Corn silage is the basic feed in the diet of dairy cows. It constitutes about 60-70 percent of the dry matter of all bulk feeds in the animal's diet. The Polish Federation of Cattle Breeders and Dairy Producers reminds us what to pay attention to when preparing corn silage to achieve the most beneficial effect.
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Mowing corn for silage. What are the prices?
The quality and nutritional value of silage translate into the profitability of milk production.
Harvesting corn intended for silage is always a compromise, because we have to decide which features of the future feed are more important to us, i.e. high starch content or digestibility of nutrients. The first is determined by the maturity of the kernels, the second by the dry matter content (the optimal range is 33-35 percent). Unfortunately, very often a conscious decision on the date of mowing is disrupted by the weather or equipment. Therefore, in some cases, after opening the silo, the feed is heated, has mold and smells bad. As a result of unfavorable fermentation, there are DM losses, which, in short, result from the intensive decomposition of protein and carbohydrates, which contributes to the heating of the feed, limits its intake and increases the risk of various health problems for the herd.
– Conclusions on the quality and nutritional value of ensiled feed and its suitability for feeding translate directly into the profitability of milk production on the farm – emphasizes Błażej Zielonka, nutritional advisor at PFHBiPM.
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Beware of tamping and picking
Fortunately for farmers, corn is characterized by a low sugar minimum, i.e. the level of sugars needed to quickly lower the pH in the ensiling process, and at the same time a high content of sugars that are easily soluble in water. In practice, this means that the plant ensiles well, which is influenced by the desired profile of organic acids with a predominance of lactic acid, as PFHBiPM explains. Unfortunately, an excess of the latter (in the case of too high dry matter content) does not favor the aerobic stability of the material after air enters the silo. Acetic acid has better fungicidal properties, but an excess is not recommended here either, because it negatively affects the palatability of the silage (in material that is too moist). Ultimately, the right time of harvesting the material, its quick transport, compaction, as well as optimal fragmentation and tight covering, as PFHBiPM emphasizes, decide which types of bacteria will be active in the fermentation process. All these procedures determine the achievement of anaerobic conditions and the optimal course of fermentation.
– In my practice, I constantly encounter improper selection of feed from the silo, which very often causes farmers to waste all the effort put into the technology of harvesting and ensiling the material. Breeders are lost in haste and routine – says Zielonka.
Another problem that the PFHBiPM advisor points out is improper compaction of the material. As he points out, it is mainly the result of too high a dry matter content of the material intended for silage, but also insufficient equipment.
– Many farmers have not been convinced by silage additives. In the meantime, they limit losses and create opportunities to obtain much better silage, because they forgive some of the farmer's mistakes – adds Zielonka.
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Inoculants support the production of good and stable silage
When is the first feed analysis?
It is assumed that properly ensiled material achieves aerobic stability after about 4 weeks. This is the right time for the first analysis of the feed, which should be repeated at least once a quarter. Lack of knowledge about the nutritional value of feed definitely makes it difficult to meet all the nutritional needs of cows. On the other hand, it can generate losses because we supply them in excess of the norm. Either way, the risk of problems related to metabolic diseases or reproduction increases. How to avoid them? The first step is to take a representative sample of feed for chemical analysis.
– We are interested in the cross-section of the entire silo. That is why I use an advanced sampler with a sharpened tip, which is screwed in to a depth of 1 m, and in the case of using an extension – even 2 m into the silo – emphasizes the PFHBiPM advisor.
How to collect silage for testing?
Zielonka points out that according to the methodology, 6 to 9 samples should be taken, which are combined and only then one aggregate sample weighing about 1 kg should be taken from the whole. Then it should be placed in a tightly closed bag (e.g. with a zip lock) and tamped down to completely remove the air. It is also a good idea to secure the bag with adhesive tape. Then you should write a description and deliver the sample to the laboratory as quickly as possible (alternatively, cool it to 1–4º C or freeze it).
Basic chemical analysis includes, among others: dry matter content, total protein, crude ash, crude starch fat and individual fiber fractions. Analysis of organic acids, ammonia nitrogen, pH or ADIN (nitrogen insoluble in acid detergent, which is an indicator of thermal damage to silage) is also of key importance, as listed by PFHBiPM.
Silage evaluation in three steps
It's time for visual verification of feed in the silo. PFHBiPM emphasizes that just a 15-minute audit by an independent advisor can provide answers to many questions that directly translate into the financial results of the farm throughout the year.
As part of the service, the PFHBiPM nutritional advisor focuses on three key measurements:
- organoleptic assessment – the colour of corn silage should not differ significantly from the starting material. Too much change may result from incorrect fermentation and excessive acetic and butyric acid (unpleasant smell). Verification of the share of uncrushed grains, which constitute a real loss of starch in the feed, is also crucial;
- structure analysis (using sweep-agro sieves) – according to the methodology, the correct proportions are: 3–8 percent (sieve I), 45–65 percent (sieve II), 20–30 percent (sieve III) and below 10 percent (tray). The general rule is as follows: the higher the DM content, the shorter the chaff can be, i.e. approx. 15–16 mm (< 28 percent DM), approx. 12–13 mm (30 percent), approx. 11–12 mm (35 percent) and approx. 10–8 mm (> 40 percent DM). The chaff can be extended by approx. 1 to 5 mm when using a mixer wagon or a milling cutter, respectively, but be careful – feed particles that are too small carry a greater risk of rumen acidosis. Recently, the shredlage method has been gaining popularity, which allows for obtaining longer chop (20–25 mm) with good grain fragmentation;
- temperature measurement – should correspond to the conditions during ensiling of the material. It is assumed that in the model prepared silage the temperature should not exceed approx. 20°C, but more importantly – the differences in measurements taken at the front and at the walls of the silo should be as small as possible. Also the difference between the temperature outside and inside the material should not be higher than 10°C.
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Before you harvest the corn
In order not to be late with the harvest date, it is essential to perform an analysis of the dry matter content of the material intended for silage. You will find professional help in this area within the framework of the "Corn Campaign" organized by PFHBiPM throughout Poland. All you need to do is take a representative sample from the field (from at least five places), i.e. cut the plant at the planned harvest height and come to the "Action" on the same day, where PFHBiPM advisors will indicate the optimal harvest date. You can also estimate the dry matter content of the material yourself, using a microwave, a mushroom dryer or a fryer. In this case, cut the sample and weigh 100 g. The dry matter content is calculated using the formula: (sample weight after drying/sample weight before drying) x 100. Details about the "Corn Campaign" at www.pfhb.pl in the nutritional consulting tab.
