Effects of Doubling the Standard Space Allowance on Behavioural and Physiological Responses of Sheep Experiencing Regular and Irregular Floor Motion during Simulated Sea Transport.

Abstract

Simple SummarySheep are sometimes transported long distances by ship, and space allowance is one of the most contentious aspects of welfare provision. Previous research has not examined major increases in space allowances, so we investigated sheep responses to a doubling of the standard Australian allowance. Sheep were exposed to simulated ship motion of a regular or irregular nature, representing smooth sailing or high seas, or a control treatment without motion. Doubling space allowance provided evidence of reduced stress: less pushing each other, less need for the sheep to hold their heads close together, less leaning against their enclosure and lower heart rates and LF/HF ratio. It did, however, increase stepping by the sheep to correct their balance. Irregular motion reduced the time sheep spent chewing the cud, also evidence of stress, however, balance corrections were more common in regular motion, possibly because the sheep could predict the movement and step accordingly. We conclude that doubling sheep’s space allowance during simulated ship transport improves their welfare, and that irregular motion limits balance control and may reduce welfare.Transporting livestock at high stocking density by ship presents significant risks to their welfare, especially if it is over long distances. Previous research has investigated small variations in density for long periods or a moderate variation for short periods. The objective of this study was to assess the effects of a doubling of space allowance during two types of simulated ship movement, regular and irregular floor motion, on the welfare of sheep for a short one-hour period. Six 25 kg sheep were restrained in pairs in a crate on a programmable platform that generated roll and pitch motion typical of that experienced on board ship. Sheep were subjected to regular or irregular movement or a control treatment at high and low stocking densities (0.26 and 0.52 m2/sheep) in a multilevel changeover design. Irregular movement was programmed as a sequence of 30 different amplitude and duration values for pitch and roll movements, which were randomly selected by computer software controlling the movement. Regular movement was the mean of these values, which represented approximately 33% of the recommended maximum tolerance for livestock carriers. Behaviour was recorded by six cameras positioned around the crate. The low space allowance increased sheep pushing each other (Low: 4.51 events/h, High: 1.37 events/h, p < 0.001), affiliative behaviour, with their heads one on top of the other (Low 8.64, High 3.75 s/h, p = 0.02) and standing supported by the crate (Low 96, High 3.2 s/h, p < 0.001). Sheep stepped more frequently when more space was provided, particularly in the forward (Low 6.4, High 8.4 steps/h, p = 0.02) and left (Low 4.0, High 4.7 steps/h, p = 0.03) directions. The low space allowance group also had i heart rates, providing evidence of physiological stress. Irregular movement reduced rumination (Irregular 288, Control 592, Regular 403 s/h, p = 0.02), which was evidence of reduced welfare, but balance corrections by stepping were more common if the motion was regular. Thus, there was evidence that the low space allowance increased interactions between sheep and was stressful, and that irregular floor motion in simulated ship transport limited balance control and reduced welfare.