Energy Content of Horse Hay

If you follow the educational content that Balanced Bay publishes, you have likely heard the importance of hay testing stressed many times. Hay is often the majority of what a horse consumes, so it only makes sense to know what the nutritional value is!

It is common that when horse owners receive their hay analysis results, they tend to focus on either the crude protein percentage or the sugar content. Of course, these values are important, but the digestible energy (DE) content (the caloric content) is frequently overlooked.

At this time of the year, many new clients inquire about working together as their horse needs to either gain or lose weight before winter. If you have an easy keeper that is overweight, it can be daunting as winter approaches and you are anticipating their workload decreasing. On the other hand, if your horse is struggling to maintain weight, ensuring this is addressed before the temperatures drop is critical to their well-being. When weight changes need to happen, the digestible energy content of the diet is a primary focus.

For the 2023 hay harvest in Ontario, Balanced Bay took hundreds of samples of locally harvested hay. When reviewing the energy content of these samples, the lowest value was 1.5 Mcal/kg, average was 2 Mcal/kg and the highest was 2.5 Mcal/kg. It can be challenging to grasp what these numbers mean, so let’s look at a few examples.

My mare Piper is a very easy keeper, so I sympathize with horse owners who are struggling to have their horse achieve and optimal weight as I truly understand how challenging that can be. For simplicity, let’s say she weighs 500 kg. Currently, she is not in any substantial workload. This puts her daily calorie requirement at 15.2 Mcal/day.

Piper is currently at a healthy body condition, so she is fed 2% of her body weight in dry matter which equates to about 10 kg of hay daily. If she is fed the average hay that has a DE content of 2 Mcal/kg her caloric intake is going to be 20 Mcal/day which is too high!! This would result in weight gain. Therefore, if this is the hay that I have and I am unable to change it, I would need to restrict her intake.

The actual energy content of the hay I have fed my mare Piper for the past year was 1.7 Mcal/kg. So, her intake needed to be restricted to 1.75% of her body weight for her to maintain an adequate body condition. This equates to 8.75 kg of hay per day which provides her with 14.8 Mcal/day.

In addition to her hay, she is provided with a pelleted vitamin/mineral product, loose salt, and some timothy hay cubes to mix it with. That supplemental feed provides the additional 0.4 Mcal that she requires to maintain her weight.

Now, imagine you are the owner of an overweight horse, and you are trying to elicit weight loss with removing energy dense concentrates, implementing slow feeding, and reducing forage intake, but the hay is 2.5 Mcal/kg in energy content. It will be next to impossible to achieve safe weight loss. If we use Piper as an example in this case, even if she is restricted to 1.5% of her body weight in dry matter intake, that hay is still providing 18.8 Mcal/day which is too much and will result in weight gain. Understanding the energy content of they hay for your easy keeper provides critical information that is required to curate an optimal management plan.

Paying close attention to energy content is also important for horses that need significant supplemental calories or need to gain weight. Let’s say that you have a 500 kg broodmare that is in her second month of lactation. Her required daily calorie intake is 31.7 Mcal/day. If she is fed a hay that is only providing her 1.5 Mcal/kg, even consuming 3 % of her BW in hay daily is only 22.5 Mcal. Therefore, she would need substantial supplemental energy from a maternity feed, and likely additional fat too. This can be challenging to manage in small meals, maintain optimal gut health, and it becomes costly too.

If we switch the hay for the highest energy option and the broodmare consumes the same 3% of her BW in hay daily, she will be provided with 37.5 Mcal/day! So, instead of trying to supplement substantial calorie content with a maternity feed, oils etc. you could simply be supplementing quality protein, vitamins and minerals.

When you are reviewing your hay analysis, take an extra few minutes to find the DE content and understand what that means for your horse. Ensuring our horses are maintaining a healthy body condition is important for their welfare, hence being able to use this information to determine whether hay needs to be restricted, or supplemental calories must be provided in the ration is better than not knowing. Often, when hay is not tested you are making feed changes in response to negative body weight fluctuations as you are not equipped with the information to make educated feeding decisions.

My lovely mare Piper will be starting to consume her 2024 hay soon, it has already been tested and I know that it is lower in digestible energy than what she is currently eating. This means that I can increase her forage allowance daily! On the other hand, I know that the other horses in her herd that have done well on the hay with 1.7 Mcal/kg may require a small increase in their supplemental calories.

Overall, hay is the majority of what a horse eats, therefore, for optimal nutritional management, it is critical to know what the nutritional value is. If your horse needs a change in their body weight, take a close look at the caloric content of the hay. One aspect of hay testing that I really enjoy, is after a few years of consistent testing and closely monitoring a horse’s nutrition, you learn what they do best on, and you can keep their overall consumption the same. For example, if the 2024 hay is lower in energy than what they have had the past few years, you can simply add supplemental calories in their daily ration to achieve the same daily digestible energy intake. This is a key aspect of reducing weight fluctuations that many horse owners struggle with.

If you have any questions about hay testing, or optimizing your horse’s nutrition plan reach out at balancedbaynutrition@gmail.com

By: Madeline Boast, MSc. Equine Nutrition