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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!!!