Review: Transport Losses in Market Weight Pigs: I. A Review of Definitions, Incidence, and Economic Impact

Transport losses (dead and nonambulatory pigs) present animal welfare, legal, and economic challenges to the US swine industry. The objectives of this review are to explore 1) the historical perspective of transport losses; 2) the incidence and economic implications of transport losses; and 3) the symptoms and metabolic characteristics of fatigued pigs. In 1933 and 1934, the incidence of dead and nonambulatory pigs was reported to be 0.08 and 0.16%, respectively. More recently, 23 commercial field trials (n = 6,660,569 pigs) were summarized and the frequency of dead pigs, nonambulatory pigs, and total transport losses at the processing plant were 0.25, 0.44, and 0.69% respectively. In 2006, total economic losses associated with these transport losses were estimated to cost the US pork industry approximately $46 million. Furthermore, 0.37 and 0.05% of the nonambulatory pigs were classified as either fatigued (nonambulatory, noninjured) or injured, respectively, in 18 of these trials (n = 4,966,419 pigs). Fatigued pigs display signs of acute stress (open-mouth breathing, skin discoloration, muscle tremors) and are in a metabolic state of acidosis, characterized by low blood pH and high blood lactate concentrations; however, the majority of fatigued pigs will recover with rest. Transport losses are a multifactorial problem consisting of people, pig, facility design, management, transportation, processing plant, and environmental factors, and, because of these multiple factors, continued research efforts are needed to understand how each of the factors and the relationships among factors affect the well-being of the pig during the marketing process

Social Isolation-Induced Aggression Potentiates Anxiety and Depressive-Like Behavior in Male Mice Subjected to Unpredictable Chronic Mild Stress

Accumulating epidemiological evidence shows that life event stressors are major vulnerability factors for psychiatric diseases such as major depression. It is also well known that social isolation in male mice results in aggressive behavior. However, it is not known how social isolation-induced aggression affects anxiety and depressive-like behavior in isolated male mice subjected to unpredictable chronic mild stress (CMS), an animal model of depression.C57/B6 male mice were divided into 3 groups; non-stressed controls, in Group I; isolated mice subjected to the CMS protocol in Group II and aggression by physical contact in socially isolated mice subjected to the CMS protocol in Group III. In the sucrose intake test, ingestion of a 1% sucrose solution by mice in Groups II and III was significantly lower than in Group I. Furthermore, intake of this solution in Group III mice was significantly lower than in Group II mice. In the open field test, mice in Group III, showed reduced locomotor activity and reduced entry and retention time in the central zone, compared to Groups I and II mice. Moreover, the distances moved in 1 hour by Group III mice did not differ between night and morning. In the light/black box test, Groups II and III animals spent significantly less time in the light box compared to Group I animals. In the tail suspension test (TST) and forced swimming test (FST), the immobility times of Group II and Group III mice were significantly longer than in Group I mice. In addition, immobility times in the FST were significantly longer in Group III than in Group II mice.These findings show that social isolation-induced aggression could potentiate anxiety and depressive-like behaviors in isolated male mice subjected to CMS

67202; ‡ ‡ Innovative Livestock Solutions, Blackie, Alberta, Canada T0L0J0; § § Livestock Behavior Research Unit

ABSTRAC

SCHEDULE-INDUCED-POLYDIPSIA EXPERIENCE DECREASES PLASMA-CORTICOSTERONE LEVELS BUT INCREASES PLASMA PROLACTIN LEVELS

International audienceTo determine the neuroendocrine pattern of response to excessive drinking induced by exposure of rats to an intermittent distribution of food (schedule-induced polydipsia, SIP), the present experiment investigated changes in plasma corticosterone, prolactin and catecholamines in chronically catheterized rats that had developed or not this form of adjunctive behaviour. It was found that rats that engage in excessive drinking displayed decreased plasma levels of corticosterone and increased levels of prolactin during the course of a SIP session. There was, however, no differences between groups in plasma catecholamine levels. The differences observed between SIP-pos and SIP-neg rats were entirely condition-specific, since they disappeared in the absence of access to water

Corticotropic and serotonergic responses to acute stress with/without prïor exercise training in différent rat strains

International audienceThe ability to cope with exercise training dépends both on environmental and genetic background; however, whether the genetic status may affect (i) the hormonal status of trained subjects and, (ii) its responses to a heterotypic stressor is unknown. Herein, we hâve used Spontaneously Hypertensive Rats (SHR) and Lewis rats, that differ with regard to their psychoneuroendocrine profiles, to study the influences of an 8-week training programme and/or a 1-h immobilization stress on plasma adrenocorticotropin (ACTH) and corticosterone levels. In addition, brain serotonin metabolism was also measured as an index of neurochemical reactivity to stress. The amplitude of immobilization-elicited increases in ACTH levels which differed with the rat strain (Lewis > SHR), was amplified by prior training; besides, training decreased the strain différence in basai corticosterone (SHR > Lewis) and affected corticosterone response to immobilization in a strain-dependent manner. Thus, immobilization, which increased corticosterone levels in sedentary Lewis but not in SHRs, did not reveal interstrain différences in trained rats. Taken with the observation of a stimulatory effect of training on adrenal weights in SHRs, but not in Lewis, it is concluded that the effects of training on the corticotropic axis dépend on the genetic profile of the individual. Lastly, training amplified the response of midbrain (but not striatum or hippocampus) serotonin metabolism to immobilization in a strain-independent manner although the levels of serotonin precursor, namely tryptophan, varied with training and immobilization in a strain-dependent manner. This study shows that some neuroendo crine and neurochemical effects of training undergo interindividual variability

Central and peripheral effects of repeated stress and high NaCl diet on neuropeptide Y

This study was performed to investigate the influence of repeated psychological stress alone or combined with high NaCl intake on the function of the sympathetic nervous system. In addition, NPY levels have been measured in brain regions of potential importance in the central regulation of stress responses (ventrolateral and dorsomedial medulla, paraventricular and arcuate nucleus of the hypothalamus, and frontal cortex). Normotensive Wistar rats received a standard diet alone or supplemented with NaCl. To accentuate differences in sodium balance, rats on the high NaCl diet (HNa) were uninephrectomized. Half the animals on each diet were subjected to chronic stress using daily sessions (1 h) of immobilization stress. After 12 days, plasma levels of neuropeptide Y (NPY), norepinephrine (NE), and epinephrine (E) were measured basally and in response to acute footshock stress. HNa intake or chronic stress alone did not significantly alter either basal or stimulated plasma levels of NPY. However, combining the treatments produced a significant interaction, increasing the NPY response to footshock by 31% compared to HNa alone (p = 0.039) and by 98% compared to stress alone (p less than 0.001). Chronic stress increased basal levels of NE and enhanced the response to subsequent acute stress: combining the treatments did not yield further increases. Plasma levels of E were not significantly affected by the treatments. In the brain, stress alone had no effect on the NPY levels in the structures studied. HNa intake induced a significant increase in NPY levels of the arcuate nucleus, and produced a significant interaction with stress in the dorsomedial medulla. In a supplementary experiment, to evaluate the role of the autonomic nervous system in plasma NPY responses, treatment with the ganglion blocker hexamethonium was shown to significantly attenuate stress-induced changes in NPY, NE, and E