Aggressive and sexual behaviour of growing and finishing pigs reared in groups, without castration

CRISPR/Cas9-editing of KISS1 to generate pigs with hypogonadotropic hypogonadism as a castration free trait

Introduction: Most male pigs are surgically castrated to avoid puberty-derived boar taint and aggressiveness. However, this surgical intervention represents a welfare concern in swine production. Disrupting porcine KISS1 is hypothesized to delay or abolish puberty by inducing variable hypogonadotropism and thus preventing the need for castration. Methods: To test this hypothesis, we generated the first KISS1-edited large animal using CRISPR/Cas9-ribonucleoproteins and single-stranded donor oligonucleotides. The targeted region preceded the sequence encoding a conserved core motif of kisspeptin. Genome editors were intracytoplasmically injected into 684 swine zygotes and transferred to 19 hormonally synchronized surrogate sows. In nine litters, 49 American Yorkshire and 20 Duroc liveborn piglets were naturally farrowed. Results: Thirty-five of these pigs bore KISS1-disruptive alleles ranging in frequency from 5% to 97% and did not phenotypically differ from their wild-type counterparts. In contrast, four KISS1-edited pigs (two boars and two gilts) with disruptive allele frequencies of 96% and 100% demonstrated full hypogonadotropism, infantile reproductive tracts, and failed to reach sexual maturity. Change in body weight during development was unaffected by editing KISS1. Founder pigs partially carrying KISS1-disruptive alleles were bred resulting in a total of 53 KISS1 ^+/+, 60 KISS1 ^+/-, and 34 KISS1 ^-/- F1 liveborn piglets, confirming germline transmission. Discussion: Results demonstrate that a high proportion of KISS1 alleles in pigs must be disrupted before variation in gonadotropin secretion is observed, suggesting that even a small amount of kisspeptin ligand is sufficient to confer proper sexual development and puberty in pigs. Follow-on studies will evaluate fertility restoration in KISS1 KO breeding stock to fully realize the potential of KISS1 gene edits to eliminate the need for surgical castration.

Does Immunocastration Affect Behaviour and Body Lesions in Heavy Pigs?

Simple Summary

Castration of piglets is routinely practiced to prevent the presence of boar taint. In Europe, around 61% of pigs are surgically castrated, 54% of which do not receive any pain-relief therapy. The increasing public awareness towards animal welfare and the ethical characteristics of animal-derived products has led to the necessity of finding more animal-friendly alternatives. Among them, immunocastration, a process of active immunisation leading to the suppression of testicular function, has shown promising results in light pig production, both in terms of animal welfare and productivity. Besides, no study has yet investigated animal welfare in immunocastrated males intended for Italian heavy pig production. This study aimed at evaluating the effect of immunocastration on the welfare of heavy pigs by monitoring behaviour and body lesions in immunocastrated and surgically castrated pigs. Salivary testosterone levels and productive traits were also evaluated. Our results confirmed that immunocastration is a suitable alternative to surgical castration with profitable productive performance, whereas the higher activity of animals and the higher presence of body lesions before the effective immunisation caused an impairment of animal welfare, which should be further investigated as a critical aspect in heavy pig production.

Abstract

Immunocastration has been pointed out as an alternative to surgical castration; though, most of the scientific studies were performed in light pig production. This study aimed to evaluate the effect of immunocastration on animal welfare in heavy pig production through the evaluation of behaviour and body lesions. A total of 188 commercial-hybrid pigs were randomly allocated into two treatment groups: surgical castration (SC) and immunocastration with Improvac^® (IC). Data on behaviour, body lesions, and salivary testosterone levels were collected the day before each vaccination at 15, 22, 32, and 36 weeks of age. IC and SC pigs were slaughtered at 40 and 41 weeks of age, respectively; productive and carcass traits data were also collected. Considering productive performance, our results confirmed that IC pigs grew faster and presented a higher weight at slaughter. A critical period for pig welfare was observed before 32 weeks: testosterone concentration and body lesion score were significantly higher in IC pigs compared to SC pigs; active behaviours were significantly more frequent in IC at 15 weeks. Immunocastration may represent a suitable alternative to surgical castration with profitable productive performances, whereas the impairment of welfare during the period before the effective vaccination should be further investigated as a potential critical aspect in heavy pig production.

Recognizing Post-Castration Pain in Piglets: A Survey of Swine Industry Stakeholders and the General Public

We need validated, practical methods for pain assessment in piglets. Pain assessment can help researchers, veterinarians and industry professionals identify the need for analgesia or other pain management approaches when applying painful procedures, such as surgical castration. A pain assessment tool, the Piglet Grimace Scale (PGS), was previously validated in this context, but it is not widely applied. It is important that the PGS can be applied by a range of people, not just pain assessment experts. Our objective was to study the validity and reliability of PGS ratings applied by swine industry professionals and the general public, to assess its potential utility in non-research applications. To do so, we conducted an online Qualtrics survey in which, after completing a brief online training module and a practice test, 119 respondents were asked to rate 9 piglet images showing facial expressions immediately after surgical castration or sham-handling. Respondents were provided information on the castration treatment for each image and had continuous access to the scale throughout the survey. The survey also contained demographic questions. Industry respondents were recruited through networking, and participants from the general public were recruited through Amazon Mechanical Turk. Four trained experts scored each image, and these scores were averaged to produce gold standard scores. Intraclass correlations indicated strong internal consistency among experts, industry and public. ANOVA demonstrated scoring to be moderately comparable between groups. Campbell and Fiske’s Multi-Trait Multi-Method framework provided qualified support for the internal validity and reliability of the PGS scale, even applied by non-experts (industry and public). Both response groups were able to recognize pain in castrated piglets. However, public respondents attributed higher levels of pain to sham-handled piglets than industry respondents (2.83 vs. 2.35; p=0.047), and both response groups systematically overestimated pain experience compared to the experts, suggesting more training may be necessary before using the scale in a diagnostic capacity. Nevertheless, overall findings support wide applicability of PGS, even with minimal training, to improve awareness, recognition and monitoring of swine pain among veterinarians, industry professionals and even members of the public.

Exploration of early social behaviors and social styles in relation to individual characteristics in suckling piglets

Social behavior is a key component of pig welfare on farms, but little is known on the development of social behaviors in piglets. This study aimed to explore social behaviors and identify early social styles in suckling piglets. Social behaviors of 68 piglets from 12 litters were scored continuously for 8 h per day at 21 and 42 days of age, and were included in a Hierarchical Clustering on Principal Components analysis to identify clusters of pigs with similar social styles. Social nosing represented 78% of all social interactions given. Three social styles were identified: low-solicited inactive animals (inactive), active animals (active), and highly-solicited avoiders (avoiders). Belonging to a cluster was independent of age, but was influenced by sex, with females being more represented in the ‘inactive’ cluster, and males in the ‘active’ cluster, whereas both sexes were equally represented in the ‘avoider’ cluster. Stability of piglets’ allocation to specific clusters over age was high in the ‘inactive’ (59%) and ‘active’ (65%) clusters, but low in the ‘avoider’ cluster (7%). Haptoglobin and growth rate were higher in ‘active’ than ‘inactive’ pigs, and intermediate in ‘avoiders’. Our findings suggest the existence of transient social styles in piglets, likely reflective of sexual dimorphism or health status.

Effect of dietary energy level in finishing phase on performance, carcass and meat quality in immunocastrates and barrows in comparison with gilts and entire male pigs

Immunocastration, a technique consisting of two vaccinations against gonadotropin-releasing hormone (GnRH), can be used as alternative to surgical castration of piglets. It reduces boar taint and allows higher economic and ecological efficiency compared to barrows. The feeding strategy of immunocastrates, however, can still be improved. After second vaccination, when immunisation becomes fully effective, feed intake of immunocastrates increases sharply. This study aimed to investigate whether energy intake of immunocastrates after second vaccination could be reduced by lowering the dietary energy level of the finishing phase, without negatively affecting animal performance and quality of pork production. We hypothesised that immunocastrates already reach their limits in voluntary feed intake after second vaccination, and therefore would not be able to compensate the lower dietary energy level, in contrast to barrows. Therefore, this study aimed to assess the effect of high-energy diet (HE, net energy (NE) = 10.2 MJ/kg) compared to low-energy diet (LE, NE = 8.8 MJ/kg) in barrows and immunocastrates and as a reference, gilts and entire male pigs on a standard high-energy diet were included. CP and standardised ileal digestible amino acid levels were similar in both diets. For each treatment, eight pen replicates of six pigs per pen were evaluated on performance, carcass quality, meat and fat quality, digestibility, economic and ecological sustainability, behaviour and effectiveness of immune response. No difference in feed intake of immunocastrates between LE and HE could be demonstrated. As a result, daily energy intake of immunocastrates was higher on HE compared to LE, which resulted in a higher daily gain on HE. Feed conversion ratio (FCR) of immunocastrates on HE did not differ significantly with FCR of entire males. Barrows did not show higher average daily gain on HE compared to LE. Nitrogen efficiency was better in HE compared to LE, without negative effects on digestibility, carcass quality, economic parameters, behaviour or immune response. Small positive effects on the palatability of the meat of immunocastrates on HE were observed, although consumers did not prefer one of both feeds. Immunocastration was successful in reducing sexual and aggressive behaviour as well as in lowering the prevalence of boar taint from 15% in EM to 0% in immunocastrates. However, in two out of 96 immunocastrates (one on HE and one on LE), the immunocastration was not fully effective. In conclusion, this study did not show advantages of feeding immunocastrates or barrows a low-energy diet.

Intelligent Perception-Based Cattle Lameness Detection and Behaviour Recognition: A Review

Simple Summary

Cattle lameness detection as well as behaviour recognition are the two main objectives in the applications of precision livestock farming (PLF). Over the last five years, the development of smart sensors, big data, and artificial intelligence has offered more automatic tools. In this review, we discuss over 100 papers that used automated techniques to detect cattle lameness and to recognise animal behaviours. To assist researchers and policy-makers in promoting various livestock technologies for monitoring cattle welfare and productivity, we conducted a comprehensive investigation of intelligent perception for cattle lameness detection and behaviour analysis in the PLF domain. Based on the literature review, we anticipate that PLF will develop in an objective, autonomous, and real-time direction. Additionally, we suggest that further research should be dedicated to improving the data quality, modeling accuracy, and commercial availability.

Abstract

The growing world population has increased the demand for animal-sourced protein. However, animal farming productivity is faced with challenges from traditional farming practices, socioeconomic status, and climate change. In recent years, smart sensors, big data, and deep learning have been applied to animal welfare measurement and livestock farming applications, including behaviour recognition and health monitoring. In order to facilitate research in this area, this review summarises and analyses some main techniques used in smart livestock farming, focusing on those related to cattle lameness detection and behaviour recognition. In this study, more than 100 relevant papers on cattle lameness detection and behaviour recognition have been evaluated and discussed. Based on a review and a comparison of recent technologies and methods, we anticipate that intelligent perception for cattle behaviour and welfare monitoring will develop towards standardisation, a larger scale, and intelligence, combined with Internet of things (IoT) and deep learning technologies. In addition, the key challenges and opportunities of future research are also highlighted and discussed.

Animal Welfare Consequences of Organic Boar Fattening and Occurrence of Boar Taint on Five Commercial Farms

Simple Summary

The usual castration of male fattening pigs is under discussion, especially in organic farming, because of the negative effects on the pig’s welfare and integrity. Nevertheless, it is feared that boars show more aggressive and mounting behaviours, resulting in stress, painful injuries and lameness, and that their meat has an unpleasant odour/taste (called “boar taint”). Therefore, it was examined to which extent these concerns come true under commercial organic conditions. Additionally, influences from management and husbandry were investigated, in order to identify conditions in organic fattening systems with low risk to welfare and meat quality. Despite more agonistic and mounting behaviours in boars compared to castrates, especially if housed next to females, no increased numbers of skin lesions, lame pigs, disease treatments or deaths were observed. Less skin lesions occurred when more space was provided. A moderate rate of wounds on penises was found, but not on farms with bulky straw bedding. A small number of carcasses (1.44%) were excluded from processing because of boar taint. In conclusion, boar fattening under the examined organic conditions appears to be a feasible alternative to castration, but penile injuries should be monitored at slaughter.

Abstract

The welfare of male fattening pigs may be improved by refraining from castration, but may be compromised, in turn, by harmful social behaviour in groups of boars. In addition, boar taint may be problematic. This study aimed to evaluate these potential problems in boar fattening under commercial organic conditions. In total, 625 boars were compared with 433 barrows and 83 gilts regarding their social behaviour, lesions and lameness at 80 kg, before and after split marketing. The mixed-model analysis showed that significantly more short agonistic interactions, fights and mounting behaviours were observed in groups of boars. Agonistic interactions were reduced in spring/summer and when boars grew older. Fights and mounts were increased when boars had contact to female pigs in the neighbouring pen. No effect of split marketing, growth rate, homogeneity of groups, group size, feeding space and illumination hours could be detected. Increased interaction frequencies did not result in significantly more skin lesions, lameness, treatments or mortality. Increased space allowance reduced skin lesions. On 9.8% of the dissected boars’ penises, wounds were detected; they were absent on two farms with generous litter provision. Boar taint prevalence, as detected by human nose method, was 1.44%. Under the studied organic husbandry conditions, boar fattening appears to be practicable, although penile injuries should be monitored at slaughter.

Adipose Tissue Gene Expression of Entire Male, Immunocastrated and Surgically Castrated Pigs

Differences in adipose tissue deposition and properties between pig male sex categories, i.e., entire males (EM), immunocastrates (IC) and surgical castrates (SC) are relatively well-characterized, whereas the underlying molecular mechanisms are still not fully understood. To gain knowledge about the genetic regulation of the differences in adipose tissue deposition, two different approaches were used: RNA-sequencing and candidate gene expression by quantitative PCR. A total of 83 differentially expressed genes were identified between EM and IC, 15 between IC and SC and 48 between EM and SC by RNA-sequencing of the subcutaneous adipose tissue. Comparing EM with IC or SC, upregulated genes related to extracellular matrix dynamics and adipogenesis, and downregulated genes involved in the control of lipid and carbohydrate metabolism were detected. Differential gene expression generally indicated high similarity between IC and SC as opposed to EM, except for several heat shock protein genes that were upregulated in EM and IC compared with SC. The candidate gene expression approach showed that genes involved in lipogenesis were downregulated in EM compared with IC pigs, further confirming RNA-sequencing results.

Welfare Aspects of Raising Entire Male Pigs and Immunocastrates

Simple Summary

Surgical castration of male piglets without pain treatment and anaesthesia is not only a welfare problem but also violates the integrity of the animals. The favoured alternatives of raising entire male pigs (EM) with or without immunocastration (vaccination against boar taint) may, however, impose additional welfare problems under the current housing and management conditions. This focused review is intended to summarise the current state of scientific knowledge and practical reports on critical welfare issues and risk factors. Raising EM with or without subsequent immunocastration could be a welfare conform, future-oriented alternative to conventional surgical castration of pigs, provided that they are kept in a healthy and socially stable environment with sufficient physical resources, as safeguarded by measures of enhanced animal care and management control.

Abstract

For a long time, scientists assumed that newborns have a severely limited sense of pain (if any). However, this assumption is wrong and led to a “start of the exit” from piglet surgical castration. Some of the currently discussed or already implemented alternatives such as general or local anaesthesia during surgical castration raise additional welfare concerns as well as legal problems and/or are hardly applicable. The favoured long-term, welfare-friendly “gold standard” is to raise entire male pigs (EM). However, this may also impose certain welfare problems under the current conventional housing and management conditions. The specific types of behaviour displayed by EM such as mounting and aggressive behaviours but also increased exploration, which are partially linked to sexual maturation, increase the risk for injuries. The current status of knowledge (scientific literature and farmer experiences) on housing of EM suggests that environmental enrichment, space, group-stability, social constellation, feeding (diet and feeder space), health and climate control are critical factors to be considered for future housing systems. From an animal welfare point of view, an intermediate variant to be favoured to reduce problematic behaviour could be to slaughter EM before reaching puberty or to immunize boars early on to suppress testicular function. Immunization against endogenous GnRH can reduce EM-specific problems after the 2nd vaccination.

Local Anesthesia in Piglets Undergoing Castration-A Comparative Study to Investigate the Analgesic Effects of Four Local Anesthetics Based on Defensive Behavior and Side Effects

Simple Summary

More than 80 million male piglets are castrated every year within the first week of life mostly without pain relief in the EU. Castration is performed to prevent boar taint, to minimize aggressive and sexual behavior associated with intact males and to gain a constant quality of meat. It is an important animal welfare issue to eliminate pain caused by castration. Local anesthesia, meaning the sole injection of a local anesthetic into the testicles and in the surrounding tissue of conscious piglets, prior to castration is a currently discussed method in Germany. Thus, it was the aim of the present study to investigate the effect of four local anesthetics (procaine, lidocaine, bupivacaine and mepivacaine) on pain relief during surgical castration in conscious piglets. To assess pain, defensive behavior of piglets undergoing injection and castration was evaluated. In addition, attention was paid to possible side effects. Considering healing, bleeding and weight gain no negative impacts were observed, but impairments of locomotor activity occurred. The results indicate that lidocaine and mepivacaine are able to achieve significant pain relief during the castration procedure, whereas procaine and bupivacaine only during the severing of the spermatic cord.

Abstract

The aim of the present study was to investigate the effect of four local anesthetics on pain relief during surgical castration under standardized conditions in conscious piglets. Therefore, 71 male piglets (three to seven days) were distributed into control groups (handling, castration without anesthesia or analgesia) and local anesthetic trial groups (procaine, lidocaine, bupivacaine, mepivacaine). Then, 20 min prior to castration, animals of the treatment groups, except piglets in the handling group, received an injection of a local anesthetic or sodium chloride of 0.5 mL intratesticularly and 0.5 mL subscrotally. During injection and castration, defensive behavior was evaluated. Locomotor activity, as well as postoperative bleeding, wound healing and average daily weight gain were assessed to detect side effects. The injection caused increased defensive movements, significantly in the bupivacaine group. Lidocaine and mepivacaine significantly reduced defensive movements during castration, and procaine and bupivacaine only during severing of the spermatic cord. Impairments of locomotor activity were found in piglets injected with lidocaine, bupivacaine or sodium chloride. Considering healing, bleeding and weight gain, no negative impacts were observed. In conclusion, lidocaine and mepivacaine were able to achieve significant pain relief during the castration procedure, whereas procaine and bupivacaine only during the severing of the spermatic cord. Moreover, the injection of bupivacaine seemed to be painful itself.

Pork Production with Entire Males: Directions for Control of Boar Taint

Simple Summary

Castration of male piglets has traditionally been carried out to control boar taint, but animal welfare concerns about surgical castration has brought this practice under scrutiny. In addition, castration decreases growth performance and increases the environmental impact of pork production, so alternatives to castration are needed to control boar taint. In this review, we summarize the current knowledge on boar taint metabolism and outline some key areas that require further study. We also describe some opportunities for controlling the boar taint problem and propose that by defining the differences in metabolic processes and the genetic variations that can lead to boar taint in individual pigs, we can design effective custom solutions for boar taint.

Abstract

Boar taint is caused by the accumulation of androstenone and skatole and other indoles in the fat; this is regulated by the balance between synthesis and degradation of these compounds and can be affected by a number of factors, including environment and management practices, sexual maturity, nutrition, and genetics. Boar taint can be controlled by immunocastration, but this practice has not been accepted in some countries. Genetics offers a long-term solution to the boar taint problem via selective breeding or genome editing. A number of short-term strategies to control boar taint have been proposed, but these can have inconsistent effects and there is too much variability between breeds and individuals to implement a blanket solution for boar taint. Therefore, we propose a precision livestock management approach to developing solutions for controlling taint. This involves determining the differences in metabolic processes and the genetic variations that cause boar taint in specific groups of pigs and using this information to design custom treatments based on the cause of boar taint. Genetic, proteomic or metabolomic profiling can then be used to identify and implement effective solutions for boar taint for specific populations of animals.

Automated Video Behavior Recognition of Pigs Using Two-Stream Convolutional Networks

The detection of pig behavior helps detect abnormal conditions such as diseases and dangerous movements in a timely and effective manner, which plays an important role in ensuring the health and well-being of pigs. Monitoring pig behavior by staff is time consuming, subjective, and impractical. Therefore, there is an urgent need to implement methods for identifying pig behavior automatically. In recent years, deep learning has been gradually applied to the study of pig behavior recognition. Existing studies judge the behavior of the pig only based on the posture of the pig in a still image frame, without considering the motion information of the behavior. However, optical flow can well reflect the motion information. Thus, this study took image frames and optical flow from videos as two-stream input objects to fully extract the temporal and spatial behavioral characteristics. Two-stream convolutional network models based on deep learning were proposed, including inflated 3D convnet (I3D) and temporal segment networks (TSN) whose feature extraction network is Residual Network (ResNet) or the Inception architecture (e.g., Inception with Batch Normalization (BN-Inception), InceptionV3, InceptionV4, or InceptionResNetV2) to achieve pig behavior recognition. A standard pig video behavior dataset that included 1000 videos of feeding, lying, walking, scratching and mounting from five kinds of different behavioral actions of pigs under natural conditions was created. The dataset was used to train and test the proposed models, and a series of comparative experiments were conducted. The experimental results showed that the TSN model whose feature extraction network was ResNet101 was able to recognize pig feeding, lying, walking, scratching, and mounting behaviors with a higher average of 98.99%, and the average recognition time of each video was 0.3163 s. The TSN model (ResNet101) is superior to the other models in solving the task of pig behavior recognition.

Influence of Housing Conditions on Reliability of Immunocastration and Consequences for Growth Performance of Male Pigs

Simple Summary

Surgical castration of male piglets is societally criticized as it is painful and violates the integrity of the animals. Pork production with boars and immunocastrates are possible alternatives. Even if immunocastration is an animal-welfare-friendly alternative, its market share is low and the reliability of this technique is discussed controversially within the pork chain. Currently, the number and the reason for non-responders to vaccination are not clear. Various factors may contribute to impaired immune response including adverse and stressful housing conditions. This study, therefore, examines the influence of different housing conditions on the immune response after two Improvac^® vaccinations. To determine vaccination success, testosterone concentrations, GnRH-binding, and boar taint compounds were evaluated. Furthermore, the growth performance of male pigs was compared. The results show that immunocastration is reliable under different housing systems and prevents boar taint. Moreover, the growth performance of immunocastrates is high and even superior to that of boars and barrows after the 2nd vaccination. Accordingly, immunocastration is not only animal-welfare-friendly but also economically attractive and suitable for different housing systems.

Abstract

Immunocastration is a sustainable alternative to piglet castration but faces limited market acceptance. The phenomenon of non-responders has not to date been examined in detail, but adverse and stressful housing conditions (e.g., mixing of groups) might impair the success of vaccinations. Therefore, we evaluated the influence of housing conditions on the immune response after two Improvac^® vaccinations at an age of 12 and 22 weeks, respectively. Boars, immunocastrates and barrows (n = 48 each) were assigned to three different housing conditions (n = 36 enriched, n = 36 standard n = 72 repeated social mixing). Immune response was quantified by measuring GnRH-binding and its consequences for testosterone concentrations, development of the genital tract and boar taint. Growth performance was evaluated via average daily gain (ADG). GnRH-binding and testosterone levels revealed that immunocastration reliably suppressed testicular functions after the 2nd vaccination. Housing conditions did not modify testicular function but influenced ADG as animals under mixing grew slower than those under enriched conditions. Gonadal status had only a slight impact on ADG except in immunocastrates, which showed a temporarily higher ADG after the 2nd vaccination. The results show that immunocastration is a reliable procedure under different housing conditions and competitive in terms of growth performance.

Mounting Behaviour Recognition for Pigs Based on Deep Learning

For both pigs in commercial farms and biological experimental pigs at breeding bases, mounting behaviour is likely to cause damage such as epidermal wounds, lameness and fractures, and will no doubt reduce animal welfare. The purpose of this paper is to develop an efficient learning algorithm that is able to detect the mounting behaviour of pigs based on the data characteristics of visible light images. Four minipigs were selected as experimental subjects and were monitored for a week by a camera that overlooked the pen. The acquired videos were analysed and the frames containing mounting behaviour were intercepted as positive samples of the dataset, and the images with inter-pig adhesion and separated pigs were taken as negative samples. Pig segmentation network based on Mask Region-Convolutional Neural Networks (Mask R-CNN) was applied to extract individual pigs in the frames. The region of interest (RoI) parameters and mask coordinates of each pig, from which eigenvectors were extracted, could be obtained. Subsequently, the eigenvectors were classified with a kernel extreme learning machine (KELM) to determine whether mounting behaviour has occurred. The pig segmentation presented considerable accuracy and mean pixel accuracy (MPA) with 94.92% and 0.8383 respectively. The presented method showed high accuracy, sensitivity, specificity and Matthews correlation coefficient with 91.47%, 95.2%, 88.34% and 0.8324 respectively. This method can be an efficient way of solving the problem of segmentation difficulty caused by partial occlusion and adhesion of pig bodies, even if the pig body colour was similar to the background, in recognition of mounting behaviour.

Pros and Cons of Alternatives to Piglet Castration: Welfare, Boar Taint, and Other Meat Quality Traits

This paper reviews the pros and cons of various alternatives to the surgical castration of male piglets without pain relief. Castration is mostly motivated by the presence of boar taint in the meat from some entire male pigs. It results in pain during surgery and markedly increases feed costs and the fat content of the carcass. Raising entire male pigs avoids pain at castration, but animals can suffer from increased stress during the finishing period because of aggressive and mounting behavior. Feed efficiency and carcass quality are much better than in surgical castrates. The quality of meat from entire male pigs is lower because of boar taint, a reduced intramuscular fat content, and increased unsaturation of the fat. Immunocastration prevents boar taint, pain associated with surgery, and stress related to aggressive and mounting behavior. Feed efficiency and carcass quality are intermediate between surgical castrates and entire males. Meat quality is similar to surgical castrates. Anesthesia alone prevents pain during surgery, but not after, while analgesia alone mitigates pain after surgery, but not during it. With the currently available methods, the cost of combined anesthesia and analgesia is too high for conventional production systems in most countries.

Sustainability of Pork Production with Immunocastration in Europe

Immunocastration, a technique to replace surgical castration of piglets, consists of two consecutive vaccinations to induce antibodies which transiently suppress testicular functions and avoid boar taint. It is a method to ensure both a high product quality and a high level of animal welfare. The impact of immunocastration on the three pillars of sustainability has been studied extensively. While all aspects of sustainability have been studied separately, however, a contemporary global overview of different aspects is missing. In immunocastrates, performance results are better than in barrows, but worse than in boars. The environmental impact of pork production with immunocastrates is lower than with barrows, but higher than with boars. The level of aggression is considerably lower in immunocastrates compared to boars. Societal concerns are mainly related to food safety, and are not supported by scientific evidence. After second vaccination, immunocastrates switch from a boar- to a barrow-like status. Therefore, the timing of second vaccination is a fine-tuning tool to balance advantages of boars with environmental and economic benefits against increased risk of welfare problems and boar taint. Nevertheless, both synergic and conflicting relationships between the pillars of sustainability must be communicated along the value chain to produce tailored pork products.

Penile Injuries in Immunocastrated and Entire Male Pigs of One Fattening Farm

Penile injuries in boars have been discussed as a relevant welfare problem in pork production with entire males (EM). The incidence of penile injuries with immunocastrated boars has not been described so far. Thus, it was the aim of this study to systematically compare frequency and severity of penile injuries in EM and IC. Incidence and size of penile injuries (wounds, scars, hematomas) were evaluated in 192 IC and 215 EM from one farm after slaughter (120 kg live weight; four batches (BA) in at least weekly intervals over five weeks). 75.8% EM and 48.4% IC showed injuries at the pars libra of the penis. Scars were observed in 71.2% EM and 44.8% IC. Scars/animal were significantly influenced by treatment (IC vs. EM), B and treatment x B and increased with age in EM (BA1: 2.61 ± 3.05; BA4: 3.59 ± 3.47), but not in IC (BA1: 2.00 ± 3.02; BA4: 1.22 ± 1.91). Wounds were obvious in 17.2% EM and 8.3% IC. Wounds/animal were only influenced significantly by treatment and were lower in IC than in EM. Thus, it is concluded that immunocastration reduces the frequency and severity of penile injuries in IC when compared to EM of same age and weight.

Perinatal Exposure to a Diet High in Saturated Fat, Refined Sugar and Cholesterol Affects Behaviour, Growth, and Feed Intake in Weaned Piglets

The increased consumption of diets high in saturated fats and refined sugars is a major public health concern in Western human societies. Recent studies suggest that perinatal exposure to dietary fat and/or sugar may affect behavioural development. We thus investigated the effects of perinatal exposure to a high-fat high-sugar diet (HFS) on behavioural development and production performance of piglets. Thirty-two non-obese sows and their piglets were allocated to 1 of 4 treatments in a 2 × 2 factorial design, with 8-week prenatal (gestation) and 8-week postnatal (lactation and post-weaning) exposure to a HFS diet (12% saturated fat, 18.5% sucrose, 1% cholesterol) or control low-fat low-sugar high-starch diets as factors. From weaning onwards (4 weeks of age), piglets were housed in group of 3 littermates (n = 8 groups/treatment) and fed ad libitum. After the end of the dietary intervention (8 weeks of age), all the piglets were fed a standard commercial diet. Piglet behaviours in the home pens were scored, and skin lesions, growth, feed intake and feed efficiency were measured up to 8 weeks after the end of the dietary treatment, i.e. until 16 weeks of age. At the end of the dietary treatment (8 weeks of age), response to novelty was assessed in a combined open field and novel object test (OFT/NOT). During the weeks following weaning, piglets fed the postnatal HFS diet tended to be less aggressive (p = 0.06), but exhibited more oral manipulation of pen mates (p = 0.05) than controls. Compared to controls, piglets fed the prenatal or postnatal HFS diet walked more in the home pen (p ≤ 0.05), and tended to have fewer skin lesions (p < 0.10). Several behavioural effects of the postnatal HFS diet depended on the prenatal diet, with piglets subjected to a switch of diet at birth being more active, and exploring feeding materials, pen mates, and the environment more than piglets that remained on the same diet. Behaviours during the OFT/NOT were not affected by the diet. The intake of the postnatal HFS diet drastically reduced feed intake, but improved feed efficiency up to 8 weeks after the end of the dietary intervention, i.e. 16 weeks of age (p < 0.0001 for both). Our study highlights the key role of prenatal and postnatal nutritional interactions for early behavioural development, and reveals programming effects of early life nutrition on voluntary feed intake of piglets later in life.

Penile Injuries in Wild and Domestic Pigs

Simple Summary

Male pigs raised for pork production on experimental and commercial farms were evaluated for scars, fresh wounds and severe injuries of the penis. A high incidence of penile injuries (64.0%–94.9% of the animals/farm) was found in boars but not in barrows (castrated males) with even severe wounds in 5.2% to 9.3% of the boars. A similar evaluation of 15 free-ranging wild boars also revealed a considerable proportion of animals with penile injuries. Thus, penis biting is a highly relevant and severe welfare problem in boars which is not limited to intensive production systems.

Abstract

In boars, sexually motivated mounting can not only cause problems such as lameness, but penile injuries are also reported. The relevance of penis biting in boars is discussed controversially, but reliable data is missing. In the present study, boars (n = 385) and barrows (n = 85) from experimental farms were therefore evaluated for scars, fresh wounds and severe injuries of the penis. Similarly, 321 boars from 11 farms specializing in pork production with boars, and 15 sexually mature wild boars from the hunting season of 2015/16 were included in the study. In domestic boars, a high incidence of penile injuries was obvious (76.6%–91.3% of animals with scars and/or wounds at experimental farms, 64.0%–94.9% at commercial farms). The number of boars with severe injuries was in a similar range in both groups (5.2% vs. 9.3%). At commercial farms, the number of scars but not that of fresh wounds increased per animal with age by 0.3 per week. Moreover, raising boars in mixed groups led to about a 1.5 times higher number of scars than in single-sex groups. In wild boars, a considerable proportion of animals (40%) revealed penile injuries, which were even severe in three animals. We therefore conclude that penis biting is a highly relevant and severe welfare problem in the male pig population, but this phenomenon is not limited to intensive production systems.

Animal welfare implications of surgical castration and its alternatives in pigs

This paper constitutes a review on the welfare aspects of piglet castration that considers the scientific literature published after 2004. Castrating during the neonatal period (1 to 3 days of age) is clearly painful. In addition, inflammatory processes may take place at the sites of incision, thus adding further pain to the procedure. Surgical castration with general and local anaesthesia, in combination with long-term analgesia, has been shown to reduce pain but the additional handling and injection of the anaesthetic, the effectiveness and limited safety margins have to be thoroughly evaluated. Raising entire males during the whole fattening period or immunocastration of males towards the end of the fattening period are other alternatives with welfare benefits in young pigs compared to current surgical castration, but with some potential welfare drawbacks regarding handling stress and behaviour during fattening. Based on the current knowledge, it can be concluded that sperm sexing and raising entire males after genetic control of boar taint are potentially preferable alternatives to current practices, but need further research, as these methods are not yet available.

Effect of local anaesthesia and/or analgesia on pain responses induced by piglet castration

Background

Surgical castration in male piglets is painful and methods that reduce this pain are requested. This study evaluated the effect of local anaesthesia and analgesia on vocal, physiological and behavioural responses during and after castration. A second purpose was to evaluate if herdsmen can effectively administer anaesthesia.

Methods

Four male piglets in each of 141 litters in five herds were randomly assigned to one of four treatments: castration without local anaesthesia or analgesia (C, controls), analgesia (M, meloxicam), local anaesthesia (L, lidocaine), or both local anaesthesia and analgesia (LM). Lidocaine (L, LM) was injected at least three minutes before castration and meloxicam (M, LM) was injected after castration. During castration, vocalisation was measured and resistance movements judged. Behaviour observations were carried out on the castration day and the following day. The day after castration, castration wounds were ranked, ear and skin temperature was measured, and blood samples were collected for analysis of acute phase protein Serum Amyloid A concentration (SAA). Piglets were weighed on the castration day and at three weeks of age. Sickness treatments and mortality were recorded until three weeks of age.

Results

Piglets castrated with lidocaine produced calls with lower intensity (p < 0.001) and less resistance movements (p < 0.001) during castration. Piglets that were given meloxicam displayed less pain-related behaviour (huddled up, spasms, rump-scratching, stiffness and prostrated) on both the castration day (p = 0.06, n.s.) and the following day (p = 0.02). Controls had less swollen wounds compared to piglets assigned to treatments M, L and LM (p < 0.001). The proportion of piglets with high SAA concentration (over threshold values 200, 400 mg/l) was higher (p = 0.005; p = 0.05) for C + L compared to M + LM. Ear temperature was higher (p < 0.01) for controls compared to L and LM. There were no significant treatment effects for skin temperature, weight gain, sickness treatments or mortality.

Conclusions

The study concludes that lidocaine reduced pain during castration and that meloxicam reduced pain after castration. The study also concludes that the herdsmen were able to administer local anaesthesia effectively.

Group characteristics influence growth rate and backfat of commercially raised grower pigs

Records from 9429 pigs raised in 353 grower groups in a commercial Australian piggery were analysed to determine whether grower-group characteristics affected daily gain and backfat of individual pigs. Individual and group effects as well as their interactions were tested for significance (P < 0.05) in a mixed model, with sire fitted as a random effect. Group characteristics affected average daily gain (ADG) more than backfat (BF). The proportion of males in a group influenced both traits significantly, as did the average number of full siblings. Groups with 10–30% of the opposite sex had the highest BF and a 21–30 g/day reduction in ADG compared with the highest-performing groups with less than 10% of males. Each additional full sibling per group increased ADG by 5.5 ± 1.60 g/day and BF by 0.12 ± 0.05 mm. Additionally, ADG increased by 9.8 ± 2.64 g/day per second of group mean flight time and by 4.5 g/day per 10% increase in the proportion of Duroc pigs per group. Group size affected ADG (linear and quadratic) and BF (linear); however, the effect on ADG was considerably larger during the warmer grower season. In commercial piggeries, it may be possible to optimise individual daily gain through the manipulation of grower-group characteristics. Advantages for growth rate arose from including a portion of a calmer line of pigs within groups, optimising the stocking density in warmer months and maximising the proportion of quieter, less fearful pigs in grower groups.

Immunisation against gonadotrophin-releasing hormone (GnRH) increases growth and reduces variability in group-housed boars

It is generally accepted that entire boars are leaner and more efficient than barrows but that they have poorer meat quality with an increased risk of boar taint. An additional issue in producing boars to meet market specifications is variation in growth performance, which may be exacerbated by high levels of aggression and mounting behaviour in group-housed animals. Immunisation against gonadotrophin-releasing hormone (GnRH), leading to immunological castration, offers a means of reducing aggression and mounting behaviour while maintaining most of the production efficiencies associated with entire boars. A total of 120 control boars, 120 immunised boars and 60 barrows (physically castrated at 5 days of age) were used in a study conducted in two replicates. Each replicate consisted of two pens each of boars, immunised boars and barrows, each pen containing 15 pigs, and two blocks of 15 individually-housed boars and immunised boars. The group-housed pigs had access to two single place electronic feeders per pen. Immunised boars were given the anti-GnRH vaccine (Improvac) at 14 and 18 weeks of age. In the 2 weeks immediately after the secondary immunisation at 18 weeks, average daily gain was greater in the immunised boars than the boars or barrows, particularly in those that were group housed, as indicated by the interaction (P = 0.035). From 18 to 23 weeks of age average daily gain was greater (P = 0.005) in immunised boars than in control boars and barrows and was greater (P < 0.001) in individually- than in group-housed pigs. The average daily gain of group-housed immunised boars and individually-housed control boars were similar over the 5-week period after secondary immunisation (1090 vs 1099 g/day), being ~20 and 15% higher than the group-housed control boars and barrows, respectively. The average daily feed intake was greater (P = 0.011) in immunised boars than in control boars with barrows intermediate. The standard deviation of bodyweight increased with age but was lower (P from 0.032 to 0.09) in immunised boars than in control boars and barrows between 18 and 22 and 17 and 21 weeks of age. Carcass fighting damage and pork pH were higher (P < 0.05) for control boars than for immunised boars or barrows. In conclusion, immunisation against GnRH increased average daily gain and average daily feed intake while decreasing variation in bodyweight and improving carcass and pork quality.