Formulating dairy diets

Diet formulation involves utilising the feeds available to meet the daily nutrient requirements of cows within their available intake capacities.

The best formulation processes ensure this is achieved in the most cost-effective way and with the greatest possible utilisation of homegrown forages for each group of cows.

While perfectly sufficient for the simplest systems involving limited ingredients, manual diet formulation is generally considered too time-consuming and cumbersome for regimes in which rations are fine-tuned to performance regularly or more than a very few separate ingredients are used.

Formulating diets manually is, however, good practice for those who wish to understand the basis by which more sophisticated systems work in order to avoid common errors in their use.

Manual diet formulation involves the following steps:

1. Establish basic cow performance parameters.
2. Establish the nutrient values of the feeds available.
3. Calculate cow energy requirements.
4. Estimate dietary energy intakes.
5. Check protein supplies.

The main focus of manual diet formulation is to ensure the energy provided by the diet is sufficient to meet overall daily requirements.

Ration formulation software follows the same process as manual diet formulation, matching animal requirements with feed supplies.

In undertaking repeated balancing calculations rapidly and reliably, software makes diet formulation far more manageable for the majority of herds, allowing:

• A wide range of different feed ingredients to be utilised or compared
• Diets to be balanced for different energy and protein types at the same time
• Specific diets to be formulated for different groups of animals
• Rations to be adjusted regularly to match changing performance or ingredient availability
• Least-cost diets to be formulated

They can even provide detailed feeding recommendations for different systems.

Accurate details of the animals, nutritional composition of available feeds and the feeding system employed are essential.

Developed from a major government- and industry-funded research project, Feed into Milk (FiM) is the nutritional model that forms the basis of most modern computer diet formulation programs.

It sets the standard for modern UK feed evaluations.

Incorporating key elements of the metabolisable protein system, FiM aided:

• New near infra red scanning (NIRS) standards for grass silage analysis
• New silage intake predictions
• Rumen stability values
• Rumen energy availability of different feeds depending on rations and production level
• Microbial protein yield calculated from rumen nitrogen and energy availability

FiM software requires considerable details of the animals to be entered, including:

• Weight (kg)
• Weight change (kg/day)
• Dry or lactating
• Milk yield (kg/day)
• Milk fat (g/100 g)
• Milk protein (g/100 g)
• Days calved
• Average day of conception
• Lactation number
• Condition score

Alongside this, the software features a comprehensive library of feed ingredient specifications which need to be regularly updated with precise feed analyses, from which available and potential ingredients are selected.

The program matches these ingredients to the cow requirements to produce diets suitable for the feeding system, displaying full details of their nutrient provision and sufficiency, together with ‘as fed’ information for making up the ration and costs.

This allows any nutritional shortfalls and excesses to be minimised by ingredient adjustments and enables diets to be formulated from different mixtures of ingredients to compare daily feeding costs.

Accurate daily allocation of the diets is as important to success as their effective formulation.

Accuracy in diet allocation demands:

• Good calibration of all feeding equipment
• Regular checking and maintenance of all feeding equipment
• Careful weighing-out of mixed ration ingredients
• Effective mixing (if using total mixed ration (TMR))
• Accurate identification and grouping of cows
• Good presentation of feeds to ensure adequate access to all cows
• Diligent feed hygiene to avoid compromising palatability
• Effective performance monitoring