameness
  o Increased protein can contribute
• Sick cows

Question 38

Evaluate cow environment (6)

Answer 38

• Can have a minor impact
• Free stalls
• Resting surfaces
• Flooring
• Ventilation

Question 39

Additional testing (7): HERD TESTING

Answer 39

• Testing alone will never solve a problem
• Test results must be corroborated by other findings
• Rumen pH by rumenocentesis/stomach tube
• Blood tests for ketosis: energy balance
• Blood NEFAs on pre-fresh cows: energy balance
• Urinary pH: hypocalcemia
• Milk urea nitrogen (MUN): protein utilization

Question 40

Diagnosis and make recommendations

Answer 40

• Individual data can contain error
• Make <3 total recommendations (ideally <1)
• Practical and specific
• Directly related to herd issues
• Related to herd’s goals
• Follow-up