Understanding Silage Inoculants


Silage has become a staple component of dairy cow diets virtually year round. Ensuring it is a cost effective feed source is critical. The efficiency of converting silage dollars to milk dollars is a significant contributor to farm profit. Today’s inoculant market has many products on offer. Choosing a quality inoculant is essential to improve feed conversion efficiency.

Multiple research projects in the USA have determined inoculants should supply 100,000 colony forming units (cfu) of initial fermentative bacteria per gram of silage. Research has also revealed cfu counts higher than this did not produce any improvement in fermentation quality. Pasture Gold guarantees a minimum of 100,000 cfu/gm of EU registered bacteria at ensiling. Further, Pasture Gold contains a third bacteria for preservation of silage when exposed to air at feed-out.

The two upfront bacteria recommended from research are L. plantarum and Pediococcus pentosaceus. Pasture Gold contains both these of strains registered under stringent proof trials by EU agriculture regulators. Few inoculants in Australia contain bacteria with EU registration as proof of their effectiveness. The third bacteria is Propionibacterium freudenreichii for the purpose of producing preservative propionic acid in silage. The two upfront bacteria will lower silage pH very rapidly stabilising it and preventing further fermentation from damaging both quality and dry matter.

Bacterial inoculants contain freeze dried bacteria which are activated when in contact with moisture. As live bacteria, stability and survival rates of bacteria are critical to the inoculant’s effectiveness in silage. Again, EU registration requires evidence of product stability. Obviously silage inoculants that do not have EU registered bacteria can, and do, produce a variety of fermentation outcomes as differing bacterial species are common in an unregulated Australian market.

Pasture Gold also contains an enzyme pack (fibre-technology) to increase silage digestibility. The science of enzymes in silage inoculant has now been reproduced in additives for mixer wagons that involve un-inoculated silage or hays and other forages or fibrous ingredients. Enzymes break down indigestible fibre (lignin), converting it to sugars that lactic acid bacteria then convert to lactic acid. Lactic acid is 10 times stronger than other fermentation acids and lowers pH rapidly to stability. This exposes increased digestible fibre to rumen bacteria for nutrient extraction and cow nutrition.

Perhaps the greatest financial return from Pasture Gold is the abundance of lactic acid. Lactic acid is very palatable to cows. This ensures high intakes, but perhaps even more important, very little wastage. Silage wastage at feed-out is by far the greatest cost to silage as a feed in conversion to milk dollars. This wastage is the greater part of what is known as shrinkage. This term relates to tonnes of silage made less tonnes of silage consumed by cows. The difference is ‘shrinkage’ and has a very significant cost. Our October article explains this more fully.

The physical shrinkage seen in bales or stacks is due to poor compaction, leaving air in the silage. Fermentation to stability is an anaerobic (no oxygen) process. The presence of oxygen will allow fermentation to continue unchecked and not achieve stability, consuming dry matter and nutrients.


Bacterial Silage Inoculant

PASTURE GOLD silage inoculant is available in granular form for application via Gandy Granular Applicators, or water soluble form.

PASTURE GOLD contains two EU registered LAB bacteria plus a preservative bacteria and an enzyme pack for increased digestibility..

PASTURE GOLD is available directly from Dairytech Nutrition or at the following Rural Stores

South West Vic                  Gippsland                                          Northern Vic

Allansford                           Leongatha                                         Cohuna

Acme Rural Supplies         Browns Stockfeeds                            J & R Cooke Trading P/L

Colac                                  Lang Lang                                         Echuca

The Co-op Colac                Larmax Agribarn                                Kober Ag Intellegence

Noorat                                Poowong                                            Kyabram

Mt Noorat Farm Supplies   Poowong Dairy & Hardware              Dunstall Rural Supplies

Simpson                              Drouin                                               Girgarre

E & RA Parlour & Co          Evison Grain & Produce                    Dunstall Rural Supplies

Terang                               Yarragon                                            Leitchville

Scanlons Dairy Centre       Yarragon Rural Supplies                     Lipps Leitchville

Terang Coop                      Tongala

GTS Farm Supplies

Central Highlands


Davies & Rose

If there is no rural store stockist near you, call Dairytech Nutrition 0400 991 814

For information and supply of


call Dairytech Nutrition 0400 991 814

24hr Digestibility – A Key to Profit


Rate-of-passage is a very important concept for both cow health, and especially, feed conversion efficiency – feed dollars to milk dollars. It is also a tension, that is, too fast from very lush pasture or sub-optimal rumen pH, will reduce feed conversion efficiency and increase feed cost per litre significantly, not to mention cow health. Our valuable feed ends up in manure pats in the paddock instead of milk in the vat. Alternately, high fibre feeds such as poor quality/mature silage or hay, will slow down rate-of-passage of feed through the digestive tract, reducing daily feed intake and crashing milk production. In both cases, the feed cost per litre will escalate.

The starting point is always cows’ access to sufficient feed to be fully fed. Then there are two states of being ‘fully fed’. Full to contentment, and physically gut fill. Obviously physical gut fill is the goal of optimum milk production, reduced cost per litre from dilution of maintenance energy cost, and maximised profit which usually is accompanied by cow health.

Assuming cows do have access to sufficient feed, which is not common outside spring, the next limitation is palatability. Feed, be it pasture, summer crops, silage, grain or anything else, must first be highly palatable to achieve potential feed intake. Now back to rate-of-passage.

High fibre feeds spend long periods in the rumen being broken down sufficiently to pass into the abomasum, the true stomach. This reduces rate-of-passage to the extent that feed intake is also reduced with consequent reduction in milk production, higher feed cost per litre, as above, maintenance energy cost per litre, all culminating, and by a multiplier effect, in a crash in profit.

Feed NDF% (Neutral Detergent Fibre – total fibre in any given feed or ration), really does not tell us much as far as predicting milk production and profit from this feed or ration. Digestibility is the key.

Good feed analysis laboratories will supply 24 hr, 30 hr and 240 hr digestibility rates for feeds submitted for testing. Although there is some debate among academics as to which, 24 or 30 hr digestibility rates, are best to predict milk outcomes, my simplistic understanding prefers the 24 hr digestibility data. Why? Because we all work on 24 hr milk production systems to inform us as to how we are producing.

The 24 hr digestibility is telling us how much fibre is still in the rumen from yesterday, and how much that is going to reduce our cow’s feed intake today; and her milk production/profit.

Let’s look at two examples of pasture from our feed test library: 1) Actively growing/short rotation ryegrass – 24 hr digestibility 81.48%, sampled in June 17. 2) Slow growing/long rotation ryegrass – 24 hr digestibility 51.73%, sampled in November 16.

If we fed 10 kgs DM (dry matter) of each pasture to two groups of cows the difference in ryegrass digested and converted to milk would be 1) 8.148 kgs DM, 2) 5.173 kgs DM. Now, to compound the issue, the quality pasture has an ME (energy value) of 10.26 MJME/kg DM. The mature ryegrass has an ME of 9.18 MJME/kg DM.

Now, our cows digesting 8.148 kgs DM of the quality 10 kg DM pasture would convert that to 14.9 lts of milk. The cows consuming 10 kgs DM of the mature pasture and digesting only 5.173 kgs DM would convert that to 8.48 litres of milk. There is $1.57 difference in milk production at 40c/lt between each group of cows! Essentially, $1.57 difference in profit.

The plot thickens: The group of cows consuming the quality pasture will have 1.852 kgs DM fibre still in their rumens tomorrow reducing their feed intake for tomorrow and limiting tomorrow’s milk production by 3.39 lts. The cows consuming the mature pasture will have 4.827 kgs DM fibre remaining in their rumens tomorrow. This reduces their feed intake tomorrow and reduces milk production by 7.91 lts.

Yes this is an extreme example for the purpose of highlighting the influence of 24 hr digestibility, as no forage fibre is 100% digestible in 24 hrs. The lesson stands nevertheless, and has devastating impacts on farm profit from not managing grazing particularly, but even worse, time/maturity stage of cutting pasture for silage’s impact on 24 hr digestibility. We have silage test data on hand with variations in 24 hr digestibility between 77% and 49%.

The Remedies

Pasture: Short rotations of actively growing and regularly re-pastured stands. This is easily done with strategic fertilizer applications and produces healthy plants. Healthy pasture plants then produce healthy soils, there is a synergy here between these two, but it starts with healthy and actively growing plants. A system proven to achieve this is light applications of a complete blend after every grazing – 21 days. Fertilizer can be reduced once soils are health and vital. Fertilizer is always the cheapest feed!

Silage: As above, maturity at cutting is number one. Time between cutting and ensiling is number two (see our article ‘Silage in a Day’ sept 15). Third is a quality lactic acid bacterial silage inoculant containing a proven enzyme pack. Enzymes will break down indigestible fibre converting it to sugars for lactic acid producing bacteria to convert to lactic acid – high palatability/silage intake. This reduction in indigestible fibre will increase 24 hr digestibility and milk production from each kg DM of silage.