Fifty-four pigs weaned at 3 weeks of age were allocated at an average weight of 5·4 kg to two experiments to examine the effects of diets having digestible energy (DE) concentrations ranging from 2910 to 3940 kcal/kg.
In the first experiment pig growth performance and the dry-matter digestibility of the experimental diets were measured between 3 and 8 weeks of age. The composition of the carcass at 8 weeks of age was correlated with the composition of various carcass joints.
In the second experiment pig growth performance was measured over the live-weight range 5-4 to 20 kg.
The findings were:
1. Growth rate was linearly related to DE intake.
2. The optimum DE level for maximum growth was 3640 kcal/kg.
3. The efficiency of utilization of DE for growth did not vary in the first experiment but was poorest at a DE concentration of 3245 kcal/kg in the second.
4. The DE content of the diet had no significant effect on carcass characteristics at 8 weeks of age in the first experiment or at 20 kg live weight in the second.
5. The proportion of fat and lean in the 8-week carcass was significantly (P < 0·01) correlated with that of the shoulder joint.