An established plan for New Zealand's pig industry to phase out all individual gestation stalls as dry-sow housing by 2015 may be brought forward due to a political row after animal activists released video footage of a farm they had entered illegally.

The film allegedly showed evidence of cruelty on the unit, owned by a former director of the NZ Pork Industry Board, although a subsequent visit by official investigators found that the housing complied with current national welfare rules.

By published estimates, under 30% of the breeding herds in New Zealand house their mated sows individually and just 10% of these employ sow stalls for the full gestation period.