Greetings my dear readers, on this occasion I would like to share with you some considerations about the importance of hydrogen potential during anaerobic fermentation of forage biomass. As described in previous installments, silage is a forage biomass conservation technique to be used in times of scarcity, whose main foundation is the production of lactic acid with the help of some bacteria capable of fermenting soluble carbohydrates, although it is not the only characteristic to consider in this process, it is one of the most important, since to achieve a quality silage, it is necessary to control the proliferation of harmful microorganisms by generating an acid medium in the preserved biomass.
The potential of hydrogen or pH as it is commonly known, can be measured through a scale ranging from 1 to 14, being extremely acidic when the value is close to 1, while the value is higher near 14 is classified as extremely basic, and in the middle value is considered a neutral pH. To take the pH reading, you can use an equipment called peachimeter, of which there are several models, one is pencil type, it is a portable equipment very easy to use and practical for field measurements, there is also a more complete equipment used at laboratory level, which takes the reading through an electrode made with glass rods and at the tip a bulb with a sensor, which measures the concentration of hydrogen ions.
In relation to silage, this characteristic is of vital importance, since the proliferation of microorganisms will depend to a great extent on the range of acidity or basicity reached by the preserved biomass, the ideal is to achieve a pH close to 3.5 or 4. 5, which together with the absence of oxygen will limit the growth of some fungi, yeasts and clostridia that can cause the decomposition of the material affecting the stability of the silage, with the lowering of the pH, the aim is to promote the production of lactic acid, to ensure a rapid and vigorous fermentation from the earliest stages of the process.
To achieve an adequate level of acidity, the amount of dry matter in the biomass must be taken into account, according to Hiriart, (2008), states that green forage when ensiled with high humidity, can present loss of soluble nutrients through the effluents, and the loss in this case of sugars, Some nitrogen compounds and minerals, among others, are necessary for lactic fermentation, a factor that can influence the delay in the stability of the ensiled mass, since high humidity can give rise to undesirable microorganisms that alter pH levels.
Another variable to consider, in addition to dry matter, is the buffering capacity or tampom, which can be considered according to Martínez, Argamentería, and de la Roza (2014), as the capacity of the phytomass to resist pH changes, i.e. the hydrochloric acid equivalents needed to bring the pH of the ensiled mass to 4.0. The higher the buffering capacity, the more fermentation is needed to achieve pH stabilization. Some plants have a high resistance to pH decrease, especially the legume family, which due to its high protein content generates resistance to pH drop.
In conclusion, although there are many variables to consider in order to achieve a good quality silage, pH is one of the fundamental ones, since the stability of the phytomass to be conserved depends to a great extent on it. Let us remember that the basis of this conservation technique consists of maintaining the bromatological characteristics of the plant for a long time after being harvested, and microorganisms are the protagonists in the process.
In conclusion, although there are many variables to consider in order to achieve a good quality silage, pH is one of the fundamental ones, since the stability of the phytomass to be conserved depends to a great extent on it. Let us remember that the basis of this conservation technique consists of maintaining the bromatological characteristics of the plant for a long time after being harvested, and microorganisms are the protagonists in the process.
Hiriart, M. (2008). Silage processing and quality. México: Trillas.
Martínez, A.; Argamentería, A. and de la Roza, B. (2014). Management of forages for ensiling. Asturias: Servicio Regional de Investigación y Desarrollo Agroalimentario.
González, M., Seguí, R., Mogni, S. and Rubio, R. (2016). Acidity-pH conditions of silage intended for ruminant feeding. (Degree work). Faculty of Veterinary Sciences UNCPBA, Tandil.
