Sizes and capacities
The size of this type of ship varies, according to market demands in different parts of the world at different times. In the latter half of the twentieth century, the principal livestock exporting nations were Australia and New Zealand and the main importers were nations in the Middle East. Vessels engaged in that trade have ranged in size from 2,000 tonnes deadweight (DWT) to 25,000 DWT. The limiting factors on ship size are complex. Bigger vessels can achieve economies of scale in their operations but also require more extensive port facilities to handle the larger numbers of livestock likely to be loaded or discharged.
Livestock carriers carry more crew members than conventional cargo ships of a similar size. Experienced stockmen are an essential part of the crew. The total number of stockmen required varies according to the number of animals and also depends on factors such as the arrangement of the livestock pens and the extent of automated systems installed for feeding and watering.
During the last three decades of the twentieth century there was a progressive trend towards large vessels carrying greater numbers of animals. Prior to that, a significant limitation had been fresh water storage capacity on ships. To maintain condition, average-sized cattle require at least forty litres of water per head, per day. Sheep require at least four litres per head – per day. Developments in water production technology (salt water evaporators or reverse-osmosis systems) eventually led to livestock carriers with equipment capable of producing up to 600 tonnes of fresh water per day. Sheep and cattle also require fodder amounting to at least 2% of their body weight per day. Livestock carriers are required to carry sufficient feedstuffs for the maximum length of the voyage plus adequate reserves for emergencies.