The forage test results are in! Let’s see how the hay that I’ve stacked in the barn will help or hinder Wilma’s Weight Loss Journey. Since hay is going to be her primary forage in the coming winter months, it’s going to play the largest role in her diet plan. It’s only by understanding it’s caloric density, can I calculate and confirm how much to feed for steady, safe weight loss.
Like you, most of my hay buying decisions are based on convenience. One of my best friends works hard to make aesthetically pleasing, good quality hay just 45 minutes away. The bales are light and tight making them easy to load and unload. She communicates with me extensively on timing and cost, and we nerd out together about fertilizer, soil tests, and the forage industry. I don’t know the calorie, fiber or protein values until it’s already stacked, because we have to pull it straight off of the field and get it into the barn before it rains. So, when the test results arrived in my inbox this week, I was excited to open it.
Unfortunately, the results are not ideal for Wilma’s Weight Loss Journey. The caloric density of the hay is higher than I had hoped at 1.05 megacalories per pound. The positive is that most of you are going to be able to relate. Whenever I get calls about horses failing to lose weight, it's due to high calorie dense forage 100% of the time. We’re going to learn what to do when you find out that the hay you stacked in the barn is hindering your horse’s health.
The very first number that I search for is relative feed value. If you are not familiar with that number, you need to read “Relative Feed Value: The #1 Most User Friendly Number for Feeding Horses” before you continue. The RFV for my 2024 1st cutting grass hay mix is 103- that’s on the “weight gain” side of the RFV spectrum- and coupled with a caloric density of 1.05 megacalories per pound. See a comparison of calculations below. There are two reasons for the higher RFV; 1) lower fiber values than I’d like (32.6% ADF) and 2) high non-structural carbohydrate values than I’d like (18% NSC on DM basis). Now, these number are fine for my heavily ridden OTTB mare and my growing 2 year old, but it’s counterproductive for Wilma. I’d have to restrict her hay intake to levels that I’m not comfortable with, so I have to go searching for a more a better fit grass hay.
2024 First Cutting Grass Hay Stacked- Already Purchased
RFV= 103
Digestible Energy= 1.05 Mcal/lb
Wilma’s Calorie Requirement from Hay= 18.5 Mcal
Pounds of Hay to Meet Calorie Requirement= 17.6 lbs hay
Intake as a Percentage of Ideal Body Weight = 1.38%
2024 MATURE First Cutting Grass Hay- Not Purchased Yet
RFV= 85
Digestible Energy= 0.93 Mcal/lb
Wilma’s Calorie Requirement from Hay= 18.5 Mcal
Pounds of Hay to Meet Calorie Requirement= 19.9 lbs hay
Intake as a Percentage of Ideal Body Weight = 1.56%
Wilma’s caloric requirement is about 20 Megacalories per day to facilitate weight loss. If I subtract 1.5 Mcal for her ration balancer, then I’m left with 18.5 Mcal from hay. As you can see from the calculations above, I could feed her 17.6 lbs of the 103 RFV hay or I could feed her 19.9 lbs of an 85 RFV hay. The intake as a percentage of ideal body weight (1,273 lbs *see Part 1) would be either 1.38% OR 1.56%. That might not seem like a big difference, but that is the difference between safe, steady weight loss that prevents ulcers and a diet with problems.
Luckily, I might already have a source of low calorie hay that is perfect for Wilma and I have the space to put it! I’m going to go test it this week and grab a few bales to try, so you’ll be getting an update shortly! Plus, my grazing muzzle should arrive this week. Stay tuned for more details about Wilma’s Weight Loss Journey.
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