Horses and cooler weather…

Given it’s getting cooler and winter is approaching, I’m going to write a mini-article each day this week about feeding and rugging your horses over the winter months. Today I will talk about thermoneutral zones and lower critical temperatures. Tomorrow’s article will be about winter and the easy keeper, Wednesday’s will focus on normal keepers, Thursday, hard keepers and Friday what the best feed options are for winter.


First let’s talk about winter…

Winter in Australia is mild. *We* may not think so as we trudge out in the cold and mud to feed, but it really is. Horses evolved in North America, not just North America, but Northern North America where it is windy, cold and snows in winter with minus temperatures being the norm.

The thermoneutral zone (TNZ) is the temperature range in which the horse is able to maintain its body temperature using little to no energy. This means the horse does not have to work to raise or lower its body temperature. The TNZ is influenced by the temperature the horse is acclimated to, its age, condition and health. It takes about 21 days for a horse to adapt to a new temperature if it moves to a different climate.

The lower critical temperature (LCT) is the lowest temperature in the TNZ. When the temperature drops below the LCT the horse must work to increase its normal body temperature. Body temperature is maintained by several metabolic processes including the heat of nutrient digestion. In horses, the fermentation of fibre produces large amounts of heat.

When the temperature is above the upper critical temperature (UCT), horses must work to lower their body temperature. They may do this by dilating blood vessels, sweating, and/or increasing their rate of respiration.

The LCT for horses will differ a little for each horse, but for a healthy adult horse at a good weight the LCT is anywhere between -15 and 5 degrees celsius. For horses in Australia I would estimate the average LCT to be around zero degrees. The thicker a horse’s natural coat and the more fat it has under the skin the higher its LCT will be. Very old, young, thin or unwell horses may have a higher LCT than healthy adult horses. Researchers have suggested that UCT are somewhere between 20 and 30 degrees meaning that horses are more comfortable in the cold than in the heat.

In tomorrow’s article I’ll talk about winter and the easy keeper and later in the week I’ll talk about what extras you may need to feed to keep your horse warm.


Winter and the easy-keeper…


If your horse is an easy-keeper, and especially if your horse is an ‘over-conditioned’ easy keeper, winter is the time for you to take advantage of more easily reducing your horse’s weight. It’s important to acknowledge that in the wild, horses naturally lose weight over the winter. This is natural, normal and expected and something for people with easy-keepers to take advantage of.


During spring and summer, when grass is typically more plentiful and higher in energy, horses naturally accumulate fat stores. These fat stores are meant to be used up over winter to sustain the horse over the colder months, when food is more scarce. It is very natural for us to be tempted to rug and provide extra food over the winter to all horses, not just those who need it. While rugging and extra feed is ideal for hard-keepers, horses carrying extra weight who aren’t allowed to naturally lose some of this weight in preparation for spring are at further risk of obesity related illnesses once spring comes. Also keep in mind that your overweight horse has an extra layer of fat that will keep it warmer over winter. Rugging your overweight horse may mean you not only stifle weight loss, but make it too hot as well. If you need to clip your overweight horse then think really carefully about how you are going to rug him/her. I used to own a thoroughbred that was an extremely good doer and in winter he would be clipped. Anything more than a cotton and unlined canvas would mean he was sweating on a sunny day and he never used to lose any weight at all in winter, and he was in full work!


So if your horse is an easy-keeper carrying extra weight you need to change nothing. This is especially important as you probably don’t ride as much in winter so your horse who may be in five days work at the moment, may only be ridden two or three days a week in winter and therefore already at risk of weight gain before you even add extra feed or a rug. What you need to change is absolutely nothing, just continue to provide adequate access to roughage and minerals to complement what’s lacking your pasture and that’s it. No rugging and no extra feed required.


Tune in tomorrow to see how to feed your ‘normal-doer’.



What to feed when ‘Winter is coming’


Now I’ve got your attention with that catchy Game of Thrones reference, let’s talk about what you need to feed as winter approaches. What you need to feed really depends a lot on your horse’s condition and age and whether he or she is an easy, normal or hard-keeper.


First let’s talk about winter…

Winter in Australia is mild. We may not think so as we trudge out in the cold and mud to feed out hay in the morning, but it really is. Horses evolved in North America, not just North America, but Northern North America where it is windy, cold and snows in winter with minus temperatures being the norm. The lower critical temperature for horses with a heavy winter coat (its own coat!) during dry, calm weather is approximately zero degrees celsius. For each 5 degree change below the critical temperature, horses require an additional intake of approximately 1 kilo of hay per day.

A strong wind PLUS zero degree weather will require normal-keeping, unrugged horses that have access to shelter to consume an additional 2 to 4 kilos of hay to meet their increased energy requirements. Strong winds in zero or minus degree temperatures just isn’t the norm for most us in Australia which means that for the majority of horses what needs to change during winter is absolutely nothing at all. I find it odd then that at the time of writing this article it’s around 20+ degrees during the day and well over 10 degrees at night and I am seeing a lot of horses with around-the-clock winter rugs on already.

I can almost guarantee that most of these horses are sweating during the day under these rugs. Sweating and being too hot can have its own very serious consequences, often far more serious than a few hours of a horse being a little chilly at night. Sweating can the skin to become over-hydrated (think of what happens when you stay in the bath too long) meaning its skin is more prone to damage, infection and fungal skin issues. If you have an ill-fitting rug then these issues are increased.

Additionally keep in mind that horses have a need for sunlight (vitamin D). Vitamin D is involved in the regulation of calcium and phosphorus in bone, and deficiency can lead to decreased bone strength. Sufficient sunlight penetrates through a horse’s winter coat, but not through winter rugs. So think twice before you rug (or overrug!) your horse this winter!


Winter and the Easy-Keeper...


So while our Australian winters may seem cold to us, they really just aren't for our horses. If your horse is an easy-keeper, and especially if your horse is an ‘over-conditioned’ easy keeper, winter is the time for you to take advantage of being able to more easily get some weight off. Going back to how horses evolved, it’s important to acknowledge that in the wild, horses naturally lose weight over the winter. They’re supposed to. This is natural, normal and expected and something for people with easy-keepers to take advantage of, not to stifle with extra feed and rugging.


During spring and summer, when grass is typically more plentiful and higher in energy, horses naturally accumulate fat stores. These fat stores are meant to be used up over winter to sustain the horse over the colder months, when food is more scarce. We are very tempted though to rug (or even stable!) and give extra food over the winter to all horses, not just those who need it. While rugging and extra feed is ideal for hard-keepers, horses carrying extra weight who aren’t allowed to naturally lose some of this weight in preparation for spring are at further risk of obesity related illnesses. If you read my article in the previous issue of TH you will understand how devastating being overweight can be to your horse’s health.


So the take-away from this is that come winter, if your horse is a easy-keeper carrying extra weight you need to change nothing. This is especially important as you probably don’t ride as much in winter so your horse who may be in five days work at the moment, may only be ridden two or three days a week in winter and therefore already at risk of weight gain before you even add extra feed to his diet. What you need to change is absolutely nothing, just continue to provide adequate access to roughage and minerals to complement what’s lacking your pasture and that’s it. No rugging and no extra feed required.


Feeding the normal-keeper over winter...


If your horse is a normal keeper, is happy and healthy and at a good weight then you may choose to continue to do exactly as you are or perhaps you may want to add a biscuit of grass or lucerne hay to his diet, a small amount (500 grams) of beet pulp and/or at most a light canvas rug or rainsheet on cold, wet, windy nights. Just adding hay may be enough as heat is produced through the digestion of feed and is useful in helping a horse maintain its body temperature in cold winter weather.


The reason I suggest hay first and foremost is because the greatest amount of heat is released when microbes in the gastrointestinal tract digest high-fibre feeds, such as hay. The higher the fibre in the feed, the more heat is released. Low fibre feeds (such as grain and most processed ‘complete feeds’) produce less heat during digestion. Although oats are a low-fibre grain, if fed whole they will produce more heat during digestion because they have a fibrous outer husk.


The average 500 kilo horse in light work requires approximately 10 kilos of forage per day. Ongoing cold, wet and windy weather can increase the amount of hay required by up to 50%. For each decrease in coldness of 0.5 of a degree C below the lower critical temperature of approximately zero (see Monday’s post for more about critical temperatures) there is an increase in digestible energy requirements of one percent to maintain body temperature. Forage (hay) is the best way to meet a horse's extra energy requirements because forages contain higher fibre than grain.

Feeding good quality grass hay is the simplest way to ensure the horse will meet its energy requirement in the cold. Of course if your horse has lots of grass or free-choice access to a roundbale then it will eat the extra roughage by itself and you don’t need to change anything.

If your horse doesn’t have free-choice access to forage then your horse will need between 1 and 3 extra biscuits of hay per day. Energy intake is the most critical factor in determining how readily a horse develops a tolerance for cold. If a horse does not eat enough energy to offset the heat loss due to the cold, the horse loses weight. The extra cost of feed to rehabilitate a thin horse back to normal will equal or exceed the cost of the feed that should have been fed to maintain the horse’s body weight during the cold.

Horses should also have access to some type of shelter – trees or a man-made shelter as they conserve up to 20% more body heat in a shed compared to an open exposed area. So ensuring your horse has shelter means you save money as you don’t need to provide as much additional hay.

Come back tomorrow at 4PM to read about winter and the hard-keeper.


Winter and the hard-keeper...

If your horse is a hard-keeper then its energy needs are increased during cold weather. Extra hay PLUS extra hard feed may be necessary to help your horse meet these needs. Also, if your horse is old or aging, has a small frame (such as a petite Arab) or has been unwell it is likely to need extra care over winter.

Thin horses need more feed than horses that are at a good weight. Besides a thick winter coat, the layer of fat under the skin is the second line of defense against cold, therefore thin horses require more feed to keep their body warm. This is why it’s a good idea for your thin horse to go into winter more fleshy than you may normally like it to be. (This doesn’t apply to normal-keeping horses that are at a good weight).

It may also be necessary to rug your thin horse over winter. Rugging can be very beneficial if you get the type and thickness of the rug right. It may also be helpful to rug a horse with a naturally thin winter coat, especially one that’s underweight. Please keep in mind that rugs can also be counterintuitive as they prevent piloerection. Piloerection is the way a horse’s hair stands up when it’s cold (like goosebumps for us). It helps keep a horse warm as it increases the depth of the hair and traps air next to its body therefore creating an insulating layer. A rug flattens the horse's hair and prevents piloerection so a rug that’s too light may actually cause your horse to be colder.

Of course your rug should fit properly, first and foremost this means not sitting back on the withers! Ill-fitting rugs cause rub at best and at worst, serious sores.


What to feed your horse over winter


Over the past week I’ve talked about how to determine if your horse need additionla feed or rugging over winter. If you've determined that your horse actually needs extra feed over winter, let’s talk about what some good options for hard feed are. I don’t like feeding grains such as corn/maize, wheat/bran/pollard/millmix and barley to horses as they are more difficult for horses to digest. Keep in mind that the large majority of bagged, pelleted and muesli type feeds contain quite a lot of wheat, barley and/or corn/maize. I urge you all to turn over the bag and read the ingredients so you understand what may be being fed to your horse. Large amounts of these grains can lead to undigested starch reaching the hindgut. Feeding large amounts of processed/grain-based feeds may lead to issues such as:


  • Decreased appetite

  • Inability to maintain weight

  • Ulcers

  • Diarrhoea

  • Colic

  • Hindgut acidosis

Excellent feed choices for your thin/hard-keeper over winter are:


  1. Hay - I know I mentioned it already, but I’m mentioning it again because it’s so important! More grass hay, a biscuit of lucerne hay, Teff hay. All of these hays are wonderful additions to your horse’s diet! Plus this is the feed that keeps your horse warm. Not a warm bran mash, this is a myth!

  2. Beet pulp - Beet pulp is the fibrous material left over after the sugar is extracted from sugar beets. I cannot stress enough how wonderful beet pulp is as an equine feed. The two major beet pulp brands are Micrbeet and Speedibeet. A few reasons I love beet pulp include:

  3. Beet pulp is considered a ‘super fibre’ because its energy content is much higher than typical hays and only slightly less than those found in grains.

  4. Beet pulp is very high in fermentable fibre and is extremely easy for horses to digest. It’s significantly more digestible than most hays. For example, grass hay is 40-60% digestible (depending on its quality) whereas beet pulp is around 80% digestible.

  5. Due to its high energy/calorie content, beet pulp is ideal for horses that have difficulty maintaining weight.

  6. It’s great for performance horses as it’s slow-release energy. It’s a ‘cool energy’ feed meaning the energy from digesting beet pulp is generated slowly and does not cause a rapid rise in blood glucose like cereal grains do. Therefore it’s also an ideal energy source for horses that can get ‘hot’ on grain

  7. It’s fed soaked and therefore promotes hydration as the horse ingests extra water. Additionally the consumption of fibre can also increase water intake.

  8. It’s perfect for horses with metabolic issues such as Cushing’s and EMS and can be safely fed to thin horses with laminitis as it’s low in sugar and starch.

  9. It’s easy for old horses with dental issues to eat as it turns to mush once soaked.

  10. It’s low in protein and can therefore be fed as a perfect complement to lucerne hay, lupins or copra.


  1. Lupins - Considered a legume, lupins are similar to peas or beans. A few reasons I love lupins include:

  2. They’re grown in Australia!

  3. They’ve very affordable.

  4. Lupins are a decent source of protein and also contain fat and fibre.

  5. They’re highly palatable to most horses

  6. Because of their low starch and high fibre content, lupins are digested efficiently in the hindgut of the horse through fermentation. They are suitable for many (but not all) horses with metabolic issues or laminitis.


  1. Copra - Copra is the dried meat or kernel of the coconut, which is the fruit of the coconut palm and is another good feed for weight gain and has some excellent qualities.

  2. Like lupins, copra is affordable, low in sugar and starch and relatively palatable.

  3. Copra is high in fat and calories and has a low risk of rancidity.

  4. It’s low in sugar and starch so is often suitable for horses with metabolic issues that have trouble handling starch and sugar, but it’s important to keep in mind that the high fat content means more energy so it’s only for horses that need to gain weight!

  5. Copra is high in fibre, estimations for actual digestible energy content of copra put it in the same energy range as beet pulp or soy hulls.

  6. Because copra is typically a powder, it is however, quite difficult to get horses to consume large amounts of it.

  7. Copra does have a lot of crude protein, but the protein isn’t of a particularly high quality. Copra does not contain a balanced complement of essential amino acids, as it is relatively poor in lysine, the amino acid essential for growth and for support of the immune system.

  8. Copra tends to be high in phosphorus and low in calcium, and this imbalance can be a problem when fed in large amounts however if you’re feeding copra with lucerne hay this will balance quite well.


  1. Soybean hulls (Maxisoy Low GI pellets) - Soybean hulls are similar to beet pulp in that they need to be soaked prior to feeding and swell to become and mash.

  2. Soybean hulls are also a ‘super fibre’, low in sugar and starch, are relatively palatable, affordable and higher in crude protein than beet pulp so not as good a compliment for horses that are also getting lupins, ‘premium’ grass hay that is likely to be higher in protein or lucerne hay which is relatively high in protein. They are excellent however for horses who are not getting fed anything else that’s high in protein. Many horses will have a preference for either soy hulls or beet pulp when it comes to taste.


So as you can see there are lots of good options for feeding horses over winter that are low in sugar and starch, easy on the wallet and great for maintaining or putting on weight. Please remember that your horse also needs a good mineral supplement (such as Performance Plus, Essentials or Lucerne Lovers) to balance these feeds, salt for hydration, to maintain fluid balance and to keep him drinking over winter when the water is cold and if you’re feeding a predominantly hay-based diet some flaxseeds or chia seeds will ensure he’s getting his omega 3 fatty acid requirements.


And remember, if your horse is overweight going into winter this is your opportunity to help them lose some weight in a natural way. I encourage you to take advantage of this opportunity as it won't come around for another year!


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