Research looking at two groups of pigs fattened on an outdoor system in Northern Ireland have showed good results and proved there is potential for this rearing method in the country.
There are currently relatively few outdoor pigs in Northern Ireland, but even with its variable weather conditions, the pigs proved they could adapt to, and thrive on an outdoor production unit, despite the challenges.
The eight-month study, carried out at AFBI’s Loughgall site, compared pig performance, health and behaviour between grassland and agroforestry systems.
Two batches of a total 96 pigs were used in the trial, including a spring/summer group and an autumn group. Both groups comprised of undocked Large White x Landrace X Hampshire boars.
Each group was assigned a 1,000sq.m plot of either grassland or agroforestry, with an insulated shelter that pigs could freely access. Pigs arrived to the trial plots at eight weeks of age weighing 22kgs and stayed on site until approximately 21 weeks of age weighing 122 kgs.
In the end, the average daily gain of 1.01kg/day was comparable to the top 10% of UK indoor finishing herds, and feed efficiency of 2.18 matched the top third.
Pigs in the agroforestry system gained 7% more weight than those on grassland. Although they ate more feed to achieve this, feed efficiency remained similar across both systems.
According to AFBI, one of the most notable results was the almost complete absence of tail injury despite pigs being undocked.
Parasites can be a key concern for outdoor pig units and to avoid preventable problems, AFBI made sure that pigs arrived clean and healthy, including giving them routine anthelmintic treatment.
This approach worked extremely well and no lice or ticks were found during the study, and only a single parasite egg was detected across all the samples collected.
Extreme weather
Weather conditions did change during the trial from extreme heat to heavy rainfall, but had little to no effect on pig welfare as shelters were available and used.
Across both systems, pigs spent 68% of the day outside their hut, far exceeding the 8% required for essential behaviours like feeding and drinking.
The pigs in woodland spent even more time outside and were more active, rooting and exploring more often which are behaviours associated with high welfare.
Even during the coldest part of the trial, pigs still spent nearly half of the daytime outdoors, showing that outdoor rearing is possible in Northern Ireland’s climate.
In terms of health issues, only a small number of pigs showed minor, temporary signs of discomfort such as mild scouring or stiffness, with no cases of lameness recorded.
Tail injuries were almost entirely absent, with just one minor case observed during the entire study. Superficial scratches were slightly more common in agroforestry pigs, likely due to rubbing or playful behaviour around trees.
Sunburn was a problem for the pigs on grassland where 58% of them showed mild signs of sunburn compared with only 9% of agroforestry pigs affected.
An AFBI spokesman said: “Overall, the study showed that from a performance and welfare perspective, outdoor pig rearing is possible in Northern Ireland, even with our unpredictable weather, and can deliver excellent welfare and acceptable performance.”
