Transcript Hoagland-WinterFeedingofBeefCows-March2013

WINTER FEEDING OF BEEF
COWS
By
Tom Hoagland
University of Connecticut
Water consumption at different environmental temperatures
Schematic of the influence of ambient temperature with
HE (heat production) and IE (intake energy). RE is energy for production.
TABLE 12 Summary of Voluntary Food Intake of
Beef Cattle in Different Thermal Environments
15 to 25°C Preferred values as tabulated in
Nutrient Requirements of Beef Cattle.
•5 to 15°C Intakes up 2 to 5 percent.
•-5 to 5°C Intakes up 3 to 8 percent.
•-15 to -5°C Intakes up 5 to 10 percent.
•< - 15°C Intakes up 8 to 25 percent.
•Intakes during extreme cold (< -25°C) or
during blizzards and storms may be
temporarily depressed.
•Intake of high roughage feeds may
be limited by bulk.
TABLE 14: Water Requirements of Beef Cattle
in Different Thermal Environments
•15 to 25°C 3 to 5 kg water per kg DM intake.
•Young and lactating animals require 10-50
percent more water.
•-5 to 15°C 2 to 4 kg water per kg DM intake.
•< -5°C 2 to 3 kg water per kg DM intake.
•Increases of 50-100 % occur with a rise in
ambient temperature following a period of
very cold temperature, e.g., a rise from -20 to
0° C.
ADJUSTMENTS TO FEEDING VALUES FOR
TEMPERATURE STRESS
A = B + B(Cf(T-20))
A = value adjusted for environment,
B = diet component value from NRC feed
composition table,
Cf: correction factor (see below), and
T = effective ambient temperature (°C).
Cf for Effect of Temp on Diet Component
Dry matter
0.0016
Energy components (ME, NE, TDN)
0.0010
Acid detergent fiber
0.0037
Nitrogen (crude protein)
0.0011
Example of Adjustment to the Feeding Value of
Alfalfa Hay for Feeding to Beef Cattle Exposed
to Warm (30C), Neutral (20C), and Cold (-5)
Environmental Conditions
Temperature (°C)
ME (Mcal/kg)
NEm (Mcal/kg)
NEg (Mcal/kg)
TDN (%)
Digest protein (%)
30
1.94
1.14
0.40
53.5
11.5
20
1.92a
1.13
0.40
53.0
11.4
a From Table 11, NRC, 1976a.
-5
1.87
1.11
0.39
51.7
11.1
Net Energym = aW0.75
where
NEm = net energy for maintenance (Mcal/day),
a = 0.077 for TNZ,
W = live weight (kg).
For each °C prior exposure to ambient temperatures above or
below 20°C, 0.0007 should be subtracted or added respectively to
a in the above equation. Thus, for cattle with prior exposure to
temperatures of 30, 20, 10, and 0°C, the value a becomes 0.070,
0.077, 0.084, and 0.091, respectively. This means that a 1400 lb
cow at 0°C will need 18 % more net energy maintenance in her
feed.
Adjustments directly to NEm , ME or TDN
Adjustments can be made directly to the NEm and maintenance energy
requirement values expressed in terms of ME or TDN by decreasing
(for heat) or increasing (for cold) the tabulated values by 0.91 % for
each °C the cattle have had prior extended exposure to conditions
above or below 20°C.
Lower Critical Temperature
Need to make adjustments when
ambient temp is below LCT
LCT for Beef Cows is lower than for
other livestock
Cold stress is generally not a practical
nutritional problem in beef cattle
Cold Hardiness of Beef Cattle
Large size
Effective thermal insulation
Large heat increment from digestion
and metabolic processes
Storms and Blizzards
Bigger Problem
Causes an immediate increase in
energy requirement
Depends on level of acclimatization
Cold Acclimatized Cattle
Increased metabolic rate
Enhanced ability to increase their
metabolic heat production
Calculating Actual LCT
Must be established to make
nutritional adjustments for cold
stress
LCT = Tc – I(HE – He)
where
LCT = lower critical temperature (°C),
Tc = core temperature (°C) (39°C satisfactory
assumption),
I = total insulation, i.e., tissue plus external,
(°C/Mcal/m2/day),
HE = heat production (Mcal/m2/day), and
He = heat of evaporation (Mcal/m2/day).
HE = (ME – NEp)/A
where
HE = heat production (Mcal/m2/day),
ME = metabolizable energy intake (Mcal/day),
NEp = net energy for production (Mcal/day), and
A = surface area (m2).
NOTE: Surface area may be calculated from body
weight according to the
general formula A(m2) = 0.09 kg0.75.
ME* = A(LCT –T)/I
where
ME* = increase in maintenance energy requirement
(Mcal/day),
A = surface area (m2),
LCT = lower critical temperature (°C),
T = effective ambient température (°C), and
I = total insulation, i.e., tissue plus external
TABLE 16 Estimates of Tissue and External Insulation for Beef Cattle
Tissue Insulation (It )a
It (°C/Mcal/m2/day)
Newborn calf
2.5
Month-old calf
6.5
Yearling
5.5 to 8.0
Adult cattle
6.0 to 12.0
External Insulation (Ie )b
Wind Speed(mph)
<1
4
8
16
Ie (°C/Mcal/m2/day) in Relation to Coat Depth
<5 mm 10 mm 20 mm 30 mm
7
11
14
17
5
7.5
10
13.5
4
5.5
8
9
3
4
5
6.5
a Cattle in thin or emaciated body conditions and breeds with thin skins
(dairy breeds and Bos indicus) have lower values than fat stock and breeds
with thick skins (e.g., Hereford).
b Presence of moisture, wet snow, or mud in the coat could reduce Ie in
affected areas by 50 to 80 percent.
Estimates of LCT , Increase in Energy Requirements of Beef Cattle Under Various ACUTE Stresses.
Environmental Stresses
weight
LCT °C
Increased Energy
per °C below LCT
Yearling Steer
Gaining 1.1 kg/d
Dry low wind
300 kg
-34.1 (-29.4)
0.202
1.3%
Yearling Steer
Gaining 1.1 kg/d
Wet snow, mud
10 mph wind
300 kg
-9.5 (14.9)
0.310
2.0 %
Dry Pregnant cow
Middle third
Dry low wind
500 kg
-25.0 (-13)
0.237
1.45 %
0.334
2.04%
Dry Pregnant cow
500 kg
-7.3 (19)
Middle third
Wet snow
10 mph wind
____________________________________________________________________
Recommendations
Feed More energy (~1.0 % more
energy / drop in 1°C below 20 °C.
Protect cattle from wind (or ↑25%).
Wet and cold climates supply shelter
and dry bedding (or ↑ 25%).
Recommendations
In Connecticut during Jan, Feb and
March, beef cattle housed outside
need to consume almost TWICE as
much energy for maintenance.
Adjustments of Non Energy
Components
Vitamin A requirement may increase
with cold.
Protein % may be decreased as feed
intake increases to maintain amino
acid requirements.
Could increase roughage as heat
increment will increase but don’t
sacrifice performance for heat.
Problem: Evaluation for a 500 kg dry cow pregnant cow in the last third of
pregnancy on a diet of brome hay. Two environmental situations have been
considered. Nonstressful conditions and a cold dry environment with
seasonal temperatures of -15 ° C but during the past several days a winter
storm with air temperatures of -25 ° C, 10 mph winds, drifting snow and lack
of suitable bedding or shelter.
nonstressful
stressful
Maintenance energy requirement (Mcal ME/day)
adjusted for acclim temp
adjusted for direct cold stress
Total
16.4 (table)
0.0
16.4
21.6
5.9
27.5
Diet on dry matter basis
energy adjusted for conditions (ME/kg)
feed required for maintenance (kg/day)
1.87
8.8
1.79
15.4
Calculations:
16.4 +(16.4 (.91%)(20-(-15))) = 21.6
(.334)(-25-7.3) = 5.9
27.5/1.79 = 15.4 kg difficult to eat this much brome hay
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