Body Condition Scoring:

Body Condition Scoring
Section: Stockmanship Standards
Body Condition Scoring
Body Condition Scoring
Score Number Condition Description Shape of body
5 Overfat Hips and backbone heavily covered Bulbous
4 Fat Hips and backbone cannot be felt Tending to bulge
3.5 Good condition Hips and backbone only felt with difficulty Tube shape
3 Normal Hips and backbone only felt with firm palm pressure Tube shaped
2.5 Somewhat thin Hips and backbone felt without palm pressure Tube shaped but flat (slab) sides
2 Thin Hips and backbone noticeable and easily felt Ribs and spine can be felt
1 Emaciated Hips and backbone visible Bone structure apparent (ribs and backbone)
Condition scores from left to right, 1: 2: 3: 4: 5

From: Managing Pig Health and the Treatment of Disease

Back fat meter may be more useful. However, note condition score and back fat correlation differs between different breeds