What is the impact on animal welfare of depriving farm animals of water during transport?

Livestock transported in Australia are routinely deprived of water for variable periods including curfew (prior to transport), during transport and in saleyards and depots. Under the Australian Animal Welfare Standards and Guidelines for the Land Transport of Livestock, the maximum time off water is 48 hours for cattle and goats over the age of six months and sheep over the age of four months. For adult pigs, the maximum time off water is 24 hours. Following this maximum time off water, animals are required to be rested with water, feed and space to lie down for a minimum prescribed period (36 hours for cattle, sheep and goats, and 12 hours for pigs) before starting another journey.

Water is required by all animals for survival including maintenance of bodily systems, fluid balance, body temperature, electrolyte concentrations, and to satisfy thirst. Periods of water restriction may pose a risk to animal health and welfare.

The effects of water deprivation can be categorised as clinical (illness or disease state), physiological (changes in functional pathways), behavioural (activity, actions and interactions), and emotional (subjective experience).

The majority of livestock studies focus on the clinical and physiological effects of water deprivation such as clinical dehydration, body weight loss, changes in blood cell counts and blood values including indicators of kidney dysfunction and failure. These studies are rarely conducted on animals subject to the range of stressors inherent in transportation. There is also little research available on the behavioural or emotional effects of water deprivation in livestock despite recommendations for animal welfare standards to take subjective experiences such as thirst into account.

It is often cited that ruminants (animals with a four-chambered stomach) such as cattle, goats and sheep can endure longer periods of water deprivation compared to monogastric animals (simple single stomach) such as pigs. The rumen, one of the four ruminant stomach chambers, is regarded as a water “store”. Several studies indicate that in the initial stages of water deprivation, fluid may be drawn from the rumen to address fluid balance. Water deprivation studies on camels (and some breeds of livestock adapted to arid desert conditions) indicate that they may be able to endure longer periods of water deprivation. However, in Merino sheep, after 48 hours water deprivation, the rumen contents become increasingly thick and by 72 hours, the “store” of fluid begins to be depleted.

The European Food Safety Authority Panel on Animal Health and Welfare in their report ‘Scientific Opinion Concerning the Welfare of Animals during Transport’ considered the literature available at the time and recommended that healthy adult sheep transported under good conditions can tolerate food and water deprivation up to 48 hours but adult cattle should not be transported longer than 29 hours without food and water due to fatigue and physiological changes. How translatable these recommendations are to Australian livestock transported in Australian conditions is unknown.

Animals’ stress status influences how long they can go without water because hormones released as part of the stress response can have a diuretic effect that contributes to dehydration. The duration of water deprivation that any animal is able to endure may also depend on factors including:

• Animal factors (e.g., species, breed, age, body condition, reproductive status, injury and illness)
• Environment factors (e.g., season, temperature, humidity, shade or shelter, social environment)
• Management factors (e.g., quantity and quality of feed and water provided prior to deprivation, frequency of loading and unloading, stocking density, handling, duration of transport and how the transport is conducted)

The ability of ruminants to endure water deprivation assumes that the animals are well fed and hydrated prior. One study concluded that sheep (in a cool temperate climate) brought immediately in from pasture were “not clinically compromised” by 48 hours of transport where they had no access to feed or water. However, when deprived of both feed and water prior to transport, sheep energy stores are depleted after 24 hours and they become approximately 10% dehydrated after 72 hours. In 2006, the authors of a report for Meat and Livestock Australia wrote, “It is the opinion of the authors of this review that a practice which routinely resulted in 10% dehydration in animals would not be regarded as acceptable in welfare terms by veterinarians.” In addition, food and water deprivation can lead to changes in the microbiology of the rumen including increased growth of harmful bacteria. In a comprehensive review of the impact of feed and water deprivation on sheep and cattle before and during transport commissioned by Meat and Livestock Australia in 2007, the authors recommended that “Based on the potential for enteropathogen growth and the potential for an increase in stress to the animal, it appears prudent to ensure that total time off food and/or water does not exceed 24 hours.” From an animal welfare perspective, just because an animal possesses adaptations to endure a period of water deprivation does not mean the animal should be pushed to their limits. In addition, it should be noted that if given the opportunity to exercise choice, these animals would drink suitable water available in a suitable presentation. For example, in most management systems, Bos taurus cattle (breeds like Angus and Hereford) will drink several times a day.

There is a lack of studies evaluating the appropriate time off water for transported livestock. In Australia, it is common practice to deprive animals of both feed and water prior to transport, known as curfew, to manipulate faecal and urine output during transport. However, the effect of water curfews in ruminants on urine output is unknown and would likely have minimal effect in keeping livestock clean during transport. Additionally, due to the long transport distances ruminants are often required to travel, imposing water curfews could make it difficult to meet the Australian Animal Welfare Standards and Guidelines for the Land Transport of Livestock maximum time off water requirements.

Contemporary understanding of good animal welfare now extends well beyond simply providing the bare minimum requirements for survival. Hence, rather than approaching the issue of water deprivation by asking what is the longest time the animal can go without water before survival is threatened, a contemporary understanding of good animal welfare would have us ask: how can we best satisfy the animals’ water needs and choices while minimising the potential clinical, physiological, behavioural and emotional effects of water deprivation.

For these reasons, applying a precautionary approach taking into account what evidence is available to date, it would appear sensible to apply a maximum time off water which best satisfies the majority of animals’ water needs and choices while minimising the potential ill effects of water deprivation. Where possible, animals should be always be provided access to water while not on the transport vehicle.