Pig welfare and water use

Novel Teagasc study finds providing pigs with a high enrichment allowance reduces water usage and wastage.

The provision of sufficient drinking water is important for animal agriculture and is essential for good welfare. Freshwater is a limited resource, and therefore the water used in agricultural systems needs to be optimised.

Pork – one of the most globally eaten meats – requires freshwater for production. Drinking water accounts for up to 87% of total farm water use, with the grower-finisher stage accounting for 64% of this. Pigs consume only part of this drinking water, with the rest going to waste. As well as being a poor use of an already limited resource, wasted freshwater also increases the volume and disposal costs of slurry and dilutes its nutrient content.

The importance of resource allowance

The amount of drinking water consumed and wasted by pigs is affected by a complex interaction of elements, including feed intake, temperature, humidity and pen design. Fundamentally, it is affected by factors that impact behaviour directed towards the drinkers. Understanding this is essential in order to reduce water wastage.

A significant factor is that pigs are highly motivated to perform foraging and exploratory behaviour. When there is a lack of appropriate environmental enrichment to facilitate this, they may redirect their attention towards drinkers, which waste water when manipulated.

Pigs engage readily with loose organic material provided in a rack over the more commonly used items in commercial farms (such as wooden chew bars, rubber toys, etc.), so this has the potential to divert attention away from drinkers. Research has also found that when the stocking density is constant, pigs in larger groups have more shared space to explore, which could also lead to less engagement with drinkers.

As of yet, no study has focused on the impact of group size and enrichment type on both drinking behaviour and water wasted from drinkers, so researchers from Teagasc and Wageningen University & Research have chosen to explore these factors.

Measuring and observing processes

For the research, grower-finisher pigs were divided into three group sizes: small (12 pigs), medium (24 pigs) and large (48 pigs). Each group had a constant space allowance of 0.86 m2 per pig. Half of the pens of each group size were assigned one of two levels of enrichment: high or low.

For every 12 pigs, the low treatment received one wooden post and one hanging rubber toy. Pigs in the high treatment received the same, as well as a rack containing fresh grass, which is highly favourable to pigs.

Water meters were installed in all pens, covering each wet-dry feeder and the bowl drinker next to it. Water use volumes were monitored every hour on a daily basis for the entire experiment using an automated online water monitoring system.

To record water wasted, a wooden box with an opening for pigs to access surrounded each drinker on all sides. Water overflow from each drinker was collected using a container placed underneath the drinker. The volume of waste water was measured one day per week for six weeks.

The researchers were primarily interested in the demonstration of damaging behaviours (such as fighting, ear and tail biting and belly nosing), enrichment use and drinking behaviour.

Damaging behaviour of pigs and enrichment use was directly observed once per week. Infrared night vision cameras were installed directly over the drinkers midway through the finisher stage, and drinking behaviour was observed continuously for one hour during the most active time of the day (10am to 11am). The duration and number of drinking bouts and total drinker occupancy during the hour were observed.

More enrichment, less waste

Daily water use recorded by the meters had a cyclical pattern, increasing from approximately 8am to 4pm, and thereafter declining during the night. It was found that group size did not affect the overall water use. However, the researchers were correct in their hypothesis regarding the provision of enrichment – overall, pens with high enrichment used less water than pens with low enrichment.

The results also showed that high-enrichment pens wasted less water compared to low-enrichment pens. This was likely because pigs in the low group had more drinking bouts than those in the high group, and as such spent more time occupying the drinkers.

As expected, pigs in the high group interacted more with the enrichment, and they also performed fewer aggressive and damaging behaviours. While group size did not affect water use, it did seem to impact behaviour, as pigs in the large group performed fewer aggressive and damaging behaviours.

The moisture content of fresh grass is approximately 80%, so it is possible that grass consumption could have somewhat satiated the pigs’ thirst, making them less motivated to visit the drinkers for the purpose of drinking. As such, further research with other materials should be performed in order to determine whether the researchers’ results are somewhat specific to the provision of grass as an enrichment material. Nevertheless, this study is novel in that it demonstrates how improving animal welfare can also provide benefits for the environment – and for the producer – when it comes to managing resources.