7.6 An experiment was performed to determine the effect of nutritionally inadequate diets on the quality of sheep’s wool. The experiment consisted of a 21-day pre-experimental period (ending on 22 October 1997), a 12-week restricted-intake period (ending on 14 January 1998) and a 6-week recovery period (ending on 25 February). Three experimental treatments were defined, namely

– Treatment 1. A control dietary regime.

– Treatment 2. An energy-deficient/protein-deficient nutritional regime.

– Treatment 3. An energy-deficient/protein-adequate nutritional regime.

Animals in the control group were fed at 1.3 times the level required for maintenance (1.3 M) throughout the experiment. The energy-deficient/protein-deficient group were fed at 0.75M during the restricted-intake period, then ad libitum up to 2M during the recovery period. The energy-deficient/protein-adequate group received the same diet as the energy-deficient/protein-deficient group except that they received a supplement of 3.3 g/day of active methionine throughout the experimental period.
Twenty-one Merino wether hoggets, each identified by a tag, were used in the experiment.
Following the 21-day adjustment period, the animals were divided into seven groups on the basis of live weight, and one randomly chosen animal from each group was allocated to each treatment. Measurements of the live weight and the fibre diameter of thewool of each animal were taken at the end of the pre-experimental period, and measurements of fibre diameter were also taken during the recovery period. The results are presented in Table 7.14. (Data reproduced by kind permission of Rachel Kirby.)
The experimental design includes a block factor which is not shown explicitly in Table 7.14.