Scientific art of Silage Making

By Dr. Amit Kumar, Dairy Nutritionist, Trouw Nutrition South Asia


Silage is a green succulent preserved fodder for the dairy animals to meet the nutritional demand when green fodder is not available. Since green fodder has a high nutritive value with a high moisture percentage, the availability of high nutritive value forage throughout the year is a big challenge for the dairy farmers. So, when green fodder is available in bulk, preserving it is a good choice, in which green fodder is chopped and stored in anaerobic conditions and can be utilized to feed animals when there is no/less availability. The process of making silage is called ensilage, and it is crucial to have a proper understanding of every step involved in making silage to make good quality silage.

The art of making quality silage includes important steps that need to be followed properly. Steps for making quality silage:

  • Selection and harvesting
  • Chopping
  • Silo
  • Pressing & packing
  • Opening and feeding
  • Physical characteristics

Selection & harvesting:

Crops selected for silage making should have a good amount of soluble or fermenting carbohydrate (for example: maize, jowar bajra) with a low protein content. These crops have thick and juicy stems. Harvesting at the right time (in between flowering and milk stage) with proper dry matter content (normally this ranges from 30 to 35%) is considered good for making quality silage; thin stem and high protein fodder crops are not suitable for making silage. Cultivated and natural grasses can be used for making silage by adding 3–3.5% molasses. Thin stem crops are preferred for making hay. Harvesting should be done in good weather to avoid excessive moisture and fungal contamination.


Chopping the selected fodder crop at the right size, b/w 2-4 cm, is essential for proper pressing of silage as it ensures that maximum amount of oxygen can be removed from the fodder spaces to reduce the length of the aerobic phase and increase the aerobic stability of nutrients.


The structure used for making silage or ensiling is called a silo. This is an airtight structure made for silage processing. Pit and trench silos are commonly used silos and are preferred by commercial dairy farmers, but the silage-making industry prefers making silage bales, bags, or bag silos that are being prepared for commercial production of silage. Normally, 1 cubic meter of space is needed for 400 kg of fodder in a pit/trench silo. Other types of silos are tower silos, which are less commonly used types of silos.

Preparation of silage:

Compression of silage using proper weight will ensure efficient removal of oxygen from the crop to reduce harmful microbial growth, avoid nutrient loss, and improve aerobic stability. Pressing can be done using a tractor (in a pit silo) or human pressing in bag silage. In the pit silo, the depth of the pit is normally 2.4 to 3 meters. The size of the silo is calculated based on the number of cows to be fed and the length of feeding. Shape of silo normally kept rectangular in pit or trench type silo. Silo should be packed in a dome shape on the top, then covered by poor-quality fodder like paddy straw and sealed with mud or dung, or it can be covered using plastic sheets pressed with sandbags or rubber tires for proper sealing to avoid oxygen entry. The dome shape will ensure proper rainwater drainage and avoid rainwater seepage. The side walls of silo pits should also be packed with straw and wall made of concrete will help in proper packing. At the bottom of the silo pit, there should be a 5–6inch layer of paddy straw, and limestone powder to avoid excess moisture accumulation.

Opening and feeding:

Silo should always be opened from one side to ensure minimum exposure to air. Uniform cutting of silage will ensure no air pockets with high temperature, which promotes yeast and mould growth. Presence of moulds & yeast makes silage unfit for feeding to the animals. Feeding contaminated silage will cause health and toxicity issue. Do not open upper cover completely but should be opened as per daily requirement. After usage, it should be packed and covered properly to avoid oxygen entrance and mould growth on the top layer of silage. Initial longer aerobic phase and when silage opened for feeding encounters air that induces production of fungal toxins due to fungal growth additionally growth of harmful microorganisms like coliforms and enterobacteria that cause damage to gut health responsible for poor nutrient absorption and gut health.

Fig 2: Silage opened and uniform cutting.

Scientific studies have proved that there are many types of toxins which are being produced due to various type of fungal growth like Aflatoxin trichothecene, DON, Zearalenone and ochratoxins along with growth of harmful bacteria, feeding such type of silage negatively impacts animal health and productivity.

Combatting mycotoxin exposure and maintaining consistent animal performance is crucial. Toxo-XL by Trouw Nutrition, a broad-spectrum mycotoxin binder that ensures 3-D mycotoxin risk management. The innovation is research proven and has blend of three unique ingredients the first it has highly purified smectite clay that efficiently adsorb wide range of mycotoxins that makes them non available for absorption in the intestine and ultimately protect the organs from toxin damage and reduces incidence of diarrhoea and enteritis. It contains glucose biopolymers of yeast origin, which supports intestinal integrity and tight junctions that prevents pathogen entry, thus, results in less cases of diarrhoea and enteritis. Thirdly, it contains purified beta glucans extracted from particulars strain of yeast that works through immunomodulation ensuring stronger immune response and protecting from pathogenic microbes which ultimately results in lesser somatic cell counts in the milk and lesser incidence of subclinical and clinical cases of mastitis.

Physical characteristics

Fig 3:  Silage
Type of silageOrganoleptic appearancePHColourButyric acidAmmonical nitrogen  
Very goodPleasant acidic taste and smell3.5-4.2Yellowish/brownish greenAbsent/free<10%
GoodAcidic taste and smell4.2-4.5Brownish greenIn traces10-15%
  FairSlight mouldy4.8 & aboveGreyish/dark brown/blackSignificant amount>20%

Colour of silage depends upon temperature, high temperature results in dark brown or black silage. Normally good quality silage colour is greenish brown or sometimes golden brown and its liked very much by dairy animals because of mild-acidic taste and pleasant smell.


The art of making quality silage depends upon various factors and the process starts from crop selection and ends at feeding of the silage to the animals with proper management at each stage to ensure good quality of silage, each step is crucial for making high-quality nutritious and palatable silage for better production and health of farm animals. 

Since complete isolation and estimation of toxins from the fiber is difficult and there is always the threat of multiple mycotoxins contamination and harmful microbial growth in silage, feeding such type of silage to the animals may compromise production, reproduction, and overall health of dairy animals.  A combination of highly purified smectite clay along with glucose biopolymers and glucans in the product like Toxo-XL  is suggestive along with silage which efficiently binds various mycotoxins and mitigates their negative impact due to non-availability for absorption and protects gut health from harmful micro-organisms that ultimately results in lesser incidence of diarrhea enteritis and lesser (SCC) Somatic cell count in the milk thus, lesser incidences of clinical and subclinical mastitis on the farm.

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