1. Birth Weights

Mr Gadd states that being 1g heavier at birth is equivalent to 2.34g heavier at 21–day weaning, which equals 20 to 30g heavier at slaughter. "In my experience, these figures at slaughter can be minimal," said Mr Gadd.

2. Birth to Slaughter

Around 50 per cent of runt pigs can reach 7kg at weaning if they are fed and managed selectively.

3. Weaning

It is best to aim for a 4–kg difference in pen weight, lightest to heaviest, in 21-28 day weaning, 4.5kg in matched pens averaging 6kg, and 5kg difference in pens of 7kg plus. These differences enable the pecking order to be established more rapidly so that the more submissive pigs get away sooner into full growth potential.

4. Adequate Trough Space

This is vital, especially at post weaning.

5. Feeder Gap Space

This should be checked every day. In comparison, by only checking once weekly, weight variation at slaughter can be widened by 20 per cent.

6. Overstocking

Overstocking by 15 per cent was also seen to widened variation at slaughter by 20 per cent.

7. Genetics

Preponderance of dam lines influences variability in both growth and grading. Mixing male lines may increase variation similarly.

8. Environment

It is important to get the temperature right. Too hot or too cold, the incorrect ventilation can affect variation.

9. Feed Intake

This can vary by 20 per cent within a pen and by a similar amount between pens. It is essential to provide your nutritionist with estimated daily intakes from each farm (or even from each house if a CWF pipeline is installed) each quarter so the nutrient intake from the diet can be revised. This helps to take care of seasonal and, to a certain extent, health changes.

10. Water Provision

Access to water can be just as important as adequacy.

11. Seasonal Effects

The time of year can affect weights as probe and carcass weights are lower in the summer months.

12. Health

Good health reduces the spread of weight within pens, according to Mr Gadd.