2.2.27 (HL)—Lower trophic level yields

Eating lower on a food chain usually yields more food energy because fewer transfers lose energy as heat and waste.

A crop eaten directly skips livestock conversion losses. The benefit depends on land, feed, species and production method, so it is a tendency rather than a universal number.

If plants provide 10,000 kJ and each transfer retains 10%, direct eating accesses about 10,000 kJ, while one livestock step leaves about 1,000 kJ.

It removes a trophic transfer, so more producer energy becomes available per unit input.

‘Lower trophic’ does not mean every plant food has identical impact; compare the actual system and resources.