Behavioral and physiological responses of livestock to simulated and actual transport by sea

Abstract

Environmental conditions in transit such as space allowance and motion are crucial to ensure welfare during long distance transport. Space has been identified among the top five welfare issues in the Australian live export sector. However, information about livestock responses to space and sea motion is limited. The overall objective of this research was to investigate the behavioural and physiological responses of livestock to different motion sequences during sea transport, with particular attention to the influence of space allowance. Understanding the nature of animals’ responses would enable improvements to areas of concern about the welfare of livestock on board, which can be used to enhance the current Australian standards for the transport of livestock (ASEL). Secondary objectives were to have a better understanding of how animals keep the balance in transit, through the analysis of stepping responses. Furthermore, I explored the current conditions experienced by calves commercially transported by sea in the south of Chile. The primary studies of this research were focused on assessing the current Australian standards (ASEL) in terms of space provided to sheep during the live export trade and comparing the animals’ responses with 15%, 35% and 50% extra space. The space allowance was also considered in relation to different motion sequences (regular and irregular) or no motion respectively (chapter 3 and 4). When the least amount of space was provided (ASEL standard=0.26m2/sheep), sheep pushed more compared with medium space (+15%, 0.30 m2/sheep) and high space (+35%, 0.35 m2/sheep). Also, sheep stepping more during low space provided under regular motion (P < 0.001, P< 0.001), particularly at the beginning of the treatment (P < 0.001). Additionally, sheep were more aggressive in the low space allowance, particularly during irregular movement (P = 0.003) and at the end of the treatment (P = 0.05). Furthermore, the lower space allowance was stressful for the animals, reflected in a decrease of heart rate variability. Both motion treatments decreased rumination (P < 0.001) and tended to increase affiliative behaviour (P = 0.06) compared with a control treatment with no motion. Thus, there was evidence that low space allowance increased both competition for space and aggression in sheep and heart rate measurements indicated that they were stressed. Thus, a second experiment investigated the animals’ responses to 100% more space, compared with the current Australian standards (ASEL). The results supported our previous findings. The ASEL standards (0.26m2/sheep) increased pushing, affiliative behaviour and standing supported by the crate, compared with the higher space allowance. However, keeping the animals loosely packed during the trial (0.52m2/sheep) increased stepping behaviour, suggesting more attempts to keep the balance and avoid slip and fall. The second main goal of this current study was to investigate how the animals maintain balance during the simulated sea conditions (Chapter 5 and 6). Heave was the most challenging movement for animals to deal with. It produced the biggest stepping responses in the forelimb compared with pitch and roll movements. In addition, sheep stepped most commonly forwards and backwards with the front limbs and then with the hind limbs. Laterality was found in terms of sheep position in the crate; those animals on the left side moved more frequently in several directions than those on the right, reflecting brain hemispherical lateralisation of the processing of responses. There was evidence that simulated ship movement produced stepping and heart rate responses consistent with stress. Due to the evidence that the lack of balance can produce discomfort and stress responses in livestock, we tested whether a combination of antiemetics can reduce the loss of balance during the heave and roll movement experience. The antiemetic reduced the frequency of some stepping behaviours, particularly by the forelimbs and during roll movement. It appears that antiemetic can reduce the consequences of a lack of balance, suggesting that sheep experience sea sickness. Finally, the welfare of calves transported by sea in the south of Chile was investigated. The behavioural and physiological responses of calves at two different space allowances during long distance transport by sea was studied. The group of calves with higher space allowance had a greater cortisol concentration at the final destination farm (7.26 mg/dl) compared with the previous transportation event (5.62 mg/dl), whereas there was no difference at the low space allowance. There was evidence of food and water deprivation, from a decreased concentration of total proteins, albumin and globulins after the unloading procedures, particularly when a higher space was provided (0.86 m2/head) (p<0.001, p=0.002 and p<0.001, respectively). This research has therefore developed a greater understanding of livestock responses to two main stressors during ship transit: low space allowances and motion. This will allow welfare standards for the transportation of livestock by sea to be targeted at the most stressful situations.