Fermentation reduces silage quality and palatability of the dairy cow ration
Managing microbial growth is essential for silage making. Fresh forage contains microbes such as bacteria, yeasts and moulds. It is a mixture of beneficial microbes, such as lactic acid forming bacteria and undesired microbes such as clostridia or moulds. Proliferation of microbes in silage for cows initially leads to consumption of the oxygen trapped in the silage. Once all oxygen is consumed, growth of anaerobic lactate forming bacteria decreases the pH of the silage. This acidification creates a good quality silage pH, resulting in stability of the silage for cows.
The balance between beneficial and undesirable microbes is one of the most important silage quality parameters. If this balance in the silage for cows is disturbed or the amount of oxygen after harvesting is too high, this acidification process will slow down. This will create favourable conditions for the growth of yeasts, coliform bacteria, clostridia and moulds, which have a negative effect on silage quality. These moulds can sometimes be recognized via visual inspection. The growth of these unfavourable microbes results in a bad smell and reduced palatability of the silage for cows. Low quality silage will ultimately lead to reduced nutritional value and palatability of the dairy ration.
Producing a healthy silage already starts before harvesting. Crop contamination with microorganisms occurs already on the field, but also before and during harvesting. Proliferation can either occur after ensiling, after opening of the silage (mainly at the cutting edge) or in the TMR once the silage is mixed into the dairy ration. Feeding high quality silage therefore requires care during the silage making process but quality of silage is also impacted by silage management.