Over-crowding and poor environmental conditions make livestock more vulnerable to disease, this requires increased use of antibiotics.

Other examples associated with intensive and over-crowded conditions include the problem of pecking by chickens and turkeys. Most commercially reared poultry in outdoor systems will have their beaks clipped to stop them damaging other birds.

Pigs, which like to roam the ground, are often kept in confined pens, breathing hydrogen sulfide and ammonia from excrement and urine. Sows in gestation stalls and farrowing crates cannot turn around.