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  • Jin Gan

Myth of High Forage Diets

Myth Of High Forage Diets

How much forage should one feed their herd? it seems like everyone is recommending a high forage diet but is that the right thing to do?

Let us look at some diets and the challenges and opportunities of each diet:

Diet 1: High forage, high corn silage

  • This is a high forage (70%) diet that has high amount of corn silage.

  • This diet fits the criteria of a high forage diet.

  • Milk production is estimated to be around 43 kg but there are some concerns.

  • Starch levels at 30.6% and peNDF at 19.2%, it seems like this diet has insufficient amount of fibre and too much starch to maintain a health rumen pH.

  • The diet could probably be adjusted with a little more haylage, hay or straw.

  • High moisture shell corn can also be replaced with dry ground corn.

Diet 2: High forage, high haylage

  • Haylage is increased for this diet.

  • One low quality haylage and one high quality haylage is utilised.

  • This diet can be frustrating to nutritionists who are strapped with high forage and high performance requirement.

  • NDF levels at 32.8% will restrict intake.

  • Starch levels at 19.3% without another source of fermentable carbs will limit production.

  • Rumen will likely be healthy but the cows may lose body condition score (BCS).

  • Maintaining DMI of 25kg is not realistic.

  • Predicted milk production of around 38kg is optimistic.

  • Forage levels will need to drop in this scenario to improve production.

Diet 3: High forage with reasonable expectations

  • Instead of forcing high forage %, many farms are looking for diet that has more forage as compared to 20 years ago.

  • Generally, most producers are most concern about the cow's health.

  • This diet has a modestly high level of forage (65%), 63% corn silage and milk production is predicted to be around 43 kg.

  • peNDF is at 21.7%. peNDF is a better measurement of effective fibre than forage percentage.

  • Although forage levels are lower than Diet 1, this is a much safer diet. It supports high milk production and keep cows healthy.

Diet 4: Mid forage, healthy cows

  • This diet is not better or worse as compared to Diet 3.

  • It has 55% forage with 54% corn silage. peNDF is at 21.7%.

  • This diet supports another kg of milk compared to Diet 3 in theory.

  • A more important thing to note is that both these diet will keep the cows healthy.

Economics rather than forage level

  • Rather than having a set of number of forage % in the diet, a more important question to ask is what are the criteria that will support milk production and healthy cows.

  • Effective fibre, particle length, consistency of diet and sortability are all important factors to be considered.

  • Forage % is far too vague to have a real meaning in dairy rations.


  • Sometimes, it is crucial to think long term and run some hypothetical diets in order to decide what is best for the future of your farm.

  • Get past the idea that "high forage" is a requirement.

  • Ensure there is a consistent ration that will keep the rumen healthy, keep the cows healthy and increases profitability for your farm.

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