Synthetic maternal pheromone stimulates feeding behavior and weight gain in weaned pigs

Cutaneous application of SecurePig® FLASH, a Pig appeasing pheromone analogue, facilitates adaptation and manages social behavior during feeding in semi-extensive conditions

BACKGROUND

Farm animals face several challenges throughout their lives, which can affect both their welfare and their productivity. Promoting adaptation in animals is one way of limiting these consequences. In various animal species, the use of maternal appeasing pheromones is efficient to reduce aggressiveness, improve adaptation and thus ensuring better welfare and productivity. This study sought to investigate the efficiency of a treatment with a Pig Appeasing Pheromone (PAP) on the behavior of pigs reared under semi-extensive conditions and exposed to a potential conflict- collective feeding. Animals (n = 14 divided in 2 groups of 7) were subjected to 3 different phases, (A) baseline - no pigs received the PAP, (B) SP - 2 out of the 7 pigs per group received the PAP and (C) AP- all pigs received the PAP. Behaviors related to feeding, aggression and locomotion were compared between the 3 phases of the study.

RESULTS

Compared to the baseline period, we observed that the number of head knocks was reduced when some pigs (p < 0.001) and all pigs (p < 0.005) received the PAP. Similarly, we observed that the number of fleeing attempts was reduced when some pigs (p < 0.001) and all pigs (p < 0.001) were treated when compared to baseline. This number was lower in the AP phase than in the SP phase (p < 0.001). When all pigs were treated (AP), we also observed that they spent less time investigating the floor than during the two other phases (p < 0.001), but they seemed more likely to leave the feeder due to the presence or behavior of another pig of the group (SP vs. AP, p < 0.05).

CONCLUSIONS

The PAP application improved adaptation in pigs by reducing aggressiveness and promoting conflict avoidance. Those results validate the efficiency of the pheromonal treatment under semi-extensive rearing conditions to help pigs to cope with a challenging situation. Using PAP in the pig industry seems interesting to limit unwanted consequences of farm practices on animal welfare and productivity, by promoting their adaptation.

Multiple administrations of bovine-appeasing substance during a 42-d preconditioning program followed by feedlot receiving and its effects on physiologic, health, and performance responses of feeder cattle

This experiment evaluated the effects of multiple bovine-appeasing substance (BAS) administration during a 42-d preconditioning program followed by a feedlot receiving period on productivity, health, and physiological variables of feeder cattle. Ninety calves were weaned, weighed, loaded into a livestock trailer, transported for 70 km, and unloaded at the Bozeman Agricultural Research and Teaching Farm for a 42-d preconditioning program. Upon arrival, calf body weight (BW) was recorded again, and both pre- and post-transport BWs were averaged and used as calf weaning initial BW. Calves were ranked by BW, sex, and age in a completely randomized design and assigned to receive 1) multiple administrations of BAS at weaning (day 0), days 14, 28, and before transport and feedlot entry (day 42; BAS; RSEA Group, Quartier Salignan, France; n = 9 pens/treatment), or 2) placebo (diethylene glycol monoethyl ether; CON; n = 9 pens/treatment). Treatments (5 mL) were applied to the nuchal skin area of each animal during the preconditioning period. Calves within treatment groups were ranked again by initial BW, sex, and age, in a manner that pens have similar initial BW, age, and three steers and two heifers and allocated to 1 of the18 drylot pens. On day 42, calves were combined within the treatment group, loaded into two different single double-deck commercial livestock trailers, and transported for 1,000 km (approximately 16 h). Upon arrival (day 43), calves were unloaded at the same feedyard. Blood samples were collected on days 0, 3, 7, 14, 21, 28, 42, 43, 46, 50, 57, 64, and 90. Average daily gain, final BW, and feed efficiency did not differ (P > 0.52) between BAS and CON calves in the preconditioning and receiving phases. A treatment × day interaction was detected (P < 0.001) for plasma haptoglobin concentrations, which was greater (P < 0.01) in CON on days 3 and 7 vs. BAS calves. During the preconditioning phase, serum NEFA concentration was reduced (P < 0.01) in BAS on day 3 compared with CON calves. A treatment × day interaction was detected (P = 0.001) for exit velocity, which was greater (P < 0.001) for CON vs. BAS calves on days 3, 7, 14, and 21 during the preconditioning phase and on day 46 of the receiving phase. Therefore, Applications of BAS reduced immunological responses and exit velocity associated with stress caused by management practices, but did not improve performance during the preconditioning and receiving phases.

Effect of Pig Synthetic Pheromones and Positive Handling of Pregnant Sows on the Productivity of Nursery Pigs

Weaning is one of the most important stress events in the life of pigs, increasing the risk for health problems and reduced performance. The release of pheromones in pig stables can be considered an environmental enrichment and alleviate the negative effects of weaning stress in nursery pigs. The present study investigated the effect of synthetic pheromones on the performance of nursery pigs. The effect of positive handling of sows in the farrowing house on the performance of the offspring in the nursery was also investigated. The study was performed in a commercial pig farm and included 24 batches of weaned piglets (216 piglets per batch). Half of the batches originated from sows exposed to positive handling. This implied that music was played from 6.00 a.m. to 6.00 p.m. from the moment the sows entered the farrowing house until weaning and that they were subjected to backscratching from the day they entered the farrowing unit the day of farrowing. During the nursery period, half of the batches were treated, and half served as controls. Piglets of treated groups were exposed to a synthetic analog of the maternal pig appeasing pheromone (PAP) (SecurePig®, Signs, Avignon, France). The product consisted of a gel block from which the pheromones were slowly released into the room. Different performance parameters were measured during the nursery period. Neither the sow treatment nor the treatment with pheromones significantly influenced the performance of the piglets during the nursery period (p > 0.05). The median values (95% confidence interval) of average daily gain, namely 318 (282-338) vs. 305 (272-322) g/day, feed conversion ratio, namely 1.64 (1.51-1.71) vs. 1.70 (1.57-1.75), and number of antimicrobial treatment days, namely 16.9 (9.6-25.0) vs. 17.3 (9.5-25.0) days, were numerically better in the nursery pigs exposed to the pheromones compared to the control groups. Mortality however was numerically higher in the treated groups, namely 4.4 (2.8-6.8) vs. 3.2 (0.9-4.2)%. Under the conditions of the present production system, pigs exposed to the pheromone treatment during the nursery did not show a significant performance increase.

Effect of wither application of an analogue of pig appeasing pheromone on encounters between unfamiliar mini-pigs

BACKGROUND

The practice of mixing unfamiliar pigs on farms is common but results in fighting, welfare problems and performance issues. Pigs have different ways of resolving social conflicts, including aggressive and affiliative behaviours. Synthetic appeasing pheromones have demonstrated many positive effects in animal husbandry and are regularly used by breeders to improve animal welfare and performance. The aim of the study was to investigate the effect of a new method of applying pig appeasing-pheromone (PAP) to the withers in an experimental model of pig mixing to determine whether PAP reduced aggression and fighting, increased prosocial behaviours, and improved behavioural and physiological indicators of welfare.

RESULTS

PAP reduced fighting between mini-pigs (df = 1; F = 13.47; P = 0.001; mixed logistic regression). Even if not significant, agonistic behaviours tended to be reduced when the treatment was applied (df = 1; F = 4.14; P = 0.058; mixed logistic regression). Likewise, mini-pigs seemed to be scored as not aggressive at all (df = 1; F = 3.61; P = 0.070; GLMM) and to be less aggressive toward the other pig than when placebo was applied. Concerning the latency of the first contact without aggression, a significant effect was found between the PAP and placebo groups (df = 1; χ² = 4.74; P = 0.0295; Cox model). Moreover, even if not significant, the treated mini-pigs seemed to spent more time looking at each other (df = 1; F = 3.59; P = 0.071; GLMM) and immobile and/or ground sniffing (df = 1; F = 3.18; P = 0.088; GLMM) than those that received placebo. No significant difference was found between groups for salivary cortisol concentration (df = 1; F = 0.10; P = 0.752; GLMM), but variances between groups were heterogeneous at every time. No significant difference was found between groups regarding alpha-amylase activity (df = 1; F = 0.25; P = 0.621; GLMM), but variances between groups were heterogeneous at T0, T1 and T3. These results indicate that the variability (dispersion) within each group was lower when PAP was applied than when the placebo was applied.

CONCLUSIONS

The new method of applying PAP improved welfare of mini-pigs (as models of domestic pigs) by reducing fighting, among other interesting results. PAP seems thus a promising biomimetic tool to enhance animal welfare in pig production systems.

Pheromones, binding proteins, and olfactory systems in the pig (Sus scrofa): An updated review

Pigs utilize multimodal communication for reproductive and other behaviors, and chemical communication is one of the key components. The success of reproduction relies on chemical communication favored by the steroid pheromones from boar saliva. These steroids were proven to be involved in advancing puberty in gilts (the boar effect) and in promoting estrus behaviors in gilts/sows, thereby helping to detect estrus and facilitating the timing of artificial insemination. The steroid pheromones bound with carrier proteins are evidenced in the mandibular (submandibular) salivary secretions of the boar. These salivary steroids bind with carrier proteins in the nasal mucus and vomeronasal organ (VNO) of the sows, eventually triggering a cascade of activities at the olfactory and endocrine levels. Besides steroid pheromones, pig appeasing pheromones (from mammary skin secretions of sows) have also been demonstrated to bind with carrier proteins in the nasal mucus and VNO of the piglets. Thus far, four different proteins have been identified and confirmed in the nasal mucus and VNO of pigs, including odorant binding proteins (OBPs), salivary lipocalin (SAL), pheromaxein, and Von Ebner's Gland Protein (VEGP). The critical roles of the chemosensory systems, main olfactory systems and VNO, have been comprehensively reported for pigs. This review summarizes the current knowledge on pheromones, their receptor proteins, and the olfactory systems of porcine species.

Interpretive review: Semiochemicals in domestic pigs and dogs

This interpretive review includes discussion of the available scientific literature with interpretations by the authors. The broad field of semiochemicals can be confusing to scientists and consumers. This review attempts to summarize the known scientific studies for pig and dog semiochemicals while at the same time attempting to refine our use of terminology. The specific objectives of this interpretive review are to summarize and interpret much of the key scientific literature (but not the lay literature) on semiochemicals in pigs and dogs to include (1) definitions of semiochemicals and related molecules including pheromones, (2) to briefly summarize olfactory organs, and (3) and to examine the scientific literature for semiochemical mechanisms and applications in dogs and pigs (two domesticated species with known olfactory acuity). Dogs and pigs have olfactory features that are similar in that they both lack certain olfactory organs (Grueneberg ganglion and Septal Organ) and they have a small vomeronasal organ (VNO) without some major receptors that are found in other species. The primary olfactory organs for both pigs and dogs are the main olfactory epithelium and perhaps the trigeminal nerve. Several examples of pheromones activating the brain via the MOE or Trigeminal nerve rather than the VNO challenge the concept that the VNO is the site of pheromone sensing. We believe it is not appropriate to label something a pheromone when evidence is not available to show that it is a pheromone. We offer definitions for the terms semiochemicals, pheromones, interomones and others and then determine if the evidence is sufficient to call certain semiochemicals a pheromone. Here we review mixed, largely negative, scientific reports of the efficacy of some products labeled as "pheromones" that are more appropriately called semiochemicals. Interomones can have a more powerful effect on dog behavior and physiology than semiochemicals marketed as pheromones. Because marketing of semiochemicals is far ahead of the science, bringing some logic and uniformity to the field will benefit animals and hopefully cause less consumer confusion. Semiochemicals have the potential to offer powerful solutions to behavioral problems using more naturally occurring molecules.

Administering an Appeasing Substance to Improve Performance, Neuroendocrine Stress Response, and Health of Ruminants

Simple Summary

Stress is present in several management activities of beef and dairy cattle, leading to health and productive losses to the herd. Therefore, strategies are warranted to reduce any losses related to these stressful situations, and bovine appeasing substance (BAS) is arising as a potential technology in livestock production settings. Several peer-reviewed publications have evaluated BAS in different production settings, such as weaning, feedlot entry, castration, transport to the slaughterhouse, and pre-weaning dairy cattle. Altogether, performance, health, and carcass traits have been positively impacted by BAS administration, demonstrating the efficacy of this technology for ruminants.

Abstract

The present review demonstrates the main attributes of stress-related responses in ruminants, and the potential interaction with the immune system of the host is also presented, demonstrating that alternatives that reduce the response to stressful situations are warranted to maintain adequate health and performance of the herd. In this scenario, pheromones and their modes of action are presented, opening space to a recent technology being used for ruminants: bovine appeasing substance (BAS). This substance has been used in different species, such as swine, with positive behavioral, health, and performance results. So, its utilization in ruminants has been reported to improve performance and inflammatory-mediated responses, promoting the productivity and welfare of the livestock industry.

Synthetic Olfactory Agonist Use in the Farrowing House to Reduce Sow Distress and Improve Piglet Survival

The aim of the study was to investigate if the application of a synthetic olfactory agonist (SOA) would reduce indicators of stress in sows, in response to a stressor prior to parturition, and if it would improve farrowing house performance of sows and their piglets. Two studies were conducted: an intensive study with 47 sows, either having their first or second litter (Control n = 24; SOA n = 23); and a commercial validation study with 418 sows, either having their first litter or have had multiple litters (Control n = 210; SOA n = 208). Within the intensive study, sows were housed with or without a synthetic olfactory agonist suspended in the creep area of the farrowing crate, whereas within the commercial validation study, sows were housed with or without a synthetic olfactory agonist suspended over the adjoining creep area of two farrowing crates. Within the intensive study, despite a discernible increase in cortisol concentration in response to a stressor (snout rope test), cortisol response was not different between treatments (p > 0.05). Farrowing duration in first-litter sows exposed to the SOA was decreased (p < 0.001) whilst there was no impact on farrowing duration in second litter sows. Piglets were not attracted by the SOA to increase their utilisation of the creep area and spent more time in proximity to the sow (p < 0.05). Within the commercial validation study, no impacts were seen on piglet production measures (p > 0.05). Largely the use of an SOA within the farrowing house did not impact the sow or her piglets in either the intensive study or commercial validation study. Based on these current results, the use of SOA within the farrowing house is not supported.

Pig pheromones and behaviors: A review

Chemical signals play indispensable roles in the communication and social behavior of many organisms. Pheromones are a class of chemical signals identified initially in insects. Later, it became evident that diverse animals secrete pheromones in their body exudates and from exocrine glands and use them for social communication. The pig is a vital food animal in which steroid pheromones have been identified and their behavioral effects known since the 1960s. More recently, non-steroidal pheromones have been identified. To date, studies have reported various pheromone sources in boars (saliva, urine, and glandular secretions) and sows (urine, mammary gland secretions, and feces) and pheromone-mediated behavioral consequences are evidenced. These include the boar effect on puberty onset and subsequent estrous behaviors as well as agonistic and avoidance behaviors. Recent research has facilitated the development and evaluation of pheromone-based applications and products to improve the welfare and reproductive performance of pigs. This review aims to summarize the current knowledge of pig pheromones, and their implications in behaviors.

Appeasing Pheromones for the Management of Stress and Aggression during Conservation of Wild Canids: Could the Solution Be Right under Our Nose?

Simple Summary

Many canid species are declining globally. It is important to conserve these species that often serve as important predators within ecosystems. Continued human expansion and the resulting habitat fragmentation necessitate conservation interventions, such as translocation, artificial pack formation, and captive breeding programs. However, chronic stress often occurs during these actions, and can result in aggression, and the physiological suppression of immunity and reproduction. Limited options are currently available for stress and aggression management in wild canids. Pheromones provide a promising natural alternative for stress management; an appeasing pheromone has been identified for multiple domestic species and may reduce stress and aggression behaviours. Many pheromones are species-specific, and the appeasing pheromone has been found to have slight compositional changes across species. In this review, the benefits of a dog appeasing pheromone and the need to investigate species-specific derivatives to produce more pronounced and beneficial behavioural and physiological modulation in target species as a conservation tool are examined.

Abstract

Thirty-six species of canid exist globally, two are classified as critically endangered, three as endangered, and five as near threatened. Human expansion and the coinciding habitat fragmentation necessitate conservation interventions to mitigate concurrent population deterioration. The current conservation management of wild canids includes animal translocation and artificial pack formation. These actions often cause chronic stress, leading to increased aggression and the suppression of the immune and reproductive systems. Castration and pharmaceutical treatments are currently used to reduce stress and aggression in domestic and captive canids. The undesirable side effects make such treatments inadvisable during conservation management of wild canids. Pheromones are naturally occurring chemical messages that modulate behaviour between conspecifics; as such, they offer a natural alternative for behaviour modification. Animals are able to distinguish between pheromones of closely related species through small compositional differences but are more likely to have greater responses to pheromones from individuals of the same species. Appeasing pheromones have been found to reduce stress- and aggression-related behaviours in domestic species, including dogs. Preliminary evidence suggests that dog appeasing pheromones (DAP) may be effective in wild canids. However, the identification and testing of species-specific derivatives could produce more pronounced and beneficial behavioural and physiological changes in target species. In turn, this could provide a valuable tool to improve the conservation management of many endangered wild canids.

An estimation of the financial consequences of reducing pig aggression

Animal welfare scientists have accumulated knowledge and developed interventions to improve livestock welfare, but these are poorly adopted in commercial practice. Animal welfare interventions are rarely tested for economic viability and this limits their uptake. This study employs Stochastic Partial Budgeting (SPB) to determine the viability of animal welfare improvements. Aggression between pigs is used as an example because there is a large literature base from which to draw interventions, and the problem has persisted for decades without resolution. Costs and benefits of three interventions to control aggression (pre-weaning socialisation, synthetic maternal pheromones and large social groups) were estimated by reviewing the academic and industry literature and by conducting a survey of sixteen pig farmers. The net effects were compared to farmers’ willingness to pay (WTP) for interventions to reduce aggression as identified by recent research. Results are consistent with prior research which indicates that improving animal welfare generally comes at a cost to producers. Nevertheless, pre-weaning socialisation resulted in a neutral or positive net effect 38% of the time and should be central to campaigns promoting the control of aggression in the industry. Exposing pigs to synthetic maternal pheromones did not improve profitability but the net costs were small and within the realms of WTP for a sub-group of farmers with animal welfare goals. The net costs of converting existing buildings in order to house pigs in large social groups were beyond the realms of farmers’ WTP. The approach adopted in this study, of combining SPB with WTP from the sector, should be extended to other animal welfare issues.

Administering an appeasing substance to beef calves at weaning to optimize productive and health responses during a 42-d preconditioning program

This experiment evaluated the impacts of administering a bovine appeasing substance (BAS) to beef calves at weaning on their performance, physiological responses, and behavior during a 42-d preconditioning program. Eighty calves (40 heifers and 40 steers; 90% British × 10% Nellore) were weaned at 233 ± 2 d of age (day 0); ranked by sex, weaning age, and body weight (BW); and assigned to receive BAS (IRSEA Group, Quartier Salignan, France; n = 40) or placebo (diethylene glycol monoethyl ether; CON; n = 40). Treatments (5 mL) were topically applied to the nuchal skin area of each animal following dam separation. Within treatment, calves were allocated to one of eight drylot pens (four pens per treatment; pen being the experimental unit) and received a free-choice total mixed ration (TMR) from day 0 to 42, intake of which was assessed daily. Live behavior observations were conducted on days 1, 2, 4, 8, 16, and 32. Temperament was assessed and blood samples were collected via jugular venipuncture on days -21, 0, 3, 7, 14, 28, and 42. Hair samples were collected from the tail switch on days 0, 14, 28, and 42. Calves were vaccinated against bovine respiratory disease viruses on days -21 and 0. Average daily gain from day 0 to 42 did not differ between treatments (P = 0.57) but was greater (P = 0.05) in BAS vs. CON calves from day 0 to 28. Intake of TMR was greater (P = 0.05) during the first week for BAS vs. CON calves (treatment × week; P = 0.08). The mean proportion of calves feeding simultaneously and performance of social and play behaviors were greater (P ≤ 0.05) for BAS vs. CON calves. Escape attempts were greater (P < 0.01) for BAS vs. CON calves on day 1 (treatment × day; P = 0.03). Exit velocity was greater (P = 0.04) for CON vs. BAS calves on day 14 and tended (P = 0.10) to be greater for CON vs. BAS calves on day 7 (treatment × day; P = 0.03). Mean plasma concentrations of haptoglobin were greater (P = 0.02) in CON vs. BAS calves. Hair cortisol concentrations were greater (P = 0.05) in CON vs. BAS calves on day 14 (treatment × day; P = 0.03). Mean serum concentrations of antibodies against bovine viral diarrhea virus were greater (P = 0.02) in BAS vs. CON calves. Collectively, BAS administration to beef calves at weaning alleviated stress-induced physiological reactions, improved temperament evaluated via chute exit velocity, enhanced humoral immunity acquired from vaccination, and appeared to have accelerated adaptation to novel management scheme and environment.

A Short Period of Darkness after Mixing of Growing Pigs Intended for PDO Hams Production Reduces Skin Lesions

Simple Summary

Mixing unacquainted growing pigs is a common practice in commercial herds to adjust the group size to the pen dimensions and to balance the body weights of pigs within pens. Aggressive behavior following regrouping may include fights that can result in skin lesions and detrimental economic effects. Strategies aimed at limiting such issues can therefore improve animal welfare in practice. In the present study, we investigated the effects of darkness, maintained for 48 h after the formation of new social groups, on the expression of agonistic behavior and on the accumulation of skin lesions of growing pigs. The provision of 48 h of darkness significantly reduced the number of skin lesions on the mid- and rear thirds of pigs’ body. However, no corresponding reduction was observed in agonistic behavior, suggesting that darkness decreases the efficacy of aggressions, rather than how often or for how long they are expressed. Furthermore, an analysis of the location of lesions indicates that aggressions towards a fleeing companion, rather than reciprocal ones, were those mostly affected by darkness. The present results identify in the provision of darkness an easily applicable and relatively inexpensive intervention, that leads to the reduction of one of the most problematic consequences of agonistic interactions, i.e., skin lesions.

Abstract

Agonistic behavior after the regrouping of unfamiliar pigs has been recognized as one of the major welfare issues for pig husbandry, as it may result in lesions, lameness, and health problems. One scarcely investigated strategy to curb agonistic behavior is reducing the availability of visual stimuli potentially eliciting aggressions. In this study, we investigated the expression of agonistic behavior by growing pigs and the resulting accumulation of skin lesions over a period of 14 days following the formation of new social groups, which occurred in a condition of darkness maintained for 48 h. Compared to a simulated natural photoperiod (12 h light/day), darkness significantly reduced the number of skin lesions on the mid- and rear thirds of pigs’ body (p ≤ 0.01). A lack of corresponding decrease in frequency and duration of agonistic interactions suggests that darkness acts by decreasing the efficacy, not the expression, of aggressions. Furthermore, the location of lesions mostly affected by darkness indicates that the latter mostly acted by reducing the possibility of pigs to convey damage to a fleeing conspecific, rather than to one involved in a reciprocal fighting. The lighting regime provided did not affect growth performance traits of a 17-weeks feeding trial. The present results identify in the provision of darkness an easily applicable, and relatively inexpensive intervention, that leads to the reduction of skin lesions.

Identification of Faecal Maternal Semiochemicals in Swine (Sus scrofa) and their Effects on Weaned Piglets

Piglets are attracted to maternal faeces early in life. Thus, the aim of this study was to identify faecal maternal semiochemicals that attract piglets and evaluate their effects on piglets at weaning. Faecal samples were collected from eight sows during gestation and lactation. Faecal semiochemicals were extracted and identified using solid phase extraction and GC/MS. A total of 26 volatiles were present in lactating and gestating sow faeces. Sows secreted no unique semiochemical after farrowing. However, the concentration of skatole and myristic acid were 2.68 and 1.13 times higher after farrowing. A free-choice preference assessment showed that piglets had a preference for a feeder sprayed with a solution containing skatole and myristic acid. No preference was found when feeders were sprayed with skatole and myristic acid individually. The application of skatole and myristic acid to the feeders of weaned pigs significantly reduced piglet aggression by 30% and tended to increase feeding behaviour by 35% the first 24 h post-weaning. These results suggest that skatole and myristic acid might be acting as a multicomponent maternal signal that attracts piglets and has a calming effect at weaning.

Feed intake of the sow and playful creep feeding of piglets influence piglet behaviour and performance before and after weaning

Creep feed intake is variable and may be partly homeostatically and exploratory driven. We studied effects of maternal feed restriction and a 'play-feeder' on piglet behaviour and performance. 37 Litters received creep feed in a conventional (CON) or play-feeder (PL) and their sows were full-fed (FF) or restrictedly-fed (RES). Eaters were determined via rectal swabs. At weaning (d24) four piglets from the same treatment were grouped (n = 36 pens). RES hindered piglet growth by 41 g/d and enhanced time eating, creep feed intake and percentage of eaters at weaning versus FF. RES-PL had the largest proportion of moderate and good eaters. PL stimulated feeder exploration and attracted more piglets to the feeder than CON. Post-weaning, RES increased exploratory behaviours, feed intake between d0-5, and growth between d0-2, and reduced body lesions between d0-2 (within CON), drinking and ear biting. PL increased ingestive behaviours, feed intake and growth between d0-15, and BW at d15 post-weaning by 5%. PL also lowered the prevalence of watery diarrhoea, number of body lesions and piglets with ear (within FF) and tail (within RES) damage at d15 post-weaning. Treatments did not affect FCR. To conclude, RES and particularly PL (broader and for longer) result in less weaning-associated-problems.

Ascaroside Pheromones: Chemical Biology and Pleiotropic Neuronal Functions

Pheromones are neuronal signals that stimulate conspecific individuals to react to environmental stressors or stimuli. Research on the ascaroside (ascr) pheromones in Caenorhabditis elegans and other nematodes has made great progress since ascr#1 was first isolated and biochemically defined in 2005. In this review, we highlight the current research on the structural diversity, biosynthesis, and pleiotropic neuronal functions of ascr pheromones and their implications in animal physiology. Experimental evidence suggests that ascr biosynthesis starts with conjugation of ascarylose to very long-chain fatty acids that are then processed via peroxisomal β-oxidation to yield diverse ascr pheromones. We also discuss the concentration and stage-dependent pleiotropic neuronal functions of ascr pheromones. These functions include dauer induction, lifespan extension, repulsion, aggregation, mating, foraging and detoxification, among others. These roles are carried out in coordination with three G protein-coupled receptors that function as putative pheromone receptors: SRBC-64/66, SRG-36/37, and DAF-37/38. Pheromone sensing is transmitted in sensory neurons via DAF-16-regulated glutamatergic neurotransmitters. Neuronal peroxisomal fatty acid β-oxidation has important cell-autonomous functions in the regulation of neuroendocrine signaling, including neuroprotection. In the future, translation of our knowledge of nematode ascr pheromones to higher animals might be beneficial, as ascr#1 has some anti-inflammatory effects in mice. To this end, we propose the establishment of pheromics (pheromone omics) as a new subset of integrated disciplinary research area within chemical ecology for system-wide investigation of animal pheromones.

Preliminary Study: Depriving Piglets of Maternal Feces for the First Seven Days Post-Partum Changes Piglet Physiology and Performance before and after Weaning

Simple Summary

Coprophagy is the behavior of eating feces. This behavior has been reported in many animals, including pigs. We aimed to assess how coprophagy affects piglet behavior, physiology, and performance by depriving piglets of maternal feces for the first 7 d post-partum. Eight litters were randomly assigned either to have access to maternal feces (control) or to be deprived of maternal feces for the first 7 d post-partum. Piglet behavior was observed for 24 h at 7 d of age and two piglets from each litter (male and female) were bled for hematological analysis at 0, 7, and 21 d of age. Piglets feed intake and weight gain were measured until 123 d post-weaning. No behavioral differences were observed between treatments. Overall, control piglets had 25% higher white blood cell counts and higher feed intake and weight gain than piglets deprived of maternal feces. At 123 d post-weaning, control piglets were 9.6 kg heavier than piglets deprived of maternal feces. In conclusion, piglets with access to maternal feces early in life exhibited better performance. The mechanisms by which coprophagy improves piglet performance needs to be elucidated in further studies, but could include effects of the nutrition, microbiome or semiochemical exposure.

Abstract

Coprophagy has been described in piglets although its importance has not been fully assessed. The aim of this study was to evaluate how deprivation of maternal feces influenced piglet physiology, behavior, and performance. Eight litters were randomly assigned to one of two treatments. Control (CON) litters had access to maternal feces while deprived (DEP) litters were deprived of maternal feces for the first 7 d post-partum. Piglet behavior was quantified for 24 h at 7 d of age. Blood samples were collected from one male and female from each litter at 0, 7, and 21 d for hematological analyses, and post-weaning performance was assessed until 123 d post-weaning. No treatment effects were observed on piglet behavior. DEP piglets had 25% lower leukocyte counts (p < 0.01). Relative to DEP litters, CON litters had increased post-weaning feed intake (0.998 vs 0.901 kg/d; p = 0.02) and weight gain (0.536 vs 0.483 kg/d; p < 0.01). At 123 d post-weaning, CON pigs were 9.3 ± 2.3 kg heavier than treatment pigs (p < 0.01). These results suggest that access to maternal feces improves immunocompetence and growth performance. Further studies are needed to explore the physiological mechanisms through which maternal feces improve growth performance, including nutritional and microbial factors, or the presence of maternal semiochemicals.

Behavior of Pigs Reared in Enriched Environment: Alternatives to Extend Pigs Attention

Three trials were carried out in a completely randomized design aiming to assess the behavior of pigs in growth phase in enriched environments. Trial 1 evaluated the effects of frequency of availability of environmental enrichment. The animals were assigned to four treatments: 1) control with no enrichment object; 2) objects provided for six consecutive days uninterruptedly; 3) objects provided on alternate days, and 4) objects provided for six consecutive days taken away by the end of the afternoon and replaced at dawn. Trial 2 assessed the effects of scent on animals’ acceptance and maintenance of interest in objects. Animals were assigned to four treatments: 1) unscented object; 2) object with banana scent; 3) object with rum scent; 4) object with scents alternated every other day. Trial 3 aimed to assess the influence of environmental enrichment based on providing rewards at different difficulty levels. Animals were assigned to three treatments: 1) object with no reward; 2) object with a reward at an easy level; 3) object with a reward at a difficult level. Each trial had six days of behavioral observations every ten minutes for eight hours each day using images from video cameras. Enrichment objects stimulated the animals’ natural behavior of nuzzling and exploring the environment. The way the objects were available did not impact the success of their use. Offering enrichment on alternate days or removing the objects by the end of the day was not an effective strategy to extend the animals’ interest. The olfactory stimulus in environmental enrichment objects had no positive effect on extending the animals’ interest on them, nor did alternating the aromas. The tactile stimulus was a key factor for object attractiveness. Providing environmental enrichment objects with rewards stimulated the exploratory behavior of pigs. The level of difficulty to obtain the reward may discourage the animals.

A natural interomone 2-methyl-2-butenal stimulates feed intake and weight gain in weaned pigs

A novel approach to potentially improve pig growth and welfare is to supplement environments with biologically meaningful odors that are deficient. The post-weaning environment lacks maternal odors that may contribute to the often-observed post-weaning lag in growth and health challenges. A recently reported rabbit maternal pheromone (2-methyl-2-butenal (2M2B)) may act as an interomone in the pig. The objective of this study was to determine if providing a maternal pheromone/interomone during transport and the post-weaning environment may enhance pig performance. A total of 40 replicated pens were used in a factorial arrangement of two transport olfactory experiences (Control v. 2M2B), two nursery olfactory experiences (Control v. 2M2B) and two sexes (barrow v. gilt). Pig body weight, average daily gain (ADG), average daily feed intake (ADFI) and gain : feed ratio (G : F) were measured and calculated over a 28-day post-weaning period. Pig sex and application of 2M2B during transport had no effect on pig performance. However, pigs that had 2M2B applied to their feeder at weaning had 15% greater feed intake (0.74 v. 0.64±0.03 kg/day, P<0.01) and 12% greater ADG (0.27 v. 0.24 kg/day, P<0.05) than control pigs. G : F ratio was not different between treatments. The interomone 2M2B is a novel, safe molecule that can improve pig post-weaning performance. This report highlights a new area of study and a natural class of compounds that can improve pig performance and potentially improve pig welfare.

Preliminary findings on the effect of the pig appeasing pheromone in a slow releasing block on the welfare of pigs at weaning

The pig appeasing pheromone (PAP) applied in spray has shown to be effective in reducing the frequency of aggression and the stress response of young and adult pigs under experimental conditions. This preliminary experiment investigates the effect of the PAP in a slow releasing block on the behaviour and skin lesions of weaners after mixing on a commercial farm. Two identical rooms containing six replicates per treatment of a commercial weaner building were used. There were two treatments (PAP block and Control) and each room contained one treatment. In the PAP treatment, the day before weaning and after washing and disinfection, two PAP blocks (1 block / 20 m²) were placed hanging on top of the pens. Six hours after mixing, there was a significant effect of the PAP block treatment on the occurrence of social negative behaviour (PAP mean; median [95 % CI] for median = 3.6; 2.7 [1.5-5.4] % vs. Control 8.3; 8.7 [6.1-11.3] % P = 0.003, social positive behaviour (PAP 5.5; 5.1 [4.5-6.8] % vs. Control 1.4; 1.3 [0-2.8] % P = 0.02), feeding (PAP 9.1; 7.4 [5.5-16.5] % vs. Control 1.6; 0.0 [0-6.1] % P = 0.02, drinking (PAP 3.1; 2.9 [2.5-3.9] % vs. Control 0.8; 0.5 [0-1.7] % P = 0.04) as well as on the sitting position (PAP 1.2; 0.9 [0-2.4] % vs. Control 4.1; 4.2 [2.1-6.0] % P = 0.02). Except for social positive behaviour (PAP 5.6; 6.0 [3.9-7.5] % vs. Control 2.9; 2.8 [1.6-4.2] % P = 0.02) those differences were not significant 24 h post-mixing anymore. The prevalence of wounded animals was not significantly different between treatments. The PAP in block form may be a promising tool to reduce food neophobia and aggression after mixing. Still, further research is needed to increase the effect of the PAP block over time under commercial farming conditions.

The Pig Olfactory Brain: A Primer

Despite the fact that pigs are reputed to have excellent olfactory abilities, few studies have examined regions of the pig brain involved in the sense of smell. The present study provides an overview of the olfactory bulb, anterior olfactory nucleus, and piriform cortex of adult pigs using several approaches. Nissl, myelin, and Golgi stains were used to produce a general overview of the organization of the regions and confocal microscopy was employed to examine 1) projection neurons, 2) GABAergic local circuit neurons that express somatostatin, parvalbumin, vasoactive intestinal polypeptide, or calretinin, 3) neuromodulatory fibers (cholinergic and serotonergic), and 4) glia (astrocytes and microglia). The findings revealed that pig olfactory structures are quite large, highly organized and follow the general patterns observed in mammals.

Influence of emotional balance during a learning and recall test in horses (Equus caballus)

Modern day horse-human relationships entail different types of sport and riding activities, which all require learning. In evaluating the interaction between learning and emotions, studying normal coping strategies or adaptive responses to the surroundings is critical. 34 horses were involved in a cognitive test, in the absence of physical effort, to analyze performance, as well as physiological and behavioral responses related to learning, memorization and recall, associated to the capacity to reverse a learned model. Synthetic Equine Appeasing Pheromone (EAP) was used in 17 horses in order to modulate their emotional state and evaluate differences in cognitive-emotional response during cognitive effort in comparison to the control group (placebo group). Both groups showed statistically significant changes in heart rate during the test, indicating emotional and physio-cognitive activation. The EAP group produced fewer errors and made more correct choices, showing behaviors related to increased attention, with less influence from environmental stimuli. The capacity to learn to learn, as shown in the bibliography, allows animals to establish conceptual learning, when a normal or positive emotional state (in this case modulated by semiochemicals) is used to control limbic system activation and, consequently, decrease stressful/fearful reactions, resulting in better learning capacities during the cognitive test.

Toward a better understanding of pig behavior and pig welfare

Pork production began to flourish in the USA after the practice of finishing pigs on corn was popularized in the late 1600s. By the 1840s, there were 35 million pigs and 20 million people in the USA and Cincinnati was the world's largest pork market. Between 1890 and the present, the total number of pigs in the USA has remained at 50-60 million, but dramatic changes in swine husbandry over the course of the 20th century have metamorphosed pig production from small, extensive (outdoor), labor-dependent enterprises into large, intensive (indoor), capital-dependent, production systems. This development has led to debate concerning the impact of swine production on animal/human health, the environment, and the welfare of the animals under our care. In a very tangible way, the future of pork production depends on effectively addressing the public's concerns regarding animal welfare and health. Here, we review basic sensory and behavioral aspects of swine with the objective of reaching a better understanding of pig behavior and pig welfare. The premise of this discussion is that safeguarding animal welfare and health is good for pigs, pork producers and the animal-conscious public.

Binding specificity of recombinant odorant-binding protein isoforms is driven by phosphorylation

Native porcine odorant-binding protein (OBP) bears eleven sites of phosphorylation, which are not always occupied in the molecular population, suggesting that different isoforms could co-exist in animal tissues. As phosphorylation is a dynamic process resulting in temporary conformational changes that regulate the function of target proteins, we investigated the possibility that OBP isoforms could display different binding affinities to biologically relevant ligands. The availability of recombinant proteins is of particular interest for the study of protein/ligand structure-function relationships, but prokaryotic expression systems do not perform eukaryotic post-translational modifications. To investigate the role of phosphorylation in the binding capacities of OBP isoforms, we produced recombinant porcine OBP in two eukaryotic systems, the yeast, Pichia pastoris, and the mammalian CHO cell line. Isoforms were separated by anion exchange HPLC, and their phosphorylation sites were mapped by MALDI-TOF mass spectrometry and compared to those of the native protein. Binding experiments with ligands of biological relevance in the pig, Sus scrofa, were performed by fluorescence spectroscopy on two isoforms of recombinant OBP expressed in the yeast. The two isoforms, differing only by their phosphorylation pattern, displayed different binding properties, suggesting that binding specificity is driven by phosphorylation.

Use of a putative maternal pheromone during transport and the effect of trailer temperatures on pig losses and welfare

The efficacy of a maternal pheromone (MP) to reduce transport stress was evaluated in a field study. In addition, we determined the appropriate field sample sizes for measures of death rate and the proportion of fatigued pigs observed before, during, and after transportation. In the first experiment, semi-truck trailers were randomly treated with 500 mL of MP or isopropyl alcohol as the control (C). Animal handling measures were collected at truck loading, unloading, and from resting pens to the stun area. Blood samples were collected from a sample of transported pigs. In the second experiment, a single truck was used repeatedly for transport to the slaughter plant. The truck and lairage pens were sprayed either with the MP or C, depending on the week (n = 11 weeks). Rate of fatigued pigs coming off the truck was 0.41% for C-treated pigs and 0.15% for MP-treated pigs (P > 0.05). Air temperature recorded in the trailers rose during truck loading and idle time, but levelled off during driving (holding at 1.7°C greater than outside). MP tended to reduce the rate of fatigued pigs (39% although not statistically significant) but it also increased handling difficulty. A power test indicated the sample size needed to detect differences with a statistical significant magnitude (P < 0.05) in future transport studies was 249 trucks (~41 085 pigs).

Reducing post-mixing aggression and skin lesions in weaned pigs by application of a synthetic maternal pheromone

In commercial pig production, piglets are often mixed after weaning which can result in severe aggression and lead to body damage, disruption of feeding behaviour and reduced growth. This experiment investigated whether application of a synthetic maternal pheromone to groups of weaned pigs in commercial housing would affect the level of aggression and skin lesions sustained after mixing. Two treatments (Pheromone and Control) were used with 16 replicate pens of pigs (20 pigs per pen). Treatments were applied on the day of weaning (average 28 days of age) on a per room basis in alternate weeks. In Pheromone pens, after routine washing and disinfection, the walls and feeders were treated one hour prior to occupation with a synthetic pheromone at a rate of 1.0 ml pig−1. Control pens were as for Pheromone except no product was applied. During the 24-h period, post mixing, pigs in pheromone-treated pens spent significantly less time fighting than those in control pens. This was reflected in reduced injury scores 24 h after mixing, with pigs in pheromone-treated pens having 39% fewer skin lesions on the front of the body compared to those in control pens. Treatment had no effect on growth rate or feed efficiency, although the feed intake for days 7–28 was significantly lower and feed efficiency tended to be lower in pheromone-treated pens. In conclusion, application of a synthetic maternal pheromone can be considered one of the arsenal of strategies to reduce aggression and safeguard the welfare of groups of weaned pigs where mixing is unavoidable.

Influence of olfactory substances on the heart rate and lying behaviour of pigs during transport simulation

This study investigated the effect of olfactory substances on the heart rate and lying behaviour of pigs during transport simulation. Five treatments were tested through the application of each substance to pigs’ snouts with a paintbrush. These consisted of: 1) control treatment (wiping without product); 2) 2 ml of a synthetic, maternal-like pheromone; 3) 5 ml of a synthetic, maternal-like pheromone; 4) a commercial, non-relevant odour and 5) 2 ml of a placebo (solvent of the synthetic pheromone without active ingredients). In total, 90 pigs took part in this study and each treatment was tested on a group of three pigs with six replicates per treatment. Pigs were vibrated in the vertical direction in a transport simulator with a frequency of 8 Hz and an acceleration of 3 m s−2. Cardiac activity and lying behaviour during vibration were quantified. The effect of vibration was found to be statistically significant, ie causing an increase in heart rate and numbers of ventricular ectopic beats (VEB). Both 2 and 5 ml of synthetic pheromone were generally found to decrease the minimum, mean, and peak heart rate values in comparison with the other treatments (in particular the control and the non-relevant odour group) but only minimum heart rate reached statistical significance. However, the number of VEBs was highest for these two synthetic pheromone groups during vibration. No dose-dependent synthetic pheromone effects were found and there were no differences in the amount of time pigs spent lying. The use of olfactory substances may support pigs’ ability to cope with real transport conditions thereby improving their welfare.

Influence of a Semiochemical Analogue on Growing Performances and Meat Quality of Broilers

Stress in broilers may have severe consequences on the final product quality. A synthetic analogue of uropygial secretion of mother hens was isolated from poultry. This mother hen uropygial secretion analogue (MHUSA) was tested in farm conditions on broilers during 12 wk. The purpose of this trial was to estimate the influence of MHUSA on growing performances, meat characteristics after processing, and stress indicators of broilers. After the 80-d period, birds under treatment were heavier at 3 different weighing ages (P <or= 0.01, P <or= 0.01, and P <or= 0.05 at 21, 63, and 80 d of age, respectively) and had higher filet weights. A strong correlation between filet weight and carcass weight was found (R2 = 0.83). No correlation between abdominal fat and carcass weight or between abdominal fat and filet weight was observed. There was no significant difference among treatments concerning abdominal fat. Corticosterone level was higher for birds under placebo treatment (P <or= 0.05). No statistical difference was observed for mixed sexes concerning filet weight lost from 24 h to d 6 postmortem. After the cooking procedure, samples from the MHUSA group were less yellow compared with the control (P <or= 0.05). Our conclusion is that the tested semiochemical MHUSA has an influence on live weights, filet weights, and corticosterone levels in Label broilers grown to 80 d of age. Constant exposure to the MHUSA enhances growth without decreasing meat quality.

Effect of drinker type and sound stimuli on early-weaned pig performance and behavior

Early-weaned pigs appear to be highly motivated to engage in motor patterns associated with nursing, which is thought to lead to the development of abnormal ingestive behaviors. If performance of these behaviors is related to sucking motivation, then the normal stimuli associated with nursing should stimulate pigs to perform these abnormal behaviors, specifically belly nosing. The goal of this study was to determine whether belly nosing could be affected by sow nursing vocalizations and whether the style of the drinker device influenced early-weaned pig behavior. Over six trials, 352 Yorkshire pigs were weaned at 15 d and assigned to pens (n = 44) of eight pigs based on litter, weight, and sex. Four pens in each of two rooms were outfitted with either a water nipple drinker or a drinker bowl. Rooms either had recorded sow vocalizations broadcast at hourly intervals or no sound (control). Pig behaviors were videotaped in a sample of pens (n = 32) on d 0, 1, 2, 5, 9, 11, 13, 16, and 18 after weaning. On d 0 to 2, pigs were observed continuously for feeding and drinking behaviors. On d 5 to 18, pigs were observed by scan sampling every 5 min for time budgets. Pigs with drinker bowls had higher apparent feed intakes during the first 2 d after weaning (P = 0.024), whereas they spent less time engaged in drinking behavior (P = 0.001). This coincided with an overall lower water use (P = 0.001) than that of pigs with nipple drinkers. Pigs with bowl drinkers also spent less time belly nosing than those with access to a nipple drinker (P = 0.012). Pigs in the sow vocalization treatment tended to have a higher ADG (P = 0.075), whereas they spent less time performing feeding behavior (P = 0.064). However, there was no effect of sow nursing grunts on belly nosing. These results suggest that there is a complex relationship between feeding, drinking and sucking, and belly nosing is not controlled by the same external stimuli as sucking. Because drinker type and the motor patterns that it accommodates affect belly nosing, it may be that the internal stimuli associated with nursing, such as the actual act of sucking, play a large role in the development of abnormal oral-nasal behaviors.

Biochemical and chemical supports for a transnatal olfactory continuity through sow maternal fluids

Recognition of the mother is of major importance for the survival of mammalian neonates. This recognition is based, immediately after birth, on the detection of odours that have been learned by the fetus in utero. If the ethological basis of a transnatal olfactory continuity is well established, little is known on the nature of its olfactory cues, and nothing about the presence of potential carrier proteins in the maternal fluids such as amniotic fluid, colostrum and milk. We have identified the components of the pig putative maternal pheromone in these fluids of the sow. We also used a ligand-oriented approach to functionally characterize carrier proteins for these compounds in the maternal fluids. Six proteins were identified, using binding assay, immunodetection and peptide mapping by mass spectrometry. These proteins are known to transport hydrophobic ligands in biological fluids. Among them, alpha-1 acid glycoprotein (AGP) and odorant-binding protein (OBP) have been described in the oral sphere of piglets as being involved in the detection of pig putative maternal pheromone components. These are the first chemical and biochemical data supporting a transnatal olfactory continuity between the fetal and the postnatal environments.