Delivering sufficient, safe, ethical and nutritious food in a sustainable manner to meet the requirements of future generations is one of the world’s greatest challenges. Over the past 10,000 years, the growing human and companion animal population has been sustained through the domestication of plant and animal species for use as food sources and the industrialisation of agricultural systems, without taking natural capital into account. A review of this strategy suggests that our modern systems are not necessarily optimal and, in some instances, are undermining the long-term food security and health of people and the planet. Intensification of livestock production systems has steadily increased since the mid-1880s and now dominates our global livestock food systems. It has contributed to the emergence, spread and maintenance of new disease agents through shifting ecological immunology, and increased interaction and movement of both people and their livestock. Simultaneously the diets of people and animals have changed leading to the double burden of under and over nutrition in people and companion animals.