By: Katie Raver, MS, PAS
Words matter. Whether it be choosing to use our words wisely, powerfully, or kindly, what we say and how we say it matters. We often consider this statement from the human perspective, and our words' impact on others; however, using the correct terminology is essential from a technical and scientific perspective as well.
There are times when we may find ourselves using words interchangeably that aren’t exactly synonymous. For example, when evaluating a feed analysis, I may infer that low fiber digestibility was impacted by maturity if starch and DM were also higher than average. If I swap out the word 'imply' for 'infer' in this statement, the meaning of the above statement and how it may be received completely changes, yet we often use 'imply' and 'infer' interchangeably.
Words that I see often used interchangeably from an analytic standpoint are 'disappearance' versus 'digestion'. When assessing disappearance values listed on an analytical report, whether it be starch or fiber or any other nutrient, it may be tempting to swap out that D at the end of NDFD for NDF digestion 30 or digestible NDF at 30 hours. However, when we think about how this value is determined analytically, it is simply the amount of nutrient that has disappeared at a certain time point.
This doesn’t really seem like a big deal, though, right? They have similar meanings after all. However, digestion is an incredibly dynamic process that is influenced by the rate at which the feed digests, and how quickly it moves through the system.
When I first started running, the idea of chip timing was a foreign concept to me, especially since my only previous running experience was high school track. But let’s consider this situation: two runners cross the finish line at the same time. Is it fair to say that they both ran at the same pace? Not necessarily because they may not have started at the exact same point. If one runner started at the back and the other at the front, the runner at the back was actually running a faster pace.
I’ll pick on NDFD 30 for a second here: if we were to simply assume this was the digested value, we would also have to assume that feed is staying in the rumen for exactly 30 hours. If the feed passes before that time, the actual amount that the rumen microbe utilizes for VFA production is lower than expected, thus the energy available to the cow is lower. We don’t have a static finish line in digestion.
Don’t get me wrong, these disappearance values are critical to the ability to determine the rate of digestion. This can then be used alongside potentially digestible fractions of the nutrient and other dietary and physiological factors, to calculate the rate of passage and model how much of this the cow is likely able to digest. Using these words interchangeably can have a huge impact on how much energy we assume we are providing to the cow, and can lead to large differences between expected production and actual production. Thankfully, we have advanced models that can uptake these values and help make sense of this dynamic process. However, when evaluating and comparing feedstuffs, simply relying on single disappearance values can be misleading, and utilizing these points alongside other disappearance values and rates of digestion reported will provide much more insight as to how the cow will be able to utilize the feed.
Words matter. Not only to the people around us, friends, colleagues, and family. But they also matter to cows.
