DRY MATTER SHOULD MATTER
To success in ruminant farming, there is one golden rule: maximise the feed intake of your animals! Dairy cows can digest cellulose to produce milk. Increase the daily intake of roughage is the easiest and cheapest way to increase milk production because local roughages still remain the cheapest feed for dairy cows. To do so, evaluation of roughage moisture is essential to manage feed intake but to produce quality forages as well.
It is still common to meet dairy farmers who think in gross matter intake (or as fed) instead of dry matter intake. In ruminant nutrition, we usually talk about dry matter intake because roughage moisture could be very different from a forage to another one, from a rainy day to a sunny one, from young stage to an old stage harvest.... You can see on table below difference in term of nutrient intake for the same quantity of king grass as fed (50kg) with different dry matter percentage (%DM). For example, when %DM decrease from 25% to 19%, it is equivalent to an underfeeding of 7200kcal/day which is roughly like a 3L milk/day loss. If the %DM of roughage is monitored, you can adapt the diet to avoid underfeeding of unbalance diet.
The roughage moisture evaluation is the first step you can take to control daily DM intake. The easiest wat to assess %DM in roughage is with a microwave. The %DM is the ratio between wet weight (initial) and dry weight (final). You can find here a detailed method to evaluate %DM with microwave with precautions to do so. Another popular method is the Koster test method that required more time but less manipulation and precautions.
Why and when measure %DM? You can consider 4 uses for DM evaluation:
Corn fresh forage before harvest
One or two weeks before the expected harvest date (i.e. 45 days after silking) of corn silage, it is important to measure %DM. Since you know it, you can calculate the right harvest day to get a 32 %DM in corn silage, which is the perfect DM. This level of DM allows a good yield, the best preservation (not too dry for a good packing) without loss of nutrients (wet corn silage can leak in the silo). Sample one whole plant (with cob), grind properly and evaluate moisture. Corn will gain 1% of dry matter every sunny day and 0.5% every rainy day. Do not forget to look at the grain as well (must be 1/3 milky, 1/3 doughy, 1/3 glassy for a good quality silage).
Source : Maize Grower Association
Fresh or preserved feed
In case of feeding fresh king grass, monbasa, fresh corn with
or without cob, evaluate the %DM is a tool to adjust TMR moisture and adapt the as fed quantity in TMR formula. It also helps to balance TMR with right dose of concentrate. For preserved forage as corn or grass silage, evaluation of %DM must be done twice a week. Actually dry matter could vary by 5 to 10% according to weather and storage condition. Similarly, you can test the wet by product once a week (beer by-product, cassava pomace…). We actually thinking and balance TMR in kg of dry matter but we actually prepare with fresh forage.
Feed intake is maximal at 40% DM / kg TMR. Evaluate it once
a week is a way to stay near this objective. Under 30%DM the TMR is compact, less palatable and there is risk of uncontrolled fermentation. Add more chopped straw or dry forage is a way to increase it. Harvest forage at the right %DM remain the first lever to avoid wet TMR. When %DM is too high, animals can sort pellets from fibre and there is risk of metabolic diseases. We can use more molasses to stick fine particles (1-1.5L/cow) or add water in the TMR (4-5L / cow if the TMR %DM is over 50%). There is also a big risk of heating quickly after the distribution. In both case, using a liquid preservative like buffered propionic acid is highly recommended because of the tropical weather and the fresh feeding practice in Asia. It helps to reduce heating and preserve palatability. Even in case of 2 or 3 distributions to dairy cow or beef per day, we can see warm TMR on farm. For heifers or dry cows, usually fed 1 time every 1-2 days or fed with dairy cows refusals, that becomes essential. Remember that moisture is the most variable aspect of roughage. Set up a quality control plan is the best way to keep the highest feed intake with the best nutrient quality. In ruminant nutrition, concentrated feed is use to correct the roughage nutritional value. Roughage quality must drive concentrate using and not the opposite.