The new NRC will drop dry matter prediction for high producing cows by about 2kg per cow per day. And, however, low producing cows They will increase the dry matter intake by about 1 kg per cow per day. The number of days, before we see a depression in dry matter intake after calving was shortened. It used to be around 90 days before we received maximum or Optimum dry matter intake that has now been reduced down to approximately 30 days. Certainly, there’s been a refinement in the dry matter requirements to change body condition score, and they also addressed fill factors. Factors including such things as forage NDF has an impact, the uNDF digestibility and fragility. Fragility is basically particle size length especially when it’s in the digestive tract, which can impact of a rate of passage in animals and impacting obviously fill factors.
Another term they brought in was the ratio of acid detergent fiber or ADF, to the ratio of NDF, or neutral detergent fiber. This is, it can be used, or you can use lignin, you have to check of which one you want to use, to determine a dry matter intake. They recommend the ratio is a bit more sensitive than the lignin test itself, but that’s a user option in the model, and of course, many of this new information will be in a new model that would predict such things as dry matter intake, based on all these variables. Interesting Also that the level of protein and fat were not used in predicting dry matter intake. So, they are neutral in terms of dry matter intake.
So, what does that mean to us as users? First of all, we know that it’s going to be pretty typical what we’re seeing in our rations when we balance rations using the model NRC 2001. Generally, we were always about 1.5 or 2 kg lower in dry matter intake and could achieve nutrient balance for high-producing cows. The bottom line is that will save us Some money. Dry matter is not free. So, they’ll be a cost savings that occurs there. Another plus is shortening the days after calving gives us a better chance for a high-producing cows to optimize higher dry matter intake and not be penalized by of the computer program. Certainly, if we can, adjust fill factors by using the various terms We just discussed that’s going to be a factor, is well here in the feeding program. So, stay tuned as we discussed more of these different options here from the new NRC 2021.
