What are the key control points in making whole-plant corn silage?

Whole-plant corn silage is made by ensiling the entire corn plant with the ear at the dough stage (when corn kernels account for more than 45% of the weight). Silage has obvious advantages: it has a fragrant aroma, is soft and juicy; it can improve cattle palatability and feed digestibility; it has a large storage capacity per unit volume, is convenient for large-scale long-term storage, and can be supplied year-round; nutrient losses are small, generally around 10%, and it can effectively maintain the fresh green state of green feed. The key control points in making whole-plant corn silage include the following aspects.

I. Budgeting the required amount of silage corn

Taking a dairy farm as an example, 12-25 kg per cow per day, with an average of 18-20 kg per day for large and small cattle, that is, about 7 tons per cow per year, can effectively ensure the supply of silage corn (generally keeping losses within 15%).

II. Preparation of silage facilities

There are many types of silage facilities, mainly silage pits, towers, tanks, bags, boxes, trenches, and flat-ground silage. Requirements for silage facilities: (1) airtight; (2) watertight; (3) the walls should be straight, and the corners of the walls should be rounded; (4) there must be a certain depth, 2.5-3 m deep and 2-10 m wide, with the length determined by the silage volume; (5) able to prevent freezing; (6) to prevent trench walls from collapsing, there should be a 1/10 slope, with an inverted trapezoidal cross-section.

The most widely used silage equipment is the silage pit. Silage pits are divided into above-ground, underground, and semi-underground types, generally 20-40 m long, 5.5-6 m wide at the top, 4.5-5.5 m wide at the bottom, and 2.5-3.5 m deep. Ground stacking can also be used, that is, using 1 mm thick polyethylene film to stack silage on the ground, with a scale ranging from 20-50 tons. The capacity of general whole-plant corn silage is 650-750 kg per cubic meter. Three days before silage making begins, the silage pit should first be disinfected. First clean it thoroughly. If it is sunny, exposing it to the sun for 3 days is enough. If sunlight cannot be used, a 1%-2% bleaching powder solution or a 0.3% peracetic acid solution can be sprayed 3 days in advance. The walls of the silage pit should be covered with plastic film. The width of the film = pit height + 1/2 pit width + 3 m, and the length of the film should be >=15 m.

III. Suitable harvest period

The best harvest period for silage corn is late milk stage to early dough stage, with dry matter content between 28% and 40%, and dry matter should not be lower than 25%.

IV. Chopping of silage corn

The stubble height for corn harvest should be at least 15 cm, preferably 20-25 cm, to avoid contamination by soil microorganisms on the ground that leads to poor silage fermentation. Silage corn needs a suitable chopping length, and the corn kernels should be crushed. Whole-plant corn silage generally requires a cutting length of 0.63-1.25 cm (abroad), and the United States requires a maximum of no more than 19 mm; domestic reports give a cutting length of 0.90-1.70 cm. If a rubbing and cutting machine is used, the chopping length should be controlled at 1.0-2.0 cm; if a chopper is used, it should be controlled at 0.5-1.3 cm. When corn dry matter content is less than 27%, a cutting length of 17 mm is recommended; when dry matter content is 28%-31%, a cutting length of 11 mm is recommended; when dry matter content is 32%-35%, a cutting length of 9 mm is recommended; when dry matter content is greater than 36%, a cutting length of 5 mm is recommended.

After corn kernels are crushed, starch can flow out quickly and fermentation is promoted. At the same time, it can also improve the digestibility of corn in the rumen and the utilization rate of starch, so kernel crushing is also crucial. The best diameter for kernel crushing is 4.75 mm (one kernel divided into four parts). To check the degree of crushing, take 1 liter of silage corn (volume, not weight) and pour it into a bucket of water, remove the corn stalks, and then count the number of whole corn kernels sinking to the bottom of the bucket; it absolutely must not be more than 5.

V. Filling and compaction

Before filling, a layer of 10-15 cm of chopped straw or other soft grass can be spread on the bottom of the pit to absorb silage juice; the time from harvest to pit entry should preferably be controlled within 4 hours (within 200 km), and the limit for pit entry time is 8 hours, otherwise the raw material is prone to oxidation and deterioration; after the transport vehicle unloads the material, it should be pushed up immediately, otherwise it is very easy to deteriorate, and deterioration is faster than when piled on the vehicle; during the filling process, avoid exposing the forage to air for more than 4 days; when loading raw materials, pay attention to compaction, 15 cm per layer, rolling each ton of raw material for 4-5 minutes; heavy tractors should be used for compaction, the tractor should run slowly, the tires should not slip, and the surrounding areas should be compacted; regularly check the compaction of the silage, and the silage density should preferably be >=750 kg per cubic meter.

(1) First dump the first load of material 10 m from the head of the pit (2 times the pit height), ensure that the angle from the unloading position of the first load to the top of the pit wall is within 30-35 degrees, keep the bucket plate of the 50 loader about 10 cm above the ground, and slowly push forward, spreading it evenly on the pit surface. Only when the bottom is compacted can the upper part be compacted better. When distributing raw materials, the material distributed to the edges should be higher than the middle of the pit. During side compaction, the vehicle will tilt toward the middle of the pit, thereby compacting the raw material at the edges.

(2) Spread layer by layer and compact layer by layer, with each layer at 15-30 cm; the head of the pit gradually rises, forming a slope of about 30-35 degrees, and the material is dumped while moving backward in sequence, compacting the pit on the slope.

(3) Do not roll too much on the top, otherwise it will lead to more serious top spoilage, because plant cells rupture, nutrients and moisture flow out, and this will accelerate the growth of aerobic spoilage microorganisms.

When checking the degree of compaction, select 5 points separately on the compacted surface, drill holes with a coarse feed sampler, take out the silage corn inside and weigh it, then place a large soft plastic bag in the hole, add water to the plastic bag until it is level with the silage surface, then lift the plastic bag and measure the volume of water with a graduated cylinder. Using the volume of the removed silage corn and the water, the density of the silage corn can be calculated.