Walk into any farm supply store and you will see heat lamp bulbs in two colors: red and white. Both produce heat. Both fit the same fixture. Both cost about the same. So which one should you hang over your piglets, chicks, lambs, or calves?
The short answer: red and white bulbs of the same wattage produce the same amount of heat. The difference is in the visible light. Red bulbs give off less visible light, which matters at night. White bulbs give off more, which matters when you need to observe animals. Choosing between them is less about heat and more about how the light affects the animals and your daily routine.
This guide covers the real differences between red and white heat lamps, when each one makes sense, and how to combine them for day and night use on a working farm.
Red and White Bulbs Produce the Same Heat
Before comparing light color, it helps to separate heat from light.
A 250W red bulb and a 250W white bulb produce the same wattage of heat. The infrared radiation — the part that actually warms the animal — is the same. If you hang both bulbs at the same height in the same pen, the floor temperature under them will be nearly identical.
The difference is in the visible light spectrum. A white heat lamp bulb emits a bright, warm-colored light similar to a normal incandescent bulb. A red heat lamp bulb filters out most of the visible light and leaves a dim red glow. The heat is still there. You just see less of it.
This is why switching from white to red will not change how warm the pen is. It will only change how bright the pen looks at night.
What Red Light Does to Animal Behavior
Red light is dim. Animals still see it, but it does not light up the pen the way a white bulb does. On a working farm, that matters in three ways.
It is less disruptive at night. Pigs, poultry, and ruminants have daily rest cycles. A bright white lamp left on overnight can interrupt sleep, especially in young animals. A red bulb keeps the pen dark enough that animals settle more easily while still providing heat.
It may reduce feather pecking in chicks. In crowded brooders, bright light can increase activity and pecking behavior. Red light tends to keep chicks calmer and reduce this risk. Many poultry keepers use red bulbs for exactly this reason.
It makes observation harder. The same dim light that keeps animals calm also makes it harder for you to see wounds, scours, or uneven distribution. In a red-lit brooder, it is easy to miss a chick that is not thriving.
Red light does not make animals warmer. It changes how they behave under the lamp.
What White Light Does to Animal Behavior
White heat lamps give off a bright, visible light. Animals can see clearly, and so can you.
It is better for observation. With a white bulb, you can check for pasty vent in chicks, scours in piglets, or injuries in lambs without moving animals into another light source. On a daily inspection routine, that saves time.
It supports normal daytime activity. White light is closer to natural daylight. Animals eat, drink, and move more during white-light hours. This is usually fine during the day, but it can disrupt rest if the lamp stays on all night.
It may increase activity in some species. Bright white light can raise activity levels in chicks and piglets. In a small brooder or creep area, that can lead to more competition at the feeder and more movement under the lamp.
White light is not inherently better or worse than red. It depends on when you use it and what you need to see.
Red vs White Heat Lamp at a Glance
| Factor | Red Heat Lamp | White Heat Lamp |
|---|---|---|
| Heat output at same wattage | Same | Same |
| Visible light | Dim red glow | Bright warm white |
| Night use | Better — less disruptive | Can disturb rest if left on |
| Daytime use | Harder to observe animals | Better for inspection |
| Feather pecking in chicks | May reduce pecking | May increase activity |
| Piglet behavior at night | Calmer, less disturbance | More active, more movement |
| Observation of wounds or scours | Difficult | Easy |
| Cost | Similar to white | Similar to red |
| Availability | Common | Common |
Neither column wins across the board. The right choice depends on what you need the lamp to do.
When to Use Red and When to Use White
On most farms, the practical answer is to use both — one during the day, one at night.
Use red bulbs when:
- The lamp stays on overnight and animals need to rest
- Chicks are in a crowded brooder and pecking is a concern
- Piglets need a calm creep area at night
- You do not need to inspect animals closely
- You want to reduce disturbance to the sow
Use white bulbs when:
- You need to observe animals, check for injuries, or inspect the pen
- The lamp is used mainly during the day
- Chicks or piglets need bright light to find the feeder and waterer
- You are checking animals after a cold night
- You are doing a morning or evening walkthrough
Many producers switch bulbs at dusk and dawn, or use two separate lamps — one red, one white — and turn them on at different times. That way the pen always has heat, but the light level changes with the animals’ routine.
Red and White Heat Lamps by Animal
Different animals respond to light color in slightly different ways.
Chicks. Red bulbs are popular in brooders because they reduce pecking and keep chicks calmer at night. White bulbs are useful during the day for inspection. Many chick brooders run red at night and white or natural light during the day.
Piglets. Red bulbs are often used at night to keep the creep area calm and reduce disturbance to the sow. White bulbs are used during the day for checking piglets and cleaning the pen. Piglets do not seem to prefer either color strongly, but the light level affects how much they move around.
Lambs. Lambs are less sensitive to light color than chicks. Red bulbs work well at night in lambing pens. White bulbs are useful for checking lambs during the day.
Calves. Calves in hutches or calf sheds respond more to temperature than to light color. Red bulbs are common at night. White bulbs are used during the day when the calf needs to be checked or fed.
Poultry in coops. Laying hens are sensitive to light hours. Red bulbs at night can help keep the coop calm without extending daylight, which matters if you are trying to manage laying cycles. White bulbs during the day are fine.
In every case, the heat output is the same. The color only changes behavior and observation.
What About Frosted and Clear Bulbs?
Bulb color (red or white) and bulb surface (clear or frosted) are two separate choices.
A clear bulb gives more concentrated light and heat. A frosted bulb softens the light and spreads heat more evenly. A red frosted bulb gives dim, even heat. A white clear bulb gives bright, focused heat.
For night use with animals, a red bulb — clear or frosted — is usually the better choice. For daytime observation, a white clear bulb makes it easier to see what is happening in the pen.
The surface choice does not change the heat output at the same wattage. It changes how the light and heat spread across the pen.
Common Mistakes When Choosing Bulb Color
- Thinking red bulbs are hotter. Red and white bulbs of the same wattage produce the same heat. Color affects light, not temperature.
- Using white bulbs all night. Bright light can disturb rest in piglets, chicks, and lambs. If the lamp stays on overnight, red is usually the better choice.
- Using red bulbs for inspection. Dim light makes it easy to miss injuries, scours, or uneven animal distribution. Use white light when you need to see.
- Switching colors to fix a temperature problem. If animals are cold or hot, the fix is height or wattage, not bulb color.
- Buying bulbs without checking fixture rating. The wattage matters more than the color. Use a bulb rated for the lamp’s maximum wattage, regardless of color.
- Assuming all animals react the same way. Chicks and poultry are more sensitive to light color than calves. Match the bulb to the animal and the task.
When Bulb Color Is Not the Real Issue
Some problems look like a bulb color issue but are not.
Animals huddling at night: this is a temperature problem, not a light problem. Lower the lamp or increase wattage.
Animals restless under a red bulb: this may be drafts, wet bedding, or a lamp that swings. Check the setup before changing bulbs.
Chicks pecking each other: red light can reduce pecking, but overcrowding, heat, and lack of feeder space are more common causes. Fix those first.
Piglets avoiding the creep area: this is usually a temperature problem. The creep area may be too hot, too cold, or too drafty. Bulb color will not fix it.
Sow disturbed at night: if the lamp is white and bright, switching to red may help. But if the sow is disturbed by noise, movement, or pen design, changing the bulb will not solve it.
Bulb color is a small lever. Use it when the real issue is light. Use height, wattage, and pen design when the real issue is heat or comfort.
Common Questions
Red light produces less visible light than white, so it is less likely to interrupt sleep. Many pig producers use red bulbs at night in farrowing houses for this reason. If pigs are still restless under a red bulb, the cause is more likely temperature, drafts, or noise than the light color.
Yes. As long as the bulb wattage matches the lamp’s rating, you can switch between red and white bulbs in the same fixture. Many farms keep both on hand and change bulbs at dusk and dawn.
In most markets, red and white heat lamp bulbs cost about the same. If one is more expensive, it is usually due to supply or brand, not a difference in heat output.
Both work for heat. Red light is often used at night because it reduces pecking and keeps chicks calmer. White light is used during the day for observation. Many brooders run red at night and white or natural light during the day.
No. Red and white bulbs of the same wattage produce the same heat. If animals are too warm, the issue is wattage or hanging height, not bulb color.
Red light is often preferred for newborn piglets, chicks, and lambs at night because it is less disruptive. During the day, white light makes it easier to check the animals. The heat output is the same either way.
References
- NC State Extension. Heat Sources for Post-Weaning Pigs. https://content.ces.ncsu.edu/heat-sources-for-post-weaning-pigs
- NC State Extension. Effects on Farrowing: Stall Size and Heat Lamps. https://swine.ces.ncsu.edu/news/effects-on-farrowing-stall-size-and-heat-lamps/
- University of Minnesota Extension. Raising layer chicks and pullets. https://extension.umn.edu/small-scale-poultry/raising-layer-chicks-and-pullets
- eXtension / University of Kentucky. Brooding Poultry Hatchlings. https://poultry.extension.org/articles/poultry-management/brooding-poultry-hatchlings/
- Penn State Extension. Brooding of Domestic Fowl. https://extension.psu.edu/brooding-of-domestic-fowl