Effect of Different Environment Enrichments on Behaviour and Social Interactions in Growing Pigs

Environmental enrichment in finishing pigs: does it promote any changes in bone biomechanics?

The resistance of pigs' bone structure was evaluated for the first time, reared with and without environmental enrichment (EE) in the finishing phase using techniques in bone biomechanics; 432 swine from the Hampshire breed, being males and females, with initial body weight between 22 and 27 kg and final body weight between 110 and 125 kg were evaluated for 112 days. The experimental design was in randomized blocks, with 6 treatments, distributed in a 2 × 3 factorial scheme (sex × conditions in creation), with 12 repetitions/treatment, totaling 72 pens. The treatments were as follows: branched chain for males (T1), sisal branched string for males (T2), males without EE (T3), branched chain for females (T4), sisal branched string for females (T5), and females without EE (T6). At the end of the experimental period, all animals were slaughtered in an industrial slaughterhouse, having their femur bones collected for bone biomechanics analysis. There was no effect (P > 0.05) of the interaction (enrichment × sex) and individual factors for bone weight. There was a tendency (P = 0.08) of the interaction for flexion force, being higher in males enriched with branched ropes and chains. For breaking stress, there was an interaction effect (P = 0.04), being the females without EE the ones showing the lowest breaking stress, favoring bone fragility. The use of branched ropes and chains strengthens the bone structure in swine in the termination phase (110-125 kg BW - 183-190 days in age), being an important strategy used to meet the animal welfare requirements.

Evaluation of environmental enrichment on productive and behavioral responses of finishing pigs

Productive and behavioral responses of finishing pigs with and without access to environmental enrichment (EE) were evaluated. A total of 432 pigs, male and female, Hampshire line, initial and final weight of 22-27 kg and 110-125 kg, respectively, were studied for 112 days. The study design was in random blocks, with 6 treatments, distributed in a factorial scheme 2 × 3 (sex × treatment) and 12 repetitions/treatment, totalling 72 pens. The animals were weighed and distributed in 3 blocks-light (20.3 to 24.8 kg), medium weight (24.8 to 27.7 kg), and heavy (27.7 to 33.8 kg). The treatments were as follows: branched chains for males (T1); branched sisal ropes for males (T2), males without EE (T3); branched chains for females (T4); branched sisal ropes for females (T5) and females without EA (T6). There was no effect (P > 0.05) of interaction (enrichment × sex) and sex on performance. Daily consumption and daily weight gain were lower (P < 0.05) in the chain group compared to the sisal rope and control groups. Feed conversion was similar (P > 0.05) between treatments under study. There was no interaction between gender and enrichment for behavioral responses (P = 0.8986). However, there was an environmental enrichment (P = 0.0017; P < 0.001) and gender (P = 0.0251; P < 0.001) effect in relation to the animals' behavior in the morning and in the afternoon, respectively. Calmer animals, regardless of sex, were observed for groups without enrichment (control) and morning and afternoon periods. The animals interacted with the types of enrichment under study, given the higher probabilities of interaction with the object for males and females in the morning and afternoon shifts. It was observed, regardless of the shifts, that the control treatment for males and females was different when compared to the other enrichments for males and females. In general, the pigs' behaviors were expressed more in the afternoon when compared to the morning. It was observed that the animal interaction and aggression (afternoon shift) behaviors are more related to the control group, while object interaction is more related to the enriched treatments. The use of sisal ropes and branched chains guarantees the performance and behavior of pigs in the finishing phase, but we recommend the use of branched chains, as this enrichment increased the profitability of the farmer by reducing feed consumption, maintaining feed conversion and animal welfare, besides being a more durable material than sisal rope.

Environmental Enrichment Differentially Activates Neural Circuits in FVB/N Mice, Inducing Social Interaction in Females but Agonistic Behavior in Males

Environmental enrichment induces behavioral and structural modifications in rodents and influences the capability of mice to cope with stress. However, little is understood about hippocampal neurogenesis and the appearance of social/agonistic (aggressive) behavior upon activation of different neuronal circuits in FVB/N mice. Thus, in this study we hypothesized that environmental enrichment differentially regulates neurogenesis, neural circuit activation and social/agonistic behavior in male and female FVB/N mice. We explored the (1) neurogenic process as an indicative of neuroplasticity, (2) neuronal activation in the limbic system, and (3) social behavior using the resident-intruder test. On postnatal day 23 (PD23), mice were assigned to one of two groups: Standard Housing or Environmental Enrichment. At PD53, rodents underwent the resident-intruder test to evaluate social behaviors. Results revealed that environmental enrichment increased neurogenesis and social interaction in females. In males, environmental enrichment increased neurogenesis and agonistic behavior. Enriched male mice expressed higher levels of agonistic-related behavior than female mice housed under the same conditions. Neural circuit analysis showed lower activation in the amygdala of enriched males and higher activation in enriched females than their respective controls. Enriched females also showed higher activation in the frontal cortex without differences in male groups. Moreover, the insular cortex was less activated in females than in males. Thus, our results indicate that environmental enrichment has different effects on neuroplasticity and social/agonistic behavior in FVB/N mice, suggesting the relevance of sexual dimorphism in response to environmental stimuli.

Preference and possible consumption of provided enrichment and bedding materials and disinfectant powder by growing pigs

Background

Domestic pigs have an evolutionary conserved exploratory behaviour. To comply with this requirement, the European Union aims at setting standards for appropriate enrichment materials for pigs (Council Directive 2008/120/EC). As recommended characteristics include ‘chewable’ and ‘edible’, pigs might also consume these materials (Commission Recommendation (EU) 2016/336), which are often additionally advertised to enhance lying comfort and hygienic conditions in stables. To date, a wide range of bedding, enrichment and disinfectant materials is available on the market to ensure environmental enrichment, a dry, hygienic environment or lying comfort. Previous studies revealed considerable amounts of undesirable substances in some of these materials possibly being a risk for food safety considering oral uptake by the animal. To determine interest and indicators for consumption of different types of materials by pigs during exploratory behaviour, a camera-assisted observational study with 12 female pigs (German Landrace) was conducted. We tested their preference for a disinfectant powder, peat, biochar and straw as reference material in a 4 × 6 factorial arrangement.

Results

Pigs manipulated and consumed all offered materials. However, longest manipulation time per pig was observed for biochar (63 min/day) and peat (50 min/day) (p < 0.05). Analyses of the bulk molecular-chemical composition and n-alkanes and acid insoluble ash as markers in the materials and in faeces clearly revealed the consumption of these materials by pigs.

Conclusions

Whether the consumption of considerable amounts together with certain levels of undesirable substances represents a risk for pig and consumer health could yet not be established. Future studies will address the quantitative contribution of undesirable substances by oral ingestion of bedding and enrichment materials and disinfectant powders to the daily feed ration.

Environmentally enriched housing conditions affect pig welfare, immune system and gut microbiota in early life

BACKGROUND

Conventional pig housing and management conditions are associated with gastrointestinal pathophysiology and disease susceptibility in early life. Developing new strategies to reduce both therapeutic and prophylactic antibiotic use is urgent for the sustainable swine production globally. To this end, housing methodology providing effective environmental enrichment could be a promising alternative approach to reduce antibiotic usage, as it has been proven to positively influence pig welfare and immune status and reduce susceptibility to infections. It is, however, poorly understood how this enriched housing affects systemic and local pulmonary immune status and gut microbiota colonization during early life. In the present study, we compared the effects of two housing conditions, i.e., conventional housing: (CH) versus enriched housing (EH), on immune status and gut microbiota from birth until 61 days of age.

RESULTS

The expected benefits of enrichment on pig welfare were confirmed as EH pigs showed more positive behaviour, less aggression behaviour during the weaning transition and better human animal relation during the post weaning phase. Regarding the pigs' immune status, EH pigs had higher values of haemoglobin and mean corpuscular volume in haematological profiles and higher percentages of T cells and cytotoxic T cells in peripheral blood. Furthermore, EH pigs showed higher ex vivo secretion of IL1ß and TNF-α after lipopolysaccharide stimulation of whole blood than CH pigs. The structure of the developing faecal microbiota of CH and EH pigs significantly differed as early as day 12 with an increase in the relative abundance of several bacterial groups known to be involved in the production of short chain fatty acids, such as Prevotella_2, Christensenellaceae_R_7_group and Ruminococcus gauvreauii group. Furthermore, the main difference between both housing conditions post weaning was that on day 61, CH pigs had significantly larger inter-individual variation of ileal and colonic microbiota than EH pigs. In addition to housing, other intrinsic factors (e.g., sex) were associated with gut microbiota development and immune competence.

CONCLUSIONS

In addition to the known welfare benefits for pigs, environmentally enriched housing also positively drives important aspects of the development of the immune system and the establishment of gut microbiota in early life. Consequently, EH may contribute to increasing productivity of pigs and reducing antibiotic use.

Tail Docking of Piglets 2: Effects of Meloxicam on the Stress Response to Tail Docking

This experiment assessed the efficacy of the cauterisation procedure with or without pain relief (injectable meloxicam) in mitigating the acute stress response to tail docking. Male piglets (n = 432) were allocated to the following treatments at 2-d post-farrowing: (1) no handling, (2) sham handling, (3) tail docked using clippers, (4) tail docked using a cauteriser, (5) meloxicam + clipper, and (6) meloxicam + cauteriser. Meloxicam treatments used Metacam^® at 5 mg/mL injected i.m. 1 h prior to tail docking. Blood samples were collected at 15 and 30 min post-treatment and analysed for total plasma cortisol. Behaviours indicative of pain such as escape attempts, vocalisations and standing with head lowered were measured. The duration of vocalisations and frequency of escape attempts during treatment were greater in all tail docking treatments compared to the sham treatment. Piglets in the clipper treatment had higher (p < 0.05) cortisol concentrations at 30 min but not 15 min after treatment and stood for longer (p < 0.001) with head lowered in the first 60 min after treatment than those in the cauterisation treatment. Meloxicam reduced (p < 0.05) both the cortisol response at 30 min after tail docking with the clipper as well as the behavioural response in the first 60 min after tail docking with the clipper. In comparison to the sham treatment, cortisol concentrations at 15 min were higher in the two tail docking treatments whereas the tail docking treatments with meloxicam were similar to the sham handling treatment. In comparison to the sham handling treatment, cortisol concentrations at 30 min post-docking were higher (p < 0.05) only in the clipper treatment. While cauterisation appears to be less aversive than the clipper procedure, the administration of meloxicam did not mitigate the behavioural response during tail docking using either procedure, but reduced standing with head lowered in the first hour after docking for both methods. The commercial viability of administration of meloxicam requires consideration before it is recommended for use compared to cauterisation alone, as it requires additional handling of piglets and costs.

Providing Effective Environmental Enrichment to Pigs: How Far Have We Come?

Science has defined the characteristics of effective environmental enrichment for pigs. We provide an overview of progress towards the provision of pig enrichment in the three largest global pork producing regions. In the USA, enrichment has not yet featured on the policy agenda, nor appeared on farms, except when required by certain farm assurance schemes. China has very limited legal animal welfare provisions and public awareness of animal welfare is very low. Food safety concerns severely restrict the use of substrates (as enrichment) on farms. Providing enrichment to pigs is a legal requirement in the EU. In practice, enrichment is not present, or simple (point-source) objects are provided which have no enduring value. Other common issues are the provision of non-effective or hazardous objects, inadequate presentation, location, quantity and size or inadequate maintenance of enrichment. Improvements can be made by applying principles from the field of experimental analysis of behaviour to evaluate the effectiveness of enrichment; providing welfare knowledge transfer, including training and advisory services; highlighting the economic benefits of effective enrichment and focusing on return on investment; increasing pressure from the financial sector; using novel drivers of change, such as public business benchmarking. The poor implementation of scientific knowledge on farms suggests that the pig industry has not fully embraced the benefits of effective enrichment and is still a long way off achieving an enriched pig population.