In this article, we discuss rate of change, rough rules of thumb, and easier ways to think about converting your horse from an old feed program to a new!
Rate of Change
The rate at which you transition a horse to a new feed program depends on 3 things; the horses history, the direction and degree of change, and your personal tolerance for risk. Above all, no matter how you go about it, the most important idea is to watch for changes in your horse's manure consistency, behavior, and water consumption!
1. The Horse’s History
Your horse’s history, and therefore his/her risk for disorder, is the most important factor when determining how to transition from old to new. The disorders of greatest concern when changing a feed program are colic, laminitis, choke and diarrhea. The first step is to place your horse in one of three categories; high risk, moderate risk, or low risk for any of these problems. Has your horse coliced before? If the answer is yes, then you will transition much slower than a horse that has not. If your horse has coliced multiple times, has had colic surgery, and/or has abnormal digestive tract physiology then he/she is at HIGH risk. If your horse coliced once at a horse show and it resolved quickly with Banamine, then your horse’s risk may be moderate. If your horse has never shown a single symptom of colic, then your risk is low. This is your first consideration.
2. Direction and Degree of Change
The direction of change is defined by the fiber values of the old diet versus the new- on a nutritional analysis of any feed stuff this would best be predicted with ADF (%) and NDF (%). It’s beyond the scope of this article to define those for you, but suffice it to say these fiber values predict how the feed or forage will behave in your horse. For example, a low fiber performance feed with lots of oats and corn will behave differently in your horse compared to a high fiber performance feed with lots of fat and no grains. Similarly, a low fiber orchardgrass hay (ADF <35%) will create a different response in your horse than a high fiber bluegrass hay (ADF>42%). These fiber values correlate with the non-structural carbohydrates like sugar % and starch %, but are better predictors of equine health.
There are two directions of change; increasing fiber and decreasing fiber. Both directions of change have the potential to shift the ecology of your horse’s microbiome disrupting the normal flow of fiber and water in the gut. This is why we watch for changes in manure consistency, water consumption and behavior. So, if the degree or amount of change is large (i.e. you go from a very low to very high fiber value) you’ll want to go slower. However, if the change in hay quality is not large, than you can go faster. Or if you are transitioning between similar feed types (first six ingredients are similar and therefore fiber values are similar) than your rate is faster.
3. Your Management and Risk Tolerance
One of the greatest voids in any discussion of equine nutrition is the admittance of our own unique management preferences. How you prioritize your time with horses versus family, facility limitations and rules, and your risk tolerance is shockingly different than your trainer’s, friend’s, or mine! I have clients with very low tolerance for risk, so they transition slower. I also have clients with high risk tolerance that transition faster. Your horse's living situation or your time and money budget might increase your tolerance for risk. These are the realities that we all face, but rarely discuss in equine nutrition and management.
Two General Rules of Thumb
The general rule of thumb for transitioning, regardless of your horse’s risk, is a) no more than 1 lb per day change for concentrate products and b) no more than 4 lb per day change for roughage products (roughly a large 2 string flake or small 3 string flake). This rule of thumb is great in theory, but not always possible in practice, so adjust depending on how you responded to factors 1 through 3 above.
Here are some examples for you.
Let's say that you’re transitioning from 4 oz of one supplement to 4 oz of another similar purpose supplement. In this case, you are safe to transition within a day or two, because the inclusion rate is less than a pound per day. This is also the case if you are transitioning from 1 lb per day of ration balancer to 1 lb per day of another brand’s ration balancer. Quick transitions between vitamin-mineral products and ration balancers is possible because of their low inclusion rates and the fact that the first few ingredients are more often than not, similar.
Where the "1lb per day" guideline becomes more applicable is if you are transitioning from one feed category to another. Here’s an example; in working with a qualified nutritionist, you decide that the supplements that you were using were not meeting your horse’s caloric needs and you decided to switch to a performance feed. Well, using this rule, we could phase out the <1 lb/day supplements quickly, but phase in the performance feed no faster than 1 lb per day.
Another scenario where this 1 lb per day rule applies is if you are feeding the recommended level of a performance or complete feed- products with higher feeding rates. So, let’s say you are currently feeding 8 lbs of a high carbohydrate, grain-rich performance feed and you want to transition to 8 lbs of a high fat/high fiber/no grain performance feed. Then, you would theoretically take 8 days to transition to the new formula. If that seems like too much hassle, refer to the next section, "transitioning in blocks".
Finally, forage changes should be considered just as critically as feed and supplement changes. I suggest making hay changes no faster than 1 flake per day (roughly 3-5 lbs) and pasture changes no faster than 1 hour per day. Consider using the "transitioning in blocks" method outlined below.
The second rule of thumb is one additional supplement per week. In our hyper supplemented horse world, I think it’s really important to know what each supplement is doing, so give it at least a week before you go and add another one- all the while watching for changes in manure, behavior and/or water consumption. In a perfect world, you’d give each supplement a month before adding another.
Transitioning in Blocks
Because the mathematics of transitioning can be complex, I like to simplify it into quarter transitions. Imagine a four step stair case where the first step is 25% new to 75% old, the second step is 50% new and 50% old, the third step is 75% new to 25% old, and the final step is 100% new. Start by transitioning to step #1 and maintaining that diet for 2-3 days. Then, if all is well, go to step #2. The important thing is to watch for changes in manure consistency, behavior, and water consumption. The idea behind the step by step approach is to keep us from going mad mixing tiny fractions of feeds and supplements.
In summary, rules of thumb are helpful, but not always practical or necessary depending on your horse's history and living situation. Remember, that your own personal risk tolerance is part of the equation and could be very different than mine or your trainer's. Use common sense and ALWAYS watch for changes in your horse.