Chapter 3: Experimental design - Setting up a fair trial


Feed trial summary

Now that all the elements of a fair trial for carrying out the two concurrent feed trials (Diet A and Diet B) have been identified, how would you state this information in practical terms?

Look at the following questions and take a few minutes to formulate a response in your mind or jot your ideas down on a piece of paper. Then compare your ideas with the suggested statements.

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Why is the trial to be carried out?

To decide whether Diet A is more efficient than Diet B.

Part 1: Find the overall average food conversion ratio (FCR) for each diet.
Part 2: Find the food cost per kilogram for each diet.
What data is to be collected?

Part 1: Two trials are run concurrently (Diet A and Diet B) under the same conditions, except different diets are given.

Data is collected daily from six ponds for a period of 16 weeks and recorded onto datasheets. The independent variable is the type of feed given to the stock in each pond and the dependent variable is the weight of the stock.

  • Ponds 1-3 are given Diet A
  • Ponds 4-6 are given Diet B

Part 2: Overall food cost per kilo is calculated for each diet.
Calculations are made using the overall average FCR and cost per kg for Diet A and Diet B.
What calculations are to be made?

Formulas are used to make calculations to determine:

  • Food conversion ratio (FCR)
  • Mortality rates (%)
  • Daily survival rate (%)
  • Food cost per kilo ($)
How are the diets to be compared?
The data collected is calculated to an average food conversion ratio (FCR) figure for each diet and this is used in conjunction with the cost per kg to determine the food cost per kg.

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