Document type: article published in Pig Progress
Author: Samaneh Azarpajouh
Preview: [...] The growing world population has increased the demand for pork products and has led to a rapid growth in the scale of swine enterprises globally. As a result, the swine production would intensify even more with farmers aiming to maximise output per animal unit, thus increasing the stocking density.On the other hand, modern pig production systems are currently the focus of public and political attention to improve production of safe and high-quality pork while maintaining high pig welfare standards. High stocking densities exert passive impact on pig health, performance and welfare. Therefore, swine producers are required to balance welfare and building utilisation and choose an optimal stocking density for application to pig production.
Mixing unacquainted pigs
When several unacquainted pigs are mixed for the first time, they show aggressive behaviour and tend to fight to establish a dominance hierarchy within 24 hours. [...] Increase in stocking density enhances stress and aggression and the instability within the dominance hierarchy. [...] Research shows more intense fighting in small groups of 10 pigs with greater space allowance than in groups of 20 pigs stocked at lesser space allowance. [...]On the other hand, low stocking density in poorly insulated and open lairages during winter results in cold stress. Group size and pen shape are highly likely to be important co-factors. If stocking density is low, aggressive behaviour may enhance because of increased space allowance and the opportunity to interact with more individuals.
Effects on individual pig groups [...]- Impact in gilts
Gilts reared in small groups of 6 pigs had a greater average of liveborn piglet number than gilts reared in a larger group with ten pigs. In addition, gilts in small litters had 1.1 more embryos at day 30 post-mating. Gilts raised in litters of 6 had 0.3 more pigs in first parity than gilts raised in litters of 12.
- Impact in grow-finishing pigs
Stocking density has a major effect on feed intake, and growth performance. Space restrictions for grow-finishing pigs leads to decreased feed intake, reduced average daily gain, and variable effects on the gain:feed ratio. Various researches have shown data supporting that young pigs thrive when allocated some more space [...].
- Impact in late finishing/ pork quality
[...] Low meat quality [...] meat relates to the recent ante mortem welfare of pigs and is an indicator of high stress levels in lairage and during transport. [...] Low meat quality is due to a combination of stressors and it is not directly associated with stocking density. Increasing stocking density enhances the risk of pale, soft, exudative meat for both short transit times and transportation time over three hours. [...]Stocking density needs to be considered in a multifactorial approach to pig welfare in lairage. [...]Lower stocking density causes unfamiliar pigs to fight more intensely. However, it allows subordinate pigs to escape from dominant pigs, and provides sufficient space for all pigs to lie down and rest.
