India is the largest producer of milk with 187.75 MT production ( Basic animal husbandry statistics, 2019). The average yield is about 1600 Kg/animal whereas the world average is about 2700 kg/animal. Israel and the USA are the leading countries with average yields of about 13000 and 10500 Kg/animal respectively. (UGAM FOUNDATION’S). The USA is the major producer of maize and contributes nearly 35 % of the total production of the world and maize is the driver of the US economy. The USA has the peak productivity (> 9.6 ton ha-1) which is double than the global average production(4.92 ton ha-1). Whereas, the average productivity in India is 2.43 ton ha-1. Maize is native to America which was introduced to India by the Portuguese during the 17th century.(Krishi.icar.gov.in)
Ensiling surplus green fodders specially corn, barley, sorghum, pearl millet and oats during harvesting period would be the most suitable strategies to feed cows and buffaloes during periods of scarcity. Study has shown this approach not only supplies the nutritionally balanced ration, but also reduces the milk production cost significantly. Ensiling is the process where energy rich green fodder is conserved under specialized controlled anaerobic conditions leading to the development of a more digestible and nutritionally enriched fodder suitable for ruminants.
Let’s understand a few basic points of the ensiling process and quality of silage. Crop must be harvested between flowering and milk stage with dry matter of 35%.
Crop suitable for silage making:
1. Crops which are rich in soluble sugars/carbohydrates are preferred. Ex:Maize,sorghum,bajra
2. Cultivated and natural grass can be used with addition of 3-3.5% molasses.
3. Mixture of grass/cereal grass fodder and legumes such as berseem and lucerne etc. can be combined in the ratio 3:1
4. Leguminous and dry fodder combination can be used in the ratio of 4:1
1. Select the day when the weather is fair and not rainy
2. Select the day when the weather is fair and not rainy.
3. Fodder should be chopped to 2-3 cm.
4. Salt at 0.5% and urea at 1% are added to improve the palatability and nitrogen content
5. Press the chopped fodder in silo layer by layer of 30-35 cm.
6. Filling of the silo should be fast as possible to prevent air accumulation.
7. After filling and pressing, the silo should be sealed with a polyethylene sheet.
8. Put weight through mud layer/sandbags to prevent air flow beneath the sheet
9. Open the silo for feeding after 45 days.
Changes during Fermentation:
Fundamentally, the process starts with reducing the presence of oxygen in ensiled fodders so anaerobic bacteria can grow and convert plant sugars and starches into lactic acid (primarily), acetic acid, and other organic acids. After a few days, the pH of the silage dropped to a point where the mold and bacterial growth is inhibited. Furthermore, the low pH will reduce the activity of enzymes associated with undesirable bacteria (e.g., secondary fermentation by clostridium bacteria).
There are mostly three phases of silage fermentation: aerobic phase, anaerobic phase, and the feedout phase.
(A) In the initial phase of ensiling (i.e., the first 12-24 hours), cell and aerobic organisms consume H2O soluble carbohydrates and produce CO2, H2O, and heat. This can be a significant source of DM loss in fodder.
(B) During this stage heterofermentative bacteria become active. As a result, acetic and some lactic acid are formed. Eventually some amount of carbohydrate is converted to alcohol and is lost in the process.
(C) In this stage, the remaining O2 in the ensiled product is spent and a transition is made to the anaerobic phase. In the absence of O2, there is the changeover to more growth by homofermentative, lactic acid-forming bacteria. Once this stage begins, the pH starts to drop rapidly.
(D) The activity of the lactic acid-forming bacteria lasts and the crop’s pH continues to drop until most of the sugar and starch is consumed or the pH gets low enough to suppress the growth of the homofermentative bacteria. The level in the drop of pH depends upon the concentration of fermentable carbohydrates, the moisture of the crop, and the density of the silage crop.
(E) Once the pH is dropped, the ensiled crop is stable as long as the forage is not exposed to O2. While silage is opened for feeding animals, O2 accumulation begins. Spoilage begins instantly once O2 intrusion, however crops that have fermented well should still stay stable for some hours before decomposition begins. Inoculating with heterofermentative bacterium could cut back the speed of spoilage.
The best practices for making ready smart quality silage:
In order to push fermentation and minimize spoilage, there are many crucial steps. These are listed below
There are several kinds of feed additives which could be used for better silage preparation and for improving silage quality. These are added at the time of preparation of silage and aid in better silage fermentation and reduce the fermentation loss. Certain feed additives improve the keeping quality of the silage and reduce the storage loss. These are natural or industrial products and are supposed to give better return on investments.
Types of fermentation:
Lactic acid producing probiotics are are of two types which are as follow
Butyric acid type: Takes the upper hand during high levels of protein in fodder with less level of soluble sugars which may lead to high butyric acid production and high level clostridium organisms.
Nutritive Value of Silage:
Silage is nutritious fodder for ruminants and can replace the green roughages in diets up to considerable level. Following is the nutritive value we can consider and add in the formulation of total mixed ration for balancing the dietary requirements of the ruminants.
Silage quality and way to measure!
Quality of silage is measured considering the percentage of organic acids present. Major organic acids are lactic acid, acetic acid and butyric acids. Lactic and acetic acids are more desirable acids in silage which should be in a ratio of 2.5-3.0:1. Butyric acid is mainly produced due to clostridial fermentation and should be as low as possible. More than 0.5% butyric acid in silage lowers the nutritive value.
Lactic acid in silage should be minimum 7.5% and above and Acetic acid should be within the range of 3 to 6 % but not less than 2% of dry matter.
Flieg Index is used to assess the fermentation quality of silage. It estimates the total amount of lactic acid and butyric acid, expressed as total acid in the silage
Y=55.95+0.07X ( Y=TDN expressed as % of DM; X=Flieg score)
Flieg Score/ Flieg Point:
Flieg point/ Flieg score is measured by taking pH and dry matter content of the silage and is calculated at the end of the silage preparation for calculation of Flieg index. Flieg point: 200+ [(2*DM-15)]-40*pH