If your silage intakes are lower than expected and/or you are struggling with milk yield then you could be suffering with metaphorical gremlins in the silage…
…Inside your silage clamp lie sleeping gremlins. These beasts of yeasts lie in wait, silently longing for the day they can breath air again. From the first grab of silage at clamp opening, these gremlins come alive and feasts ravenously on the lactic acid you had so carefully crafted to preserve your silage. As they eat away the lactic acid, the silage’s pH starts to rise. This allows the gemlins’ mouldy friends to come out of the dark and also get to work on consuming nutrients that should have been destined for the cows. Things are now hotting up as energy, proteins and dry matter are all whisked away by these invisible forces. Once the best of the nutrients are sucked dry, the hoards move deeper into the silage stack until the air runs out. But this isn’t the end of the story. The gremlins have not finished their trail of destruction. Reinvigorated by a quick airation in the mixer wagon and the addition of new nutrients, a PMR or TMR provides a fresh victim. You would think that once safely in the anaerobic environment of the rumen that would be that. But the gremlins have even more mischief in store!
What are they?
The gremlins refered to are yeasts. Specifically Lactate Assimilating Yeasts (LAY), due to the fact they consume lactic acid. These are one of the most important organisms in the alchemy of silage. Whilst rarely discussed, Lactate Assimilating Yeasts (LAY) have the potential to significantly reduce your silage dry matter yield, dry matter intakes, silage and TMR/PMR nutrients, affect digestibility and affect production. Importantly, they kickstart aerobic instability in your silage.
Whilst present throughout the whole clamp, one of their main locations can be in the top and shoulders. If the clamp wasn’t rolled enough (or too much) and/or there was a delay in sheeting up, yeast numbers can rocket. This is also true if oxygen can permeate through the sheet. This reservoir of yeasts are ready to kick off a riot when the clamp is opened. If they are put into the mixer wagon they are going to cause instability in the fed out ration.
Why is this important?
Trials1 have shown higher levels of LAY in the ration can substantially reduce the digestibility of the NDF. The chart below shows the results of a trial where rumen fluid containing a TMR were monitored in a glass jar. The level of yeasts were classed as low, medium or high. As you can see, as yeast counts increase, the digestibility of the NDF reduces*.
We know from other trials2 that improving NDF Digestibility by one unit increases DMI by 0.17kg and 0.25kg increase in fat corrected milk. So reducing digestibility will have the reverse effect. Other work3 showed similarly, a 0.22kg change in DMI and 0.33kg of milk for evey 1% change in DOMD. Whilst there is not a 1:1 relationship between DOMD and NDF, its pretty close.
Ultimately the picture is that lower digestibility isn’t good for DMI or milk yield. So keeping silages free from Lactate Assimilating Yeasts and not giving them the environment to multiply is good for business and good for the cows.
When silage is already in the clamp all we can do now is be mindful that these gremlins are likely present and ready to act. Keeping the sheet tight to the face, good face management etc. is a must. Those doing the feeding out must be aware that even small amounts of ‘bad’ silage could potentially cause issues. Dealing with top and shoulder waste is a pain, but it’s best chucked in the slurry rather than potentially impacting the cows and production.
Think about next silage season. What is your strategy to protect your investments against LAY.
On many farms too much LAY will result in low forage DMI and lead to the feeding of more blend or parlour cake. This will increase cost for less gain than would have been achieved feeding more in the absence of LAY. It is just one of the many reasons farms are in the bottom half of the Kingshay Milk Map.
So remember, do not feed gremlins after midnight or get them wet!
1 – Effects of a spoilage yeast from silage on in vitro ruminal fermentation M.C.Santos et al. J. Dairy Sci. 98 :2603–2610
2– Evaluation of the Importance of the Digestibility of Neutral Detergent Fiber from Forage: Effects on Dry Matter Intake and Milk Yield of Dairy Cows M.OBA and M. S.ALLEN 1999 JDairySci 82:589–596
3 – Production and utilization of ensiled forages by beef cattle, dairy cows, pregnant ewes and finishing lambs — A review. Keady T.W.J., Hanrahan J.P., Marley C.L., Scollan N.D. Agric. Food. Sci. 2013;22:70–92
* This has not yet been found within the rumen of live animals