I was recently involved with Yara in writing an article for the Farmers Guardian (February 2018) on the economic cost of producing a poor grass silage.  I based my workings on two similar farms who had contrasting forages but different feed rates.  Table 1 demonstrates the difference between the two forages. The poor silage was cut 3 weeks after the good silage.

People often focus on the top 3 characteristics, but as much importance should be given to the other presented figures.  NH3-N (%) represents nitrogen-ammonia where high levels deter intake (as seen in Table 1; 5.5%), damage of proteins into amines and poor fertiliser application/absorption.  Ash (10.5%) and VFA’s (50g/kg) are also high, suggesting soil contamination and poor fermentation which is reinforced by a high PH figure (5.5).  For good silage making to occur, a stable PH is required (PH3.8-4.2) with good energy, protein, fibre and lactic acid levels.  A cow breaks down grass sugars into lactic acid.  The art of good silage making is to enhance lactic acid production (as seen in Table 1; 75g/kg), so the cow can use more energy on milk production rather than digestion.

Both farms fed 75% grass silage to 25% maize silage and then the following raw materials to achieve the same milk output (Table 2).

As you can see, more concentrate was required where the poor silage was fed; this was because we needed to boost palatability, energy density, bypass protein and provide fermentable energy for NDF digestion.
The 30-litre cow fed the poorer grass silage required 10.85kgs of concentrate as opposed to 7.54kgs on the better silage.  Assuming 120 milking cows stay in all year round, this additional feed cost would translate into £32,000, with a further lift in milk yield, likely due to feeding a better silage.  Table 3 shows significant differences in concentrate use/litre (-0.11kg), purchased feed (-3.19ppl) and total ration cost/cow (-£0.5).

I have based the value of 1st cut grass silage at £27.50/tonne and I will explain this in the March 2018 newsletter.

To help improve forage performance, please contact Wesley at wesleyhabershon@fcgagric.com or your local FCG Office.