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
Age
Lower Critical
Temperature
Newborn Calf
50°F
Month-old Calf
32°F
Dry dairy cow
8°F
Cattell, 1999
• Calves experience cold
stress at moderate
temperatures
• Lower critical temperature
decreases with age, greater
energy intake, and ruminal
development
Environmental Effects on Critical Temperature
Solar Environment
Critical
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
Cattell, 1999
• 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
Temperature Effects on
Maintenance Energy Requirements
Body Weight
(lbs)
ADG,
lbs/day
Metab. Energy
Mcal/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. Energy
Mcal/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
85%
Increase
10°F
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
Straw
Shavings
ADG, lbs/day
3
2.5
Straw:
Shavings:
82 lbs of gain thru d 56
73 lbs of gain thru d 56
2.36
2.04
2
1.5
1
1.17 1.06
0.64 0.58
0.5
0
d 1-21
Hill et al., 2007, PAS, 23:656
d 1-42
Period
d 43-56
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 MR
70°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
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
10°F 20-20
1.25
1.50
Protein ADG (lb/day)
0.72
0.91
Energy ADG (lb/day)
Weight Loss
Weight Loss
-0.65
-0.12
Energy balance, Mcal/d
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
10 oz/2 quarts
12 oz/2 quarts
None
15.0%
18.0%
2 oz
16.5%
19.5%
4 oz
18.0%
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)
32°F 20-20 2 oz/d fat
1.25
10°F 20-20 2 oz/d fat
1.25
Protein ADG (lb/day)
0.75
Protein ADG (lb/day)
0.78
Energy ADG (lb/day)
0.28
Energy ADG (lb/day)
Weight Loss
32°F 20-20 4 oz/d fat
1.25
10°F 20-20 4 oz/d fat
1.25
Protein ADG (lb/day)
0.78
Protein ADG (lb/day)
0.78
Energy ADG (lb/day)
0.56
Energy ADG (lb/day)
0.09
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
Effect of Liquid Feeding Rate on MR Intake (lbs/day)
Mixing Rate (oz/2 quarts)
Quarts
2.0 fed 2X
10 oz
1.25
12 oz
1.50
2.5 fed 2X
1.56
1.875
3.0 fed 2X
1.875
2.25
100 lb Calf – 20-20 MR
110
210
70°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
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
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
oz powder dissolved into 2 quarts, calves fed 2.5 quarts twice daily
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 Program
All winter
Add KCAL @
4 oz/calf/day
OR
Mix MR @
12 oz/2 quarts
Daytime temp < 20°F
Feed an extra 1-2
quarts daily
Economics
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
Strategy
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!!!