Effects of Transport at Weaning on the Behavior, Physiology and Performance of Pigs

miRNA Expression Analysis of IPEC-J2 Cells Damaged by Soybean 7S Globulin Reveals ssc-miR-221-5p as the Factor Alleviating Cell Damage

The most significant and sensitive antigen protein that causes diarrhea in weaned pigs is soybean 7S globulin. Therefore, identifying the primary target for minimizing intestinal damage brought on by soybean 7S globulin is crucial. MicroRNA (miRNA) is closely related to intestinal epithelium's homeostasis and integrity. However, the change of miRNAs' expression and the function of miRNAs in Soybean 7S globulin injured-IPEC-J2 cells are still unclear. In this study, the miRNAs' expression profile in soybean 7S globulin-treated IPEC-J2 cells was investigated. Fifteen miRNAs were expressed differently. The differentially expressed miRNA target genes are mainly concentrated in signal release, cell connectivity, transcriptional inhibition, and Hedgehog signaling pathway. Notably, we noticed that the most significantly decreased miRNA was ssc-miR-221-5p after soybean 7S globulin treatment. Therefore, we conducted a preliminary study on the mechanisms of ssc-miR-221-5p in soybean 7S globulin-injured IPEC-J2 cells. Our research indicated that ssc-miR-221-5p may inhibit ROS production to alleviate soybean 7S globulin-induced apoptosis and inflammation in IPEC-J2 cells, thus protecting the cellular mechanical barrier, increasing cell proliferation, and improving cell viability. This study provides a theoretical basis for the prevention and control of diarrhea of weaned piglets.

Purine Metabolism and Hexosamine Biosynthetic Pathway Abnormalities in Diarrheal Weaned Piglets Identified Using Metabolomics

Post-weaning diarrhea significantly contributes to the high mortality in pig production, but the metabolic changes in weaned piglets with diarrhea remain unclear. This study aimed to identify the differential metabolites in the urine of diarrheal weaned piglets and those of healthy weaned piglets to reveal the metabolic changes associated with diarrhea in weaned piglets. Nine 25-day-old piglets with diarrhea scores above 16 and an average body weight of 5.41 ± 0.18 kg were selected for the diarrhea group. Corresponding to the body weight and sex of the diarrhea group, nine 25-month-old healthy piglets with similar sex and body weights of 5.49 ± 0.21 kg were selected as the control group. Results showed that the serum C-reactive protein and cortisol of piglets in the diarrhea group were higher than those in the control group (p < 0.05). The mRNA expression of TNF-α, IFN-γ in the jejunum and colon, and IL-1β in the jejunum were increased in diarrhea piglets (p < 0.05), accompanied by a reduction in the mRNA expression of ZO-1, ZO-2, and CLDN1 in the jejunum and colon (p < 0.05); mRNA expression of OCLN in the colon also occurred (p < 0.05). Metabolomic analysis of urine revealed increased levels of inosine, hypoxanthine, guanosine, deoxyinosin, glucosamine, glucosamine-1-p, N-Acetylmannosamine, chitobiose, and uric acid, identified as differential metabolites in diarrhea piglets compared to the controls. In summary, elevated weaning stress and inflammatory disease were associated with the abnormalities of purine metabolism and the hexosamine biosynthetic pathway of weaned piglets. This study additionally indicated the presence of energy metabolism-related diseases in diarrheal weaned piglets.

Consequences of Transport Conditions on the Welfare of Slaughter Pigs with Different Health Status and RYR-1 Genotype

This study assessed the influence of transport conditions on welfare indicators of slaughter pigs with different health status and RYR-1 genotype. The group of pigs, predominantly consisting of Nn (56.67%) and subclinically diseased (60.00%) individuals, that were exposed to short transportation (<30 min) at high loading density (~235 kg/m2) had the highest slipping (p < 0.0001), falling (p = 0.0009), turning back (p < 0.0001), reluctance to move (p < 0.0001), panting (p < 0.0001) and shivering (p < 0.0001) frequencies at unloading. Subclinically diseased Nn pigs subjected to short transportation (<30 min) and high loading density (~235 kg/m2) had the highest lactate (p < 0.0001 and p < 0.0001), glucose (p = 0.0450 and p = 0.0002), CK (p < 0.0001 and p = 0.0010), LDH (p < 0.0001 and p = 0.0484), AST (p = 0.0208 and p = 0.0170), ALT (p = 0.0500 and p = 0.00081), ceruloplasmin (p = 0.0334 and p < 0.0001) and MDA (p = 0.0048 and p < 0.0001) concentrations, but the lowest sodium (p < 0.0001 and p < 0.0001), chloride (p = 0.0001 and p = 0.0432), albumin (p < 0.0090 and p < 0.0001), PON-1 (p = 0.0122 and p = 0.0500) and GSH (p = 0.0042 and p = 0.0340) levels, respectively. In the group consisting of of stress-resistant (100%) and predominantly healthy (60.00%) pigs subjected to short transportation (<30 min) at high loading density (~235 kg/m2), none of the individuals showed irregular behavioural reactions during unloading. Healthy NN pigs that underwent short transportation (<30 min) at high loading density (~235 kg/m2) had the lowest lactate (p < 0.0001 and p < 0.0001), glucose (p = 0.0450 and p = 0.0002), CK (p < 0.0001 and p = 0.0010), LDH (p < 0.0001 and p = 0.0484) and ceruloplasmin (p = 0.0334 and p < 0.0001) levels, but the highest sodium (p < 0.0001 and p < 0.0001) and chloride (p = 0.0001 and p = 0.0432) concentrations, respectively. In conclusion, the most compromised welfare was recorded in subclinically diseased Nn pigs exposed to short transportation (<30 min) and high loading density (~235 kg/m2), while under the same conditions, the welfare of healthy NN pigs was not compromised. Therefore, stress-carrier pigs with subclinical pathological lesions should not be considered fit for transportation, indicating that the health status and genotype are the key factors for optimising pig welfare.

The Effect of Sodium Alginate-Coated Nano-Zinc Oxide on the Growth Performance, Serum Indexes and Fecal Microbial Structure of Weaned Piglets

High dose of zinc oxide (ZnO) could improve growth performance and alleviate disease status, whereas it caused serious environmental pollution and bacterial resistance. This study was to investigate whether low doses of sodium alginate-coated nano zinc oxide (saZnO), a new type of zinc resource, could serve as a potential alternative to pharmacological doses of traditional ZnO in weaned piglets. A total of 144 crossbred piglets were randomly allocated into three groups, including a basal diet without the addition of Zn (CON), a basal diet with 1600 mg Zn/kg from traditional ZnO (ZnO), and a basal diet with 500 mg Zn/kg from saZnO (saZnO). The experiment lasted for 28 days. The results showed that supplementing with ZnO and saZnO for 14 and 28 days significantly improved body weight (BW) and average daily gain (ADG) (p < 0.01) and markedly reduced the feed intake-to-gain ratio (F/G) (p < 0.05) and diarrhea rate. In addition, dietary ZnO and saZnO significantly increased the activities of the total antioxidant capacity (T-AOC) and alkaline phosphatase (ALP) (p < 0.01). Supplementing with saZnO also promoted the levels of superoxide dismutase (SOD), IgM and copper- and zinc-containing superoxide dismutase (Cu/Zn-SOD) in serum (p < 0.05), whereas a ZnO addition decreased the concentration of malondialdehyde (MDA) (p < 0.05), indicating the beneficial effect of Zn on antioxidant and immune functions. Piglets fed the ZnO diet showed higher serum Zn accumulations than those fed the CON and saZnO diets at d 28 (p < 0.01), and supplementing with ZnO and saZnO markedly contributed to Zn excretion in feces, especially in the ZnO diet (p < 0.01). Additionally, piglets fed the saZnO diet had greater valeric acid concentrations (p < 0.05) in their feces, while other short chain fatty acids (SCFAs) were not affected by different treatments (p > 0.05). Microbial alpha diversity was reduced in the saZnO group compared with the CON group (p < 0.05), while an obvious separation of microbial composition, the marker of beta diversity, was shown among the three groups (p < 0.05). At the genus level, six genera, including Clostridium_sensu_stricto_1, Terrisporobacter, f_Muribaculaceae, Subdoligranulum and Intestinibacter, were pronouncedly increased in the ZnO and saZnO groups (p < 0.05); another nine species were dramatically downregulated, such as f_Lachnospiraceae, f_Prevotellaceae, f_Butyricicoccaceae and f_Ruminococcaceae (p < 0.05). Finally, a functional analysis indicated that altered microbes significantly changed the "Metabolism" pathway (p < 0.05). These findings suggested that saZnO could act as a feasible substitute for ZnO to reduce Zn emission and enhance growth performance, antioxidant and immune functions, and to adjust the structure of gut microbiota in piglets.

Impact of Early Weaning on Development of the Swine Gut Microbiome

Considering that pigs are naturally weaned between 12 and 18 weeks of age, the common practice in the modern swine industry of weaning as early as between two and four weeks of age increases challenges during this transition period. Indeed, young pigs with an immature gut are suddenly separated from the sow, switched from milk to a diet consisting of only solid ingredients, and subjected to a new social hierarchy from mixing multiple litters. From the perspective of host gut development, weaning under these conditions causes a regression in histological structure as well as in digestive and barrier functions. While the gut is the main center of immunity in mature animals, the underdeveloped gut of early weaned pigs has yet to contribute to this function until seven weeks of age. The gut microbiota or microbiome, an essential contributor to the health and nutrition of their animal host, undergoes dramatic alterations during this transition, and this descriptive review aims to present a microbial ecology-based perspective on these events. Indeed, as gut microbial communities are dependent on cross-feeding relationships, the change in substrate availability triggers a cascade of succession events until a stable composition is reached. During this process, the gut microbiota is unstable and prone to dysbiosis, which can devolve into a diseased state. One potential strategy to accelerate maturation of the gut microbiome would be to identify microbial species that are critical to mature swine gut microbiomes, and develop strategies to facilitate their establishment in early post-weaning microbial communities.

Road Transport: A Review of Its Effects on the Welfare of Piglets

The purpose of this review is to present the best available scientific knowledge on key effects of pre-transport and transport factors influencing the response of piglets to transport stress and post-transport recovery. To date, research on piglet transportation particularly focused on the effects of season (i.e., heat and cold stress), vehicle design features (ventilation type and deck/compartment location), space allowance and transport duration, and piglet genetics. More specifically, in this review the effect of transport duration has been dealt with through its impact on death rate, behaviour and physiological response, and feeling of hunger and thirst. Based on the available literature, clear conclusions can be drawn on the vulnerability of piglets to heat stress during transport. Both short and long transportation have an effect on piglet welfare, with effects being biased by the genetic background, ambient conditions and vehicle design. Further studies investigating the impact of factors such as vehicle design, truck stocking density and environment, piglet genetic background, and weaning age are needed.

The Effect of an Essential Oil Blend on Growth Performance, Intestinal Health, and Microbiota in Early-Weaned Piglets

Essential oils (EO) are promising feed additives for their antibacterial, antioxidant, and immune-enhancing abilities with low toxicity. Carvacrol, thymol, and cinnamaldehyde are commonly used to synthesize EO. However, few studies focus on combining these three EO in early-weaned piglets. In the present study, 24 piglets weaned at 21 d of age were randomly divided into 2 groups (6 replicate pens per group, 2 piglets per pen). The piglets were fed a basal diet (the control group) and a basal diet supplemented with 400 mg/kg EO (a blend consisting of carvacrol, thymol, and cinnamaldehyde, the EO group) for 28 days. At the end of the experiment, one piglet per pen was randomly chosen to be sacrificed. Growth performance, hematology, plasma biochemical indices, antioxidant capacity, intestinal epithelial development and immunity, colonic volatile fatty acids (VFA), and microbiota were determined. The results indicated that the diet supplemented with EO significantly improved average daily feed intake (ADFI, p < 0.01) and average daily gain (ADG, p < 0.05) in the day 0 to 28 period. EO supplementation led to a significant decrease in plasma lysozyme (p < 0.05) and cortisol levels (p < 0.01). Additionally, EO significantly promoted jejunal goblet cells in the villus, jejunal mucosa ZO-1 mRNA expression, ileal villus height, and ileal villus height/crypt depth ratio in piglets (p < 0.05). The ileal mucosal TLR4 and NFκB p-p65/p65 protein expression were significantly inhibited in the EO group (p < 0.05). Colonic digesta microbiota analysis revealed that bacteria involving the Erysipelotrichaceae family, Holdemanella genus, Phascolarctobacterium genus, and Vibrio genus were enriched in the EO group. In conclusion, these findings indicate that the EO blend improves ADG and ADFI in the day 0 to 28 period, as well as intestinal epithelial development and intestinal immunity in early-weaned piglets, which provides a theoretical basis for the combined use of EO in weaned piglets.

Effects of short-distance transportation on physiological indexes, intestinal morphology, microbial community, and the transcriptome of the jejunum in weaned piglets

Transportation of livestock is unavoidable in animal production. A total of 72 piglets were randomly divided into the CON group and the TSG group, and the piglets in CON group were transported for two hours. The purpose of this study was to determine the effects of short-distance road transportation lasting 2 h on the jejunum of weaned piglets. Our results showed that compared with the control group, there was no impact on the growth performance of piglets in the transport group (P > 0.05). The concentrations of cortisol, heat shock protein (HSP)70, HSP90, C-reactive protein, interleukin (IL)-6, IL-8, IL-12, and interferon-γ and the activity of reactive oxygen species were increased in the jejunum of piglets in the transport group (P < 0.05 compared with the control group). The concentrations of glutathione peroxidase, claudin-1, occludin, and zonula occludens-1 showed no between-group differences (P > 0.05). Regarding intestinal morphology, the transport group showed infiltration of a small amount of lymphocytes into the jejunum mucosa epithelium that was accompanied by edema of the lamina propria, whereas the control group showed no obvious abnormalities. At the genus level, in the transport group, the 16S rRNA sequencing revealed a downward trend in the relative abundance of Lactobacillus and an upward trend in the relative abundance of Muribaculaceae_unclassified. There was also increased mRNA expression of genes associated with inflammation in the transport group, but the genes and pathways related to apoptosis were not activated. In summary, weaned piglets undergoing 2 h of short-distance road transportation showed stress and inflammatory reactions of the jejunum but did not exhibit oxidative damage or activation of the apoptosis pathway of the jejunum. Furthermore, the growth performance of the piglets was not affected by the trip.

Landscapes of Enteric Virome Signatures in Early-Weaned Piglets

Diarrhea caused by early-weaning-induced stress can increase mortality rates and reduce growth performance of piglets, seriously harming the livestock industry. To date, studies on the gut microbiome of early-weaned piglets have focused almost exclusively on bacteria, while studies on their gut virome are extremely lacking. Here, we used metagenomic and metatranscriptomic sequencing combined with bioinformatic analysis techniques to preliminarily characterize the intestinal virome of early-weaned piglets at different biological classification levels. The alpha diversity of enteroviruses was generally elevated in early-weaned piglets with diarrhea, compared to healthy piglets, whereas the two groups of piglets showed no significant difference in beta diversity. In addition, the species compositions of the gut virome were similar between healthy piglets and piglets with diarrhea, while their respective dominant species were somewhat different. We also identified 58 differential DNA viruses and 16 differential RNA viruses between the two groups of piglets at all biological taxonomic levels. Of these, 1 (family Dhakavirus) and 6 (phylum Artverviricota, class Revtraviricetes, order Ortervirales, family Retroviridae, genus Gammaretrovirus, and species Kirsten murine sarcoma virus) specific viruses disappeared from the intestines of healthy piglets and piglets with diarrhea, respectively. Moreover, we found that some DNA and RNA viruses formed strong correlations among themselves or between them. IMPORTANCE This study systematically reveals the biological diversity, structure, and composition of intestinal DNA and RNA virus profiles in early-weaned piglets. Furthermore, characteristics of differences in gut viromes between early-weaned healthy piglets and piglets with diarrhea were also elucidated. Importantly, some potential biomarkers for early-weaned piglets with diarrhea were identified. These findings fill a gap for the early-weaned piglet gut virome and lay the foundation for the development of strategies to target enteroviruses for the prevention and treatment of early-weaning-induced piglet diarrhea.

Effect of distance and daily periods on heat-stressed pigs and pre-slaughter losses in a semiarid region

Effective planning animal transport is essential to safeguard animal welfare and reduce production losses. Environmental conditions, specifically extreme temperatures in combination with ranges of relative humidity are highlighted as one of the main risk factors for production losses during transport (e.g., fatalities). The majority of research evaluating both welfare and production impacts of pig transport have been primarily undertaken in Europe and North America, which cover a relatively limited range of distinct climates (e.g., temperate, sub-arctic, etc.). As a result, research on pig transport in semi-arid conditions is lacking. In this study, we evaluated the effects of both distance (short, 30 km; and long, 170 km) and transport daily periods (morning, (05:00-11:00); afternoon (12:00-17:00); and night, (23:00-04:00)) on the preslaughter losses and heat stress of pigs in commercial transport in a semiarid region. Across 19 journeys of standard slaughter-weight pig loads (124.0 ± 2.8 kg), 684 focal animals (36 per journey) were evaluated. For each journey, the load's thermal profile (THI_adj and enthalpy) and physiological responses of individual pigs were recorded. On arrival at designated slaughterhouses, the percentage pig of non-ambulatory non-injured (NANI), non-ambulatory injured (NAI), death on arrival (DOA), and total losses were recorded. Short journeys in the afternoon were shown to be more detrimental to the thermal comfort of pigs, with higher rectal temperatures recorded. The highest percentage of total losses and DOA occurred in afternoon journeys, irrespective of distance, followed by the morning, with the lowest losses observed in pigs transported at night. Additionally, total losses and DOA were further exacerbated by journey distance, with higher rates observed in short journeys. Higher percentage averages of NANI and NAI were observed in shorter journeys, but daily periods effects were only observed for NANI. These results further demonstrate the welfare and production loss risks associated with journey distance and time of day (representing varying environmental conditions) during road transport of pigs, whilst providing novel data in semiarid conditions. Careful and effective planning for pig transportation is essential to minimize heat stress and production losses. Consideration of the thermal environment on the day of travel, as well as providing flexibility to adjust travel times (e.g., early morning or evening), should help to mitigate risks of heat stress and production losses during pig transport.

Evidence-Based Recommendations for Herd Health Management of Porcine Post-Weaning Diarrhea

Simple Summary

In this paper, you will find recommendations on how to prevent post-weaning diarrhea in pigs kept in indoor pig herds. The recommendations are based on the scientific knowledge that is currently available. The authors first validated that Danish veterinarians working with pigs demanded such recommendations. Then, we collected papers written by other researchers who had summarized the scientific knowledge on different topics related to post-weaning diarrhea. From the papers, we extracted and synthesized 79 specific recommendations that may help veterinarians and pig producers make good decisions for their pig herd. The paper exemplifies a novel approach to summarizing and transferring science into practice that may be of interest to people that are not involved with pigs and post-weaning diarrhea.

Abstract

Aided by their advising veterinarians, pig producers need to make difficult decisions regarding herd health management strategies. For instance, the preventive use of antimicrobials and medicinal zinc oxide must be substituted with more sustainable preventive approaches to porcine post-weaning diarrhea. Veterinarians and pig producers may find assistance in knowledge based on evidence in this regard; however, the overwhelming scientific literature is not always readily available. The overall aim of this paper is to suggest herd health management decision-support tools that can aid veterinary-assisted decision making in the control of porcine post-weaning diarrhea at a tactical level. The first objective was to validate the need for a herd health management concept, including two decision-support tools. The second objective was to develop evidence-based recommendations that can aid veterinary-assisted decision-making for the herd health management of post-weaning diarrhea. The first objective was investigated by a questionnaire-based study among veterinary pig practitioners in Denmark. For the second objective, we conducted a scientific summary based on scientific review papers identified through a systematic search in three databases. From the papers, we synthesized and extracted 79 specific recommendations. In this paper, we report comprehensive evidence-based recommendations for the herd health management of post-weaning diarrhea.

The Role of Probiotics in Alleviating Postweaning Diarrhea in Piglets From the Perspective of Intestinal Barriers

Early weaning of piglets is an important strategy for improving the production efficiency of sows in modern intensive farming systems. However, due to multiple stressors such as physiological, environmental and social challenges, postweaning syndrome in piglets often occurs during early weaning period, and postweaning diarrhea (PWD) is a serious threat to piglet health, resulting in high mortality. Early weaning disrupts the intestinal barrier function of piglets, disturbs the homeostasis of gut microbiota, and destroys the intestinal chemical, mechanical and immunological barriers, which is one of the main causes of PWD in piglets. The traditional method of preventing PWD is to supplement piglet diet with antibiotics. However, the long-term overuse of antibiotics led to bacterial resistance, and antibiotics residues in animal products, threatening human health while causing dysbiosis of gut microbiota and superinfection of piglets. Antibiotic supplementation in livestock diets is prohibited in many countries and regions. Regarding this context, finding antibiotic alternatives to maintain piglet health at the critical weaning period becomes a real emergency. More and more studies showed that probiotics can prevent and treat PWD by regulating the intestinal barriers in recent years. Here, we review the research status of PWD-preventing and treating probiotics and discuss its potential mechanisms from the perspective of intestinal barriers (the intestinal microbial barrier, the intestinal chemical barrier, the intestinal mechanical barrier and the intestinal immunological barrier) in piglets.

A multi-suckling system combined with an enriched housing environment during the growing period promotes resilience to various challenges in pigs

Little is known about the impact of social and environmental enrichment on improving livestock resilience, i.e. the ability to quickly recover from perturbations. We evaluated the effect of an alternative housing system (AHS) on resilience of pigs, as compared to conventional housing (CONV). The AHS consisted of multi-litter housing during lactation, delayed weaning, extra space allowance and environmental enrichment at all times. We assessed recovery to a 2 h-transport challenge, an LPS injection, 2 h-heat stress and a biopsy wound in 96 pigs. Additionally, indicators of long-term “wear and tear” on the body were determined. AHS pigs had better physiological recoveries with quicker returns to baseline in the transport and LPS challenges, showed lower cortisol accumulation in hairs and lower variance in weight gain over the experimental period compared to conventionally-housed (CONV) pigs. They also had higher levels of natural antibodies binding KLH than CONV pigs. Their response to heat stress revealed a different strategy compared to CONV pigs. Taken together, AHS pigs appear to be more resilient and experience less chronic stress. Enhancing welfare by provision of social and environmental enrichment that better meets the behavioural needs of pigs seems to be a promising approach to improve their resilience.

Field Trial of Factors Associated With the Presence of Dead and Non-ambulatory Pigs During Transport Across Three Colombian Slaughterhouses

Transport by land is an essential component for the commercialization of fattening pigs and can have a negative impact on animal welfare. In slaughterhouses, the presence of dead and non-ambulatory animals is an indicator of poor welfare during transport. The objective of the study was to identify risk factors associated with the frequency of dead and non-ambulatory pigs during transport. A survey was conducted in three Colombian slaughterhouses. Data were collected from 372 batches (n = 18,437 gilts barrows) and transported directly from the farms to the slaughterhouses. Each truck was individually evaluated; a structured survey was administered to drivers, non-ambulatory and dead pigs on arrival were identified and blood samples were obtained from non-ambulatory pigs to assess physiological indicators of stress. Mortality rates per batch at arrival ranged from 0.08 to 0.17% and prevalence of non-ambulatory pigs per batch ranged from 0.84 to 1.37%.The results of the multilevel mixed effects linear regression model identified the following as risk factors associated with the frequency of total transport losses: truck speed (P = 0.04), distance (P < 0.01), transport time (P < 0.01), load size (P < 0.01) and the driver (P < 0.01) including the farm as a fixed effect. This study identified risk factors that increased the probability of total transport losses during land transport under Colombian commercial conditions. But more research that involves commercial drivers is needed to develop effective strategies to improve Colombian pig's transportation chain.

Linking Animal Welfare and Antibiotic Use in Pig Farming-A Review

Preventative measures, such as biosecurity and vaccinations, are essential but not sufficient to ensure high standards of health in pig production systems. Restrictive, barren housing and many widely used management practices that cause pain and stress predispose high-performance pigs reared in intensive systems to disease. In this context, antibiotics are used as part of the infrastructure that sustains health and high levels of production in pig farms. Antimicrobial resistance (AMR) is a global emergency affecting human and animal health, and the use of antibiotics (AMU) in intensive livestock farming is considered an important risk factor for the emergence and spread of resistant bacteria from animals to humans. Tackling the issue of AMR demands profound changes in AMU, e.g., reducing their use for prophylaxis and ending it for growth promotion. In support of such recommendations, we revise the link between animal welfare and AMU and argue that it is crucial to sustainably reduce AMU while ensuring that pigs can live happy lives. In support of such recommendations, we aimed to revise the link between animal welfare and AMU in pigs by analysing stress factors related to housing and management and their impact on pig welfare. In particular, we reviewed critical management practices that increase stress and, therefore, pigs' susceptibility to disease and reduce the quality of life of pigs. We also reviewed some alternatives that can be adopted in pig farms to improve animal welfare and that go beyond the reduction in stress. By minimising environmental and management stressors, pigs can become more immunocompetent and prepared to overcome pathogenic challenges. This outcome can contribute to reducing AMU and the risk of AMR while simultaneously improving the quality of life of pigs and, ultimately, maintaining the pig industry's social license.

Physiological response of weaned piglets to two transport durations observed in a Canadian commercial setting

Observational studies describing the impact of transport duration on weaned piglet welfare are limited. Current Canadian transport regulations are heavily informed by studies involving market hogs. Due to physiological differences between weaned piglets and market hogs, additional data on their response to transport are needed for age-specific evidence-based recommendations. A cohort study was conducted to describe and compare mortality, injury, weight change, hematological or biochemical changes in hydration, muscle injury and stress response observed in weaned piglets undergoing short duration (SD, <3 h), or long duration (LD, >30 h) commercial summertime transport events. Data collection on 440 of 11,434 transported piglets occurred the morning of the day before transport (T0), at arrival (T1) and approximately 3 to 4 d (78 to 93 h) after arrival at the nursery barn (T2). Low mortality occurred over all transport events (0.06%) with no association observed between transport duration and odds of death during transport (P = 0.62). The incidence of lameness between T0 and T1 was low (1.84% of the 435 focal piglets scored) with all lameness cases identified as mild in severity. Lesions on ears and skin were more prevalent than other injury types after transport (T1) and may have been related to mixing aggression associated with weaning rather than transport alone. LD piglets weighed 0.39 kg less than SD piglets at T1 (P < 0.01), but no difference in group weight was observed at T2 (P = 0.17). Hematological and biochemical differences were present between groups at T1. LD piglets had increased hematocrit levels compared with SD piglets (P = 0.01), suggesting increased body water losses. SD piglets showed greater levels of muscle injury compared with LD piglets including elevated aspartate aminotransferase (P < 0.01) and creatine kinase (P < 0.01). However, these parameters were within normal reference ranges for piglets of this age group. Indicators of physiological stress response including cortisol and neutrophil to lymphocyte ratios were elevated in SD piglets compared with LD piglets (P = 0.02 and P < 0.01, respectively). The results of this study demonstrate that both short and long transport durations can result in detectable physiological changes in weaned piglets. The overall impact of these durations on piglet welfare should be further explored by analyzing behavioral time budgets during and after transport.

Environmental Enrichment for Pig welfare during Transport

This study aimed to assess the effects of environmental enrichment for pigs during transportation in different phases of their productive cycle. Two trials were conducted, the first during transportation of pigs from the piglet production unit (PPU) to the nursery (n = 250) and the second during the transportation of nonhuman animals from the finishing unit (FU) to the slaughterhouse (n = 120). This work was an observational study with five environmental enrichments: Control - no enrichment; object - use of enrichment objects in the truck; aroma - use of lavender aroma in the truck; music - music in the truck; and vehicle sound. Animal behavior during transportation, respiratory rate, skin surface temperature, and skin lesion score were assessed. Piglets from the treatment music had the lowest frequency of agonistic behaviors during transportation from the farrowing to the nursery and lower skin temperature after transportation. Piglets from the control had the highest respiratory rate prior to transportation. Pigs familiarized with vehicle noises spent most of their time lying during the trip to the slaughterhouse. The creation of a familiar environment to pigs seems promising in enhancing animal well-being during transportation.

Quantitative analysis of the blood transcriptome of young healthy pigs and its relationship with subsequent disease resilience

Background

Disease resilience, which is the ability of an animal to maintain performance under disease, is important for pigs in commercial herds, where they are exposed to various pathogens. Our objective was to investigate population-level gene expression profiles in the blood of 912 healthy F1 barrows at ~ 27 days of age for associations with performance and health before and after their exposure to a natural polymicrobial disease challenge at ~ 43 days of age.

Results

Most significant (q < 0.20) associations of the level of expression of individual genes in blood of young healthy pigs were identified for concurrent growth rate and subjective health scores prior to the challenge, and for mortality, a combined mortality-treatment trait, and feed conversion rate after the challenge. Gene set enrichment analyses revealed three groups of gene ontology biological process terms that were related to disease resilience: 1) immune and stress response-related terms were enriched among genes whose increased expression was unfavorably associated with both pre- and post-challenge traits, 2) heme-related terms were enriched among genes that had favorable associations with both pre- and post-challenge traits, and 3) terms related to protein localization and viral gene expression were enriched among genes that were associated with reduced performance and health traits after but not before the challenge.

Conclusions

Gene expression profiles in blood from young healthy piglets provide insight into their performance when exposed to disease and other stressors. The expression of genes involved in stress response, heme metabolism, and baseline expression of host genes related to virus propagation were found to be associated with host response to disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07912-8.

Early-Life Intervention Using Exogenous Fecal Microbiota Alleviates Gut Injury and Reduce Inflammation Caused by Weaning Stress in Piglets

Fecal microbiota transplantation (FMT) could shape the structure of intestinal microbiota in animals. This study was conducted to explore the changes that happen in the structure and function of microbiota caused by weaning stress, and whether early-life FMT could alleviate weaning stress through modifying intestinal microbiota in weaned piglets. Diarrheal (D) and healthy (H) weaned piglets were observed, and in the same farm, a total of nine litters newborn piglets were randomly allocated to three groups: sucking normally (S), weaned at 21 d (W), and early-life FMT + weaned at 21 d (FW). The results demonstrated that differences of fecal microbiota existed in group D and H. Early-life FMT significantly decreased diarrhea incidence of weaned piglets. Intestinal morphology and integrity were improved in the FW group. Both ZO-1 and occludin (tight junction proteins) of jejunum were greatly enhanced, while the zonulin expression was significantly down-regulated through early-life FMT. The expression of IL-6 and TNF-α (intestinal mucosal inflammatory cytokines) were down-regulated, while IL-10 (anti-inflammatory cytokines) was up-regulated by early-life FMT. In addition, early-life FMT increased the variety of the intestinal microbial population and the relative amounts of some beneficial bacteria such as Spirochaetes, Akkermansia, and Alistipes. Functional alteration of the intestinal microbiota revealed that lipid biosynthesis and aminoacyl-tRNA biosynthesis were enriched in the FW group. These findings suggested that alteration of the microbiota network caused by weaning stress induced diarrhea, and early-life FMT alleviated weaning stress in piglets, which was characterized by decreased diarrhea incidence, improved intestinal morphology, reduced intestinal inflammation, and modified intestinal bacterial composition and function.

Weaning-associated feed deprivation stress causes microbiota disruptions in a novel mucin-containing in vitro model of the piglet colon (MPigut-IVM)

BACKGROUND

Risk factors for the etiology of post-weaning diarrhea, a major problem in swine industry associated with enormous economic losses, remain to be fully elucidated. In concordance with the ethical concerns raised by animal experiments, we developed a new in vitro model of the weaning piglet colon (MPigut-IVM) including a mucin bead compartment to reproduce the mucus surface from the gut to which gut microbes can adhere.

RESULTS

Our results indicated that the MPigut-IVM is able to establish a representative piglet archaeal and bacterial colon microbiota in terms of taxonomic composition and function. The MPigut-IVM was consequently used to investigate the potential effects of feed deprivation, a common consequence of weaning in piglets, on the microbiota. The lack of nutrients in the MPigut-IVM led to an increased abundance of Prevotellaceae and Escherichia-Shigella and a decrease in Bacteroidiaceae and confirms previous in vivo findings. On top of a strong increase in redox potential, the feed deprivation stress induced modifications of microbial metabolite production such as a decrease in acetate and an increase in proportional valerate, isovalerate and isobutyrate production.

CONCLUSIONS

The MPigut-IVM is able to simulate luminal and mucosal piglet microbiota and represent an innovative tool for comparative studies to investigate the impact of weaning stressors on piglet microbiota. Besides, weaning-associated feed deprivation in piglets provokes disruptions of MPigut-IVM microbiota composition and functionality and could be implicated in the onset of post-weaning dysbiosis in piglets.

Identification of trailer heat zones and associated heat stress in weaner pigs transported by road in tropical climates

Heat stress is major welfare concern during transport of pigs in tropical climates, which can also lead to direct production costs. This study evaluated the dynamics of heat zones through the load and their relationship with heat stress of weaner pigs during road transport in a tropical climate. Both environmental (e.g. temperature and relative humidity) and physiological (e.g. respiratory frequency and lactate) measures were recorded from four vehicle journeys (70 km distance, 216 weaner pigs within each trailer load) within Ceará, northeastern Brazil. Geostatistics and fluid dynamics simulation techniques were applied to understand the dynamics of heat zones and ventilation patterns the truckload. Statistics based on canonical discriminant analysis and ANOVA were performed to verify the relationship between heat zones and heat stress in pigs. The results showed that, during transport, the generation of heat zones occurred with different magnitudes along the load (P < 0.05), which was harmonized by the ventilation dynamics. There was a heat core with high energy content, in the front region of the lower deck (LD) of the trailer. In this zone, weaners pigs had higher rectal temperature (+1.8 °C temperature difference), respiratory frequency (LD = 94 ± 1.3 breaths/min; UD = 86 ± 1.3 breaths/min), and blood cortisol concentration (LD = 32.9 ± 0.8 ng/mL; UD = 30.18 ± 0.6 ng/mL) (all P < 0.05). Weaners pigs transported in the upper deck (UD) compartments had the highest skin temperature (LD = 38.13 ± 0.3 °C; UD = 38.9 ± 0.22 °C) and the highest mean values of blood lactate (LD = 65.5 ± 1.11 m/M; UD = 71.60 ± 1.19 m/M) and Creatine kinase (LD = 3891.23 ± 69U/L; UD = 4107.43 ± 62U/L) (P < 0.05). Weaners transported in compartments of the LD of trailer were more susceptible to heat stress, while weaners in the UD compartments were more susceptible to physical stress and muscle exhaustion. These results provide additional evidence of heat zones within trailer compartments and highlight the requirement for the planning of pig transport operations in tropical climates to mitigate risks of heat stress.

Effect of omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation to lactating sows on growth and indicators of stress in the postweaned pig1,2

Dietary omega-3 polyunsaturated fatty acids (n-3 PUFA) are precursors for lipid metabolites that reduce inflammation. Two experiments were conducted to test the hypothesis that enriching the sow diet in n-3 PUFA during late gestation and throughout lactation reduces stress and inflammation and promotes growth in weaned pigs. A protected fish oil product (PFO; Gromega) was used to enrich the diet in n-3 PUFA. In the initial experiment, time-bred gilts were fed a gestation and lactation diet supplemented with 0% (control; n = 5), 0.25% (n = 4), 0.5% (n = 4), or 1% (n = 5) PFO from 101 ± 2 d of gestation to day 16 of lactation. Adding 1% PFO to the diet increased the n-3:n-6 PUFA ratio in colostrum and milk compared with controls (P = 0.05). A subsequent experiment was performed to determine whether supplementing the sow diet with 1% PFO improved growth and reduced circulating markers of acute inflammation and stress in the offspring. Plasma was harvested from piglets (16 per treatment group) on day 0 (d of weaning) and days 1 and 3 postweaning. Pigs from the 1% PFO treatment group weighed more (P = 0.03) on day 3 postweaning and had a greater (P ˂ 0.05) n-3:n-6 PUFA ratio in plasma on each day sampled compared with 0% PFO controls. There was an overall treatment effect on plasma total cortisol (P = 0.03) and haptoglobin (P = 0.04), with lesser concentrations in pigs on the 1% PFO diet. Plasma corticosteroid-binding globulin (CBG) concentrations were not different between treatment groups but were less (P ˂ 0.001) on days 1 and 3 when compared with day 0. The resultant free cortisol index [FCI (cortisol/CBG)] was less (P = 0.02) on days 1 and 3 for pigs from the 1% treatment group compared with the controls. An ex vivo lipopolysaccharide (LPS) challenge of whole blood collected on days 0 and 1 was used to determine whether 1% PFO attenuated release of inflammatory cytokines (IL-1β, IL-6, and TNF-α). Blood from pigs within the 1% PFO treatment group tended (P = 0.098) to have a lesser mean concentration of TNF-α in response to LPS compared with blood from controls. These results suggest that providing a PFO supplement as 1% of the diet to sows beginning in late gestation and during lactation can increase the n-3:n-6 PUFA ratio in their offspring, which may improve growth and reduce the acute physiological stress response in the pigs postweaning.

Effects of Transport Duration and Environmental Conditions in Winter or Summer on the Concentrations of Insulin-Like Growth Factors and Insulin-Like Growth Factor-Binding Proteins in the Plasma of Market-Weight Pigs

In previous work using market-weight pigs, we had demonstrated that insulin-like growth factors (IGFs) and insulin-like growth factor binding proteins (IGFBPs) are regulated during shipment characterized by changing conditions of stress due to loading or unloading, transportation, lairage, and slaughter. In addition, we found in a previous study that IGFBP-2 concentrations were lower in pigs transported for longer periods of time. Therefore, we performed a more detailed study on the effects of transport duration and season on the plasma concentrations of IGFs and IGFBPs in adult pigs. For the study, exsanguination blood was collected from 240 market-weight barrows that were transported for 6, 12, or 18 h in January or July. IGF-I and -II were detected using commercial ELISAs whereas IGFBPs were quantified by quantitative Western ligand blotting. In addition, established markers of stress and metabolism were studied in the animals. The results show that plasma concentrations of IGFBP-3 were significantly reduced after 18 h of transport compared to shorter transport durations (6 and 12 h; p < 0.05). The concentrations of IGF-I in plasma were higher (p < 0.001) in pigs transported 12 h compared to shorter or longer durations. Season influenced plasma concentrations of IGFBP-3 and IGF-II (p < 0.05 and p < 0.01, respectively). Neither transport duration nor differential environmental conditions of winter or summer had an effect on glucocorticoids, albumin, triglycerides, or glucose concentrations (p > 0.05). However, low-density lipoprotein concentrations decreased after 18 h compared to 6 h of transport (p < 0.05), whereas high-density lipoprotein concentrations were higher (p < 0.05) in pigs transported for 12 or 18 h compared to those transported for only 6 h. Our findings indicate differential regulation of IGF-compounds in response to longer transport duration or seasonal changes and support current evidence of IGFs and IGFBPs as innovative animal-based indicators of psycho-social or metabolic stress in pigs.

Relación entre las características de los transportes, con las características nutricionales de la carne porcina destinada a consumo humano en el Valle de Aburrá, 2017

Pork meat is considered a source of high nutritional value due to its high protein content, however, transport is a critical link to generate economic losses by producing alterations in animal welfare, which have an impact on nutritional parameters, decreasing the capacity of water retention, and generating protein losses. The objective of this study was to relate the characteristics of transport, with the nutritional characteristics of pork for human consumption in the Valle de Aburrá in 2017. Three slaughterhouses of Valle de Aburrá were visited with probabilistic sampling, stratified by plant and equal affixation, obtaining information from 338 animals. The nutritional parameters of the meat samples and sociodemographic variables, infrastructure, animal welfare and driving practices in the transporters were analyzed. Chi square tests were performed for dichotomous qualitative variables, logistic regression for qualitative polytomous variables and U Mann - Whitney for quantitative variables. An association was found between several of the parameters investigated with statistically significant p values (p = 0.000), where, having no permanent water supply for the animals increases the possibility of presenting nutritionally inadequate meats 46.55 times (IC 18.08 - 120.07). It concludes that factors such as lack of water supply to pigs, poor condition of the floors and separators, lack of training in transporters, lack of supervision of animals, lack of mechanical technical certification and average speed of 80 Km/Hr are associated with the generation of nutritionally inadequate meat products.

Gut Microbiota Dysbiosis in Postweaning Piglets: Understanding the Keys to Health

Weaning is a critical event in the pig's life cycle, frequently associated with severe enteric infections and overuse of antibiotics; this raises serious economic and public health concerns. In this review, we explain why gut microbiota dysbiosis, induced by abrupt changes in the diet and environment of piglets, emerges as a leading cause of post-weaning diarrhea, even if the exact underlying mechanisms remain unclear. Then, we focus on nonantimicrobial alternatives, such as zinc oxide, essential oils, and prebiotics or probiotics, which are currently evaluated to restore intestinal balance and allow a better management of the crucial weaning transition. Finally, we discuss how in vitro models of the piglet gut could be advantageously used as a complement to ex vivo and in vivo studies for the development and testing of new feed additives.

Comparison of Intramuscular or Subcutaneous Injections vs. Castration in Pigs-Impacts on Behavior and Welfare

Simple Summary

Physical castration (PC) of piglets is a painful and stressful procedure and alternatives are being sought to improve animal well-being, such as immunological castration (IC). However, IC requires injections which may also cause pain and stress during handling. In this study, piglets and finishing pigs were placed in the following treatment groups: no handling or treatment (NO), sham-handling (SHAM), intramuscular injection (IM), subcutaneous injection (SQ), or PC on piglets only. Behavior was monitored for 1 h prior and 1 h post treatment in each age group. Social behavior and feeding behavior, and signs of pain were recorded. Physical castration caused measurable pain-like behaviors and general behavioral dysregulation at a much higher level than changes associated with handling associated with IM or SQ injections. Overall, injections did not cause a change in weaning pig behaviors. Finishing pigs given SQ injections showed a lower number of feeding behaviors post treatment but other changes were not observed in the other treatment groups.

Abstract

Physical castration (PC) is painful and stressful for nursing piglets. One alternative to PC is immunological castration (IC), but the pain and stress of handling associated with injections have not been assessed. The objectives of this study were to measure the pain and distress of subcutaneous (SQ) and intramuscular (IM) injections compared to PC in piglets, and to compare SQ or IM injections in finishing pigs. After farrowing, 3 to 5 d old male piglets were randomly assigned to (control) no handling treatment (NO), sham-handling (SHAM), IM, SQ, or PC. Finishing pigs were assigned to NO, SHAM, IM, or SQ. Behavior was monitored for 1 h prior and 1 h post treatment in each age group. Social, feeding behaviors, and signs of pain were recorded. Finishing pigs treated with SQ injections had higher feeding behaviors pre-treatment than they did post-treatment. Overall, physical castrations caused measurable pain-like behaviors and general behavioral dysregulation at a much higher level than the other treatment groups. SQ and IM injections did not cause either significant behavioral or physiological alterations in piglets. SQ injections caused a decrease in finishing pig feed behaviors post treatment (p = 0.02) and SHAM treated finishing pigs spent significantly more time lying than the other treatment groups. In general IM and SQ injections did not cause any other significant changes in behavior or physiology.

Impact of Providing Feed and/or Water on Performance, Physiology, and Behavior of Weaned Pigs during a 32-h Transport

Simple Summary

Transportation has the potential to negatively affect the health and welfare of weaned pigs, especially those already experiencing weaning stress. Piglets were transported for 32 h, with and without feed and water, and measures of performance, physiology, and behavior were taken to assess piglet welfare. Transportation negatively impacted body weight, Neutrophil to Lymphocyte Ratio (N:L), and post-transport body weight gain, indicating that not providing water during transport can negatively impact the well-being of recently weaned pigs. Provision of water may aid in reducing stress during long distance transport and improve the animals’ well-being.

Abstract

Transportation at weaning is a complex stressor made up of many factors, including withdrawal from feed and water, which can potentially negatively affect the health and welfare of pigs, especially those already experiencing weaning stress. The objective of this study was to evaluate the effect of weaning and extended transport durations (up to 32 h), with and without the provision of feed and/or water, on pig welfare. Treatment groups included: pigs neither weaned nor transported, control (CON); weaned pigs transported and provided with feed and water (T+); weaned pigs transported without feed and water (T−); weaned pigs transported with only feed (T+F); and weaned pigs transported with only water provided (TRAN+W). The effect of transport (with and without feed and/or water) on weaned pigs was assessed using behavior, performance, and physiology. After a 32-h transport period, pigs transported without water lost markedly more weight than those transported with water (p < 0.01). Furthermore, the neutrophil to lymphocyte ratio was markedly higher in male pigs transported without water (p < 0.05). Overall, transportation had a negative effect on pig well-being, especially when water was not provided.

Cholinesterase in porcine saliva: Analytical characterization and behavior after experimental stress

The purpose of this study was to measure and characterize the enzyme cholinesterase (ChE) in porcine saliva, as well as to evaluate its behavior in experimental stressful conditions. The results of ChE characterization by using different substrates and the selective inhibitors ethopropazine and physostigmine showed that the main enzyme existing in porcine saliva was butyrylcholinesterase (BChE). An automated assay using butyrylthiocholine iodide as substrate was validated providing adequate reproducibility, linearity results and limit of detection. Salivary ChE was measured using the validated assay in two models of acute stress: twenty pigs stressed for 2min with a nasal snare and other twenty pigs subjected to a short-term road transport. Salivary ChE significantly increased after restraint and transport stress in pigs, as well as the ChE to total protein ratio. In conclusion, BChE is the predominant isoenzyme in porcine saliva, it can be measured by the fast, simple and automated method described in this paper and it increases in the models of stress used in this study.

Effect of Provision of Feed and Water during Transport on the Welfare of Weaned Pigs

Simple Summary

Transportation is a complex stressor, which has the potential to negatively impact the health and welfare of weaned pigs. Transport duration and withdrawal from feed and water are two factors that could potentially adversely affect the welfare of pigs transported at weaning. In this study, the effect of a 32 h transport period and the provision of feed and water on the welfare of weaned pigs was investigated using a multi-disciplinary approach. Body weight decreased in weaned pigs over time and this response was exacerbated by exposing pigs to a 32 h transport period and withdrawing feed and water. The greatest changes in body weight loss were observed after 8 h of transport or weaning. Furthermore, the neutrophil to lymphocyte ratio (N:L) stress measure was elevated in pigs in response to an 8 h transport period or 8 h after weaning alone. With the exception of weaned pigs provided with feed and water, transported and weaned pigs continued to be different from control pigs until 16 h after weaning or exposure to a 16 h transport period. These findings suggest that pigs experience an acute stress response due to transport and weaning, but these two stressors do not appear to be additive. Overall, transportation had a negative effect on performance, physiology and behavior of weaned and transported pigs, especially if not provided with feed and water for more than 24 h.

Abstract

Transportation is a complex stressor made up of factors including weaning itself and withdrawal from feed and water. Therefore, transportation has the potential to negatively impact the health and welfare of weaned pigs. Pigs were transported for 32 h and measures of performance, physiology, and behavior were taken to assess piglet welfare. Treatment groups included pigs not weaned or transported (CON), weaned pigs provided with feed and water (WEAN+), weaned pigs not provided with feed and water (WEAN−), weaned and transported pigs provided with feed and water (TRANS+), and weaned and transported pigs not provided with feed and water (TRANS−). Body weight loss was different among treatments (p < 0.01). CON pigs had a 6.5% ± 0.45% gain in body weight after 32 h. WEAN+, WEAN−, TRANS+, and TRANS− groups all had a loss in body weight of 5.9% ± 0.45%, 7.8% ± 0.45%, 6.5% ± 0.45% and 9.1% ± 0.46%, respectively. The N:L was greater in all weaned pigs at 8 h compared to CON pigs (p < 0.01). WEAN− and transported pigs had significantly higher N:L than CON pigs from 8 h through 16 h, however, all treatment groups were similar to CON pigs after 16 h irrespective of provision of feed and water. Blood glucose levels were lower in transported and/or weaned pigs than CON pigs after 16 h irrespective of the provision of feed and water. TRANS+ females had higher creatine kinase (CK) levels than males (p < 0.05). After a 16 h transport period, TRANS− pigs had higher total plasma protein (TP) levels than all other treatment groups (p < 0.05). Significant changes in behavior were observed during and after transportation, which could also be indicative of stress. Overall, transportation and weaning had a negative effect on performance, physiology and behavior (both during and post-weaning) of pigs, especially when feed and water was not provided. Transporting pigs without feed and water for more than 24 h was a welfare concern as indicated by changes in body weight and physiology measures of stress.