NUTRITION LIBRARY

With winter finally upon us loss of weight is often a concern for many owners. Increased energy demands as a result of cold weather and the reduced nutritional value of pastures generally means horses may need more feed (this includes hay, grazing and concentrate feed) during winter than in summer in order to maintain body condition. Generally, we aim to have our horses’ winter ready prior to cold spells arriving however all is not lost and we can still make changes during the winter to try and prevent further condition changes.

How do horses keep warm?

Horses are warm blooded animals and therefore try to keep their core temperature as close to a constant 101 ˚F as possible. To keep their temperature constant the horse will use various methods to thermoregulate and maintain this constant internal temperature no matter the surrounding environment. In the winter this may be through one of the following:

• Vasoconstriction which is when the capillaries under the skin contract to reduce the amount of heat lost.
• Insulation where the horse will use fat reserves to generate energy for warmth.
• Shivering where rapid contraction of muscles produces heat.

How do I know if my horse needs extra calories?

All these processes require energy (calories) in order to work and so it makes sense that the diet will need to be closely looked at.

When looking at the horse’s diet in winter we need to consider what the horses Lower Critical temperature (when the horse would start to feel cold) would be. Studies have shown that for the average healthy horse the lower critical temperature (LCT) would be around 32°F to 40°F.

Research has shown that LCT can vary both within a breed and even between different breeds. For example, it has been indicated that pony breeds have a LCT of 34.5°F to 51.44°F but for Thoroughbreds the range is 28.22 to 46.22˚F and 25.88 to 45.32˚F for Warmbloods (Marlin, 2018). This might come as a surprise but it’s much easier to lose heat when your body size is small (larger relative surface area) and harder when the body size is larger so small animals have the advantage in warmer climates and big horses in colder ones. However, don’t forget that all types of horses can adapt to various ranges overtime but in general this theory applies.

Critical temperature can also vary depending upon the horse’s condition, age and if it is adapted to colder temperatures or not. Mature horses that are unclipped, have a thick coat and are accustomed to cold climates may have a critical temperature of as low as 5˚F. It’s also been seen that LCT may even change during the winter period itself once the horse becomes accustomed to the colder temperatures.

These critical temperatures are important as horses require a total feed increase in order to provide more energy/calories to produce the extra heat required as the temperature falls below these LCT. But how do you determine what your horse’s LCT is?

This may come from experience of your horse, for example does he normally keep condition well in winter despite cold temps in your area, then your horse’s LCT may be on the lower end of the scale. However, if your horse is new to you, or you recently moved to a new area then you may need to use the above average figures as a starting point and monitor over winter.

How many more calories does my horse need?

It’s thought that 15-20% more calories per day will be needed for every 10 ˚F below the LCT.  So, for a 1100lb horse needing 16Mcal per day this would increase by 2.4-3.4Mcal per day. This would equate to around 2-3pounds of good quality hay per day for every 10 ˚F the temperature drops below 32 ˚F.

This amount would obviously keep on changing as the weather does and so it’s not uncommon to start with feeding a few pounds more at the start of winter and by the end you have increased it substantially. The average horse needs 1.5% of body weight in forage dry matter per day, in winter this total could increase to closer to 2-2.5% of body weight per day.

It might be tempting to simply increase the daily concentrate intake because it is the easiest way to add more calories. However, as the general concern in winter is ensuring the horse is provided with added calories to maintain temperatures (stay warm) providing a diet high in fiber is a good way to do that.

Forages such as hay require microbial fermentation in the hindgut to maximize their use in the digestive tract. This isn’t a completely efficient process, and fermentation results in energy being lost as heat. This heat helps your horse to stay warm, so rather than increasing concentrate feed we should always look at providing more roughage first to help horses in the winter months.

Added (over and above their normal amount) roughage will also provide additional energy/calories, with the added benefit of being healthier for the gut. If possible, look for more immature hay (characterized by soft stems and a larger portion of leaf matter) rather than overly mature (very stalky with little leaf) as this provides better nutritional value. This is important during the winter as winter forage often has a reduced quality which means more hay would need to be provided than in summer to ensure the same calorie value, so factor that in when purchasing.

Immature, leafy, hay, also has a water-holding capacity that more mature hay does not have. Impaction colic can be more common in winter when horses often drink less because of cold water that is not palatable or even water that is frozen and so this can help combat this. Also, if your horse is used to a predominately fresh forage diet (i.e. only grass) then normally he will be receiving more water from his forage. Changing to a predominantly conserved forage diet (hay) drastically alters this hydration status and so introduce forage slowly to reduce the risk of impaction colics. Salt is not only for the summer months and adding salt to the diet can also encourage more drinking during this time of year. One tablespoon per 500 lbs of body weight is a good rule of thumb for salt consumption year round.

For some (older, younger, poor doers) they may need more energy than can be provided from additional hay alone and so changes to concentrates may also need to be considered alongside additional forage. Horses that experience an increase/decrease in workload in winter may also need to have their energy levels adjusted also.

How do I add extra calories?

Adding extra energy/calories can be done in several ways:

1. Increasing the current feed. This is perfectly fine for those not receiving much feed and a simple increase may be all that’s needed. Note that if feeding a balancer, these feeds are not designed to be fed in large quantities and most should not be fed at more than 2 pounds per day. Therefore, if currently feeding a balancer you will need to look elsewhere for additional concentrate calories.
2. For those that are being fed higher amounts of performance or senior type feed currently, changing the feed to one which contains a higher energy/calorie level per pound is more advisable. This will allow more energy to be provided while keeping within recommended feeding amounts, thus avoiding the trap of simply adding more and more pounds of hard feed to the horse’s diet without results. This is especially important if you only feed concentrate feed once a day as concentrate meal sizes should really stay below 5 lbs per meal for average sized horses or there is the risk of digestive tract disruption. If the concern is that the horse may become “hot” temperament wise, then look towards a feed that provides a higher energy level per pound but that uses high fat and fiber sources. This will help provide more but in a calming fashion.
3. If a feed change is not possible or necessary (perhaps the horse does well on his current feed) but more calories are needed in winter then this can be done by providing additional oil. Feeding for coat condition would require 50-100ml but feeding for additional energy/calories would need a level of 150ml-300ml per day to assist. Added oil also helps to provide “calm” calories and will be less likely to heat a hot horse.

For horses looking at a reduction in workload during winter, changes to the diet may also need to be considered and may be as simple as a slight reduction in concentrate feed. If the horse is a “good doer” and going from hard to no work, it may be time to decrease concentrates or remove completely and replace with a balancer type product to ensure that the daily essentials are still provided without the calories. For pooer doers who will be working less, reducing concentrates while increasing forage through the use of either more hay or perhaps a forage extender such as beet pulp is an ideal way to keep the calories while reducing hard feed.

For some, winter can be a great opportunity for weight loss as keeping warm uses extra energy and thus energy expenditure will be greater than what is consumed leading to a reduction in weight. So, keep that in mind for overweight horses when looking at diet changes.

Another great tool to have on hand for winter months is a forage extender. These are designed to replace a portion/or be used in addition to the horse’s daily forage in times when hay or grazing may be of poorer quality or not as available. Keeping some on hand is useful in case hay stocks run lower than expected due to storms or unusual drops in temperatures where you feed more than you planned to. Forage extenders are available in many forms such as super fibers (soy hulls and beet pulp) or conserved grass options such as hay pellets, chaffs and cubes.

Should I blanket my horse?

A common question from many owners’ is should I blanket my horse? The answer to this is possibly not. Here are some factors which may affect this decision.

WEATHER- the coldest condition for any horse would be low air temperature combined with strong winds and rain as the colder the air temp the bigger the difference between the horses’ skin/coat temp and the air, thus the faster heat moves from hot to cold. Add in wind, and heat is lost even quicker especially if the horse is wet. Therefore, if this is a concern in your area blanketing may be an advantage.

AGE- generally older and younger horses will not cope with colder temperatures as well as the average adult horse. Generally younger horses are smaller and have less body fat and older horses may be less efficient at controlling their body temperature, may have health problems and/or have less body fat. However much younger horses may also not be used to being blanketed and so keep this in mind.

COAT- clearly coat will play a big factor in the horse’s ability to retain heat, and whether a horse has a thick coat, hasn’t grown one yet or has been clipped should be considered before deciding on a blanket. Those that are clipped are going to need more help than those that have a thick coat.

SHELTER- obviously shelter plays an important role in horses needing additional help with keeping warm. If your horse has adequate shelter this may negate the need for heavy blankets.

Additional points to consider when blanketing:

• Don’t blanket based on how cold you feel, horses have a very different critical temperature to us.
• For healthy unclipped horses blanketing shouldn’t be considered until temperatures drop below 32°F.
• Don’t use your horses face, legs and ears to feel how warm they are. These areas are not accurate as they can be colder due to the horse purposely reducing the extremities by controlling how much blood flows through them to conserve heat. Always feel inside the rug to gauge how well it is working.
• If the horse is sweating, he is likely to be over rugged. Damp skin can cause the horse to feel colder, as well as being more prone to skin damage and infection.
• Consider clipping working horses as it will allow them to dry faster. There are different clips that can be used depending on your horse’s workload and needs.
• Ensure blankets are correctly fitting so rubbing doesn’t occur
• For “Good doers” or those that are overweight, winter can be a good time to reduce weight. Over blanketing means that less energy is lost, and instead could be deposited as fat and for those that are overweight already this could cause an unhealthy increase in weight. So, for these types of horses blanketing isn’t necessary. Also, horses with a high body condition score will be better “insulated” and thus will generally need less blanketing.
• Conversely for “poor doers” using a blanket may reduce the need to feed additional calories for weight maintenance.
• Horses can adapt to the cold and thus you may find your needs to change from a heavier to lighter rug after a few weeks.
• “Rugs and stabling prevent sunlight reaching the skin which is necessary for generation of Vitamin D. Vitamin D is involved in the regulation of calcium and phosphorus in bone and deficiency can lead to decreased bone strength and so ensure the horse is at least allowed exposure without a rug for at least 1 hour per day” (Marlin, 2018)

BLANKETING GUIDELINES

If you have concerns or questions about how to ensure your horse goes through the winter maintaining weight reach out for a consultation. We would love to help.

Research information taken from Dr David Marlin 2018, https://www.facebook.com/233421046862124/posts/917577288446493