Correction: Gonçalves Vero et al. Transport of Pigs of Two Market Weights at Two Space Allowances: Effects on Behaviour, Blood Parameters, and Meat Quality under Summer and Winter Conditions. Animals 2023, 13, 2767.

In the original publication [...].

Transport of Pigs of Two Market Weights at Two Space Allowances: Effects on Behaviour, Blood Parameters, and Meat Quality under Summer and Winter Conditions.

This study was carried out through two separate experiments aiming at evaluating the effects of two space allowances (0.54 and 0.62 m2/pig in summer and 0.44 m2/pig and 0.50 m2/pig in winter) on the behavioural and physiological response, and meat quality of pigs of two slaughter weights (120 kg and 140 kg). In summer, higher blood haematocrit levels were found at slaughter in heavier pigs transported at a smaller space allowance (p = 0.04). During lairage, pigs transported at a smaller space allowance started fighting later (p = 0.04). Fighting behaviour was greater in heavier pigs (p ≤ 0.05), whilst their drinking activity was lower (p < 0.05). This resulted in greater exsanguination blood CK levels (p < 0.01) and drier hams (p = 0.05) in heavier pigs. In winter, only lower space allowance influenced some meat quality traits (p < 0.05), but these effects were minor. The effects of space allowance during summer transports on within-truck ambient conditions, post-transport pigs' welfare, and meat quality are similar. Mixing heavier pigs may result in greater aggressiveness and more fatigue-related meat quality variation during summer. Overall, winter transport results may have been biased by the short journey and within-truck load distribution.

The protective role of wallowing against heat stress in gestating and lactating sows housed outdoors.

The objective of this study was to describe the physiological response of gestating and lactating sows to naturally-occurring environmental conditions, and to identify factors that may contribute to or prevent heat stress, while being kept outdoors in Québec, Canada during the summer. Six groups of 4 Yorkshire-Landrace sows lived in outdoor pens equipped with a wallow, shade structure, farrowing huts and access to a pasture from July to September 2018. Between week 15 of gestation and week 3 of lactation (inclusive), we recorded the location of each sow 5 days/week during 5 daily 15-min observation periods, and additionally measured the sow's respiratory rate and mud cover at the end of each observation period. Simultaneously, we collected sow body temperature data with vaginal temperature loggers 24 h/d on week 15 of gestation and week 2 of lactation, and monitored environmental conditions with temperature and humidity loggers to calculate the temperature humidity index (THI). Sows had significantly higher and more variable body temperatures during lactation compared to gestation (P ≤ 0.0001), and when THI was analysed as a continuous variable, it was positively associated with sow body temperature during the night in lactation. During gestation, neither respiratory rate nor body temperature were associated with high or low levels of THI (P = 0.15 and 0.79, respectively) or mud cover (P = 0.29 and 0.94, respectively). However, in lactation, respiratory rate was higher when, simultaneously, THI exceeded 74 and mud cover was low (P = 0.006), while a THI higher than 74 and a low mud cover had independent effects on body temperature (P = 0.012 and 0.004, respectively). In lactation, sows that spent an entire observation period in the farrowing hut also had a higher respiratory rate than sows that left the hut at least once (P = 0.009). In summary, lactating sows were more likely to show increases in respiratory rate and body temperature in warmer conditions than gestating sows, and our findings also suggest that time in the farrowing hut may be a risk factor for heat stress. However, mud cover may limit these physiological consequences when sows have access to a wallow.

Social status and previous experience in the group as predictors of welfare of sows housed in large semi-static groups.

Mixing gestating sows implies hierarchy formation and has detrimental consequences on welfare. The effects of social stress on the most vulnerable individuals may be underestimated and it is therefore important to evaluate welfare between individuals within groups. This study aimed at investigating the impact of social status and previous experience in the group on well-being of sows housed in large semi-static groups. We assessed aggression (d0 (mixing), d2, d27, d29), body lesions (d1, d26, d84) and feeding order on 20 groups of 46-91 animals. Social status was based on the proportion of fights won during a 6-hr observation period between d0 and d2. Dominants (29%) were those who won more fights than they lost, Subdominants (25%) won fewer fights than they lost, Losers (23%) never won any fight in which they were involved while Avoiders (23%) were never involved in fights. Resident sows (70%) were already present in the group in the previous gestation while New sows (30%) were newly introduced at mixing. Subdominants and Dominants were highly involved in fights around mixing but this was more detrimental for Subdominants than Dominants, Losers and Avoiders since they had the highest body lesion scores at mixing. Avoiders received less non-reciprocal agonistic acts than Losers on d2 (P = 0.0001) and had the lowest body lesion scores after mixing. However, Avoiders and Losers were more at risk in the long-term since they had the highest body lesions scores at d26 and d84. They were followed by Subdominants and then Dominants. New sows fought more (P<0.0001), tended to be involved in longer fights (P = 0.075) around mixing and had more body lesions throughout gestation than Resident sows. Feeding order from one-month post-mixing was influenced both by the previous experience in the group and social status (P<0.0001). New sows, especially with a low social status, are more vulnerable throughout gestation and could serve as indicators of non-optimal conditions.

The effects of feeding finishing pigs of two genders with a high fiber and high fat diet on muscle glycolytic potential at slaughter and meat quality.

A total of 160 pigs, in groups of 8 pigs of mixed genders, were fed four finishing feeding strategies with the aim to reduce muscle glycolytic potential and improve meat quality. Pigs were fed a control diet (C; fat = 5.0%, ADF = 3.0%, NDF = 8.8%), a high-fat and high-fiber diet (HFF; fat = 11.2%, ADF = 9.1%, NDF = 19.5%), a blend of 50-50% C and HFF diets (fat = 8.2%, ADF = 6.7%, NDF = 14.2%) or the C diet and transferred to the HFF diet after a diet transition. Dietary treatments alone or in interaction with gender had no effect on pig growth performance, carcass quality traits, Longissimus and Semimembranosus muscle glycolytic potential and meat quality (P > 0.10). The inefficiency of the dietary treatments applied in this study may be due to the low ratio between fat and digestible carbohydrate in the diets combined with the mild pre-slaughter stress conditions pigs were exposed to.

Estimation of forage biomass and vegetation cover in grasslands using UAV imagery.

Grasslands are among the most widespread ecosystems on Earth and among the most degraded. Their characterization and monitoring are generally based on field measurements, which are incomplete spatially and temporally. The recent advent of unmanned aerial vehicles (UAV) provides data at unprecedented spatial and temporal resolutions. This study aims to test and compare three approaches based on multispectral imagery acquired by UAV to estimate forage biomass or vegetation cover in grasslands. The study site is composed of 30 pasture plots (25 × 50 m), 5 bare soil plots (25 x 50), and 6 control plots (5 × 5 m) on a 14-ha field maintained at various biomass levels by grazing rotations and clipping over a complete growing season. A total of 14 flights were performed. A first approach based on structure from motion was used to generate a volumetric-based biomass estimation model (R2 of 0.93 and 0.94 for fresh biomass [FM] and dry biomass [DM], respectively). This approach is not very sensitive to low vegetation levels but is accurate for FM estimation greater than 0.5 kg/m2 (0.1 kg DM/m2). The Green Normalized Difference Vegetation Index (GNDVI) was selected to develop two additional approaches. One is based on a regression biomass prediction model (R2 of 0.80 and 0.66 for FM and DM, respectively) and leads to an accurate estimation at levels of FM lower than 3 kg/m2 (0.6 kg DM/m2). The other approach is based on a classification of vegetation cover from clustering of GNDVI values in four classes. This approach is more qualitative than the other ones but more robust and generalizable. These three approaches are relatively simple to use and applicable in an operational context. They are also complementary and can be adapted to specific applications in grassland characterization.

The Role of Genetic Selection on Agonistic Behavior and Welfare of Gestating Sows Housed in Large Semi-Static Groups.

Confinement of gestating sows is becoming banished in favor of group-housing in countries worldwide, forcing breeding companies to develop genetic lines adapted for social living. This study aimed at assessing the influence of two genetic lines selected for high performance (HP1, HP2, derived from Landrace × Yorkshire) on welfare and reproductive performance of sows housed in large semi-static groups (20 groups of 46-91 animals) across several parities. To address this, agonistic behaviors were recorded on d0, d2, d27, and d29 post-mixing while body lesions were scored on d1, d26, and d84. Sows' individual and reproductive performances were also recorded. HP2 sows were more aggressive than HP1 sows since they fought (p = 0.028) and bullied (p = 0.0009) pen-mates more frequently on d0-d2. HP2 sows had more total body lesions throughout gestation than HP1 sows at higher parities (p < 0.0001). Regarding reproductive performance, HP2 sows lost less piglets (p < 0.0001) and tended to wean more piglets (p = 0.067) than HP1 sows. In conclusion, while HP2 sows were the most aggressive, HP1 sows had piglets with lower survivability, which raises ethical issues in both cases and points to the need of considering social aspects when developing genetic lines for group-housing.

Association Between Tail-Biting and Intestinal Microbiota Composition in Pigs.

Tail-biting (TB) in pigs is a serious behavioral disorder. It is an important challenge in swine production as it impacts animal welfare and health and the economics and safety of the pork meat supply chain. To prevent TB, approaches including enrichment material and tail docking are proposed but none are optimal. Nutrition appears to be an important factor in TB behavior, perhaps by modulating the intestinal microbiota (IM). Our aim was to assess the association between TB behavior and IM in pigs through comparisons of IM in groups of biter, bitten and non-biter/non-bitten pigs. Each group composed of 12 pigs was formed at the beginning of the growing/finishing phase based on a target behavior analysis centered on TB behavior for the biter group and a score of damages caused to the tail for the bitten group. Blood and fecal samples were collected from each pig during a TB episode, at time 0, t0, and when the TB episode was considered finished, 4 weeks later, at time 1, t1. Serum cortisol level was determined by ELISA and used as an indicator of stress. The pig's fecal microbiota was analyzed from DNA extracted from freshly collected fecal matter using amplicon sequencing of the V4 hypervariable region of the 16S rRNA gene. Serum cortisol levels were significantly higher in either the biter or bitten pig groups compared to the negative control group (p = 0.02 and p = 0.01, respectively). The microbiota alpha-diversity was not significantly different between all groups, biter, bitten and negative control. Analyses of beta-diversity, however, revealed a significant difference between either the biter or the bitten group in comparison to the non-biter/non-bitten negative control group in terms of structure and composition of the microbiota. Lactobacillus were significantly more abundant in the negative control group compared to the two other groups (p = 0.001). No significant difference was revealed between the biter and bitten groups. Quantitative real-time PCR (qPCR) confirmed that lactobacilli were more abundant in the negative control group. Our study indicates that TB behavior is associated with the IM composition in pigs.

Application of extended feed withdrawal time preslaughter and its effects on animal welfare and carcass and meat quality of enriched-housed pigs.

A total of 144 barrows were distributed into four treatment groups. One group was housed conventionally and fasted for 16 h preslaughter, while the other three groups were housed in enriched conditions (straw-bedding and low density) and fasted for 16, 24 and 32 h preslaughter. When compared with conventionally-housed pigs, enriched-housed pigs were heavier (P < .05) and fatter (P < .01), but easier to handle at loading (P < .05) and produced less exudative pork (P < .05) possibly resulting from a lower post-mortem muscle glycolytic potential (P = .10). Extending fasting time up to 32 h reduced dressing yield (P < .001) and increased skin lesion scores (P < .01), but did not result in any clear or major effect on muscle metabolism and meat quality. In conclusion, given the beneficial effects of enriched housing conditions on stress response and pork quality, the application of an extended fasting time (32h) preslaughter is not required for this production.

Validation of Anatomical Sites for the Measurement of Infrared Body Surface Temperature Variation in Response to Handling and Transport.

This study aimed at validating the anatomical sites for the measurement of infrared (IR) body surface temperature as a tool to monitor the pigs' response to handling and transport stress. The selected anatomical sites were the neck (infrared neck temperature-IRNT), rump (infrared rump temperature-IRRT), orbital (infrared orbital temperature-IROT) and behind ears (infrared behind ears temperature-IRBET) regions. A total of 120 pigs were handled from the finishing pen to the loading dock through a handling test course. Two handling types (gentle vs. rough) and number of laps (1 vs. 3) were applied according to a 2 × 2 factorial design. After loading, pigs were transported for 40 min and returned to their home pens. Animal behavior, heart rate, rectal temperature and salivary cortisol concentration were measured for validation. Increased IR body temperature, heart rate and salivary cortisol levels were observed in response to rough handling and longer distance walk (P < 0.05 for all). The greatest correlations were found between IROT and IRBET temperatures and salivary cortisol concentration at the end of the handling test (r = 0.49 and r = 0.50, respectively; P < 0.001 for both). Therefore, IR pig's head surface temperature may be useful for a comprehensive assessment of the physiological response to handling and transport stress.

Effect of Slat and Gap Width of Slatted Concrete Flooring on Sow Gait Using Kinematics Analysis.

The housing of gestating sows in groups requires sound information about the adapted design of the pen floor. Slatted concrete floors are commonly used for effective drainage of manure but can cause feet injuries and lameness. In the present study, kinematics were used to characterize the gait of 12 gilts and 12 lame sows walking in a corridor on slatted concrete floors with different combinations of slat (85, 105 or 125 mm) and gap (19, 22 or 25 mm) widths. The nine experimental floors were tested with slats in the perpendicular and parallel orientation to the direction of animal walk, according to a duplicated lattice design. Gait parameters were quantified using spatial, temporal and angular kinematics for front and rear limbs. Some parameters were significantly affected by the treatments (p < 0.05), but the effects differed between gilts and lame sows and between slat orientations. Gap width had a significant effect on parameters such as back angle, stride length, foot height, and carpal and tarsal joint angle amplitudes. Slat width significantly affected parameters such as foot height, and carpal and tarsal joint angle amplitudes. Comparisons of the different combinations of slat and gap widths revealed that slats with a width of 105-125 mm and gap width of 19-22 mm had the least effect on the gait characteristics of the gilts and sows.

Growing Pigs' Interest in Enrichment Objects with Different Characteristics and Cleanliness.

Enrichment objects can be a practical way to provide rooting and chewing material to growing pigs, on which they can express species-specific behaviors. The challenge is to provide enrichment objects that will satisfy pigs' behavioral needs, while being practical and low-cost for the producers. Two trials were conducted to evaluate the effects of object characteristics such as design, location, cleanliness or degree of wear, on pigs' interest over time. The first trial compared seven objects, varying in their design and location, presented individually for five consecutive days to groups of 12 ± 3 (average ± SD) pigs, weighing 61 ± 9.2 kg. The pigs' interest in the objects was evaluated based on the frequency, total duration and mean length of manipulation with the objects. All objects were manipulated at different levels depending on their characteristics. On average, the pigs interacted more frequently (p < 0.001) with a chewable object made of three polyurethane balls, spring-mounted and anchored to the floor, and spent more time manipulating a dried wood beam on the floor (p < 0.05), which was destructible and chewable, than suspended ropes, plastics and rubber objects, and a plastic ball on the floor. The second trial used two-choice preference tests to compare objects varying in their degree of cleanliness or wear, presented in pairs to growing pigs weighing 47 ± 7 kg and housed in groups of 14 ± 1. Two identical objects were placed simultaneously in a pen over 5 days, and only one of them was cleaned or replaced daily (treatment) while the duplicate was left untouched (control). The results showed no clear preference between control and treatment objects, indicating that short-term maintenance of the objects might be unnecessary.

A preliminary study of the effects of individual response to challenge tests and stress induced by humans on learning performance of weaned piglets (Sus scrofa).

This study investigated whether individual behavioural characteristics of piglets and stress induced by experience with humans can influence learning performance. After weaning, piglets received a chronic experience with humans to modulate their emotional state: rough (ROU), gentle (GEN), or minimal (MIN) experience. Simultaneously, they were trained on a discrimination task. Afterward, their behaviour during challenge tests was assessed. The first learning step of the task involved associating a positive sound cue with a response (approach a trough) and success of piglets depended mostly on motivation to seek for reward. Although the experience with humans did not have direct effect, the degree of fear of handler, measured based on their reactivity to a human approach test, was related to motivation to seek rewards and learning speed of this first step in stressed ROU piglets, but not in MIN and GEN piglets. In contrast, the second learning step was more cognitively challenging, since it involved discrimination learning, including negative cues during which piglets had to learn to avoid the trough. Locomotion activity, measured during an open-field test, was associated with performance of the discrimination learning. To conclude, fearfulness towards humans and locomotion activity are linked with learning performance in relation to task complexity, highlighting the necessity to take into account these factors in animal research and management.

The Way Humans Behave Modulates the Emotional State of Piglets.

The emotional state can influence decision-making under ambiguity. Cognitive bias tests (CBT) proved to be a promising indicator of the affective valence of animals in a context of farm animal welfare. Although it is well-known that humans can influence the intensity of fear and reactions of animals, research on cognitive bias often focusses on housing and management conditions and neglects the role of humans on emotional states of animals. The present study aimed at investigating whether humans can modulate the emotional state of weaned piglets. Fifty-four piglets received a chronic experience with humans: gentle (GEN), rough (ROU) or minimal contact (MIN). Simultaneously, they were individually trained on a go/no-go task to discriminate a positive auditory cue, associated with food reward in a trough, from a negative one, associated with punishments (e.g. water spray). Independently of the treatment (P = 0.82), 59% of piglets completed the training. Successfully trained piglets were then subjected to CBT, including ambiguous cues in presence or absence of a human observer. As hypothesized, GEN piglets showed a positive judgement bias, as shown by their higher percentage of go responses following an ambiguous cue compared to ROU (P = 0.03) and MIN (P = 0.02) piglets, whereas ROU and MIN piglets did not differ (P > 0.10). The presence of an observer during CBT did not modulate the percentage of go responses following an ambiguous cue (P > 0.10). However, regardless of the treatment, piglets spent less time in contact with the trough following positive cues during CBT in which the observer was present than absent (P < 0.0001). This study originally demonstrates that the nature of a chronic experience with humans can induce a judgement bias indicating that the emotional state of farm animals such as piglets can be affected by the way humans interact with them.

The perception of humans by piglets: recognition of familiar handlers and generalisation to unfamiliar humans.

Humans are part of the environment of domestic animals and interact with them daily, providing a good basis for the study of interspecific relationships. Abilities to discriminate and recognise individuals form the basis of these relationships, and they are crucial skills for domestic animals, since individual humans can differ in their behaviour towards them. At the same time, with experience, animals may develop a general memory of humans and generalise their behaviour towards strangers. This study aimed to determine the extent to which weaned piglets can discriminate familiar humans and generalise their past experience when faced with unfamiliar humans. Forty-eight groups of three piglets were submitted to two consecutive 5-day conditioning periods of the same or opposite valence (positive and/or negative) given by one (A) or two (A then B) handlers. The reactivity of piglets to a motionless human and to an approaching human was measured before and after conditioning periods with unfamiliar and familiar handlers. Thereafter, piglets which received treatments with the two handlers A and B were subjected to a choice test between both handlers. The reactivity to an approaching human appeared to better reflect the past experience with familiar handlers since piglets clearly recognised them and adapted their behaviour accordingly. In contrast, reaction of piglets to a motionless human reflected their natural propensity to seek interaction, even after a negative experience. Although piglets were able to extend their memory of humans to an unfamiliar human through generalisation, many factors seemed to interact in this process, especially the complexity of the previous experience (inconsistent vs consistent) and the context in which piglets met the unfamiliar human (motionless vs approaching). We conclude that discrimination and generalisation processes of reactivity to humans do not simply rely on past interactions, but also depend on the context according to the degree of similitude with their past experience.

Hormones, IgG and lactose changes around parturition in plasma, and colostrum or saliva of multiparous sows.

Blood, colostrum and saliva samples were serially taken from 6 multiparous sows from day 109 of gestation until day 3 postpartum. Plasma was assayed for oestradiol-17beta (E2), progesterone (P4), prolactin (PRL), cortisol, immunoglobulin G (IgG) and lactose. Colostrum was assayed for E2, P4, IgG and lactose. Lactoserum, obtained after ultra centrifugation of colostrum, was assayed for PRL. Saliva was assayed for cortisol. Time-related variations in hormone, IgG and lactose concentrations measured in plasma were parallel to those measured in colostrum, lactoserum or saliva. However, the concentrations were higher in colostrum or lactoserum and lower in saliva than in plasma. Ratios of concentrations of cortisol in saliva and PRL in lactoserum over those in plasma did not vary with time and averaged 0.2 and 1.6, respectively. Conversely, the ratios of concentrations of E2 and P4 in colostrum over those in plasma varied with time (P < 0.05) but were quite constant before the end of parturition, averaging 2.7 and 3.6, respectively. The ratios of concentrations of IgG and lactose in colostrum over those in plasma also varied with time (P < 0.05). The concentrations of hormones in plasma on the one hand and in colostrum, lactoserum or saliva on the other hand were significantly correlated but correlations varied with time (PRL across periods: r = 0.31; cortisol across periods: r = 0.60; E2 during parturition: r = 0.83; P4 before parturition: r = 0.82; P4 during parturition: r = 0.67). The present results indicate that around parturition, assays of hormones in colostrum or saliva can be used to study the hormonal status of sows. Furthermore, variations in colostrum and plasma concentrations of IgG and lactose are good indicators of the transition from colostrum to milk synthesis.