Silage crop quality down but performance should hold up

Based on these early samples, the traditional nutrient parameters indicate the crop is of slightly lower quality in comparison to 2016. However the NutriOpt Dairy parameters indicate performance should remain similar to last year if diets are correctly balanced to unlock potential.

Key points:

• DyNE = 5.21 MJ/kg DM suggesting that this year’s wholecrop should perform the same, if not better than last year

• RFC and TFC are lower than the expected average wholecrop sample; reflecting increased lignin and reduced starch levels

• Low acid load and high fibre index will help to support rumen health

Currently over 3,650 first cut silages and over 1,990 second cut silages have now been analysed this season. With the extra sample numbers included in the data sets both the first cut and second cut silages averages have changed.

Here the key points are:

With additional samples in the database reflective of later first cuts, SFC has increased in the average second cut silage with increased digestible NDF, where RFC has decreased slightly. This is reflected in a decreased risk of rumen health issues, decreased acid load and increased fibre index in second cuts.

Crude protein is the same in both first and second cuts at 15 per cent but it is clear that this protein is being used differently by the cow as second cut silages are much lower in rapidly fermentable protein than first cuts.

Additional samples have also resulted in the NFEPB being almost zero in first and second cuts, suggesting that these forages are balanced in terms of rumen fermentable energy and protein. This could have implications for diet formulation where there is a need to ensure sufficient fermentable protein is supplied to balance the rumen.

When feeding 2017 grass silage (first and second cut) and 2017 wholecrop silage to achieve 12kg forage DM, it is important to recognise that the diet will be significantly different to last year.

Diets will need rumen fermentable protein to balance the diet; rapeseed meal or DDGS

Diets will require some RFC; but care needs to be taken not to exceed acid load

Bypass starch will be required to meet energy requirements, for example Ultra Starch W

There is a real opportunity to maximise milk from forage using this season's silage. However it is important to note that milk potential will not be achieved if the rumen is not balanced. It is extremely important to remember the large variation in results between farms and individual clamps should be regularly analysed to accurately balance diets.

Angus Little, NWF Agriculture