Cold Stress & Feed the Difference
Finds the critical temperature
Find the lower critical temperature (LCT) for your animal and coat, let wind chill shift it, and get the extra feed energy needed below it — about 1% more maintenance per °C (2% with a wet coat).
Cold-stress feed energy
Next: add about 1.37 kg of extra feed per animal per day (roughly 0.96 kg TDN, a 16% lift in maintenance energy) to cover the cold — feed energy-dense supplement, ideally before and during the cold snap. Add a windbreak to cut the wind-chill component.
Rule of thumb: ~1% extra maintenance energy per °C below LCT with a dry coat, ~2% with a wet coat (NRC Beef/Dairy cold increment). LCT shifts with coat — heavy dry coat lowest; wet/shorn highest. Wind chill makes the effective temperature colder. Maintenance-TDN anchors are representative adults; scale to your animal's size and lactation.
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Cold stress — key facts
- Beef cow LCT (dry coat)
- ≈ −8 °C
- Dairy cow LCT
- ≈ −10 °C (lactation heat)
- Extra energy
- ≈ 1% per °C below LCT (dry)
- Wet coat
- ≈ 2% per °C · LCT up ~15 °C
- Shorn / summer coat
- LCT up ~20–25 °C
- Wind chill
- ≈ −3 °C at 8 km/h → −12 °C at 32 km/h
- Cheapest fix
- Windbreak + dry bedding
- Privacy
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Lower critical temperature by species (dry coat)
| Animal | Base LCT | Maint. TDN (ref) | Note |
|---|---|---|---|
| Beef cow (mature) | -8 °C | 6 kg | heavy winter coat, ~600 kg |
| Dairy cow (lactating) | -10 °C | 8 kg | high heat output of lactation lowers LCT |
| Feedlot steer | -5 °C | 5 kg | high-energy ration raises heat output |
| Sheep (full fleece) | -15 °C | 1.1 kg | fleece is excellent insulation; shorn raises LCT ~+25 °C |
| Goat | 0 °C | 0.9 kg | poorer cold tolerance than sheep |
| Grower–finisher pig | 12 °C | 1.6 kg | little hair; LCT depends on group size & floor |
| Broiler (grown) | 18 °C | 0.12 kg | feathered but small; needs warm housing |
| Laying hen | 13 °C | 0.085 kg | comfort 13–24 °C; below adds feed for warmth |
| Horse (winter coat) | -10 °C | 5 kg | good cold tolerance with dry coat & shelter |
Coat condition shifts the LCT
| Coat | LCT shift | Energy per °C below | Note |
|---|---|---|---|
| Heavy dry winter coat | +0 °C | 1.0% | best insulation; lowest LCT |
| Moderate / fall coat | +7 °C | 1.3% | partial winter coat |
| Wet or mud-matted coat | +15 °C | 2.0% | insulation collapses; energy need doubles |
| Summer / shorn coat | +20 °C | 2.0% | little insulation; high LCT |
Wind-chill offset
| Wind speed | Effective temperature drop |
|---|---|
| 0 km/h | −0 °C |
| 8 km/h | −3 °C |
| 16 km/h | −6 °C |
| 24 km/h | −9 °C |
| 32 km/h | −12 °C |
| 40 km/h | −14 °C |
| 50 km/h | −16 °C |
Source: NRC Nutrient Requirements of Beef Cattle / Dairy Cattle (lower critical temperature & cold increment, ≈1% extra maintenance energy per °C below LCT, ~2% with a wet hide); cooperative-extension winter-feeding and wind-chill-for-cattle bulletins. Species LCTs generalised from animal-environment references; values are representative and vary with body condition, size, housing and acclimation.
The cold side of the comfort zone
Most heat-stress tools tell you when an animal is too hot. This one handles the opposite end: the cold. Every animal sits in a thermoneutral zone where its own metabolism keeps it warm, but once the effective temperature drops below the lower critical temperature, it has to spend feed energy on heat — and if you do not feed that extra energy, it comes off the animal's back as lost condition, lost growth or lost milk. The cruel part is that the threshold moves: a wet coat or a stiff wind can shift it by 15 to 25 degrees, so a temperature that was harmless yesterday is costly today.
This tool pins down where that threshold sits for your animal and conditions. It sets the base LCT from the species, shifts it for the coat, drops the effective temperature for wind chill, and then converts the degrees below the LCT into a percentage of extra maintenance energy and finally into kilograms of feed a day. Crucially it shows how much of the cost is the coat and the wind — which is why a dry bedding pack and a windbreak so often pay for themselves. Pair it with the Income Over Feed Cost and Average Daily Gain tools to see the production consequences.
How to use it — 5 steps
- 1
Pick the animal
Choose the species to set the base lower critical temperature and maintenance energy.
- 2
Set the coat condition
Heavy-dry, moderate, wet/muddy or summer — this shifts the LCT and the per-degree cost.
- 3
Enter temperature and wind
Type the air temperature and wind speed; the tool computes the wind-chill effective temperature.
- 4
Read the cold stress
See how many degrees the animal is below its LCT, the severity band, and the extra energy percentage.
- 5
Feed the extra
Read the extra TDN and kilograms of feed per day; add shelter and dry bedding to lower the LCT and cut the bill.
Frequently Asked Questions
What is the lower critical temperature (LCT)?+
The lower critical temperature is the temperature below which an animal must burn extra energy just to keep warm. Above it, in the thermoneutral zone, body heat from metabolism is enough. Below it, every degree colder raises the animal's maintenance energy need. For a beef cow with a heavy dry winter coat the LCT is about minus 8 degrees Celsius; for a lactating dairy cow it is lower because lactation produces a lot of heat; for a grown broiler it is well above freezing.
How much extra feed does cold weather need?+
As a rule of thumb, maintenance energy rises about 1% for each degree Celsius below the LCT with a dry coat, and about 2% with a wet or mud-matted coat. The tool turns that percentage into extra TDN and then into kilograms of extra feed per day using the energy density of the supplement you choose. A beef cow 10 degrees below her LCT, for example, needs roughly 0.6 kg of extra TDN — close to a kilogram of grain — every day.
How does coat condition change the LCT?+
Coat is the biggest lever. A heavy dry winter coat is the best insulation and gives the lowest LCT. A wet or mud-matted coat collapses that insulation and raises the LCT by about 15 degrees Celsius while also doubling the energy cost per degree, and a summer or freshly shorn coat raises it by around 20 degrees. The same cow on the same night can be comfortable with a dry coat and severely cold-stressed with a wet one.
Why does wind matter?+
Wind strips away the warm air trapped in the coat, so the effective temperature the animal feels is colder than the thermometer reads. The tool subtracts a wind-chill offset — about 3 degrees at 8 km/h rising to roughly 12 degrees at 32 km/h — from the air temperature before comparing it to the LCT. A windbreak is often the cheapest way to cut the cold-stress feed bill because it removes the wind-chill component entirely.
How is the extra feed calculated?+
First the tool finds the adjusted LCT (species base LCT plus the coat shift). Then it computes the effective temperature (air temperature minus wind chill) and the degrees below the LCT. It multiplies those degrees by the per-degree energy factor (1% dry, 2% wet) to get the extra maintenance energy percentage, applies that to the animal's maintenance TDN, and finally divides by the feed's TDN fraction to express it as kilograms of feed as fed.
Below what temperature do beef cows need more feed?+
It depends entirely on coat and wind. With a heavy dry winter coat a mature beef cow's LCT is about minus 8 degrees Celsius, so she only needs extra feed below that. But with a wet coat her LCT jumps to around plus 7 degrees, and adding a stiff wind can make a minus 18 degree night feel like minus 24 — leaving her more than 30 degrees below her effective LCT. That is why the same temperature can mean no extra feed or a lot of extra feed.
Does lactation lower the cold tolerance threshold?+
Yes. A lactating dairy cow generates a large amount of metabolic heat producing milk, which warms her from the inside and pushes her LCT lower than a dry cow's. That is why the dairy cow in this tool has a lower base LCT than a beef cow. The flip side is that she has high baseline energy demand, so the absolute kilograms of extra feed can still be substantial when it does turn cold.
What about sheep, pigs and poultry?+
Sheep in full fleece have an exceptionally low LCT — fleece is superb insulation — but shearing raises it by roughly 25 degrees, which is why freshly shorn sheep are vulnerable to cold. Pigs and poultry have little insulation and high LCTs (around plus 12 to plus 18 degrees), so they rely on warm, draft-free housing rather than extra feed alone. The tool includes representative figures for each so you can compare.
Should I feed extra before or during the cold snap?+
Both, but feeding extra energy before and during the cold helps most, because the heat of digestion (especially of forage fermenting in the rumen) directly warms the animal. Feeding good-quality forage in the late afternoon so fermentation peaks overnight is a classic cold-weather tactic. Pair the extra feed with dry bedding and wind shelter to keep the LCT low so you need less of it.
Are these figures exact?+
They are solid planning figures built on NRC cold-increment guidance and extension wind-chill tables, generalised across species. Real LCT and energy needs vary with body condition, body size, housing, bedding, acclimation and ration, and the maintenance-TDN anchors are for representative adults. Use the result to budget winter feed and to see the value of a windbreak or dry bedding, and adjust to your own animals' size and condition.