Forage Sampling for Wildlife
A post on social media brought up forage sampling and this is a topic that I covered at a recent deer school in Michigan. At times, companies or individuals make claims as to how a forage tests. I was asked about 25% protein winter rye at the deer school. My answer was the same as to someone asking me this year about 37% protein clover. "For a couple days in their growth cycle." I replied.
When I did my first forage trial for a project with a research farm and the state, I was forage sampling every Thursday what paddock the animals were about to enter. Each area animals would graze it for 1 day and then would be off of it for 28-35 days depending on weather, season, etc. It taught me so much back in the early 90's and that information carried forward to the last decade where I have been doing extensive research for myself as well as other companies in the area of wildlife forages. Here is my protocol and I’ll explain why.
Many forages mature in 60 days post plant. Their growth habits vary as annuals take off way faster than perennials. The nutrient quality is much different day 20 vs day 35 vs day 50. Once forages move from the vegetative phase to the reproductive phase, their nutrient composition really plunges in the case of the fastest growing forages. The slower growing forages grow slow for a reason. The as a result also lose quality at a slower rate.
To create a benchmark, I decided on day 50 for all forages I ever sample post plant. If it's multiple samples per season, then i use a day 25 post clip as that point would be relatively similar to day 50 post plant.
For annuals perhaps one can get enough feel for a forage in 1 year but for perennials you need 2 and preferably 3 years before forming an opinion. Why is this? The perennials that will last the longest might also start the slowest. One ladino clover might be the lowest yielding in a trial year 1 but year 2 it might be the highest yielding forage in your trials. That forage more likely will persist more years than the other clovers. That is mother nature.
Another issue that can skew samples is weather. Some clovers handle wet better than others. Some handle dry better than others. The forages that handle wet better, tend to test better during wet conditions. They also tend to be higher in brix (sugars). Those forages also tend to be more attractive to deer.
One last trait I’ll cover is nutrient composition. So many people focus on the protein aspect of a forage but that is not a ruminants biggest limiting factor, that factor is energy. Protein also comes in various “types”. Some proteins break down much faster than others. This term is called protein solubility. There are also factors like “Lignin.” Lignin is undigestible fibers. Fiber is what helps any forage stand. Fiber also can affect the energy that a deer gets out of that forage. The higher the lignin the less digestible. Energy is affected by lignin, fat, sugars, other fiber sources and even the protein fraction. So, whenever someone hears someone talking about protein in a food plot forages there are a myriad of factors that affect how relevant that information is and even if it’s valid. If I took forage samples every day of the month on a test plot, it would be a wonderful teaching tool. Maybe someday I will have the time and means to do just that. Instead, my library is still as extensive as anyone’s but only tells a small part of the reality of plant life.