Impact of early socialization environment on social behavior, physiology and growth performance of weaned piglets

Impact of environmental enrichment on growth, behavior, and welfare of weanling piglets from pre-weaning to 6 weeks of age

The experiment was carried out to study the effect of environmental enrichment before and after weaning on the growth, behaviours, and welfare of weaning pigs. A total of 360 weaning pigs (average initial body weight 6.32 ± 0.10 kg) were randomly allotted to one of the three treatments on the basis of initial body weight. A completely randomized design was used to conduct this study. There were ten pigs per pen, with 6 replicates for each treatment. The experimental treatments were control; WBW-1, play object included one week before weaning/not included; and WBW-2, play object included two weeks before weaning/not included. Weaning pigs raised under environmental enrichment treatments had greater average daily gain and average daily feed intake in phase 1 and greater average daily gain and average daily feed intake in phase 2 and overall than pigs reared in the control group. However, treatment and interaction between treatment and play object installation did not exhibit significant differences. The WBW-1 exhibited a lower body weight coefficient of variation of weaning pigs in phase 1 and phase 2 than weaning pigs that were raised in the control group, however, the interaction between treatment and enriched environment did not show significant differences in phase 1 and 2. The incidence of diarrhea was numerically reduced by enriched environment effect in early phase 1 (d 7) and there were no significant differences in d 14 and d 28. Behaviour traits results showed lower agonistic behaviour, including tail and ear biting by enriched environment effect in phase 1. The enriched environment reduced the skin lesion score in phase 1, however, there were no significant differences in skin lesion score in phase 2. The concentration of hair cortisol was reduced by enriched environment effect at the end of phase 2. These findings suggest that environmental enrichment prior to the weaning process increased growth, group uniformity, and reduced incidence of diarrhea, agonistic behaviour, skin lesions, and concentration of hair cortisol during the post-weaning period. Impact of environmental enrichment on growth, behavior, and welfare of weanling piglets from pre-weaning to 6 weeks of age.

Environmental enrichment affects immunity and reduces disease severity in pigs after co-infection, with stronger effects when applied from birth than from weaning

We investigated whether environmental enrichment applied at different life stages of pigs affects the susceptibility to and severity of disease by studying immune cell functions around weaning and during nursery, the effects of infection in ex vivo models and in vivo using a co-infection model of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) followed by an Actinobacillus pleuropneumoniae infection. Pigs were either conventionally housed (CCH) or enriched housed throughout life, with enrichment consisting of extra space, rooting materials and co-mingling with another litter before weaning (EEH), or they were switched from conventional to enriched housing at weaning (CEH). Sixty days after birth, ten pigs per treatment were infected with PRRSV followed by an A. pleuropneumoniae infection eight days later. Six other pigs per treatment were euthanized before their pen mates were exposed to the co-infection. From these piglets, bronchial-alveolar fluid was collected, and precision cut lung slices were taken to test the effect of the treatments in an in vitro infection model. At six days after weaning EEH pigs had higher whole blood cell counts and higher concentrations of IL1ß and TNFα than CCH and CEH pigs. In the ex vivo precision cut lung slice model no differences in cytokine response in lung tissue after infection with swine influenza or A. pleuropneumoniae were observed between treatments. After experimental co-infection the proportion of EEH pigs with lung lesions (3/10) tended to be lower than in CCH (8/10), with CEH (6/10) being in between. In conclusion, enriched housing from birth reduced disease severity to co-infection with PRRSV and A. pleuropneumoniae. Enrichment applied after weaning also seemed to decrease the pathological lung deviations to the co-infection as compared to barren housed pigs, but to a much lower extent.

Precise evaluation of the nutritional value of yeast culture and its effect on pigs fed low-protein diets

The purpose of the present study was to assess the nutritional value of yeast culture (YC) and to explore the effect of YC on growth performance and health of piglets fed low-protein diets. In Exp. 1, 12 growing barrows were allocated into control diet and YC diet treatments to determine the available energy of YC. Results showed that the digestible energy and metabolizable energy of YC are 12.12 and 11.66 MJ/kg dry matter (DM), respectively. In Exp. 2, 12 growing barrows were surgically equipped with a T-cannula near the distal ileum and were assigned to 2 dietary treatments (nitrogen-free diet and YC diet), and the amino acid digestibility of YC was determined. In Exp. 3, a total of 96 weaned piglets were randomly divided into 4 treatments, including low-protein basal diet (Basal), Basal + 0.5% YC (0.5%YC), Basal + 1.0% YC (1.0%YC), and Basal + 1.5% YC (1.5%YC). The results were as follows: YC supplementation linearly improved the weight gain and feed intake ratio (P < 0.001), linearly increased the activity of glutathione peroxidase on d 14 (P = 0.032) and linearly decreased the concentration of malondialdehyde on d 14 (P = 0.008) and d 32 (P = 0.004) in serum, and linearly decreased the concentration of total short-chain fatty acid on d 14 in feces (P = 0.045). Compared with other treatments, 1.5%YC group showed a greater abundance of various probiotics, such as Prevotellaceae, Prevotella and Turicibacter. In Exp. 4, twelve growing barrows with an ileal T-cannula were randomly assigned to Control and 1.5%YC treatments to clarify the impact of YC supplementation on nitrogen balance and nutrient digestibility. Results showed that YC had no significant effect on nitrogen efficiency and nutrient digestibility, except for trend of reducing the total tract digestibility of organic matter (P = 0.067). In conclusion, the present study assessed the digestible and metabolizable energy values (12.12 and 11.66 MJ/kg DM, respectively) and standardized ileal digestibility of amino acid (from 43.93% to 82.65%) of YC in pig feed and demonstrated that moderate supplementation of YC (1.5% of diet) can effectively improve feed conversion efficiency, enhance antioxidant capacity, and promote a balanced gut microbiota in piglets.

Early behavioral indicators of aberrant feces in newly-weaned piglets

BACKGROUND

Post-weaning diarrhea (PWD) is a frequently occurring health and welfare issue in weaned piglets. Behavioral changes indicating impaired health may be detectable before the onset of signs and could be useful to detect the development of PWD early, enabling targeted and timely interventions. Current algorithms enable automated behavioral classification on the group level, while PWD may not affect all piglets in one pen and individual level analysis may be required. Therefore, this study aimed to assess whether changes in pen activity or individual piglet behavior can be early indicators of the occurrence of PWD. During 3 replicated rounds, 72 piglets (Sus scrofa domestica, Landrace x Large White) weaned at 27 days of age, were housed in 4 pens with 6 piglets each. Individual fecal color and consistency were scored (0-5; ≥ 3 considered as aberrant feces) six times during the first two weeks post-weaning using rectal swabs. Additionally, using a similar scoring scale, feces on the pen floor were assessed daily. Two methods were applied for behavioral scoring. Individual behaviors (eating, drinking, standing, walking; n = 48) were scored manually and instantaneously with a five-minute interval from videos of the first two rounds, while pen activity (eating, drinking, moving; n = 12) was analyzed automatically and continuously using a commercially available algorithm from videos of all three rounds.

RESULTS

Piglets showing a relatively higher proportion of standing behavior one day before fecal scoring had increased odds of an aberrant fecal color score (odds ratio (OR): 4.8; 95% confidence interval (CI): 1.5-15.3). Furthermore, odds of aberrant colored feces increased in pens where piglets showed more moving activity two days before (OR: 6.14; 1.26 < 95%CI < 29.84), which was also found for fecal consistency (OR: 4.77; 95%CI: 1.1-21.6).

CONCLUSIONS

Our results indicate that increased standing in individual piglets and an increased moving activity on the pen level may be important behavioral indicators of PWD before the onset of diarrhea. Further development of current algorithms that can identify behavioral abnormalities in groups, from the pen to the individual level, may therefore be a promising avenue for improved and targeted health and welfare monitoring.

Burlap and buddies: the effects of social enrichment (preweaning mixing) and object enrichment (burlap) on piglet performance, behavior, and welfare in the preweaning environment

When weaned in commercial operations, piglets are not only separated from their sow but also mixed with unfamiliar pigs in an unfamiliar environment with a new diet. These abrupt changes can be stressful for piglets, often having negative welfare consequences. Our objective was to study the effects of early-life preweaning socialization and object enrichment in the preweaning environment. We compared piglet performance, behavior, and welfare across six treatments that combined multi-litter group size (1 vs. 2 vs. 4 litters) and burlap (yes vs. no). We recorded piglet behavior and lesion-scored sows and piglets. Normal conforming data, expressed per experimental unit (and behavior data were averaged over time), were analyzed by ANOVA. When given the opportunity in the sow barn, piglets in multi-litter groups socialized with other litters. Burlap use (P = 0.08) was observed in < 5% of the observations but tended to increase in mixed litter groups. Cross-sucking was observed in ~12% of the observations within mixed litter groups and tended to increase with mixed group size (P = 0.08). While there was no difference in the proportion of piglets nursing (P > 0.10), piglets were less active in the single crate groups and most active in the groups of two litters mixed (P = 0.03). Additionally, observed piglet/sow biting behaviors did not differ between treatments; however, piglet-piglet biting (P = 0.07), and pen object manipulation (P = 0.07) tended to be observed more frequently in non-enriched groups. Piglet displacements were observed more often in non-enriched groups around the pen (P = 0.03) but tended to be observed more often in enriched groups at the teat (P = 0.07). Preweaning socialization and object enrichment had no impact on the average number of piglets weaned per sow or total piglet mortality (P > 0.10). However, the proportion of laid-on piglets decreased as the number of mixed litters increased (P = 0.02). The average number of lesions per piglet did not differ between treatments. Although the final lesion scores of sow teat and udder condition did not differ between treatments (P > 0.10), sow udder scores tended to worsen more in the single litters than in the mixed litters (P = 0.08). Overall, social and object enrichment allows piglets to socialize at a younger age and to redirect their attention toward an object (burlap) which does not negatively impact piglet or sow performance, or behavior, and may improve piglet welfare around weaning.

Burlap and buddies: the effects of social enrichment (preweaning mixing) and object enrichment (burlap) on piglet behavior and welfare in the postweaning environment

The process of weaning piglets in commercial swine operations subjects them to numerous abrupt and stressful changes often resulting in negative welfare consequences. The objective was to study the postweaning effects of early-life (1 to 3 d of age) preweaning socialization in multi-litter groups as well as object enrichment (burlap sheet) in the pre- and postweaning environment by comparing six treatments that combined mixing of one vs. two vs. four litters mixed preweaning with and without burlap provision. An ANOVA linear model was run on all normal data, expressed per experimental unit (and behavior data were averaged over time), while non-normal data were analyzed using the Kruskal-Wallis test. Non-enriched groups of piglets were observed manipulating pen objects more often than the enriched groups (P = 0.005). Biting behaviors, including the chewing of ears and tails of pen-mates but excluding fighting, were observed the least in groups of pigs of four litters mixed preweaning, while piglets that were not mixed preweaning were observed biting the most (P = 0.03). Piglets who were not mixed preweaning also manipulated the burlap more frequently than the piglets from groups of 4 litters mixed preweaning (P = 0.02). Biting (P < 0.001) and displacements (P = 0.03) and fighting (P = 0.002) throughout the pen were observed less in the enriched groups. There were fewer lesions per pig in the enriched groups vs. non-enriched groups initially (P = 0.07) and 1 wk after weaning (P = 0.10). Furthermore, pigs mixed in groups of four litters preweaning also tended to have lower lesion scores (P = 0.07) 1-wk postweaning compared to the other treatments. However, there were no differences between treatments in the proportion of piglets resting, eating/drinking, being active, or using the burlap, or for the observed frequency of displacements at the feeder, social behaviors, or belly nosing (P > 0.10). Overall, social enrichment encourages socialization with unfamiliar conspecifics at a younger age while object enrichment allows pigs to redirect their attention toward objects such as burlap. Both may improve pig behavior and welfare after weaning.

Effects of socialising piglets on sow and piglet performance and behaviour of entire male piglets

Entire male pigs show more aggressive behaviour and mounting than female pigs. By sorting growing pigs into male and female pens, at least half of the pigs are protected from the aggressive behaviour and mounting of the entire males. Mixing of unknown pigs provokes them to perform such behaviours which increase the risk for injuries. The idea behind socialising piglets is to create groups of piglets from several litters that become familiar with each other and thus show less aggressive behaviour and mounting later, when housed together after weaning. The effect of socialising piglets on animal welfare was studied on 24 sows and their 235 piglets. Male piglets were not castrated. Sows were housed in individual farrowing pens without crates. A small door was opened between two adjacent pens at a piglet age of two weeks for half of the litters (12 litters), and the other half was regarded as a control (12 litters). At weaning, control piglets were kept in groups of eight litter mates whereas socialised piglets were kept in groups of either eight entire males or eight females from two litters. Sow weight, body condition and health were recorded together with nursing events and social behaviour of piglets (aggressive, mounting, contact). There was no effect of socialisation on udder lesions or sows' relative change in body reserves. Socialised and control piglets did not differ in daily weight gain before weaning, but socialised piglets tended to have higher growth rate during the week after weaning (P = 0.07). The day after opening between pens, skin lesions were more common among socialised piglets (as compared to control piglets at the same age, P = 0.02) but at weaning, skin lesions were more common among control piglets than socialised piglets (P = 0.01). Almost all lesions were mild. No aggressive behaviour of sows towards piglets was observed. No difference between control and socialised piglets in social behaviour was seen before weaning. The frequency of aggressive and mounting behaviours was low after weaning for both socialised and control piglets, but socialised piglets showed more contact behaviour (P = 0.02). Socialised entire males showed as little aggressive and mounting behaviour as females. Nursing frequency was not affected by piglet socialisation and cross-suckling was rare. Based on the performance of piglets and sows, nursing frequency, and health of piglets and sows, we conclude that socialising entire male piglets (and their sisters) improve piglet welfare without any negative effect on the sows.

Socializing Models During Lactation Alter Colonic Mucosal Gene Expression and Fecal Microbiota of Growing Piglets

The enrichment of the social environment during lactation alleviates the stress of weaned piglets. It is significant to understand how the enriched social environment improves the weaning stress of piglets. RNA sequencing (RNA-seq) of colonic mucosa, 16S rRNA sequencing of feces, and short-chain fatty acids (SCFAs) of colonic content were used to determine the effects of social contact during lactation. In this study, thirty litter lactating piglets were divided into intermittent social contact (ISC) group that contacted with neighbors intermittently, continuous social contact (CSC) group that contacted with neighbors starting at day (D) 14 after birth, and control (CON) group in which piglets were kept in their original litter. The piglets were weaned at D35 and regrouped at D36. The colonic mucosal RNA-seq, fecal microbes, and SCFAs of colonic contents of 63-day-old piglets were analyzed. The results of RNA-seq showed that compared with the CON group, the pathways of digestion and absorption of minerals, protein, and vitamins of piglets were changed in the ISC group, whereas the pathways of retinol metabolism and nitrogen metabolism in the colonic mucosal were affected and stimulated the immune response in the CSC group. Compared with the CON group, the abundances of pernicious microorganisms (Desulfovibrio, Pseudomonas, Brevundimonas, etc.) in the CSC group and pernicious microorganisms (Desulfovibrio, Neisseria, Sutterella, etc.) and beneficial bacteria (Bifidobacterium, Megamonas, and Prevotella_9) in the ISC group were significantly higher (p < 0.05). The abundances of proinflammatory bacteria (Coriobacteriaceae_unclassified, Coprococcus_3, and Ruminococcus_2) in the CSC group were significantly increased (p < 0.05), but the abundances of SCFAs producing bacteria (Lachnospiraceae_UCG-010, Parabacteroides, Anaerotruncus, etc.) and those of anti-inflammatory bacteria (Eubacterium, Parabacteroides, Ruminiclostridium_9, and Alloprevotella) were significantly reduced (p < 0.05) in the CSC group. Compared with the CON group, the concentrations of microbial metabolites, acetate, and propionate in the colonic contents were reduced (p < 0.05) in the ISC group, whereas the concentration of acetate was reduced (p < 0.05) in the CSC group. Therefore, both ISC and CSC during lactation affected the composition of fecal microbes and changed the expression of intestinal mucosal genes related to nutrient metabolism and absorption of piglets.

Early social contact alters the community structure and functions of the faecal microbiome in suckling-growing piglets

Social contact during suckling, in an enriched social environment, can reduce the aggressive behaviours of piglets during regrouping at weaning, and improve their production performance and welfare. The aim of this study was to determine the possible impact of suckling social contact on gut microbes. We performed 16S rRNA sequencing to measure the faecal microbial structure and function in piglets experiencing social contact. Eighteen-litter piglets were allocated to two treatments: an early continuous social contact (CSC) group where piglets from adjacent pens shared a mutual pen starting at 14 days postpartum and a control (CON) group where piglets had no contact with individuals from adjacent pens during the suckling period. The piglets were regrouped at 36 days of age. The litter weights at 35 and 63 days of age were measured. Faecal samples were randomly collected at 16, 35, 42, and 63 days of age and faecal DNA was determined. The results showed that the litter weight of piglets in the CSC group was significantly decreased at 63 days compared with the CON group. Continuous social contact also significantly decreased the microbial richness at 16 and 35 days of age (P < 0.05). Firmicutes was the most abundant bacterial phylum in both groups at all detected time-points and the abundance increased with social contact. At the genus level, Lactobacillus was the most abundant bacterium after weaning and the abundance increased in the piglets with social contact. Compared with the faecal microbiota of control piglets, a total of 22 genera at 16 days, 20 genera at 35 days, 12 genera at 42 days, and 27 genera at 63 days in the faeces of CSC piglets were observed to be significantly different in abundance (linear discriminant analysis score > 3, P < 0.05). Furthermore, functional analysis of the microbial composition showed that the changes induced by early CSC mainly altered the relative abundance of metabolic and related pathways. The social contact notably had an effect on the abundance of microbial pathways for amino acid and carbohydrate metabolism. In conclusion, CSC changed the microbial composition in the faeces of piglets, which might have a negative effect on nutrient metabolism for the suckling-growing piglets. Our study provided new insight into the influence of social contact on the suckling-growing piglets.

Early socialisation in group lactation system reduces post-weaning aggression in piglets

BACKGROUND

Pre-weaning group housing for sows and their litters is expected to enhance animal welfare. However, knowledge of potential benefits of pre-weaning socialisation for piglets after weaning is still lacking.

METHODS

Weaner pigs were mixed in groups of 10, using littermates (LM) from pre-weaning group housing (Gr) and from farrowing pens with crates (Co). Groups were formed as follows: Gr/Gr (5 LM from Gr + 5 LM from Gr), Gr/Co (5 LM from Gr + 5 LM from Co), Co/Co (5 LM from Co + 5 LM from Co).

RESULTS

During 24 h after mixing, piglets in Co/Co fought more than in Gr/Co and Gr/Gr. Piglets in Co/Co had more unclear fighting results than in Gr/Co and Gr/Gr. Four days after mixing, piglets in Co/Co were more injured than in Gr/Co and Gr/Gr.

CONCLUSION

Early socialised piglets may have better social skills when meeting familiar and unfamiliar conspecifics after weaning.