Need for balance
Mostly a ration at the feed fence is balanced between 15% and 17% crude protein (CP). On top of this, most farmers feed concentrates in the milking robot with 18% to 20% CP. When housing the cows this is not normally an issue. However, when cows go out for grazing, this changes. The typical young fresh grass growing in the pasture is rich in proteins and low in fiber. This changes during the season to lower proteins and higher fiber, and again in the late season to higher proteins and low fiber. This adding up could mean a (too) high intake of CP resulting in a (too) high urea level, even as high as >30. This is not negative per se, but there should be a balance between protein, energy and fiber. Supplying too much protein does not only have a negative effect on the cows’ efficiency; it is also unnecessary spending of money on (expensive) proteins.
The difficult part is to monitor what cows eat in the pasture, especially because this can fluctuate from day to day. Factors such as rain, sunshine, tastiness, system/intensity of grazing and type of grass have an influence. Based on this you need to correct the ration. There are several tools that give an insight into intake, but the human eye, cow signals and common sense are equally important.
Just looking at the manure a couple times a day already gives a good indication. Do you see a lot less fiber? Is it thick or smooth? Maybe even use a sieve to judge the indigestible part of the ration. When judging the manure, be aware that you are judging the digested ration of the last 24 hours. The manure color says something about protein and energy balance, when taking the milk urea into account. A low milk urea in combination with a light manure color indicates a protein shortage. A high milk urea and light manure indicates a low efficiency of the cow, also see figure 1*. Secondly, rumination is an indicator. Do the cows ruminate enough? Low rumination could indicate too little fiber/structure; too much rumination could indicate too much fiber/structure.
Find the balance
Finding the correct balance means correcting when needed. Changing the type of concentrates before the grazing season starts from a protein-rich to a more starchy type of concentrate already builds the basis. This prevents too much protein in the basic ration and leads to cost savings. Secondly, it enables farmers to balance the protein/starch level within the ration at the feed fence. When needed, the ration protein/energy/fiber level can be corrected at the feed fence.
In addition, preparation before the season starts is essential. What has been the experience in the past? What is available on the farm? If fiber needs to be purchased when rumination drops it is hard to correct instantly. Discuss with the farmer, local feed advisor and Farm Management Advisor to discover the best approach for the grazing season.
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