Automatic recording of individual oestrus vocalisation in group-housed dairy cattle: development of a cattle call monitor.

Oestrus detection remains a problem in the dairy cattle industry. Therefore, automatic detection systems have been developed to detect specific behavioural changes at oestrus. Vocal behaviour has not been considered in such automatic oestrus detection systems in cattle, though the vocalisation rate is known to increase during oestrus. The main challenge in using vocalisation to detect oestrus is correctly identifying the calling individual when animals are moving freely in large groups, as oestrus needs to be detected at an individual level. Therefore, we aimed to automate vocalisation recording and caller identification in group-housed dairy cows. This paper first presents the details of such a system and then presents the results of a pilot study validating its functionality, in which the automatic detection of calls from individual heifers was compared to video-based assessment of these calls by a trained human observer, a technique that has, until now, been considered the 'gold standard'. We developed a collar-based cattle call monitor (CCM) with structure-borne and airborne sound microphones and a recording unit and developed a postprocessing algorithm to identify the caller by matching the information from both microphones. Five group-housed heifers, each in the perioestrus or oestrus period, were equipped with a CCM prototype for 5 days. The recorded audio data were subsequently analysed and compared with audiovisual recordings. Overall, 1404 vocalisations from the focus heifers and 721 vocalisations from group mates were obtained. Vocalisations during collar changes or malfunctions of the CCM were omitted from the evaluation. The results showed that the CCM had a sensitivity of 87% and a specificity of 94%. The negative and positive predictive values were 80% and 96%, respectively. These results show that the detection of individual vocalisations and the correct identification of callers are possible, even in freely moving group-housed cattle. The results are promising for the future use of vocalisation in automatic oestrus detection systems.

Perches or grids? What do rearing chickens differing in growth performance prefer for roosting?

The domestic fowl (Gallus gallus f. dom.) is highly motivated to roost on elevated structures. Previous studies indicated that broiler chickens hardly use elevated perches but frequently use elevated platforms. However, it is unclear which height and type of elevated structures broilers prefer at various daytimes.We investigated the use of elevated perches and grids varying in height (10, 30, and 50 cm above the floor) by chickens of 3 strains differing in growth performance. In 2 successive trials, male chickens of Ross 308 (Ross, fast growing, n = 200), Lohmann Dual (Dual, medium growing, n = 200), and Lohmann Brown Plus (LB, slow growing, n = 200) were tested in 12 experimental compartments (each strain in 4 compartments), respectively. Usage of structures was recorded on video and analyzed with time-sampling observation for each week of age during dawn, the light period, dusk, and the dark period. In addition, behavioral activity was measured with an antenna-transponder system.The results showed that Ross and Dual chickens preferred grids to perches throughout the entire observation period. With increasing age, chickens of all strains increasingly used the elevated structures during all daytimes. In contrast to Dual and LB, Ross chickens reduced the use of structures from the 3rd to 4th week of age during the light but not the dark period. Additionally, during the dark period, chickens of all 3 strains at the end of fattening period used elevated structures at 50 cm height most often. The behavioral activity decreased significantly in all 3 strains but was much lower in Ross chickens compared with Dual and LB.The results indicated that chickens are motivated to roost at nighttime on high-elevated and suitable structures such as grids. Further studies are needed to assess the space requirements for elevated structures that should be offered to chickens.

Moderate high or low maternal protein diets change gene expression but not the phenotype of skeletal muscle from porcine fetuses.

The aim of our study was to characterize the immediate phenotypic and adaptive regulatory responses of fetuses to different in utero conditions reflecting inadequate maternal protein supply during gestation. The gilts fed high- (250% above control) or low- (50% under control) protein diets isoenergetically adjusted at the expense of carbohydrates from the day of insemination until the fetuses were collected at day 64 or 94 of gestation. We analyzed body composition, histomorphology, biochemistry, and messenger RNA (mRNA) expression of fetal skeletal muscle. Both diets had only marginal effects on body composition and muscular cellularity of fetuses including an unchanged total number of myofibers. However, mRNA expression of myogenic regulatory factors (MYOG, MRF4, P ≤ 0.1), IGF system (IGF1, IGF1R, P ≤ 0.05) and myostatin antagonist FST (P = 0.6, in males only) was reduced in the fetal muscle exposed to a maternal low-protein diet. As a result of excess protein, MYOD, MYOG, IGF1R, and IGFBP5 mRNA expression (P ≤ 0.05) was upregulated in fetal muscle. Differences in muscular mRNA expression indicate in utero regulatory adaptive responses to maternal diet. Modulation of gene expression immediately contributes to the maintenance of an appropriate fetal phenotype that would be similar to that observed in the control fetuses. Moreover, we suggest that the modified gene expression in fetal skeletal muscle can be viewed as the origin of developmental muscular plasticity involved in the concept of fetal programming.

Similar clinical features in follicular lymphomas with and without breaks in the BCL2 locus.

Approximately 15% of follicular lymphomas (FLs) lack breaks in the BCL2 locus. The aim of this study was to better define molecular and clinical features of BCL2-breakpoint/t(14;18)-negative FLs. We studied the presence of BCL2, BCL6 and MYC breaks by fluorescence in situ hybridization and the expression of BCL2, MUM1, CD10, P53 and Ki67 in large clinical trial cohorts of 540 advanced-stage FL cases and 116 early-stage disease FL patients treated with chemotherapy regimens and radiation, respectively. A total of 86% and 53% of advanced- and early-stage FLs were BCL2-breakpoint-positive, respectively. BCL2 was expressed in almost all FLs with BCL2 break and also in 86% and 69% of BCL2-breakpoint-negative advanced- and early-stage FLs, respectively. CD10 expression was significantly reduced in BCL2-breakpoint-negative FLs of all stages and MUM1 and Ki67 expression were significantly increased in BCL2-break-negative early-stage FLs. Patient characteristics did not differ between FLs with and without BCL2 breaks and neither did survival times in advanced-stage FLs. These results suggest that the molecular profile differs to some extent between FLs with and without BCL2 breaks and support the notion that FLs with and without BCL2 breaks belong to the same lymphoma entity.

Surgical implantation and functional assessment of an invasive telemetric system to measure autonomic responses in domestic pigs.

The first aim of this study was to establish a surgical procedure to implant a new telemetric device for the continuous recording of electrocardiogram (ECG) and blood pressure (BP) in freely moving pigs. A second aim was the functional assessment of cardiovascular parameters, including heart rate variability (HRV) and blood pressure variability (BPV), so that these data could be used as the basis for the objective evaluation of autonomic activity and balance in different behavioural contexts. Eleven domestic pigs (German Landrace) underwent surgery for the placement of a telemetric device. At day 15 after surgery, 512 consecutive inter-beat intervals and pressure waves were analysed using different detection methods (automatic and manually corrected) while the animals were resting or feeding, respectively. HRV and BPV were calculated. Incomplete datasets were found in four pigs due to missing ECG or BP signals. Technical and surgical issues concerning catheterisation and detachment of the negative ECG lead were continuously improved. In the remaining pigs, excellent signal quality (manually corrected data of 1%) was obtained during resting and acceptable signal quality (<10%) was obtained during feeding. Automatic triggering was sufficiently reliable to eliminate errors in BP recordings during active behaviour, but this was not the case for ECG recordings. Sympathetic arousal with accompanying vagal withdrawal during feeding was documented. The established surgical implantation and functional assessment of the telemetric system with the reliable registration of cardiovascular parameters in freely moving pigs could serve as a basis for future studies of autonomic regulation in context of stress and animal welfare.

Membrane and centrifugal therapeutic plasma exchange: practical difficulties in anticoagulating the extracorporeal circuit.

Therapeutic plasma exchange (TPE) is a well-established treatment modality for nephrology patients, using two conventional methods: membrane (mTPE) or centrifugal TPE (cTPE). Although the efficacy of both treatments has been described, there are few reports that compare these methodologies. Here we describe three nephrology patients who were treated with both mTPE and cTPE. The mTPE method, but not the cTPE method, was associated with persistent difficulty anticoagulating the extracorporeal circuit in all three patients. In mTPE procedures, the doses of heparin bolus and infusion rate were important determinants of whether the circuit clotted. With a heparin bolus at or below 2000 IU, clotting occurred in 67% of treatments, dropping to 25% with a bolus of >2000 IU. Likewise, a heparin infusion rate during the procedure was indicative of clotting. With a maintenance infusion of <2000 IU/h, most circuits clotted. No clotting was observed during cTPE procedures using acid citrate dextrose formula A solution as an anticoagulant of the extracorporeal circuit. Overall, difficulties maintaining the extracorporeal circuit in mTPE required the use of additional disposable sets, high doses of heparin and nursing time. In addition, mTPE procedures took longer to perform than cTPE.

Long-term cognitive enrichment affects opioid receptor expression in the amygdala of domestic pigs.

Enriching the housing environment by stimuli that challenge both reward and cognitive mechanisms may enhance behavioural experiences and can improve animal welfare, particularly in farm animals. A newly developed experimental feeding system for domestic pigs using food-rewarded learning of discriminatory and instrumental tasks enabled the animals to successfully master a cognitive challenge and to be rewarded ca. 30 times per day with small food portions. Reward-related behaviour is expected to be modulated by endogenous opioid systems. Furthermore, recent evidence supports a role for the amygdala in processing positive affects by stimulus-reward learning. Hence, the present study investigates mRNA expression of cerebral receptors, which are involved in these processes. In an initial step, reverse transcription-polymerase chain reaction (RT-PCR) provided the first evidence that transcripts of three different opioid receptors (MOR, DOR, KOR), as well as the neuropeptide Y 5 receptor (NPY5R), leptin receptor (LEPR) and proopiomelanocortin (POMC), are expressed in both the porcine amygdala and hypothalamus. Using real-time PCR we could show that the expression of two receptors of the opioid system (amygdala: KOR, DOR), in addition to the expression of NPY5R (hypothalamus) in eight enriched housed pigs was markedly downregulated compared to that of conventionally housed and fed pigs. Focusing on opioid receptors in the amygdala, the present study shows that long-term cognitive enrichment acts as a biologically relevant stimulus that causes modifications of gene expression of reward-sensitive cerebral receptors in domestic pigs.

pH measurement as quality control on human post mortem brain tissue: a study of the BrainNet Europe consortium.

AIMS: Most brain diseases are complex entities. Although animal models or cell culture experiments mimic some disease aspects, human post mortem brain tissue remains essential to advance our understanding of brain diseases using biochemical and molecular techniques. Post mortem artefacts must be properly understood, standardized, and either eliminated or factored into such experiments. Here we examine the influence of several premortem and post mortem factors on pH, and discuss the role of pH as a biochemical marker for brain tissue quality. METHODS: We assessed brain tissue pH in 339 samples from 116 brains provided by 8 different European and 2 Australian brain bank centres. We correlated brain pH with tissue source, post mortem delay, age, gender, freezing method, storage duration, agonal state and brain ischaemia. RESULTS: Our results revealed that only prolonged agonal state and ischaemic brain damage influenced brain tissue pH next to repeated freeze/thaw cycles. CONCLUSIONS: pH measurement in brain tissue is a good indicator of premortem events in brain tissue and it signals limitations for post mortem investigations.

A single exposure to social isolation in domestic piglets activates behavioural arousal, neuroendocrine stress hormones, and stress-related gene expression in the brain.

Stressful early life events can have short- and long-term effects on neuroendocrine and behavioural mechanisms of adaptation. Here, we investigated the effects of a single social isolation (4 h) of domestic piglets on both behavioural alterations in open-field tests and modifications in the expression of genes regulating glucocorticoid response in stress-related brain regions at 7, 21 or 35 days of age. The mRNAs of glucocorticoid receptor (GR), mineralocorticoid receptor (MR), 11ss-hydroxysteroid dehydrogenase 1 and 2 (11ss-HSD1 and 11ss-HSD2) and c-fos were analysed by real-time RT-PCR in the hypothalamus, hippocampus and amygdala. The social isolation caused both elevated stress hormone concentrations (e.g. cortisol) and open-field reactivity (e.g. locomotion, vocalisation) compared to control piglets. The enhanced behavioural and neuroendocrine activity was associated with distinct changes in gene expression in the limbic system. The hypothalamic GR, MR and 11ss-HSD1 mRNA expressions and the hippocampal 11ss-HSD1 mRNA was significantly higher in isolated piglets, whereas in the amygdala social isolation caused a significant decrease in MR mRNA expression. Isolated piglets also displayed significantly higher c-fos mRNA expression, an estimate of neuronal activation, in hypothalamus and amygdala. The mRNA alterations as well as the behavioural and hormonal pattern show an effect of social isolation on days 7 and 21, but no effect on day 35. In conclusion, a single social isolation in piglets caused age-dependent neuroendocrine and behavioural changes that indicate increased arousal and experienced distress. The present results also suggest that psychosocial stress effects should be considered for the assessment of livestock handling practices with respect to health and welfare.

Behavioural, endocrine and immune responses to repeated social stress in pregnant gilts.

Pregnant sows are exposed to various stressors in intensive pig husbandry that may have negative consequences on their health, reproductive performances and welfare. Social stress is one of these challenges, because gestating sows have to be housed in groups according to EU guidelines (2001/88/CE). The purpose of this study was to determine the consequences of repeated social stress in pregnant female pigs on their behavioural, endocrine and immunological responses and on pregnancy outcome. Pregnant gilts were submitted to a repeated social stress procedure induced by housing unfamiliar gilts in pairs changed twice a week between days 77 and 105 of gestation (S group, n = 18). Control gilts were housed in stable pairs during the same period (C group, n = 18). Agonistic behaviour was observed during the first 3 h after each grouping. Skin lesions were numbered 2 h after each grouping. Salivary cortisol was measured before and repeatedly during the 4 weeks of grouping. Gilts were immunized against keyhole limpet haemocyanin (KLH) on days 81 and 95 of gestation. Immunoglobulins G against KLH, proliferative responses to concanavalin A, lipopolysaccharide, pokeweed mitogen and KLH and peripheral blood leukocyte numbers were evaluated 1 week before the first grouping and 3 days after the last one. Agonistic interactions and skin lesions were observed in S gilts at each grouping, although there was a decline between the first and the last grouping (P < 0.05). The repeated social stress induced a sustained endocrine response as shown by elevated salivary cortisol levels from 1 to 48 h after grouping in S gilts compared to C gilts. The cellular as well as the humoral immunity and the leukocyte numbers were not influenced by social stress. Gestation length tended to be shorter in S gilts (P = 0.09), but litter size, piglet weight or mortality at birth were not affected. Variability of the response of S gilts to groupings was partly explained by their average success value determined according to the outcome (defeat or win) of all the groupings. In conclusion, our study demonstrates that the application of repeated social stress to pregnant gilts during the last third of their gestation repeatedly activates their hypothalamo-pituitary-adrenal axis but does not impair their immune function and pregnancy outcome.

Cell migration patterns and ongoing somatic mutations in the progression of follicular lymphoma.

Follicular lymphoma (FL) constitutes the neoplastic equivalent of germinal center B-cells. Like its physiological counterpart, FL grows in (atypical) follicular structures, the formation of which is as yet poorly understood. Recent data indicate that in early tumour stages, neoplastic FL cells home to and colonise reactive germinal centers. Laser microdissection (LMD) and micromanipulation techniques now allow for the molecular genetic analysis of single cell mutation patterns in FL. The purpose of the present study was the analysis of the sequence and order of somatic mutations in FL, i.e. the influence of the germinal center microenvironment on the clonal evolution in different grades of FL. By generating phylogenetic trees as calculated from tumour cell sequences, the clonal evolution from a putative progenitor cell was elucidated and finally, the tumour cell migration pattern in disease progression was assessed by analyzing biopsies at different time points in relapsed tumours. Four patients suffering from FL were included in the study. A primary FL grade 1 showed clustering of genetically related subclones in distinct follicles. A moderate interfollicular exchange of tumour cells was detected. Three cases of FL grade 2 were found to show decreased subclonal clustering in follicles and an increase in the interfollicular migration. Accumulations of replacement mutations in antigen binding domains (CDR) and silent mutations in non-antigen binding domains (FR), respectively, indicating antigen influence on hypermutation were only found in the case of FL grade 1. Our conclusion is that the microenvironment in germinal centers exercises influence on clonal evolution and tumour cell distribution patterns in FL. With increasing histologic grade during disease progression, a reduced intraclonal diversity and selection of subclones also occurs outside the setting of transformation to high-grade lymphoma. Antigen-dependent hypermutations were only seen in FL grade 1, while in progressed FL, random mutation patterns and a decrease of clonal diversity were found.

Altered vocalization rate during the estrous cycle in dairy cattle.

Correct detection of estrus is a problem in dairy herds. In practice, several procedures exist for detection of estrus besides conventional visual observation by humans. These procedures deliver very different results regarding detection of estrus. It is known that the calls of female mammals can contain information about reproductive status. It is also suspected that the vocalizations of cattle contain information about age, sex, dominance status, and stage in the estrous cycle. In the present study, a methodology for the continuous automatic recording of vocalization of heifers during the periestrous period is presented. It was shown in 10 tethered heifers that the estrous climax results in an increase in vocalization rate. Vocalization rate of heifers increased approximately 84% from d -2 to 0 (related to observed estrus) and approximately 59% from d -1 to d 0. After d 0, vocalization rate decreased about 79%. Increased vocalization was correlated with the visual observation of estrus by humans. We also found 2 different structures in the vocalization of heifers. The harmonic structure showed regular frequency bands, whereas the nonharmonic structure was noisy. The hypothesis that the disharmonic structure increases near the estrous climax was confirmed. Hence, it seems possible to get information about stage of the estrous cycle of dairy cattle by means of monitoring vocalization. The presented method of automatically detecting the rate of cattle vocalization (patent pending) could be used solely or in combination with other automated systems for detecting estrus and could considerably increase current estrus detection rates once its applicability can be demonstrated in nontethered cattle.

Effects of attention and rewarded activity on immune parameters and wound healing in pigs.

Challenging animals with a demanding situation they are able to cope with and where they are rewarded may be a source of positive emotions and possibly of increased welfare. In order to test if this results in changes of immunological parameters and wound healing, 56 pigs (7-20 weeks of age), housed in groups of 8 animals each, were successfully trained to recognize and localize an individual acoustic summons and to receive a small portion of feed as a reward. Immune reactions and the development of a standardized biopsy wound were compared to values of conventionally fed control groups of equal size and animal-to-feeding-place ratio (2:1). In the experimental animals a significantly higher concentration of IgG as well as an increased in vitro T-cell proliferation to ConA but a reduced LPS-induced proliferation of B-cells was found, while basal salivary cortisol concentrations were similar. Wound development was better in the experimental animals as measured by the area of the inflammatory corona. It decreased more rapidly in the experimental animals since the 5th day after biopsy and was significantly smaller than in the control groups. We conclude that environmental enrichment by equipment provoking attention and cognitive activity which is rewarded by feed may play a beneficial role for physical welfare of intensively housed pigs.

[Reaction of muscles to a stimulating environment--effects on the loin muscle (M. longissimus) of Landrace pigs]. / Reaktion der Muskulatur auf eine stimulierende Haltung--Befunde am Kotelettmuskel (M. longissimus) von Landrasse-Schweinen.

The effects of an enriched environment on growth, meat quality, and muscle biological traits were investigated using 64 castrated pigs (age range 7 to 20 weeks). Positive emotional appraisal was induced by a system that acoustically frequently called individuals out of a group (n=32) to a feeding station, where they were rewarded with small portions of feed. The results were compared with traditional fed pigs (Control; n = 32). There was no environmental effect on live weight and lean muscle percentage. However, the stimulating keeping regime reduced the intramuscular fat content of the M. longissimus by 0.2 % and increased the protein content by 0.5 %. Moreover, the drip loss of M. longissimus was 1.1 % lower in the treatment group. The analysis of muscle fibre traits (biopsy samples of M. longissimus) showed a 7 % higher proportion of oxidative muscle fibres in the pigs reared in the enriched environment. This fibre type showed a tendency to increased fibre areas. These findings indicate a higher oxidative capacity of the muscle. However, the activity of the inarker enzyme citrate synthase (CS) was not influenced and the activity of lactate dehydrogenase (LDH) was even increased compared to the control animals.

[Effects of muscle needle biopsy on parameters of humoral and cellular immunity in pigs]. / Effekte einer Muskelschussbiopsie auf Parameter der humoralen und zellvermittelten Immunität beim Schwein.

The shot biopsy is a common experimental technique for the collection of samples to investigate muscle tissue characteristics or to determine meat quality features in pigs. Its application seems to be also possible in interdisciplinary research projects investigating animal stress, behaviour, and welfare. The present study on 12 group-housed pigs (age: 12 weeks, weight: 29.3 kg) shows the influence of this wound-causing technique on different humoral and cell-mediated parameters of the immune system at 1, 3, 5, and 9 days after biopsy compared to the initially investigated levels before. An enhancement of the blood sedimentation rate and both the IgG and the cellular immune response in vivo (leukocytes, lymphocytes) as well as in vitro (ConA) was observed. Furthermore, there were signs of a secondary wound infection 5 days after biopsies were taken possibly caused by mutual oral manipulation of the animals. We conclude that the muscle shot biopsy technique can be used on group-housed pigs as a method to investigate muscle physiological characteristics. The technique, however, induces immunological reactions which may interfere with stress-induced immune reactions.

Linear prediction coding analysis and self-organizing feature map as tools to classify stress calls of domestic pigs (Sus scrofa).

It is assumed that calls may give information about the inner (emotional) state of an animal. Hence, in the last years sound analysis has become an increasingly important tool for the interpretation of the behavior, the health condition, and the well-being of animals. A procedure was developed that allows the characterization, classification, and visualization of the cluster structures of stress calls of domestic pigs (Sus scrofa). Based on the acoustic model of the sound production the extraction of features from calls was performed with linear prediction coding (LPC). A vector-based self-organizing neuronal network was trained with the determined LPC coefficients, resulting in a feature map. The cluster structure of the calls was then visualized with a unified matrix and the neurons were labeled for their input origin. The basic applicability of the procedure was tested by using two examples which were of special interest for a possible evaluation of the normal farming practice. The procedure worked well both in discriminating individual piglets by their scream characteristics and in classifying pig stress calls vs other calls and noise occurring under normal farming conditions.

Early identification of neonates at risk: traits of newborn piglets with respect to survival.

Despite technological changes and improved management, piglet mortality remains a problem for both production and welfare. Most preweaning mortality occurs within the first 3 days after birth because of problems with adaptation and development. Thus, the purpose of our study was to determine the physiologic state of newborn pigs with respect to piglet survival. Data were collected from 1024 live-born piglets of 106 primiparous German Landrace sows to analyze relationships between farrowing traits, early postnatal vitality and blood chemistry, including immunity of piglets at birth. Surviving piglets were compared with those that died during the first 10 days of life. The survivors were significantly heavier at birth (P=0.001), were born earlier in the birth order (P=0.04), reached the udder and took in first colostral milk more quickly (P=0.001) and had a smaller drop in rectal temperature I h after birth (P=0.001) than dead. However, dead piglets had significantly higher blood levels of inorganic phosphorus (P=0.0001), calcium (P=0.04) and urea (P=0.05), but a lower concentration of alpha2-macroglobulin and lower lymphocyte proliferation indices in response to pokeweed mitogen (P=0.05). Models fitted for discrimination between survivors and piglets that died included, in addition to birth weight and litter size, the foraging behavior of neonates (time from birth to first suckle) and their thermoregulatory capacity (rectal temperature 1 h after birth) in the first experimental unit, as well as prenursing biochemical measures (inorganic phosphorus, calcium and glucose) in the second experimental unit. These ethophysiological and biochemical traits of early postnatal vitality are important determinants of maturity and development at birth. Hence, breeding programs and perinatal housing and feeding conditions should ensure a high physiological maturity to improve mortality rates of neonates.

Effects of dominance and familiarity on behaviour and plasma stress hormones in growing pigs during social confrontation.

Behavioural patterns and plasma adrenaline, noradrenaline and cortisol responses were studied in domestic pigs with different dominance status during 10-h social confrontation tests with a familiar and an unfamiliar group. Eight trials were carried out, where in each trial two groups of nine growing pigs (12 weeks old) were randomly formed. The pigs with the highest (HR) and lowest (LR) rank from each group were selected as test animals, provided with surgically implanted catheters and kept in single housing for 2 to 3 weeks. After this period, each test animal was introduced once into the familiar and once into the unfamiliar group for 10 h. Introduction of the test animals into the groups caused frequent agonistic interactions during the first 30 min and significantly more agonistic interactions during the confrontation with the unfamiliar group. The agonistic behaviour was accompanied by a rapid increase of plasma catecholamines and cortisol. HR pigs showed significantly higher plasma catecholamine concentrations and more agonistic interactions during the first 30 min compared with the LR pigs. During confrontation with the unfamiliar group, HR pigs experienced more defeats and showed a higher increase of plasma cortisol levels than during the confrontation with the familiar group. No influences of rank or familiarity were found on the other behavioural patterns examined. The results show that agonistic behaviour and activation of the sympatho-adrenomedullary and the hypothalamic-pituitary-adrenal system in pigs during a social confrontation test are determined by the former dominance rank of the animals and the familiarity of the group.

Monitoring of piglets' open field activity and choice behaviour during the replay of maternal vocalization: a comparison between Observer and PID technique.

The paper presents a new system for the automatic monitoring of open field activity and choice behaviour of medium-sized animals. Passive infrared motion detectors (PID) were linked on-line via a digital I/O interface to a personal computer provided with self-developed analysis software based on LabVIEW (PID technique). The set up was used for testing 18 one-week-old piglets (Sus scrofa) for their approach to their mother's nursing vocalization replayed through loudspeakers. The results were validated by comparison with a conventional Observer technique, a computer-aided direct observation. In most of the cases, no differences were seen between the Observer and PID technique regarding the percentage of stay in previously defined open field segments, the locomotor open field activity, and the choice behaviour. The results revealed that piglets are clearly attracted by their mother's nursing vocalization. The monitoring system presented in this study is thus suitable for detailed behavioural investigations of individual acoustic recognition. In general, the PID technique is a useful tool for research into the behaviour of individual animals in a restricted open field which does not rely on subjective analysis by a human observer.

Effects of social status after mixing on immune, metabolic, and endocrine responses in pigs.

The effects of social rank on immune, metabolic, and endocrine responses were studied in 10 newly mixed groups of German Landrace pigs (9 individuals each) at an age of 12 weeks. Immediately after mixing, the agonistic interactions (AI) of all group members were continuously recorded over 3 days (10 h daily). An individual dominance value (DV) was calculated by the number of wins minus defeats in relation to all decisive fights (DV < or = 0, subordinate; DV > 0, dominant). Blood samples were taken 24 h before and 3 days after mixing. The data showed that the social status had a significant effect on lymphocyte proliferation in responses to different mitogens: socially dominant pigs had higher proliferative response than subordinate pigs. In addition, during the observation period the lymphocyte activation by mitogens increased in the dominant animals and decreased in the subordinate animals with increasing number of agonistic interactions. The rise in total serum IgG concentration 3 days after mixing was higher in dominant pigs compared with subordinates. The dominance status did not significantly affect plasma metabolic levels nor cortisol concentrations. However, mixing appeared to increase glucose and total protein values and to decrease alkaline phosphatase and cortisol levels in both, dominant and subordinate pigs. In conclusion, mitogen induced cell proliferation seems to be a valuable marker for acute social stress in pigs.