Adroaldo J. Zanella

Physiological and reproductive correlates of behavioural strategies in female domestic pigs

Abstract Thirty-seven pregnant primiparous domestic pigs, Sus scrofa , were introduced into a large indoor pen. The pigs were divided into three groups according to their ability to displace others in agonistic interactions and the behavioural characteristics of these groups were investigated. High Success pigs were able to displace at least as many individuals as displaced them. They were characterized by low levels of inactivity, high involvement in social interactions and high aggression. No Success pigs never displaced any other pig and were most inactive, least aggressive and showed low involvement in social interactions. Low Success pigs were able to displace some pigs but were more often displaced themselves. They were aggressive, despite their relative lack of success, and experienced the highest levels of aggression from and displacement by others. During the first month in the group, High Success pigs gained the most weight. Low Success pigs had the highest basal levels of salivary cortisol and showed the highest peak cortisol levels in response to an adrenocorticotrophic hormone challenge test. At the first parturition, Low Success pigs produced the lowest weight of piglets born alive. Hence there were more adverse effects associated with being aggressive and often displaced than with being aggressive and usually winning, or being unaggressive and involved in few interactions. The strategy used to cope with the social environment may be as important as the success achieved in agonistic interactions, at least in terms of consequences for physiology and reproduction.

A comparison of the welfare of sows in different housing conditions.

Twelve sows in good quality unstrawed stalls, three groups of five sows in strawed pens with individual feeding stalls and sows in a 38-sow group in a strawed yard with an electronic sow feeder were compared during the first four parities. They originated from the same source, were about 9 months of age and in the 7th week of their first pregnancy at the start of the experiment and were kept in adjacent rooms in a building, cared for by the same staff and given the same diets at a rate of 2·2 kg/day per animal. No new animals were added to the groups or stalls during the study and animals returned to the same condition after periods in farrowing and service accommodation. Using a wide range of welfare indicators, it was clear that stall-housed sows had more problems than group-housed sows and that tliese problems were worse in the fourth than in the first pregnancy. By the fourth pregnancy, stall-housed sows spent proportionately 0·14 of time showing activities which were clearly stereotypies and much time on activities which were sometimes stereotyped, i.e. ‘drinking’ and rooting or chewing at pen fittings making a total of proportionately 0·50 of time. Comparable figures for group-housed sows were much lower (0·037 and 0·081 in total). Stall-housed sows were also more aggressive than group-housed by the fourth pregnancy and their body weights were lower. There were no differences using physiological or immunological tests or measures of reproductive output. When the two group-housing systems were compared, sows in the electronic feeder system showed more fighting, especially soon after initial mixing, but fewer total agonistic interactions than sows in groups of five during the first pregnancy. Oral stereotypies were slightly higher in small groups, perhaps because of smaller pen space, than in larger groups but much lower than in stalls. By the fourth pregnancy there were few differences between sows in small and large groups and all seemed to have adapted well to the conditions. Evaluation of welfare in different housing systems requires use of a wide range of measures and of long-term studies.

Behavioral and physiological responses of horses to initial training: the comparison between pastured versus stalled horses

Horses kept in stalls are deprived of opportunities for social interactions, and the performance of natural behaviors is limited. Inadequate environmental conditions may compromise behavioral development. Initial training is a complex process and it is likely that the responses of horses may be affected by housing conditions. Sixteen 2-year-old Arabian horses were kept on pasture (P) (n ¼ 8) or in individual stalls (S) (n ¼ 8). Twelve horses (six P and six S) were subjected to a standardized training procedure, carried out by two trainers in a round pen, and 4 horses (two P and two S) were introduced to the round pen but were not trained (C; control). On sample collection day 0, 7, 21 and 28, behavior observations were carried out, blood samples were drawn and heart rates were monitored. Total training time for the stalled horses was significantly higher than total time for the pastured horses (S: 26:4 � 1:5 min; P: 19:7 � 1:1; P ¼ 0:032). The stalled group required more time to habituate to the activities occurring from the start of training to mounting (S: 11:4 � 0:96; P: 7:3 � 0:75 min; P ¼ 0:007). Frequency of unwanted behavior was higher in the stalled horses (S: 8:0 � 2:0; P: 2:2 � 1:0; P ¼ 0:020). Pastured horses tended to have higher basal heart rates on day 0 (S: 74:7 � 4:8; P: 81:8 � 5:3 bpm; P ¼ 0:0771). While the physiological data failed to identify differences between housing groups, the behavioral data suggest that pasture-kept horses adapt more easily to training than stalled horses. # 2002 Elsevier Science B.V. All rights reserved.

Brain opioid receptors in relation to stereotypies, inactivity and housing in sows.

When animals encounter difficult conditions, endogenous opioids are often released and may help in coping with the difficulties. In sows, prolonged confinement results in behavior abnormalities: high levels of stereotypies or excessive inactivity and unresponsiveness. The possibilities of causal links between endogenous opioids and these behavioral indicators of poor welfare have been raised. Mu receptor density was found to be greater in tethered sows than in group-housed sows and to be positively correlated with time spent inactive. There were negative correlations between both mu and kappa receptor densities and stereotypy duration. Kappa agonists are associated with aversion, and there are complex links between endorphin levels, dynorphin levels, and dopamine action. These results provide the first demonstration of a relationship between abnormal behavior in pigs and opioid receptor density, and help to clarify the links between behavioral responses and opioid action.

Effects of early weaning and social isolation on the expression of glucocorticoid and mineralocorticoid receptor and 11β-hydroxysteroid dehydrogenase 1 and 2 mRNAs in the frontal cortex and hippocampus of piglets

Pigs weaned at young ages show more abnormal and aggressive behaviors and cognitive deficits compared to later weaned pigs. We investigated the effects of age, weaning and/or social isolation on the expression of genes regulating glucocorticoid response [glucocorticoid receptor (GR), mineralocorticoid receptor (MR), 11beta-hydroxysteroid dehydrogenases 1 and 2 (11beta-HSD1 and 11beta-HSD2)] in the frontal cortex and hippocampus. Early- (EW; n = 6) and conventionally-weaned (CW; n = 6) piglets were weaned at 10 and 21 days after birth, respectively. Non-weaned (NW) piglets of both ages (NW; n = 6/group) remained with their dams. Immediately before euthanasia, half of CW, EW and NW animals were socially isolated for 15 min at 12 (EW, NW) and 23 (CW, NW) days of age. Differences in amounts of 11beta-HSD1, 11beta-HSD2, GR and MR mRNA were determined by quantitative real-time RT-PCR and data subjected to multivariate linear mixed model analysis. When compared with NW piglets at 12 days of age, the hippocampi of EW piglets showed decreased gene expression (P < 0.01). Social isolation decreased gene expression (P < 0.05) in the frontal cortex of all piglets. Twelve-day-old piglets showed higher MR mRNA in the frontal cortex (P < 0.01) and lower 11beta-HSD2 and GR mRNA (P < 0.05) in the hippocampus compared to 23-day-old animals. Results indicate that EW affected the hippocampus of piglets at 12 days of age, while social isolation affected frontal cortex regardless of age. These results may be correlated with behavioral and cognitive changes reported in EW piglets.

Exploring non-invasive methods to assess pain in sheep

The aim of this study was to determine whether changes in eye temperature, measured using infrared thermography (IRT), and heart rate variability (HRV) can detect moderate levels of pain in sheep. Six ewes received the following treatments: 1) noxious ischaemic stimulus by application of a forelimb tourniquet (S), 2) noxious ischaemic stimulus and flunixin meglumine (S+F), and 3) flunixin meglumine (F). Maximum eye temperature, HRV, mechanical nociceptive threshold, blood pressure and behaviour were recorded for up to 60 min, including 15 min of baseline, 30 min during intervention and 15 min post-intervention. There was a tendency towards a decrease in the heart rate variability parameters RMSSD (the root mean square of successive R-R intervals) and SDNN (the standard deviation of all interbeat intervals) in treatment S compared to treatment F, and a significant increase in the same parameters between test day 1 and 3. A reduction in eye temperature was detected for all treatments during intervention, but no difference was found between S and F and S+N and F during intervention. The eye temperature decreased more in test day 2 and 3 compared to test day 1 during intervention. A significant reduction for both lip licking and vocalisation was observed between test day 1 and 3, and forward facing ears was the ear posture most frequently recorded in test day 1. We suggest that HRV is a sensitive, non-invasive method to assess mild to moderate pain in sheep, whereas IRT is a less sensitive method.

Maternal Catecholamine Levels in Midpregnancy and Risk of Preterm Delivery

Associations between stress hormones and preterm delivery have not been fully explored. In this study, pregnant women enrolled from 52 clinics in 5 Michigan communities (1998-2004) provided urine samples for 3 days (waking and bedtime) during midpregnancy. Urinary catecholamine levels (epinephrine, norepinephrine, and dopamine) were measured in a subcohort (247 preterm and 760 term deliveries), and a 3-day median value was calculated. Polytomous logistic regression models assessed relations between catecholamine quartiles (of the median) and a 4-level outcome variable (i.e., term (referent) and 3 preterm delivery subtypes: spontaneous; premature rupture of membranes; and medically indicated). Final models incorporated other relevant covariates (e.g., creatinine, demographic, behavior). The risk of spontaneous preterm delivery was increased in the highest versus lowest quartile of norepinephrine and dopamine: norepinephrine, waking (adjusted odds ratio (AOR) = 3.7, 95% confidence interval (CI): 1.8, 7.9) and bedtime (AOR = 2.5, 95% CI: 1.3, 4.9); dopamine, waking (AOR = 2.6, 95% CI: 1.4, 5.1) and bedtime (AOR = 2.3, 95% CI: 1.2, 4.6). Adjusted odds ratios were further strengthened after removing women whose placentas showed evidence of acute infection or vascular pathology. High catecholamine levels in maternal urine may be indicative of excess stressors and/or predisposition to elevated sympathetic activation that contributes to increased risk of spontaneous preterm delivery.

Investigation of changes in global gene expression in the frontal cortex of early-weaned and socially isolated piglets using microarray and quantitative real-time RT-PCR.

We hypothesize that early-weaned piglets experience aberrant expression of stress-responsive genes in the frontal cortex, a key brain area involved in cognitive function and behavior organization. To test this hypothesis, female early-weaned piglets (EW; n = 6) were weaned 10 days after birth, while non-weaned piglets (NW; n = 6) were left with their dams. Half of EW (n = 3) and NW (n = 3) animals were socially isolated (SI) for 15 min at 12 days of age, when all animals (n = 12) were euthanized and tissue collected. The effects of EW and SI were examined by gene expression profiling using cDNA microarray hybridizations, generated from a porcine brain cDNA library. A total of 103 genes were differentially expressed (P < 0.05, fold change >1.25) among four direct comparisons. Forty-two genes had known functions, from which 24 showed relevant brain-related functions. Quantitative real-time polymerase chain reaction (Q-RT-PCR) was used to confirm regulation of expression of a subset of 6 genes with important brain functions, selected from the microarray outcomes. In non-weaned animals, a significant suppression of mRNA abundance for carboxypeptidase E, 14-3-3 protein and phosphoprotein enriched in astrocytes 15 kDa was observed in response to SI. Also, in early-weaned animals, diazepam binding inhibitor and actin-related protein 2/3 complex mRNA levels were suppressed in response to SI. Results suggest that social isolation of non- and early-weaned piglets may impact expression of genes involved in regulation of neuronal function, development, and protection in the frontal cortex of young pigs.

Gentle vs. aversive handling of pregnant ewes: I. Maternal cortisol and behavior.

The aim of the experiment was to study the effects of aversive vs. gentle handling in late pregnancy on maternal behavior of ewes. Sixteen Norwegian Dala ewes bearing twins were subjected to 10 min of either gentle (GEN--soft talking and calm behavior) or aversive (AVS--swift movements and shouting) handling twice a day during the last 5 weeks of pregnancy. Salivary cortisol was recorded before and after treatments. The following behaviors were recorded post-partum in the ewes: grooming duration, number of vocalizations and in the lambs: number of vocalizations, latency and duration of standing, latency and duration in udder-directed position. The ability of the ewe to follow her lamb carried away by a human was scored on day 1 and 7. After the treatment sessions, cortisol levels tended to increase in AVS ewes but not GEN ewes. At parturition, AVS ewes groomed their offspring for a longer duration than GEN ewes. AVS lambs tended to be heavier than GEN lambs at 24 h of age. Follow Scores from GEN ewes were higher than for the AVS ewes at day one, but no difference between treatment groups was detected after one week. These results show that aversively treated ewes increased their grooming behavior towards their offspring, but that fear of humans disrupted their ability to follow their lambs closely when carried away by a human. We conclude that the type of handling of ewes during pregnancy may have some impact on important maternal behaviors.

Factors affecting mechanical (nociceptive) thresholds in piglets

Objective To evaluate the stability and repeatability of measures of mechanical (nociceptive) thresholds in piglets and to examine potentially confounding factors when using a hand held algometer. Study design Descriptive, prospective cohort. Animals Forty-four piglets from four litters, weighing 4.6 ± 1.0 kg (mean ± SD) at 2 weeks of age. Methods Mechanical thresholds were measured twice on each of 2 days during the first and second week of life. Data were analyzed using a repeated measures design to test the effects of behavior prior to testing, sex, week, day within week, and repetition within day. The effect of body weight and the interaction between piglet weight and behaviour were also tested. Piglet was entered into the model as a random effect as an additional test of repeatability. The effect of repeated testing was used to test the stability of measures. Pearson correlations between repeated measures were used to test the repeatability of measures. Variance component analysis was used to describe the variability in the data. Results Variance component analysis indicated that piglet explained only 17% of the variance in the data. All variables in the model (behaviour prior to testing, sex, week, day within week, repetition within day, body weight, the interaction between body weight and behaviour, piglet identity) except sex had a significant effect (p < 0.04 for all). Correlations between repeated measures increased from the first to the second week. Conclusions and Clinical relevance Repeatability was acceptable only during the second week of testing and measures changed with repeated testing and increased with increasing piglet weight, indicating that time (age) and animal body weight should be taken into account when measuring mechanical (nociceptive) thresholds in piglets. Mechanical (nociceptive) thresholds can be used both for testing the efficacy of anaesthetics and analgesics, and for assessing hyperalgesia in chronic pain states in research and clinical settings.