Impact of farrowing system and prepartum nest-building material on nest-building behaviour and farrowing in sows.

Farrowing crates are widely used as the main housing system for farrowing and lactating sows on commercial farms although they have a negative impact on sow welfare and behaviour. One of the main reasons for using farrowing crates is to reduce piglet mortality during farrowing and lactation. We compared the effects of temporary crating (TC) versus free farrowing (FF) with different nest-building materials on production and welfare measures. Sows were investigated using a 2 × 3 factorial design. Sows were allocated to two farrowing treatments: FF sows were not crated around farrowing, and TC sows were crated from 2 days before expected farrowing until 3 days after farrowing, when the crate was opened. In both farrowing treatments, the nest-building material was given from 7 days prior to farrowing as follows: (1) 1 L of straw twice per day, (2) 1 sheet of newspaper twice per day or (3) fastened jute fabric to the farrowing crate. The study consisted of two parts; part 1 included a total of 87 sows for data on piglet mortality and growth, and part 2 included data on nest-building and farrowing behaviour from a subset of these sows (n = 34). Farrowing treatment affected piglet mortality; FF sows had a lower number of stillborn piglets than TC sows (P = 0.04), but the number of crushed piglets was higher (P < 0.01). Nest-building material tended to have an impact on total number of crushed piglets (P = 0.08) and piglets that died during 3 days of lactation (P = 0.09). Litter growth was better in the FF group than in the TC group from piglet age of 1 day to 3 weeks (P = 0.04). Overall, little nest-building-related behaviour occurred, probably due to the small amount of nest-building material. The usability of the nest-building material varied with farrowing treatment; FF sows used newspaper most for nest-building, while TC sows used straw and jute fabric (P = 0.01). There were no differences in the piglet birth intervals or the farrowing duration. In conclusion, free farrowing can have positive effects on piglet growth but negative effects on piglet survival in early lactation. Different nest-building materials have different effects depending on the type of farrowing system.

The use of social network analysis to describe the effect of immune activation on group dynamics in pigs.

The immune system can influence social motivation with potentially dire consequences for group-housed production animals, such as pigs. The aim of this study was to test the effect of a controlled immune activation in group-housed pigs, through an injection with lipopolysaccharide (LPS) and an intervention with ketoprofen on centrality parameters at the individual level. In addition, we wanted to test the effect of time relative to the injection on general network parameters in order to get a better understanding of changes in social network structures at the group level. 52 female pigs (11-12 weeks) were allocated to four treatments, comprising two injections: ketoprofen-LPS (KL), ketoprofen-saline (KS), saline-LPS (SL) and saline-saline (SS). Social behaviour with a focus on damaging behaviour was observed continuously in 10 × 15 min bouts between 0800 am and 1700 pm 1 day before (baseline) and two subsequent days after injection. Activity was scan-sampled every 5 min for 6 h after the last injection in the pen. Saliva samples were taken for cortisol analysis at baseline and at 4, 24, 48, 72 h after the injections. A controlled immune activation affected centrality parameters for ear manipulation networks at the individual level. Lipopolysaccharide-injected pigs had a lower in-degree centrality, thus, received less interactions, 2 days after the challenge. Treatment effects on tail manipulation and fighting networks were not observed at the individual level. For networks of manipulation of other body parts, in-degree centrality was positively correlated with cortisol response at 4 h and lying behaviour in the first 6 h after the challenge in LPS-injected pigs. Thus, the stronger the pigs reacted to the LPS, the more interactions they received in the subsequent days. The time in relation to injection affected general network parameters for ear manipulation and fighting networks at the group level. For ear manipulation networks, in-degree centralisation was higher on the days following injection, thus, certain individuals in the pen received more interactions than the rest of the group compared to baseline. For fighting networks, betweenness decreased on the first day after injection compared to baseline, indicating that network connectivity increased after the challenge. Networks of tail manipulation and manipulation of other body parts did not change on the days after injection at the group level. Social network analysis is a method that can potentially provide important insights into the effects of sickness on social behaviour in group-housed pigs.

To be blamed or pitied? The effect of illness on social behavior, cytokine levels and feed intake in undocked boars.

Tail biting is detrimental to animal welfare and has negative consequences for producer economy. Poor health is one of the risk factors for tail biting. The first aim of this study was therefore to test for links between health status and behavior related to tail biting at the individual level. The second aim of this study was to test whether variation in cytokines was related to variation in social behavior. These small molecules produced upon immune activation are known to influence behavior both in the direction of withdrawal and increased aggression. This could potentially increase non-functional social behavior and thereby the risk of a tail biting outbreak. To investigate this, we collected behavioral data, health data, feeding data and blood samples from undocked boars at a test station farm in Norway. We compared groups with three different diagnoses: osteochondrosis diagnosed by computer tomography scanning (OCSAN), osteochondrosis diagnosed by clinical examination (OCCLIN) and respiratory tract disease (RESP), with healthy controls (CTR). We tested whether the diagnoses were associated with feeding and growth, social behavior and cytokine levels. We then tested whether there were correlations between cytokine levels and social behavior. We also provide raw data on cytokine levels in the extended sample (N=305) as there are few publications on cytokine levels measured in pigs living under commercial conditions. OCCLIN pigs visited the feeder less, and fed longer compared to CTR pigs. Pigs diagnosed with RESP showed a large drop in growth the first week after filming, which corresponds to the week they were likely to have been diagnosed with illness, and a tendency to compensatory increase in the week after that. Social behavior differed between experimental groups with OCSCAN pigs receiving more social behavior (both aggressive and non-aggressive) compared to CTR, and RESP pigs tending to perform more ear- and tail-biting than controls. There were no differences in absolute levels of cytokines between categories. However IL1-ra and IL-12 showed correlations with several behaviors that have been shown by others to be associated with current or future tail biting activity. To our knowledge, this is the first published study indicating a role for illness in non-functional social behavior in pigs and the first showing a correlation between cytokine levels and social behavior.

Health parameters in tail biters and bitten pigs in a case-control study.

Health in relation to tail-biting behaviour was investigated on a problem farm. Quartets (n = 16) of age- and gender-matched fattening pigs including a tail biter (TB, n = 16), a victim (V, n = 16), a control in the same pen (Ctb, n = 10) and a control in a pen where no tail biting was observed (Cno, n = 14) were chosen by direct behavioural observation. Haematological and clinicochemical analyses, autopsy and histological examination of 16 different tissues were carried out. Tail lesion severity was evaluated both macroscopically, on the basis of inspection, and histologically, in the sagittally cut tail. Category effects were tested using Friedman's ANOVA by Ranks, Cochran's Q or a repeated-measure GLM and, if significant, pair-wise tests were conducted using Wilcoxon Signed Ranks or McNemar's Test. The number of received tail bites correlated better with histological than with macroscopic tail lesion scoring because of deep inflammation beneath healthy skin in some cases. Most individuals had mild inflammatory lesions in internal organs suggestive of generalized activation of the immune system, and 30% of the animals were anaemic, possibly because of systemic spread of infectious agents. V had more severe respiratory organ lesions and higher serum protein concentrations than all other categories of pigs. Liver- and muscle-specific enzymes (alanine aminotransferase, alkaline phosphatase and creatine kinase) differed between categories. In conclusion, most animals had signs of generalized activation of the immune system, possibly because of systemic spread of infectious agents. V pigs suffered from more severe inflammatory lesions than TB, Ctb or Cno. Deep infections may exist under healthy skin in the tail of bitten pigs.

Environmental enrichment in early life affects cortisol patterns in growing pigs.

Effects of environmental enrichment at different stages of life on stress physiology of pigs were investigated in a trial with 63 groups, each of four siblings. In each of the three growing phases (suckling 0 to 4 weeks of age, nursery 5 to 9 weeks, fattening 10 to 24 weeks) pens either were (=E) or were not (=0) enriched. Accordingly, the treatments were (i) 000, (ii) E00, (iii) EE0, (iv) 00E, (v) 0EE and (vi) EEE. The enrichment material, renewed twice daily to leave a thin layer, consisted of wood shavings and chopped straw. Salivary cortisol was sampled hourly from 0700 to 1900 h at the age of 9 and 21 weeks. The presence of a circadian secretion rhythm was evaluated by an intra-assay coefficient of variation-based method. An adrenocorticotropic hormone test was performed at 21 weeks. Treatment effects on the odds of a physiological cortisol rhythm were assessed by logistic regression, and effects on cortisol concentrations with a repeated measures GLM. Substrate-enrichment from 0 to 9 weeks of age increased the odds of a rhythm as compared to barren housing (odds ratio (OR) = 30.0, P < 0.01). A flat cortisol secretion pattern may indicate chronic stress and/or delayed maturation of the rhythm. Barren as compared to enriched rearing (0 to 4 weeks of age) seemed to cause a blunted secretion rhythm at 21 weeks of age. Although behavioural and tail lesion observations provided support to the assumption that a blunted rhythm indicates chronic stress, the biological significance of these cortisol results needs confirmation in future studies.

Fertility of sows fed ad libitum with a high fibre diet during pregnancy.

The effect of ad libitum (ADLIB) feeding strategy on the fertility of the group housed sow was studied in a prospective field trial during 1.5 years. All study animals farrowed under standard farrowing circumstances in crates, and they were provided with an ad libitum feeding throughout the 30-day lactation. After weaning, animals were randomly allocated to one of the two dry sow feeding strategies (AD LIB or CONT). After oestrus detection in groups, they were artificially inseminated and moved into pregnancy pens with partially slatted floor, in groups of 40 sows each. The ADLIB sows (n = 447) were loose housed and provided with ad libitum access to 7.7 MJ/kg feed high in fibre from two feeders per group. The control sows (n = 479; CONT) were also loose housed and given a standard dry sow feed in feeding stalls once a day (2.5 kg/day. The energy content of the feed was 9.3 MJ/kg NE). The feeding strategy (ADLIB vs CONT) had no effect on pregnancy rate (85.8 vs 90.9, p > 0.05), weaning to oestrus interval (7.7 vs 7.3 days, p > 0.05), piglets born alive (11.5 ± 3.5 vs 11.6 ± 3.3, p > 0.05), stillborn piglets (1.2 ± 1.8 vs 0.9 ± 1.5, p > 0.05) nor on progesterone concentration (p > 0.05). CONT sows weaned more piglets (9.7 ± 2.2 vs 9.4 ± 2.0, p < 0.01), whereas the piglets of AD LIB sows were heavier at weaning (8.8 ± 0.9 vs 8.0 ± 1.3 kg, p < 0.05). In conclusion, ad libitum feeding with a high in fibre diet during pregnancy did not affect the reproductive performance.

Re-modelling the piggery breeding unit may affect the farrowing rate.

The objective of this retrospective cohort study was to clarify the effect of re-modelling the breeding unit on farrowing rate. The original study population included 63 sow herds that participated in the Finnish herd surveillance system. In these herds, the breeding units were re-modelled between 1995 and 2002. Information about the production system and other herd data for the last year before and the second year after re-modelling were available for 47 herds. The herds had an average of 68.5 (SD 45) sows per herd. Data were collected during one farm visit per herd. Initially, all herds had individual cages in their breeding units. The piggeries had either re-modelled their cages or switched to a group housing system with deep-litter, solid or slatted (partly or totally) floors. Farrowing rates were gathered from the national database, and data were tested with a linear regression model. Re-modelling did not have an effect on farrowing rate if initial reproductive performance of the herd was neglected. However, when farms were stratified according to performance prior to the beginning of study, namely into 'farms with initially high farrowing rate' (HF) and 'farms with initially low farrowing rate' (LF), the re-modelling had a significant effect on farrowing rate. In the HF farms, re-modelling caused a decrease in farrowing rate. Correspondingly, farrowing rate increased after remodelling in the LF farms. Farrowing rate was also influenced by mean parity of sows and by proportion of sows culled because of leg problems. This study could not show a profound impact of the design of the breeding unit on the fertility of the sow in the modern commercial production environment if the farm's reproductive performance before re-modelling was neglected. However, when initial performance was taken into account, re-modelling revealed significant, although varying effects on farrowing rate.

Short or long day light regimes may not affect reproductive performance in the sow.

The objective of this study was to evaluate the effect of short or long day light regimes on the reproductive performance in the sow. The study comprised approximately 1300 sows and their 3400 breedings in three commercial sow pools, in which a batch farrowing of 40 sows was employed. Each batch remained in the farrowing unit for 8 weeks under either a short day (10 h light, 14 h dark) or a long day (14 h light, 10 h dark) light regime. After weaning and transportation to the central unit, all sows were kept under the long day regime until they were moved back to the farrowing unit. Production results for each individual sow were recorded. The effect of the two different light regimes on the farrowing rate (FR) and on the weaning-to-oestrous interval was evaluated using logistic and Poisson regression models, respectively. The light regime affected none of the parameters significantly. The FR in June, July and August did, however, drop below that in December, January and February (OR 0.7, p < 0.05). The FR was affected by the sow pool (p < 0.01). Parity two sows exhibited a lower FR (OR 0.5, p = 0.05) and higher incidence of delayed first oestrus (IRR 2.7, p < 0.01) than did older sows. This study indicates that despite an artificial light regime, sows may still react to changes in season. In conclusion, use of simple light regime to obtain complete control over reproductive performance appears to be difficult.

Housing during early pregnancy affects fertility and behaviour of sows.

From 1.1.2013 EU legislation will permit stall-housing of dry sows for only 4 weeks post-service. Stalls are associated with compromised animal welfare, but group housing comes with risks from social confrontations. Studies on housing effects on fertility have produced contradictory results as systems are inconsistently defined. Effects of housing on pregnancy rate 28 days post-service (P28), early disruption of pregnancy (EDP) and behaviour were investigated in 12 replicates of 40 sows. Half of the animals were stalled (treatment S, mean parity 2.4) and half group-housed adjacent on 5.1 m(2) deep litter per sow (treatment G, mean parity 2.3). Pregnancy was detected using real-time ultrasound. An EDP-diagnosis required a drop of salivary progesterone concentration from >15.9 to <15.9 mmol/l in a series of samples taken on days 17, 20, 24 and 27 post-service. Behaviour was scan sampled on day 27 for 120 min with 10-min intervals. Data was analysed using mixed regression models in MLwiN. Treatment S increased the odds for P28 with 2.3 and the pregnancy rate of a treatment group with 0.1 compared with G. G increased the odds for EDP with 4.6. Treatment did not affect total exploratory or total passive behaviour. S sows explored floor and fixtures (not bedding) more and performed more passive sitting than G sows. Social stress may have caused the impaired reproductive performance in G sows. S sows showed behavioural signs of decreased welfare, but no corresponding reproductive effects. An interdisciplinary approach is needed when evaluating the appropriateness of housing systems.

Photoperiod and luteinizing hormone secretion in domestic and wild pigs.

During seasonal anoestrus (long-days), oestradiol can effectively inhibit the pulsatile secretion of luteinizing hormone (LH) in sheep. The aim of our trial was to determine whether the same regulatory mechanism exists in the pig. Altogether, 20 ovariectomized and oestradiol-implanted gilts (16 domestic pigs, 4 European wild boars) were randomly allocated to two treatment groups. The first group was kept under a short-day light-dark cycle of 8L:16D, and the second group under a long-day light regime of 16L:8D. After a 6-week treatment period, blood samples were taken at 20-min intervals for 12h. After sampling, the light regimens were switched. Sampling was then repeated following another 6 weeks of treatment. In both treatment groups, 2.3 LH pulses occurred every 12h. The basal LH level was 0.7+/-0.4 ng/ml for the short-day group and 1.0+/-0.5 ng/ml for the long-day group. The mean LH level was 0.9+/-0.4 and 1.3+/-0.6 ng/ml and the LH pulse amplitude 0.5+/-0.4 and 0.6+/-0.5 ng/ml, respectively. The basal and mean LH levels were therefore lower in short-day gilts (P<0.05), while LH pulse amplitude and frequency remained unaffected by treatment. In conclusion, the 6-week period under two different light regimes resulted in higher basal LH concentration in long-day gilts but was not able to produce changes in LH frequency in prepubertal gilts.

Welfare index and reproductive performance in the sow.

To study the relationship between on-farm welfare and reproductive performance in the sow, the TGI 35L Animal Needs Index was modified for use in Finnish pig production. The modified index had a maximal total score of 100. It was comprised of six categories: 'locomotion' (maximal score 21 for dry sows and 11 for lactating sows), 'social interaction' (12/8), 'floor quality' (16/9), 'stable climate' (16/21), 'feeding' (16/23) and 'health and stockmanship' (19/29). Index scorings were performed separately in farrowing, breeding and gestation units on 28 representative Finnish sow farms. One-year production parameters were collected. Multiple linear regression was used for statistical analysis. Total ANI-points varied between 36.5-68.0 for lactating and 39.5-86.0 for dry sows. Litter size increased with increasing scores for 'feeding' in the dry sow unit. Controlling for breed, high scores for 'health and stockmanship' and 'floor quality' shortened the reproductive cycle, probably because of good leg health. The number of weaned piglets per sow per year (PSY) increased with increasing scores for dry sow 'health and stockmanship', 'floor quality' and an interaction of 'feeding' in the farrowing and mating units. PSY increased with decreasing scores for farrowing pen 'climate'. High-quality floors and stockmanship appear to correlate positively with reproductive performance in the sow. Effects of a welfare-promoting feeding strategy on reproduction are contradictory.

Effect of feeding level on progesterone concentration in early pregnant multiparous sows.

The effect of three feeding regimens on progesterone level was tested during early pregnancy in multiparous sows. A total of eighteen sows in their eighth parity (8.1 +/- 2.8, mean +/- S.D.) were used. During lactation the sows were fed to appetite and after weaning they received 4 kg (52 MJ) a commercial feed per day. Following ovulation, sows were allocated to one of three treatment groups and fed 2 kg/day (low feeding, LLL) or 4 kg/day (high feeding, HHH) throughout the trial or 2 kg/day for 11 days, 4 kg/day for 10 days, and 2 kg/day for the remaining days of the study (modified feeding, LHL). Blood for progesterone and cortisol analyses was collected daily throughout the study, and for luteinizing hormone (LH) assay for 12 h at 15 min intervals on days 14 and 21 of pregnancy. An adrenocorticotropic hormone (ACTH) challenge test was performed on all sows day 28 of pregnancy. Dietary treatment did not significantly affect hormonal parameters. However, progesterone concentration tended to be lower (P = 0.08) in the HHH group than in the LLL group. In the LHL group venous progesterone concentration seemed to fluctuate. No effects of feeding were observed on progesterone concentration in allantoic fluid on day 35 of pregnancy. Venous cortisol level was significantly higher (P < 0.05) during proestrus and oestrus in all groups and there was no significant difference between groups in response to ACTH challenge. The mean amplitude of LH pulses decreased significantly (P < 0.01) from days 14 to 21 of pregnancy in all groups. In addition, an interaction was found between feeding level and baseline LH concentration and also between feeding level and mean LH concentration. Embryonic recovery was highest in the LLL (69%), lowest in the HHH (45%) and moderate in the LHL (55%) group. Neither high feeding nor modified feeding provided any benefits for reproductive performance in multiparous sows. A low feeding regimen thus appears optimal for multiparous sows in early pregnancy at least with the management regime described.