Cold Weather Feeding Strategies

What Influences Calf Growth?• Nutrition• Health• Genetics• Environment

Biology of Cold Stress• Maintaining body temperature

requires energy– Cold stress increases maintenance

energy req’t

• Calves have limited capability to regulate their body temperature– Immature metabolism

• Preruminant – lack of ruminal fermentation

– Lack of appreciable fat stores– Must consume enough calories to

generate enough heat

Thermoregulation• Thermoneutral zone

– Range where maintenance energy requirements are relatively constant

– 50-80°F for young calves

• Lower critical temperature– Temperature at which

maintenance energy requirements increase

– More energy required to maintain core body temperature, at the expense of growth and immune function

From the book The Development, Nutrition, and Management of the Young Calf; Davis and Drackley, 1998

Age Effects on Lower Critical Temperature

AgeLower Critical Temperature

Newborn Calf 50°F

Month-old Calf 32°F

Dry dairy cow 8°F

• Calves experience cold stress at moderate temperatures

• Lower critical temperature decreases with age, greater energy intake, and ruminal development

Cattell, 1999

Environmental Effects on Critical Temperature

Solar EnvironmentCritical

Temperature

Dry, calm, sunny -7°F

Dry, calm, overcast 8°F

Dry, calm, night 22°F

Dry, 10 mph wind, overcast

27°F

Raining, 10 mph wind, overcast

35°F

• Housing environment impacts degree of cold stress

• Key Factors– Free of drafts– Dry– Deep bedding allows for:

• Insulation• Nesting behavior• Increased lying time• Drier hair coat

Cattell, 1999

Temperature Effects on Maintenance Energy Requirements

Body Weight (lbs)

ADG, lbs/day

Metab. EnergyMcal/day

20-20 Needed, lbs/day

100 0.00 1.75 0.84

100 0.50 2.29 1.10

100 0.72 2.60 1.25

Body Weight (lbs)

ADG, lbs/day

Metab. EnergyMcal/day

20-20 Needed, lbs/day

100 0.00 3.25 1.56

100 0.50 3.81 1.83

100 0.72 4.10 1.97

70°F

10°F

85% Increase

Impacts of Cold Stress on Calves• Deplete body fat reserves

– Young calves don’t have much anyway!– Can literally starve to death

• Depressed immune function– Energy not available to fight disease– Poor response to treatment

• Decreased growth performance

Key Management Practices• Calf jackets• Straw > wood chips or sand

Effect of Bedding Type

0.64

1.17

2.36

0.58

1.06

2.04

0

0.5

1

1.5

2

2.5

3

d 1-21 d 1-42 d 43-56

Period

AD

G, l

bs/

day

Straw Shavings

Hill et al., 2007, PAS, 23:656

Straw: 82 lbs of gain thru d 56Shavings: 73 lbs of gain thru d 56

Key Management Practices• Calf jackets• Straw > wood chips or sand• Air quality

– As barns get closed up, airborne bacteria may increase – greater respiratory and scours problems

– Maintain air flow while eliminating draft• Water availability

– Offer warm water for 30 minutes twice daily

Cold Weather Calf Management

• Objectives– Exceed maintenance

energy requirements and maintain desired growth rates

– Focus on young calves• <3 weeks old

• Nutritional strategies– Increase amount of powder

• 10 → 12 oz per 2 quarts

– Utilize a fat supplement• 2 to 4 oz/calf/day

– Increase liquid feeding rate• 2 → 2.5 to 3 quarts/feeding

– Add a 3rd feeding• 2 quarts/feeding fed 3X

Considerations for Strategies• Does the farm use bottles or pails?

– Bottle size limits how much liquid is fed• 2 quart bottles are common• 3 quart bottles are available

– Will be a factor in what strategy is recommended

• Key question: Increase energy density, feed more volume, or both?

Strategy #1: Increase Solids Percentage

• Standard mixing rates– 8 oz dissolved in 2 quarts fed twice daily (12% solids)– 10 oz dissolved in 2 quarts fed twice daily (15% solids)– 12 oz dissolved in 2 quarts fed twice daily (18% solids)

• 18% solids is maximum recommended!– Ability to increase intake is limited w/ this approach– Mix rate of 12 oz/2 quarts is upper limit

100 lb Calf – 20-20 MR70°F 20-20 1.25 1.50

Protein ADG (lb/day) 0.72 0.91

Energy ADG (lb/day) 0.72 1.07

Energy balance, Mcal/d +0.85 +1.37

10°F 20-20 1.25 1.50

Protein ADG (lb/day) 0.72 0.91

Energy ADG (lb/day) Weight Loss Weight Loss

Energy balance, Mcal/d -0.65 -0.12

32°F 20-20 1.25 1.50

Protein ADG (lb/day) 0.72 0.91

Energy ADG (lb/day) Weight Loss 0.41

Energy balance, Mcal/d -0.09 +0.43

Strategy #2: Use KCAL (7-60 Fat Supplement)

• What is KCAL?– 7% crude protein, 60% fat supplement

• How much do we feed?– 2 or 4 oz/calf/day

• How much fat if KCAL is added to a 20-20?– 2 oz/calf/day = 24% Fat– 4 oz/calf/day = 27% Fat

Strategy #2: Areas of Caution, Solids % with KCAL

Influence of KCAL on Milk Replacer Solids Percentage

KCAL Feeding Rate, oz/day

Mixing Rate None 2 oz 4 oz10 oz/2 quarts 15.0% 16.5% 18.0%12 oz/2 quarts 18.0% 19.5% 21.0%

Take-Home Message: Increase MR powder mix rate OR add a fat supplement, NOT BOTH

Strategy #2: Use KCAL (7-60 Fat Supplement)

10°F 20-20 4 oz/d fat 1.25

Protein ADG (lb/day) 0.78

Energy ADG (lb/day) 0.09

32°F 20-20 2 oz/d fat 1.25

Protein ADG (lb/day) 0.75

Energy ADG (lb/day) 0.28

32°F 20-20 4 oz/d fat 1.25

Protein ADG (lb/day) 0.78

Energy ADG (lb/day) 0.56

10°F 20-20 2 oz/d fat 1.25

Protein ADG (lb/day) 0.78

Energy ADG (lb/day) Weight Loss

Take-Home Message: 2 oz/calf/day – not enough energy

4 oz/calf/day – recommended feeding level during moderate cold

Strategy #3:Increase Liquid Feeding Rate

Mixing Rate (oz/2 quarts)

Effect of Liquid Feeding Rate on MR Intake (lbs/day)

1.501.252.0 fed 2X

1.8751.562.5 fed 2X

2.251.8753.0 fed 2X

12 oz10 ozQuarts

100 lb Calf – 20-20 MR70°F 20-20 1.25 1.561 1.8752

Protein ADG (lb/day) 0.72 0.96 1.20

Energy ADG (lb/day) 0.72 1.15 1.56

10°F 20-20 1.25 1.561 1.8752

Protein ADG (lb/day) 0.72 0.96 1.20

Energy ADG (lb/day) Weight Loss Weight Loss 0.58

32°F 20-20 1.25 1.561 1.8752

Protein ADG (lb/day) 0.72 0.96 1.20

Energy ADG (lb/day) Weight Loss 0.51 0.97

110 oz powder dissolved into 2 quarts, calves fed 2.5 quarts twice daily210 oz powder dissolved into 2 quarts, calves fed 3 quarts twice daily, or 2 quarts three times daily

Strategy #4:Add a 3rd Feeding of MR Solution

• Ideal Approach– Spread out feedings– Reduce risk of refusals

• Implementation Issues– Labor– Inconvenience

• Feed an extra 1-2 quarts at noon

Feeding ProgramAll winter Add KCAL @

4 oz/calf/dayMix MR @

12 oz/2 quartsOR

Feed an extra 1-2 quarts daily

Daytime temp < 20°F

Mix MR @ 10 oz/2 quarts

EconomicsStrategy

Energy Allowable Gain @ 32°F, lbs/d Feed cost, $/day

Cost/lb of gain @ 32°F

MR, 10 oz rate,2 quarts twice daily

Weight loss $1.20 HIGH

MR, 12 oz rate,2 quarts twice daily

0.41 $1.44 $3.51

MR, 10 oz + 2 oz KCAL,2 quarts twice daily

0.56 $1.54 $2.75

MR, 10 oz rate, 2.5 quarts twice daily

0.51 $1.50 $2.94

Assumed $0.96/lb for 20-20 MR; $0.085/oz for KCAL fat supplement

Conclusions• Calves need more calories during cold weather for

maintenance, growth, and immune function

• Focus on housing and bedding will decrease maintenance energy requirements

• Increasing liquid feed intake and fat supplementation are effective strategies

• Good calf starter management is key

• Focus efforts on calves ≤ 3 wks old!!!