Optimising forage in rations using NutriOpt

Forage utilisation is the foundation of any profitable feeding strategy but with such wide variations in fibre, protein, and carbohydrate characteristics in forages, it is critical to have the models to quantify these factors.

The development of the NutriOpt model provides an opportunity for us to look at forages and their roles in diets differently. It has long been established that the traditional crude protein, D-value, and Non Digestible Fibre (NDF),

“NutriOpt feed analysis gives detailed information on what will happen to the feed once fed”

figures are far too vague to capture the best out of forage. Have you ever had first and second cut samples that look the same on paper but when changing to second-cut, milk
production falls? This is common when looking at crude figures and highlights the potential gains to be made from more accurate forage sampling and modelling.
One of the principals of NutriOpt is dividing carbohydrate and protein into rapidly, and slowly, fermentable fractions. This means we can provide more synergy between ingredients to balance the rumen more accurately. Interpreting this information means you can match the speed of degradation of products in the rumen, using supplementary feeding to plug the gaps.

Relationships between different factors

Maximising Rumen Fermentable Carbohydrates (RFC) to satisfy rumen microbial production, whilst maintaining rumen stability, is a key principal in NutriOpt. To achieve this balance, understanding fibrous portions of feeds and their digestibility rates is vital. RFC is the faster degrading proportion of total carbohydrates, so by looking at the balance between RFC and Total Fermentable Carbohydrates (TFC), we can better understand the gaps that need filling by supplementary feeding.


Maximising rumen function is a balance between fibre supply and acid load that is created by acidic feeds and rumen fermentation. Just looking at NDF is not good enough, as
this figure contains everything from lignin (which is totally undisguisable) through to pectin which degrades relatively quickly in the rumen. The resulting effects on rumen function, health, and production, could be very different. There is a demand for all types of fibre within the rumen environment, but using NutriOpt Digestible Fibre, along with the Fibre Index, we can get the balance right; maintaining good rumen function without reducing intakes, glucogenic energy and, therefore, milk yield.

Supplying the rumen with what it needs

NutriOpt lets us exploit forage, leaving concentrates to balance the rumen. Rumen Degradable Protein (RDP) is well supplied with most grass silage based diets and hard to fully utilise; evident with high milk urea results. With traditional rationing techniques, it is very challenging to supply the rumen with enough carbohydrates to utilise that protein. With advances made using NutriOpt, there is more opportunity to achieve this improvement in efficiency. Dividing protein into Rapidly Fermentable Protein (RFP) and Total Fermentable Protein (TFP), goes a step further than just looking at RDP, so making it more obvious which type of protein needs to be added.

Dynamic Net Energy

Dynamic Net Energy (DyNE) is the total amount of net energy available to the dairy cow for milk production. It is the sum of energy in the nutrients that are being formed during fermentation and absorbed in the digestive tract (small and large intestine) including; volatile fatty acids, glucose, amino acids and fatty acids.
When there is a shift in site of digestion, this is reflected in energy content, hence the name Dynamic Energy. The evolution from Metabolisable Energy (ME) to this figure better displays the results of ratios and proportions of feed types added. Crucially, by calculating the Volatile Fatty Acid (VFA) production into this figure, formulation is more focused on maximising VFA production; improving efficiency of rumen function.

Reducing Diet Costs

Average first cut samples this year calculate to supplying maintenance plus 6L using the traditional ME calculations, but when using DyNE; interpreting the full picture of what would happen to silage once fed, the same silage has a potential of producing an additional 2L. This shows by using NutriOpt parameters, there is potential to get more milk production from the same forage. There can be cost savings to be made in concentrates fed also. Cheap commodities like; wheat, Soya hulls, and Nutritionally Improved Straw (NIS) can be mainstays in rationing when fully understood, and significant costs can be made on bought-in protein where forage protein can be utilised NutriOpt feed analysis gives detailed information on what will happen to the feed once fed, and when used to its potential provides an opportunity to improve feed margins on farm.

Mark Price
Dairy Specialist
Follow Mark on Twitter @m_priceo or contact a Dairy Specialist here.

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