Grass and silage: Reasons for using a silage additive
More than 70 per cent of dairy farmers with 100 or more cows regularly use silage additives on most of their forages, according to a survey.
Shirley Heron, of Volac, says the survey of more than 600 producers showed there was a variety of reasons why respondents chose to use an additive, the main ones being the weather, faster fermentation and better performance.
Dr Heron says because farmers seem to be increasingly up against the weather, timing when to make silage is often a case of making the most of the best opportunity, rather than waiting for perfect conditions.
“Fermentation can be a challenge in wet weather because wet crops have to reach a lower pH to inactivate all undesirable bacteria. More sugar is also required as the extra water dilutes the acids produced.
“With silages below 30 per cent DM there is more risk of a poor fermentation, so use an effective inoculant to reduce pH fast using the least amount of sugar. This will reduce DM losses and protein breakdown.”
Dr Heron says a rapid wilt, up to 24 hours to around 30 per cent DM, will minimise effluent and result in a restricted fermentation, requiring less sugar and stabilising at a higher pH.
“Although there is less risk of undesirable bacterial activity, such silages can still benefit from the faster, more efficient fermentation provided by inoculation with reduced losses and protein breakdown and higher residual sugars.”
Getting the right microbial population is crucial for making quality silage and the best way to control the process is to make sure there are large numbers of the right type of bacteria present says Dr Heron.
“Grass contains a very high number of bacteria when cut but most of them will not benefit the fermentation. The ones you want are the homofermentative lactic acid bacteria (LAB). They ferment the sugars in grass mainly to lactic acid which is the best acid for lowering the pH fast with the minimum of losses.
“It is effectively ‘pickled’ which inhibits the growth of spoilage microorganisms.
“Unfortunately, the natural population of LAB on grass can be low and they are not the ideal types. Inoculation with large numbers of specially selected strains ensures they control the fermentation, maximising the chance of a good outcome.”
Dr Heron says aerobic spoilage, heating and moulding, results in very high DM losses and is more common in high DM material as it is harder to compact.
“Proven additives will inhibit the growth of the yeasts and moulds responsible. Some additives combine inoculants with preservatives to improve fermentation and reduce aerobic spoilage.”
Published research shows using a proven additive can result in improved performance for both dairy and beef enterprises.
“If you are among the few farmers who do not use a silage additive, then have another think. Forage is the most cost effective form of energy and protein available on your farm.
“Poorly produced forage results either in lower animal performance or an increase in bought-in supplementary feed, which can make the difference between profit and loss.
“Although additives cannot turn poor quality grass into good silage, using a proven silage additive this season will help to overcome potential weather issues, improve fermentation and ultimately ensure your cattle get the most out of your forage.”