We have recently judged the Herefordshire Grassland Society silage competition. He then gave a presentation to the group of farmers present and we feel that the points made in his presentation maybe of interest to you.
Shown below are some example forage analysis:
| Maize Silage | Grass Silage A | Grass Silage B | |
| Dry Matter % | 27 | 22 | 37.4 |
| Crude Protein % | 7.2 | 15.5 | 13.5 |
| ME mj/kg | 11.0 | 11.6 | 11.7 |
| PH | 3.8 | 3.7 | 4.2 |
| VFAS g/kg | 30 | 40 | 10 |
| Lactic Acid g/kg | 140 | 131 | 47 |
| Rumen Stability Value | 295 | 260 | 357 |
| FiM PAL | 1076 | 1023 | 601 |
Over the last few years, plant breeders have developed 'stay green' varieties of maize. The cobs dry out sooner and the crop is harvested whilst the leaves are green. However, this leads to problems in the cow's rumen.
The maize analysis, shown above is fairly typical of these on farms this winter. Maize used to be a 'buffer' to wet grass silage. This is no longer the case. The pH of the maize is 3.8 and it contains 140 gms of lactic acid- which is 14%.
If this is fed with Grass Silage A, the total level of lactic acid fed is almost 14% of 13kg of forage intake, almost 2kg of lactic acid, (remember lactic acid is what drives down the Ph in clamp silages and has the same effect in the rumen).
SARA (Sub Acute Rumen Acidosis) is very likely to result with all the consequential problems of loose dung, lameness, poor performance and fertility. Remember that 1 point on the pH scale e.g. 4.5 to 3.5 represents a 10x increase in acidity.
Silage A also represents a silage that has continued to ferment, (many of you will recognise the effects of a "popular silage additive" on silage pH and lactic acid content)
Silage B is a much better product to use with the maize silage. This has a much reduced lactic acid, but may not be stable, especially when fed in the spring or summer. We need to make this type of silage to counteract the maize silage acidity. This needs an effective additive to produce stability.
Ecosyl has the most trial work and always does well in comparisons such as Kingshay. A lot of farmers are at the mercy of their buying group and often find that the choice of silage additive has been made for them, because of price and a 'deal for the group'. The unfortunate thing is that, the choice of silage additive has a profound effect on what is then fed to the animals for a whole season! Double Action Ecosyl contains an innoculant and a preservative to improve the stability of higher dry matter silage like silage B.
Silage analyses also now show rumen stability values RSV. This RSV value is derived from the Neutral Detergent Fibre (NDF) in the forage and the Potential Acid Load (PAL)
PAL is a measure of the potential acid load in the rumen with high lactic acid forages having higher values. Diets with high PAL content will have a low RSV. RSV of less than 300 can lead to an increase risk of SARA (Sub Acute Rumen Acidosis).
The silage analyses are only part of the story. No account is taken of :
- Chop length of forages
- Over mixing in the FEEDER WAGON
- Feed sorting
- Inadequate feed space per cow or poor feed availability or access
- Diet balance using blends containing slower release starches such as PB maize.
- Palatability of forages/ diet mix.
We understand that all the above may seem very complex. However, these factors may well be crucial in the profitability of your herd. We at GP Feeds have the expertise to use the above information to balance diets and help plan forages for next winter that reduce that risk of SARA. We provide custom blends and the compounds are formulated to reduce the risk of SARA ( Sub Acute Rumen Acidosis).