Diet evaluation and diet design

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The first step in using CNCPS is feed evaluation.

In other words, feed evaluation is to match the model (=CNCPS) with the actual situation.

And it refers to quantifying and evaluating what is happening inside the body of the cow. That's the starting point.

If any problems are found in the evaluation, it is possible that simply improving them will lead to improved production.

Feed design is the step to further increase production after evaluation.

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Request amount setting

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A method called the factor approach is used to set the required amount in the feed evaluation and design program.

From the difference between the amount of intake and the amount of excretion, it is possible to calculate the approximate amount of nutrients required by the whole individual, but it is not possible to know where in the body and how much. Therefore, if you divide it into factors and find out how much nutrients are required for each factor, the accuracy of predicting the required amount will increase.

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Normal distribution is assumed

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It is assumed that feed evaluation and design should be done not for individual animals, but for groups.

If a herd's milk yield is the average value of a herd with a normal distribution, the accuracy of the model's prediction of milk yield increases.

(The figure below shows an example of the milk yield distribution of a mid-lactation herd on a US farm).

This is the reason why the diet evaluation and design in CNCPS is approached separately for each pen (high milk production, low milk production, early dry milk, late dry milk, etc.).

For distributions that deviate significantly from the normal distribution, the mean may not necessarily reflect the average milk yield of the herd.

In that case, it is better to apply the mode or median value, or to calculate the average value by excluding extreme values, so it is necessary to check the variation in milk yield.

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Diet design approach

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The diagram below was introduced in a course at Cornell University as a basic approach to feed design.

It is explained that it is basic to assemble in the order of 1 to 4.

Although the material is about 10 years old, the basic concept has not changed.

It is thought that it is good to check the "feed evaluation" to judge whether the current feed content is appropriate in the same order.

 

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The basics of a program are inputs and outputs

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Whether the usefulness of the feed evaluation and design program is high or low depends on whether the feed analysis values, which are input items, and the production indicators of milk yield, milk composition, and body changes, which are output items, are theoretically compatible. (Daniel et al., 2020).

In addition to feed analysis values, input items include information on the cows that make up the herd and the rearing environment.

If the usefulness of the program is judged to be high, the next important thing is whether the input information required by the program is entered accurately.If feed analysis values, cattle information, and environmental information are rational and based on actual measured values, the accuracy of predicting output values will increase.

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importance of weight

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Weight is recognized as one of the most important input items in all feed calculator software.

Traditionally, it is essential for the calculation of predicted dry matter intake (figure below), and in CNCPS, it is also a determinant of feed passage speed. Maintenance and accumulation requirements in the demand factor approach, as well as individual demand predictions in growing and gestating cows.

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