A bacterial silage inoculant is often considered an integral part of the silage-making process. Farmers Guardian looks the importance of different strains of bacteria and highlights some of the latest silage inoculant technology research.
Selecting the right silage inoculant for the right situation can improve the fermentation process, preserve more of the valuable nutrients and provide your animals with a highly palatable ad nutritious feedstock to be used through summer and winter.
Dr. Ivan Eisner, global product manager for the silage inoculant portfolio at Chr. Hansen, explains there are different types of bacteria when it comes to silage inoculants.
He says: “We talk in general terms about lactic acid bacteria (LAB). We refer to homofermentative and heterofermentative strains when we discuss their broad modes of action.
“We also talk about their species names, such as Lactobacillus plantarum or Lactococcus lactis. But I realise to the untrained eye, this does not always tell us what we really need to know.”
Dr. Eisner say while all LAB produces lactic acid, some also produce acetic acid, and the speed, amount, and conditions required for them to do that change according to the specific strain of bacteria being used.
He says: “It is at the strain level that we really start to understand what a bacteria is doing. The strain name is usually a jumble of letters and numbers on the end of the bacteria name.
“These letters and numbers are what tell us exactly which bacteria we are speaking of. At a gene level, the difference between two strains of the same bacteria species could be bigger than the difference between humans and mice, so the difference in their performance can be quite substantial.
Equal
“What this really means is not all bacteria are created equal. There are thousands of different strains of all bacteria species, including the ones we use in variations in the way each of them behaves in the different conditions we present them with, and variations in the results we will get.”
Dr. Eisner says this means that simply because two silage inoculants contain the same species of bacteria, such as Lactobacillus buchneri, those two bacterial strains could behave quite differently with other bacteria in the inoculant and in the fermentation process, ultimately resulting in a different response both in the silage and eventually the animal.
He says: “We know that many products on the market contain similar species, but these are not the same strains. Each manufacturer uses their own strains for their own reasons.
“We know that some strains hold certain advantages. We know that when it comes to making well-fermented, palatable silage, which stays fresh and promotes intakes, strains matter.”
Dr Eisner says much of the knowledge on silage inoculants in the market today is not necessarily incorrect but is a little outdated.
He says: “We should start any conversation about making better silage by first referring to silage management. These principles are the same as they have always been; get the air out, keep the air out.”
“This was, and still is, a great place to start. Once we get into inoculants, it is science-based and research-proven, which means new findings are shaping our thinking on a very regular basis.”
Traditionally, the theory behind a good inoculant for silage-making was to promote a rapid reduction of the pH by using organisms which produce very high levels of lactic acid, creating an unfavourable environment for spoilage organisms and reducing the loss of dry matter.
Enemy
Dr Eisner says: “In many ways this is not completely incorrect, but with new technology we can now go one step further. The real enemy of good fermentation is oxygen and the speed at which we can get most of that oxygen out of the silage.”
“All the bacteria used in silage inoculants are designed to do their job in anaerobic conditions. Until the oxygen is gone, we cannot benefit from the anaerobic LAB to reach our terminal pH, so this must come first.”
In most silage clamps, the process of removing oxygen is started during compaction and finishes under the sheet up to six weeks later.
Oxygen
Dr Eisner says, however, that there are now products available to purchase on the UK market which ‘actively scavenge oxygen’ from the silage, so almost oxygen0free conditions can be established in less than 24 hours.
Another assumption made in silage inoculants, according to Dr Eisner, is that heterofermentative products are only useful in preventing aerobic spoilage and heating.
Dr Eisner agrees clamp management plays a huge role in aerobic stability, but that there has to be more to it or heating would never happen in well-managed clamps.
He says: “While it is true that heterofermentative species of bacteria, such as Lactobacillus buchneri, help prevent aerobic spoilage, they do so much more than that.”
“In many cases, it is the combination strains which makes the biggest differences. Sometimes when you add two strains together, you get the benefits of both strains in what we would call an ‘additive’ effect.”
“Sometimes though, through the right research, you can find two strains which give a multiplicative effect, where one and one now equals three or four or even five.”
Some new combination products containing both homo- and hetero-fermenting strains can provide more than just the sum of their parts.
Some products offer early opening with silage which has finished fermenting in only seven days, providing improvements in palatability and feed intakes and even inhibition of clostridium.
Research
Dr Eisner says: “These are real second and third generation technologies we are seeing in some silage inoculants, and if it is backed with genuine research, they can make a real difference to the quality of your silage.”
“It is not just about protecting yourself from a silage disaster anymore. Modern inoculants are about making significant improvements.”
