Evidence for residence-induced enhancement of aggressiveness in the non-territorial pig

Posted in: Production, Welfare by admin on July 25, 2011 | No Comments

Wild pigs (Sus scrofa) are only territorial during the peri-parturient period and when young compete for access to teats. In other species, territorial defence is affected by contextual factors including resource quality. Territoriality could be stimulated in species such as pigs by artificial mixing and intensive housing. Test pigs were introduced to a novel opponent for 5 min on consecutive days (days 1 and 2) in two locations (home pen of the test pig (P) or a neutral arena (A)) in a randomised block design. On day 1, animals tested in their home pen were more likely to initiate an escalated attack (proportion of pigs 0.43 vs 0.19 in the pen and neutral arena, P < 0.01). A shorter latency to attack on day 2 in the PP (pen on both days) and PA (pen then arena) treatments suggested that a previous encounter in the home pen affected later aggressiveness. The time spent engaged in non-escalated aggressive behaviours (parallel walking, pushing, knocking and biting) with the opponent was similar in the two environments. Some capacity for territorial defence through escalated aggression and the enhancement of subsequent aggressiveness appears to occur in pigs when in their home pen. The suppression of escalated aggression in the neutral arena by handling and environmental exploration cannot be discounted, but appears not to have affected the occurrence of non-escalated aggression. The mixing of pigs in an occupied pen is likely to enhance escalated aggression from the occupants without reducing that from the intruders and should be avoided.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues

Agonistic behaviour after mixing in pigs under commercial farm conditions

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The aim of the study was to investigate agonistic behaviour of pigs after regrouping pigs under commercial sow farm conditions. The behavioural patterns were observed over a 48-h period, directly after weaning and 40 days later. Agonistic interactions were analysed by noting the times (start and finish), the aggressor/receiver and the winner/loser of a fight. Differences in agonistic behaviour within and between the two age groups were recorded. The median number of fights per pig was 40.0 and 6.5, respectively, and varied between 0 and 139 fights. A circadian rhythm for the number of fights per pig and hour was shown for both age groups. A dominance index (DI) was calculated to examine possible relations between the agonistic behaviour shown and the dominance of an individual pig. The DI was defined as the ratio of wins minus defeats divided by the sum of wins, defeats and stand-off outcomes. Dominant pigs (DI > 0) were engaged in more agonistic interactions, had a longer total fight time and initiated more fights than subordinate pigs. Significant correlations were found between the overall fight time and the dominance index. Potential coherences between agonistic behaviour and the number of skin lesions were investigated with a lesion score (LS). The LS ranked from 0 to 4 and was determined at the beginning and at the end of the observation period. The analyses of the LS showed significant preferences for the front third of the body. However, unambiguous findings were only made concerning the older age group. Growing pigs with an increased LS after 48 h had more fights per pig, a longer overall fight time and initiated more fights (p < 0.05) compared to pigs showing a lower or unchanged LS. In conclusion, the applied dominance index and lesion score are feasible methods to analyse fighting behaviour under commercial sow farm conditions. Potential relationships between agonistic behaviour and growth or reproductive performance should be analysed in further investigations. It might be beneficial to consider agonistic behaviour in pig breeding. In this context, the presented approaches are simple tools to measure agonistic pig behaviour.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues

Genetic and environmental effects on piglet survival and maternal behaviour of the farrowing sow

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There is growing external pressure to abolish the farrowing crate, however alternative farrowing systems need to equal or surpass the performance (i.e. piglet survival) of more restrictive systems. In order to achieve consistent improvement in piglet survival genetic selection strategies targeting specific survival traits could be used. One of the key components of survival in alternative, loose-housed farrowing systems is maternal behaviour and understanding the characteristics of sows that influence survival in such environments should be an essential component when developing new breeding indices. In this study 65 gilts and their piglets (757) from two genetic selection lines, High postnatal Survival (HS) or Control (C), were studied in both indoor loose-housed and outdoor farrowing systems. The influence of genetics and environment on piglet survival and maternal characteristics was studied. Genotype affected total mortality at a piglet level in the outdoor system (C: 17.90% (±3.23) vs. HS: 12.21% (±3.46)), but there was no effect in the indoor loose-housed environment (C: 12.29% (±2.69) vs. HS: 14.86% (±3.18)). Genotype influenced maternal characteristics, with C gilts in both environments being significantly more likely to crush their piglets when changing posture during farrowing. High Survival gilts in the indoor environment were aggressive towards their offspring, and were the only genotype to display savaging behaviour. This suggests a genetic effect on environmental sensitivity and thus, in order to make effective improvements it is important to estimate genetic parameters (both behavioural and physiological) under the conditions in which the animals will be kept.

Breed differences in pig temperament scores during a performance test and their phenotypic relationship with performance

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Nucleus populations of Chester White, Duroc, Landrace, and Yorkshire boars and gilts were used to estimate breed differences in temperament and the relationship with performance. Adjusted backfat, adjusted loin depth, days to 113.4 kilograms (DAYS), estimated percent fat-free lean (LEAN), and three temperament scores: load score, scale score, and vocal score were recorded, on a scale of 1 (calm) to 5 (highly excited), during a performance test. Logistic regression for temperament scores included fixed effects of breed, sex, contemporary group (barn-farm-test date), and body weight as a covariate was used. The order that a pig was loaded into the scale, within pen, was included as a fixed effect for load score. After initial analysis, it was determined that vocal score was best described as two categories, vocal or nonvocal, and was reanalyzed accordingly. Linear mixed models for backfat, loin depth, DAYS, and LEAN included fixed effects of breed, sex, and load score, scale score, or vocal score. Growth rate was adjusted to 113.4 kg, while backfat and loin depth were adjusted to 113.4 kg through regression on mean body weight of the respective breed. The odds of increased load score were greater for Landrace than Duroc and Yorkshire respectively. Landrace had a greater probability of a higher scale and vocal scores compared to Chester White, Duroc and Yorkshire. Yorkshire had greater odds of increased load score, scale score, and vocal score than Duroc. Chester White had greater odds of increased load score and scale score than Duroc and Yorkshire, respectively. Chester White were 1.66 times more likely to have a higher vocal scores than Duroc. Phenotypic correlations for scale score with load score, vocal score, backfat, loin depth, DAYS, and LEAN were 0.13, 0.32, −0.15, −0.07, 0.10 and 0.17, respectively. Landrace were more excited and vocal in the scale than Chester White, Durocs and Yorkshire. Landrace were more difficult to load into the scale than Durocs and Yorkshire. Chester White were more active in the scale than Durocs and Yorshire, and more vocal than Durocs. Yorkshire were harder to load, more active and vocal than Durocs. It was concluded that temperament differs between breeds, and pigs with lower temperament scores were fatter, had greater loin depth and grew faster. 

For more information the full article can be found at http://www.journals.elsevierhealth.com/periodicals/livsci

The effect of feed trough position on choice of defecation area in farrowing pens by loose sows

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The primary aim of the present study was to investigate how the feed trough position affects the sow’s choice of defecation area in a loose house farrowing pen. The eliminative behaviour of 24 1st parity sows was studied in a cross-over design. The feed trough and the water were positioned either in the activity area towards the neighbouring pen or in the activity area towards the aisle. On day 15 after farrowing, the feed trough and the water were moved to the opposite position. Videotapes were observed continuously on real time and the time of urination or defecation were recorded along with head and hindquarter positions in the period of days 7–14 and in the period of days 21–28 after farrowing. The feed trough position had a significant effect on sow head position when eliminating. Sows preferred the head to be located as far away from the resting area and the feed trough as possible when eliminating. For the hindquarter position, there was a significant effect of feed trough position on the number of observations that the hindquarter was over the slatted area when eliminating. A confounding effect could be that the sow’s hindquarter position was influenced by a partition wall placed in one end of the pen. No significant difference was found between observations periods on frequency of urination or defecation. The results demonstrate the importance of design of farrowing pens for loose housed sows to ensure that the sow eliminate in the designated areas.

Increasing the piglets’ use of the creep area—A battle against biology?

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Indoor farrowing systems are based upon the assumption that the newborn piglets will leave their mother after suckling and enter a heated creep area, but newborn piglets are motivated to remain close to the sow. Several creep area features attractive to piglets were used to attempt to increase time spent in the creep area the first two days after birth and to find out whether increased time spent in the creep area would affect early piglet mortality in farrowing pens. Forty-six loose-housed sows and their litters kept in individual farrowing pens were subjected to one of three creep area treatments; control (CON); concrete floor in the creep area, bedding (BED); an insulated and soft bedding in the creep area and HUT; an insulated and soft bedding in the creep area plus an additional wall to increase the heat conserving capacity in the creep area. The pens were video-recorded from 0–72 h after birth and analysis was conducted from 08:00 h to 14:00 h and from 20:00 h to 02:00 h on each day. The attempts to make the creep area attractive did not increase the use of the creep area; piglets in the HUT treatment spent less time in the creep area and more time resting near the sow than piglets in the CON and BED treatment. Improving the thermal comfort and increase the layer of bedding in the creep area did not increase time spent away from the sow, nor did it reduce piglet mortality. Quality of the creep area thus appears to have little impact on piglet survival.

Playing and fighting by piglets around weaning on farms, employing individual or group housing of lactating sows

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In the pig industry, piglets are weaned earlier than in nature. Early weaning has an impact on piglet growth and feeding behaviour, but this may differ, apart from the weaning age, according to the housing environment. Piglets from sow group housing systems (GH), where several litters and sows live together, may be better prepared for weaning than those from individual housing of sows with litters (IH) because increased freedom of movement and social contact as well as co-mingling litters before weaning are known to affect piglet social behaviour positively. However, these issues have rarely been investigated on commercial pig farms. Therefore, we assessed piglets playing, fighting and biting behaviour before and after weaning and how they were affected by the housing system and weaning age as well as how the three behaviours are related to each other and piglet post-weaning weight gain. We recorded playing, fighting and biting behaviour in 5 GH farms (6–11 lactating sows and their litters kept in a large straw-bedded pen), and in 5 IH farms (each sow and litter kept in a pen with less straw) in Sweden. We observed 16 piglets (2 males and 2 females per litter) from 4 litters (in GH farms belonging to the same group) in each farm on the day before weaning (W -1), the weaning day (W) and 5 days after weaning (W+5). Weaning was accomplished (without mixing litters) by removing the sows after on average 39 days of lactation. All statistics were based on farm averages. There was no difference between GH and IH farms in the frequency of playing, fighting or biting behaviour, and weaning age did not affect any of the three behaviours. However, the frequency of playing and fighting differed significantly across the three observation days. Play was higher on day W-1 and on day W than on W+5, fighting was lower on W-1 than on W or W+5. On W-1 and W+5, playing correlated with fighting but biting correlated with neither playing nor fighting. In farms with higher weight gain between W and W+ 5 days, piglets played and fought more on W+ 5 day. We conclude that social piglet behaviour around weaning was not different between GH and IH farms; play and fighting (but not isolated biting) seemed to form one continuum; and playing and fighting in weaned (nonmixed) piglets seemed to indicate good adaptation.

Validation of accelerometers to automatically record sow postures and stepping behaviour

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  Two studies were performed to develop and validate an automated method of detecting postures and stepping behaviour in sows. In the first study, two accelerometers were simultaneously tested on 23 multiparous sows to detect the following postures: standing, sitting, lying ventrally and lying laterally. First off, a data set from 11 sows was used to establish the methodology and algorithm to automatically detect postures, and a second set from 12 sows was used for validation purposes. Sows were housed in gestating stalls, pens, farrowing crates or farrowing pens with straw. One accelerometer was fastened to a hind leg and the other to the back of the sow (between shoulder blades). The data loggers recorded the acceleration on three axes every 5s for 6 h; these data were then converted into degrees of tilt, which were used to discriminate between postures according to angles determined with the first data set. Based on video observations, sows spent an average time of 23.1% standing, 24.6% lying ventrally, 48.1% lying laterally and 4.2% sitting. The second study was performed to validate the use of accelerometers for counting hind limb stepping behaviour around feeding in 10 sows. Animals were housed either in gestating stalls or in pens and had an accelerometer fastened to one rear leg. The data logger recorded the acceleration on the vertical axis 10 times per s for 30 min, starting at the time of feeding. The accelerometer data was compared to video observations and 1448 steps were assessed in total. In conclusion, accelerometers can be successfully used to detect postures and the number of hind limb steps in sows.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues

Aggression in replacement grower and finisher gilts fed a short-term high tryptophan diet and the effect of long-term human–animal interaction

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Aggression can be a major problem for swine production as it negatively impacts the pigs’ health and welfare. Increasing tryptophan (TRP) intake to raise brain serotonin (5-HT)—key for aggression control, and long-term positive social handling can reduce stress in pigs. Objective was to feed a short-term high-TRP diet to grower (3 months) and finisher (6 months) maternal gilts that were either socially handled or not and measure their behavioural activity and aggressiveness. Eight pens of six unrelated gilts were split into two blocks balanced for litter, social handling (non- vs. handled) and dietary treatment (control vs. high-TRP). Social-handling was applied three times per week, from day 45 until 6 months of age. At 3 months, two handled and two non-handled pens were assigned to control while the other four pens were assigned to the high-TRP diet fed ad libitum for 7 days. At 6 months of age, pen assignment to dietary treatments was swapped. Body weights and blood were taken at the start and at the end. Blood samples were analyzed for TRP and 5-HT concentrations using high pressure liquid chromatography. Behaviour was recorded from days 1 to 5 and scan-sampling used to determine time-budget behaviours and postures in a 12-h period each day. Aggression evaluation in the home pen focused on counts of agonistic interactions, bites and head-knocks per interaction during three, 30-min intervals (08:00, 12:00, and 16:00 h) from days 1 to 5. Resident–intruder test was carried out for a maximum of 300s at days 6 and 7 to measure aggressiveness, predicted by the latency to the first attack and attack outcomes. A 2×2 factorial arrangement of dietary treatment and social handling within age was analyzed by repeated measures of mixed models and Tukey adjustments. The TRP-added diet raised blood TRP concentration of 3- and 6-month-old gilts by 180.7% and 85.2% respectively, reduced behavioural activity and time spent standing, while increasing lying behaviour, mostly in grower gilts. High-TRP diet reduced the number of agonistic interactions, and aggressiveness in 3-month old gilts, which took longer to attack the intruder pig, and displayed fewer attacks on the first day of testing. Long-term positive social handling improved growth performance and had a slight effect on behaviour (P< 0.05). Provision of enhanced TRP diet reduced behavioural activity and aggressiveness of grower gilts, and these results are likelymediated by activation of brain serotonergic system. Short-term high-TRP dietary supplementation may be used to reduce aggression at mixing in young pigs.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues

Social hierarchy affects the adaption of pregnant sows to a call feeding learning paradigm

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The aim of the study was to test whether adult sows are able to learn an individual acoustic signal for call-feeding in groups supplied with an electronic feeder. Further, we investigated whether and how the social rank of sows affects learning success. Thirty-six sows were examined in 6 successive trials. In each, the animals were kept together for establishing a social hierarchy a week before conditioning started. Agonistic interactions were observed and a dominance index (DI) was calculated for the sows of each trial. Based on the DI sows were categorised as dominant, subordinate, or submissive. Afterwards groups were transferred to the experimental pen which was equipped with one electronic feeder supplemented with a loudspeaker and software, the call-feeding station (CFS). The training started with classical conditioning (7 days) where the animals entered the CFS spontaneously 6 times daily and received a portion of feed immediately after an individual acoustic signal had been played. In the following operant conditioning phase (13 days) the individuals had to learn that they could enter the CFS and receive feed only after they had heard their signal. The animals were called 6 times daily to feed the respective fraction of the daily feed allowance. On the average, after 8 days of operant conditioning the animals reached the learning criterion of following 80% of their calls. The success rates differed significantly between the three rank groups. In the dominant and subordinate groups 93% and 71% of the animals reached the learning criterion at the end of the experiment after 13 days of operant conditioning, while only 64% of the submissive sows did so. If only the number of successful, i.e. rewarded, enters of the station was considered those submissive animals who had reached the learning criterion did not differ significantly from the others. During learning, the time required to approach the CFS decreased significantly as well as the rate of false attempts to enter if another animal was called. At start of the operant training dominant sows blocked the entrance of the CFS. With increasing learning success of these sows this behaviour decreased significantly. The experiment has demonstrated that call feeding can be applied successfully with pregnant sows. It has the potential to increase animal welfare because, by calling them individually to the feeder, it provides the animals with a positive short time anticipation of unaffected feeding.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues