A review of environmental enrichment for pigs housed in intensive housing systems

Rearing entire pigs may lead to meat quality and welfare problems in relation to pubertal development. A better knowledge of the sources of variation of pubertal development, behaviour and boar taint is needed before generalizing entire male pigs. From 84 days of age, entire male pigs were reared in groups of 10 either in a conventional (C, 1 m²/animal, slatted floor) or an enriched (E, 2.5 m²/animal, straw bedding, outdoor run) housing during spring or autumn and fed ad libitum (n = 10/housing/season). Mounting behaviour was observed for 3 h during the third (M3), fourth (M4) and fifth (M5) months of age. The total number of skin lesions was counted on both sides of the pigs 1 day before the behavioural recordings. The time spent in the outdoor run was also recorded during 3 days per month. The animals were slaughtered at 161 ± 1 days of age (122 ± 9 kg live weight). Blood samples were collected at 89 (M3), 119 (M4) and 152 (M5) days of age and at slaughter for the testosterone and oestradiol measurements. The testes were collected at slaughter, freed from the surrounding tissues and weighed. The fat samples were collected for the androstenone and skatole concentration measurement. Plasma testosterone and oestradiol-17β (oestradiol), fat androstenone and skatole and weight of the testes did not differ between the housing systems. Plasma testosterone (8.3 v. 3.9 nmol/l, P < 0.05) and oestradiol (12.0 v. 9.2 pmol/l, P < 0.1) at M3, fat skatole (0.124 v. 0.043, P < 0.03) and weight of the testes (587 v. 512 g, P < 0.05) were higher in the autumn than in the spring trial, suggesting that the pubertal development was accelerated. The number of received mounting behaviours was slightly higher in the autumn ( P = 0.08) trial and was markedly higher in the E than in the C environment ( P < 0.003). Skin lesions were more numerous in the C than in the E housing at M4 and M5 and in the spring than in the autumn trial at M3 and M4 ( P < 0.05). Fat androstenone and the number of performed mounting behaviours were significantly correlated between each other and with numerous indicators of the pubertal development ( P < 0.05). The number of skin lesions was correlated with plasma testosterone and live weight ( P < 0.05). Overall, this study suggests the effect of season on sexual development, the effect of the housing system on behaviour, and demonstrates the links between sexual hormones, behaviour and boar taint.Keywords: pig, season, housing, testosterone, androstenone ImplicationsFinding solutions to rear entire male pigs without drawbacks on the meat quality and welfare during fattening are essential for the EU pig industry that is engaged in a process of stopping surgical castration. The present study evaluates the housing system and the season as two possible sources of variation of pubertal development, behaviour and boar taint. We found a positive effect of enriching the environment on the number of skin lesions but not on the other parameters. Decreasing day length seems to accelerate the pubertal development. The m...

Section: Indicators Of the Pubertal Developmentmentioning

confidence: 76%

Section: Indicators Of the Pubertal Developmentmentioning

confidence: 95%

Influence of housing and season on pubertal development, boar taint compounds and skin lesions of male pigs

Prunier

Brilloüet²,

Merlot³

et al. 2013

“…Additionally, in most of the studies in which non-slatted flooring was used, deformable substrates, such as straw bedding, were also provided to pigs, which might account for the differences found in the predicted lying behaviour. It is known that the use of deformable substrate on the floor is a source of environmental enrichment, having a recreational function and therefore promoting the physical activity of pigs (Van de Weerd and Day, 2009). Nevertheless, the same maximal value for lying behaviour in slatted and non-slatted floors was found in this study, which would suggest that the presence of substrate did not interfere with resting behaviour when sufficient floor space was provided.…”

Section: Discussionmentioning

confidence: 99%

Quantitative assessment of the effects of space allowance, group size and floor characteristics on the lying behaviour of growing-finishing pigs

Averós

Brossard

Dourmad

et al. 2010

To obtain quantitative information that can be later used in animal welfare modelling, the relationship between the lying behaviour of growing-finishing pigs (initial body weight (BW) between 19 and 87 kg) and different factors related to the housing conditions, with a potential negative effect on their welfare, was studied by means of a meta-analytical approach. Data from 22 experiments reported in 21 scientific publications were collected. The space allowance, expressed on an allometric basis by means of a k-value (m 2 /BW 0.667 ), the group size (n) and the floor characteristics (fully and partly slatted v. non-slatted floor), as well as their significant two-way interactions were used as fixed effects, and the experiment was used as a random factor to take into account the interexperiment effect. Further regression analyses were performed on the predicted values of observations in order to improve the adjustment of data. A significant quadratic relationship was established between space allowance ( k-value, P , 0.05; squared k-value, P , 0.01) and the percentage of time spent lying. A significant interaction between the k-value and the floor type was also found ( P , 0.05), showing that the relationship between space allowance and lying behaviour is affected by the presence or absence of slats. Threshold k-values were obtained using broken-line analyses, being about 0.039 for slatted floors and almost double for non-slatted floors. Compared to other studies, these values suggest that the ability to rest as space availability decreases may be compromised before a reduced performance becomes apparent. Group size did not show a significant effect. Additional information should be added to the model, as further data become available, to adjust the proposed parameters as well as to try to include the effect of other important aspects such as that of ambient temperature.

“…Manipulable materials which are attractive to pigs as measured by their motivation to access them (Holm et al, 2008;Jensen et al, 2008) or by the time pigs spend interacting with them over a sustained period have the characteristics 'ingestible', 'odorous', 'chewable', 'deformable' and 'destructible' ( Van de Weerd et al, 2003;Studnitz et al, 2007;Van de Weerd and Day, 2009). The opportunity to perform investigation and manipulation behaviours are in themselves important for pig welfare (Studnitz et al, 2007;Van de Weerd and Day, 2009), but here we focus on whether manipulable materials can reduce damaging tail biting apparently by providing an alternative outlet for investigatory behaviour.…”

Section: Availability Of Manipulable Materialsmentioning

confidence: 99%

“…The opportunity to perform investigation and manipulation behaviours are in themselves important for pig welfare (Studnitz et al, 2007;Van de Weerd and Day, 2009), but here we focus on whether manipulable materials can reduce damaging tail biting apparently by providing an alternative outlet for investigatory behaviour.…”

Section: Availability Of Manipulable Materialsmentioning

confidence: 99%

Injurious tail biting in pigs: how can it be controlled in existing systems without tail docking?

D’Eath

Arnott

Turner

et al. 2014

150

143

Tail biting is a serious animal welfare and economic problem in pig production. Tail docking, which reduces but does not eliminate tail biting, remains widespread. However, in the EU tail docking may not be used routinely, and some 'alternative' forms of pig production and certain countries do not allow tail docking at all. Against this background, using a novel approach focusing on research where tail injuries were quantified, we review the measures that can be used to control tail biting in pigs without tail docking. Using this strict criterion, there was good evidence that manipulable substrates and feeder space affect damaging tail biting. Only epidemiological evidence was available for effects of temperature and season, and the effect of stocking density was unclear. Studies suggest that group size has little effect, and the effects of nutrition, disease and breed require further investigation. The review identifies a number of knowledge gaps and promising avenues for future research into prevention and mitigation. We illustrate the diversity of hypotheses concerning how different proposed risk factors might increase tail biting through their effect on each other or on the proposed underlying processes of tail biting. A quantitative comparison of the efficacy of different methods of provision of manipulable materials, and a review of current practices in countries and assurance schemes where tail docking is banned, both suggest that daily provision of small quantities of destructible, manipulable natural materials can be of considerable benefit. Further comparative research is needed into materials, such as ropes, which are compatible with slatted floors. Also, materials which double as fuel for anaerobic digesters could be utilised. As well as optimising housing and management to reduce risk, it is important to detect and treat tail biting as soon as it occurs. Early warning signs before the first bloody tails appear, such as pigs holding their tails tucked under, could in future be automatically detected using precision livestock farming methods enabling earlier reaction and prevention of tail damage. However, there is a lack of scientific studies on how best to respond to outbreaks: the effectiveness of, for example, removing biters and/or bitten pigs, increasing enrichment, or applying substances to tails should be investigated. Finally, some breeding companies are exploring options for reducing the genetic propensity to tail bite. If these various approaches to reduce tail biting are implemented we propose that the need for tail docking will be reduced.