The welfare of livestock transported by ship.

The transport of livestock by ship is growing in importance, but there are concerns about the welfare impact on the animals. Short sea journeys are usually completed in the vehicles that are used to transport the animals by road, and injury and stress can result. Long sea journeys require offloading of the animals into pens, where they are mixed and provided with feed, water and sometimes artificial ventilation. In addition, animals are often exposed to high stocking densities, elevated temperature and ammonia concentration, as well as noise and changes in photoperiod and light intensity. Mortality rate is the main measure of welfare used by the Australian live export industry for long distance shipments, and the rate is higher at sea compared to the same period of transport on land. Heat stress often challenges livestock when they are transported from cold to hot regions at high stocking densities with no diurnal temperature fluctuation. Sheep cope with heat stress better than cattle, but can still develop respiratory alkalosis if hyperventilation ensues. Bos taurus cattle cope less well with heat stress than Bos indicus breeds. High ammonia concentrations may accumulate on long voyages, causing mucosal irritation and pulmonary inflammation. Some sheep and goats do not adapt to the pellets provided after extensive grazing in Australia, resulting in inanition, often in combination with salmonellosis, which together are the main cause of high mortality rates. Long distance transport may also result in disease transmission to the recipient country and high standards of biosecurity are necessary. It is concluded that there are significant risks to the welfare of livestock caused by transporting them in ships, especially over long distances.