Effects of amperozide and azaperone on aggression and productivity of growing-finishing pigs

Efficacy of the intranasal application of azaperone for sedation in weaned piglets

The aim of the study was to compare the efficacy of the intranasal and parenteral administration of azaperone in order to achieve pig sedation. A total of 32 weaned piglets divided into 4 groups (8 piglets in each group) were used. Group A was injected intramuscularly (i.m.) with azaperone (Stresnil®, 40 mg/ml inj.; Elanco Animal Health) at a dose of 2 mg/kg of body weight (b.w.). Group B received a dose of 2 mg/kg b.w. of azaperone intranasally. Group C was given azaperone intranasally at a dose of 4 mg/kg b.w. Group D was given 1 ml of saline intranasally and served as the control group. The response to the defined stimulus (a blunt blow of a metal rod into a metal edge of a pen), the degree of salivation, movement level, body temperature and serum azaperone concentration were included in the trial. We found that in order to induce an adequate level of sedation comparable to the standard method of application, i.e., 2 mg/kg b.w. i.m., the intranasal administration of azaperone at a dose of 4 mg/kg body weight is required.

The effects of buccal administration of azaperone on the sedation level and biochemical variables of weaned piglets

The aim of the study was to compare the efficacy of buccal and parenteral administration of azaperone in order to achieve pig sedation. The type of study was prospective randomized and double blinded. A total of 40 weaned piglets were divided into 4 groups (10 each) and monitored. Group A was injected intramuscularly (i.m.) with azaperone (Stresnil®, 40 mg/ml inj., Elanco Animal Health) at a dose of 2 mg/kg body weight (b.w.). Group B (control) was given 1 ml of saline buccally. Group C received a dose of 2 mg/kg b.w. of azaperone buccally. Group D was given azaperone buccally at a dose of 4 mg/kg b.w. The response to defined stimulus (a blunt blow of a metal rod into the metal edge of the pen), degree of salivation, movement level, blood plasma azaperone concentration, and the haematological and biochemical variables were included in the study. We found that the buccal administration of azaperone is effective, however, a dose of 4 mg/kg b.w. is required to induce a sedation level comparable to the standard 2 mg/kg b.w. i.m. administration.

Interaction effects of pen environment and sex on behavior, skin lesions and physiology of Windsnyer pigs

Objective

The study was carried to determine the interaction effects of pen enrichment and sex on behavioral activities, skin lesions and physiology of Windsnyer pigs.

Methods

Forty-eight growing Windsnyer pigs of both sex, with an average initial body weight of 21.6 (±9.01) kg were used. Four pigs were randomly assigned to either enriched or barren pens at a stocking density of 0.35 m²/pig. Enriched pens contained 2 L bottles filled with stones and suspended at head level on ropes stretching across the pens. In addition, two plastic balls (90 mm in diameter) and 500 mL bottles (235 mm long) were placed on the floor of each enriched pen.

Results

Pigs in barren environments had higher heart rates (p<0.001) than those in enriched pens. There was an interaction of pen environment and sex on rectal temperature (p<0.001). Females in enriched pens had higher rectal temperatures (p<0.05) than females in barren pens. There was no interaction of pen environment and sex on time spent eating and drinking (p>0.05). Time spent bullying was influenced (p<0.05) by pen environment and sex. Female pigs in barren environment spent more time on bullying than females in enriched pens. There was an interaction of pen environment and sex on time spent lying down and walking (p<0.05). Female pigs in enriched pens spent more time lying down than females in barren pens. Males in barren pens spent more time walking than males in enriched pens while no effect of pen environment was observed in females. There was an interaction of pen environment and sex on the number of skin lesions in the head, neck and shoulder region and other parts of the body (p<0.05).

Conclusion

It was concluded that pen enrichment reduced the number of skin lesions and anti-social behaviors, especially for female pigs. There is a need, therefore of housing indigenous pigs under confinement.

A Role for Oxytocin in the Etiology and Treatment of Schizophrenia

Schizophrenia is a chronic debilitating neuropsychiatric disorder estimated to affect 51 million people worldwide. Several symptom domains characterize schizophrenia, including negative symptoms, such as social withdrawal and anhedonia, cognitive impairments, such as disorganized thinking and impaired memory, and positive symptoms, such as hallucinations and delusions. While schizophrenia is a complex neuropsychiatric disorder with no single "cause," there is evidence that the oxytocin (Oxt) system may be dysregulated in some individuals. Further, treatment with intranasal Oxt reduces some of the heterogeneous symptoms associated with schizophrenia. Since Oxt is known for its modulatory effects on a variety of social and non-social behaviors, it is perhaps not surprising that it may contribute to some aspects of schizophrenia and could also be a useful therapeutic agent. In this review, we highlight what is known about Oxt's contributions to schizophrenia and schizophrenia-related behaviors and discuss its potential as a therapeutic agent.

Acoustic-reward learning as a method to reduce the incidence of aggressive and abnormal behaviours among newly mixed piglets

The aim of the study was to test whether aggressive actions among piglets could be redirected by an automatically generated sound signal followed by a sweet food reward. Per round, four litters of 25-day-old piglets (BHZP breed) were trained 5 times per day over 8 days to expect a sweet feed reward from a dog feeder after hearing a specific sound. In total 144 piglets in 14 entire litters were trained in five trials. At the end of the training 71% of the piglets were around the feeder 5 s after the feeder sound. After the training period, the piglets were weaned and mixed in two pens, 12 piglets per pen. During 2 days (3 h/day) after mixing two observers (one per pen) hidden behind a wooden wall activated the feeder when aggressive or abnormal behaviour started. A total of 616 aggressive events and 31 incidences of abnormal behaviour (ear biting) were used for the analysis. The logistic regression showed that the type of behaviour had a significant effect on the piglets’ response to the feeder sound (P < 0.001). The results showed the possibility of interruption of the aggressive behaviours such as head thrust [odds ratio (OR) = 0.43], jump on other (OR = 0.56) or attack with bite (OR = 0.61). Ear biting was very unlikely to continue (OR = 0.55). The risk of continuing elevated aggression level behaviours was doubled in the event of chasing (OR = 2.16) and the risk that fight would continue after the feeder sound was released was 7 times higher (OR = 7.89). Categorical analysis showed a significant effect (<0.001) of the time intervals t ≤ 1 s and 1 s < t ≤ 3 s on interruption of aggression by the feeder sound release. The piglets’ response to the feeder sound differed significantly between the experimental days (P < 0.001). On the second day of mixing, the feeder sound interrupted 74.9% of aggressive events, compared with 33.7% on the first day. The results suggest that acoustic-reward treatment can distract pigs from performing certain aggressive behaviours and ear biting in piglets when properly applied in time.

Reducing stress in piglets as a means of increasing production after weaning: administration of amperozide or co-mingling of piglets during lactation?

The aim of this experiment was to reduce piglet stress and improve performance following moving and mixing at weaning by use of the anti-aggressive drug amperozide and the practice of co-mingling piglets during lactation. Thirty-six piglets weaned at 29 days of age were allocated to a 2 × 2 factorial arrangement of treatments as follows: (1) injection of 1 ml amperozide or placebo (0.9% saline) at the time of weaning, and (2) co-mingling or no comingling of piglets from day 10 of lactation to weaning. At weaning all piglets were injected with pliytohaemagglutinin or saline, their change in skin-fold thickness was measured 24 h later and behaviour was recorded every 5 min for the first 120 min after weaning. At 4 and 24 h after weaning the depth and extent of injuries were recorded. Daily live-weight gain, apparent voluntary food intake and food conversion ratio were not improved (P > 0.05) by administration of amperozide or co-mingling of piglets during lactation. Cell-mediated immunity, as evidenced by a 0.17 proportional decrease (P <; 0.001) in skin-fold thickness following the injection of phytohaemagglutinin, was decreased in piglets not given amperozide at weaning. Injection of amperozide caused a 0.26 proportional increase (P < 0.001) in the amount of time piglets spent lying and caused piglets to display no interest in the feeder (P < 0.001) in the first 2 h after weaning. Consequently piglets not given amperozide were more active, spent more time at the feeder and participated in more aggressive encounters (P < 0.01). A significant interaction occurred between co-mingling and amperozide for mean injury score at both 4 (P < 0.01) and 24 h (P < 0.05) after weaning. When measured 4 h after weaning, co-mingling of piglets during suckling reduced mean injury score regardless of whether piglets were given amperozide or not at weaning. When piglets were not allowed to co-mingle during lactation, amperozide reduced mean injury score proportionately by around 0-44 (P < 0.01) compared with piglets administered with saline. Despite the administration of amperozide and the practice of comingling causing a reduction in stress and an improvement in welfare in this experiment, there was no beneficial effect on performance in the first 2 weeks after weaning.

Behavior, physiology, and performance of bulls mixed at the onset of finishing to form uniform body weight groups

In some production settings, beef bulls are mixed at the beginning of the finishing period to obtain homogeneous groups to facilitate finishing and to produce more homogeneous carcasses. Given the stress induced by mixing, we questioned whether this practice was profitable. Sixty-four young bulls were finished in groups of four over 8 mo. They were either mixed or unmixed and had either homogeneous vs. heterogeneous BW at the beginning of finishing. Behavioral traits (social behavior following mixing and general activities during the finishing period), stress measurements (cortisol concentration, adrenal weight, catecholamine-synthesizing enzyme activity, and pain sensitivity), and production traits (growth rate, homogeneity, feed efficiency, and carcass measurements) were evaluated. Bulls reacted to the mixing with increased frequency of social interactions (agonistic interactions: 17.9 in mixed vs. 1.2 in unmixed bulls, P < 0.001; sexual interactions: 9.6 vs. 1.7, P < 0.001; nonagonistic interactions: 5.25 vs. 3.1, P < 0.05). Agonistic and sexual interactions were more frequent between bulls of homogeneous BW (P < 0.05). Throughout the finishing period, the synchronization of activity tended to be lower between mixed bulls (P = 0.09). At slaughter, the activity of tyrosine hydroxylase, a catecholamine-synthesizing enzyme, was increased in mixed bulls (1.52 vs. 1.16 nmol.h(-1).mg(-1), P < 0.05), which may indicate chronic stress. No differences were noted in ADG or carcass traits among treatments. The variability of BW within groups increased in groups that were initially homogeneous, whereas it decreased in groups that were initially heterogeneous. In conclusion, mixing young beef bulls at the beginning of the finishing period did not have detrimental effects on health and production, but mixing induced stress, perhaps due to decreased cohesion within groups. Thus, we failed to confirm the proposed benefit of mixing bulls to homogenize their BW at the onset of finishing because BW homogeneity within groups was not maintained throughout the finishing period.

Influence of social status on the welfare of growing pigs housed in barren and enriched environments

One hundred and twenty-eight pigs were reared in barren or enriched environments from birth to slaughter at 21 weeks of age. Pigs remained as litter-mate groups until 8 weeks of age when they were mixed into groups of eight animals. These groups were balanced for gender and weight and contained two pigs from each of four different litters. Each pig was assigned high or low social status on the basis of relative success in aggressive interactions at mixing. Injury levels were assessed on a weekly basis from 8 to 21 weeks of age. Pigs were exposed to two group food competition tests after a period of food restriction at 10 weeks of age, and to an individual novel pen test at 11 weeks of age. Behavioural and plasma cortisol responses to both types of test were recorded. Low social status was associated with increased injuries to the head, neck and ears, and therefore reduced welfare. Pigs with low social status showed reduced resource-holding ability in the food competition test, and greater avoidance of a novel object during the novel pen test It is suggested that avoidance of the novel object reflected ‘learned’ fearfulness in these individuals. Environmental enrichment did not negate the effect of low social status on injury levels, but did appear to reduce the negative influence of low social status on stress during food restriction, and led to a reduction in fearfulness in response to the novel pen test. These results suggest that environmental enrichment may improve the welfare of growing pigs with low social status.

Effects of cocaine and putative atypical antipsychotics on rat social behavior: an ethopharmacological study

The effects of cocaine, amperozide, clozapine, olanzapine and cocaine/atypical antipsychotic combinations on aggression, affiliation and defensive behaviors was examined. Acute cocaine (30.0 mg/kg) decreased basal aggression and affiliation yet increased basal defense. Amperozide (1.0, 3.0 and 5.0 mg/kg) decreased basal aggression, affiliation and defense had no effect on the cocaine-induced decrease in affiliation, and accentuated the cocaine-induced decrease in aggression. Near basal levels of defense were observed for animals treated with either amperozide, clozapine (3.0 and 10.0 mg/kg but not 30.0 mg/kg) or olanzapine followed by cocaine. Clozapine (3.0, 10.0 and 30.0 mg/kg) decreased basal aggression and affiliation. Clozapine (30.0 mg/kg but not 3.0 or 10.0 mg/kg) decreased basal defense. Clozapine attenuated the cocaine-induced decrease in aggression. Although 3.0 and 10.0 mg/kg clozapine attenuated the cocaine-induced decrease in affiliation, 30.0 mg/kg clozapine accentuated this cocaine-induced effect. Olanzapine (1.0, 3.0 and 10.0 mg/kg) decreased basal aggression, affiliation and defense. Olanzapine had no effect on the cocaine-induced decrease in aggression. Olanzapine (3.0 mg/kg but not 1.0 or 10.0 mg/kg) attenuated the cocaine-induced decrease in affiliation. Thus, acute cocaine administration had an antiaggressive effect, suppressed affiliative behavior and enhanced defensive behavior. Amperozide, clozapine and olanzapine have anticonflict and anxiolytic effects, as well as potent and specific antiaggressive effects.

Influence of Environmental Enrichment on Aggressive Behaviour and Dominance Relationships in Growing Pigs

This study examined the effects of environmental enrichment on aggressive behaviour and dominance relationships in growing pigs. Three hundred and twenty pigs were reared from birth to 15 weeks of age in either barren or enriched environments. The barren environments were defined by common intensive housing conditions (ie with slatted floors and in terms of recommended space allowances), while the enriched environments incorporated extra space and substrates for manipulation. Aggressive behaviour was observed in a social confrontation test during the suckling period and dominance relationships were assessed from a food competition test at 12 weeks of age. Animals were weighed at regular intervals throughout the experiment. Environmental enrichment reduced the expression of aggressive behaviour. Pigs from enriched rearing environments fought significantly less with unfamiliar animals than those from barren environments when tested under standard conditions (mean of 1.46 vs 2.75 fights per 30min test for enriched vs barren environments; SEM 0.20, P < 0.001). The nature of dominance relationships also appeared to differ between barren and enriched environments. In barren environments, dominance among pen mates was correlated with aggression (r = 0.33, P < 0.01), whereas in enriched environments it was correlated with body weight (r = 0.24, P < 0.01). Correlations between behaviour in the social confrontation and food competition tests suggested that dominance characteristics were established early in life and remained stable through the growing period.

The cardiovascular effects of amperozide: interactions with cocaine

Amperozide is a 5-HT2A receptor antagonist that significantly reduces the acquisition and expression, by rats, of a cocaine conditioned place preference. In order to rule out the possibility that amperozide affects a cocaine conditioned place preference due to effects on blood pressure or heart rate, the cardiovascular effects of amperozide were investigated. Alternating cumulative doses of amperozide (0.5, 1.0, 1.5 and 2.5 mg kg(-1)) or saline and phenylephrine (8 microg kg(-1)) were administered through the femoral vein of awake freely-moving Sprague-Dawley rats and blood pressure and heart rate were recorded from the femoral artery. A single dose of cocaine (5.0 mg kg(-1)) was administered after all the amperozide or saline doses were given. Amperozide (0.5, 1.0, 1.5 and 2.5 mg kg(-1)) did not have any significant effect on blood pressure compared to the saline control treatment to the same animals. However, 0.5 mg kg(-1) amperozide significantly decreased heart rate at 5 and 10 min. after administration. but higher doses did not further depress heart rate. Amperozide did not affect the increased blood pressure and decreased heart rate caused by phenylephrine. an alpha1-adrenoceptor agonist. In addition, amperozide did not affect the cardiovascular response to an intravenous dose of 5.0 mg kg(-1) cocaine. These results suggest that amperozide does not cause direct cardiovascular effects. The mechanism by which the lowest dose of amperozide caused a decrease in heart rate is unknown. Amperozide affects neither alpha-adrenoceptor mediated vasoconstriction nor the increased sympathetic activity caused by the peripheral and central effects of cocaine. The significance of these results, in terms of locomotor activity and the cocaine conditioned place preference paradigm, is discussed.

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.

Effects of fighting after grouping on plasma cortisol concentration and lymphocyte blastogenesis of peripheral blood mononuclear cells induced by mitogens in piglets

One litter (Group A) of three unacquainted groups of littermates (4 piglets/litter), 64.0 +/- 0.8 days old, was moved to the pen of another litter (Group B) and they were housed together for 19 days after grouping (phase 1). The pigs in Group B violently attacked all the pigs in Group A for 9 hr after grouping. The remaining group was not grouped and used as controls. The plasma cortisol concentrations 1 hr after grouping were significantly higher than those 1 hr before and 24 hr after grouping, and the suppression of lymphocyte blastogenesis of peripheral blood mononuclear cells (PBMC) induced by mitogens was observed on 3, 8 and 19 days after grouping. After phase 1 ended, the pigs in Group A were returned to their own pen for 7 days, and then they were regrouped with the pigs in Group B and reared together for a further 14 days. Neither agonistic behavior nor change of plasma cortisol after regrouping was seen. Though the lymphocyte blastogenesis of PBMC induced by the mitogens on day 0 after regrouping was significantly lower in the pigs of Groups A and B compared to those in control pigs, a significant difference in lymphocyte blastogenesis among three groups was not seen on 7 and 14 days after regrouping. These findings indicate that fighting after grouping unacquainted litters increases plasma cortisol, and suppresses lymphocyte blastogenesis for 26 days after grouping.

Selective reduction by the 5-HT antagonist amperozide of alcohol preference induced in rats by systemic cyanamide

This investigation was undertaken to determine the effect of a unique psychotropic agent on the volitional drinking of alcohol induced pharmacologically in the rat by an inhibitor of aldehyde dehydrogenase. Following administration of cyanamide in a dose of 10 mg/kg twice daily for 3 days, the pattern of drinking of ethyl alcohol was determined in each of 12 Sprague-Dawley rats by means of a standard preference test for 3-30% alcohol vs. water. Then, each rat was offered water and its maximally preferred concentration of alcohol, which ranged from 7-15%. After a 4-day predrug test, either the saline control vehicle or the diphenylbutylpiperazinecarboxamide derivative, amperozide, was administered subcutaneously. The injections of amperozide were given b.i.d. at 1600 and 2200 h over 3 days in a dose of 0.5, 1.0, or 2.5 mg/kg. The intake of alcohol during the sequence of amperozide injections was significantly reduced in a dose-dependent manner in terms of both absolute g/kg and proportion of alcohol to water intake, whereas the saline control vehicle was without any effect on alcohol consumption. Although the highest dose of amperozide reduced the total intake of fluid due to the sharp decline in alcohol drinking, neither the consumption of food nor level of body weight was affected by any dose of the drug either during or after its administration. Because amperozide acts centrally on the synaptic activity of dopaminergic and serotonergic neurons in limbic system structures, it is envisaged that the drug ameliorates the aberrant drinking of alcohol by virtue of a direct effect on either one or both of these classes of neurons.(ABSTRACT TRUNCATED AT 250 WORDS)