Cortisol In Pigs Research Articles

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The quality and safety of pork is influenced by many factors before and after slaughter. Complex of biochemical and physicochemical processes take place in the maturation of the meat. One of the key factors that affect the quality of meat from slaughtered animals is the level of cortisol in the blood, because glucocorticoid hormone is the trigger for the development of a chain of stress biochemical reactions. This paper contains results of examination of the blood concentration of cortisol and lactate and meat pH. Samples were taken in two animal groups. The first one constituted of industrially reared and slaughtered animals, and the other group consisted of animals grown and slaughtered on small farms. In the blood of industrially reared pigs in comparison with domestic animals, the concentration of cortisol is significantly higher by 39.9% (P˂0.05), as well as the level of lactate — 2.3-fold (P˂0.01). The main reason is due to the stress experienced by animals during transportation and pre-slaughter handling. There is a marked difference between the maximum and the minimum plasma level of cortisol in pigs within one group. Under stress the breakdown of glucose and glycogen in the liver and muscles took place in anaerobic condition with formation of lactate. At 1, 24 and 48 hours of pork meat maturation in case of industrial rearing and slaughtering, compared to domestic, the pH of meat was lower. Obtained results gives the possibility to suggest the lower quality of the industrially reared and slaughtered pork compared with domestic.

Providing Meaningful Environmental Enrichment and Measuring Saliva Cortisol in Pigs Housed on Slatted Flooring.

As pork is the most consumed meat worldwide, the welfare of animals in the swine industry has increasingly become a major public concern, which imposes a substantial pressure coming from customers, legislators and other stakeholders, to make management changes to improve the well-being of these animals. Several studies have demonstrated that providing environmental enrichment to pigs allows them to express their natural behavior, such as rooting and exploring, as well as nesting prior to farrowing, and is associated with reduced stress and improved production and welfare. However, many considerations should be taken into account when providing environmental enrichment, such as the type of floor, drainage and sewage systems, the pigs' stage in life, the material, as well as its hanging method, height and location within the pen. The objectives of this paper are (1) to give methodologic information on how to provide a relatively simple and practical meaningful environmental enrichment for pigs which are housed on slatted floors during the different stages of their life, and (2) to demonstrate how to collect saliva samples for the measurement of cortisol concentrations, as a biomarker for acute stress. Protocols include information regarding the use of jute, cotton ropes, straw in racks, as well as chewable silicone sticks devices as environmental enrichment in pens of farrowing and lactation, weaners and finishers. In addition, the use of cotton rope for a non-invasive saliva samples collection for cortisol concentrations analysis is detailed. The protocols provided are relevant for professionals aiming to improve and monitor animal welfare, in both research and industrial swine farming.

Providing Meaningful Environmental Enrichment and Measuring Saliva Cortisol in Pigs Housed on Slatted Flooring

Providing Meaningful Environmental Enrichment and Measuring Saliva Cortisol in Pigs Housed on Slatted Flooring

Effects of weight, temperature and behaviour on the circadian rhythm of salivary cortisol in growing pigs

In farm animals, salivary cortisol has become a widely used parameter for measuring stress responses. However, only few studies have dealt with basal levels of concentration of cortisol in pigs and its circadian rhythm. The aim of this study was to examine the effects of ambient temperature and thermoregulatory behaviour on the circadian rhythm of salivary cortisol levels in fattening pigs. Subjects were 30 fattening pigs of different weight (60 to 100 kg), kept in six groups in an uninsulated building in pens with partly slatted floors. Saliva samples were taken every 2 h over periods of 24 h at different ambient temperatures at two times in winter and four times in summer. Thermoregulatory behaviour was recorded in the same 24-h time periods. The effect of time of day, body weight, ambient temperature and behaviour on the cortisol level was analysed using a mixed-effects model. Two peaks of cortisol levels per day were found. This circadian pattern became more pronounced with increasing weight and on days where thermoregulatory behaviour was shown. Mean cortisol levels per day were affected by weight but not by thermoregulatory behaviour. From our data, we conclude that long-term variations in cortisol concentration may be influenced by increasing age and weight more than by the respective experimental situation. In assessing animal welfare, it seems more reliable to consider the circadian pattern of cortisol concentration instead of only one value per day.

Population and systems genetics analyses of cortisol in pigs divergently selected for stress

This study presents a systems genetic analysis on the physiology of cortisol in mice and pigs with an aim to show the potential of a comprehensive computational approach to quickly identify candidate genes and avoid a costly whole-genome quantitative trait locus (QTL) mapping. Population genetics analyses were performed on measurements of cortisol from a pig selection experiment. Expression QTL were mapped and gene networks were built using gene expressions for Crhr1 (corticotrophin-releasing hormone receptor) gene and single nucleotide polymorphisms from public mouse data. Results from mouse data were used to infer potential candidate regulatory genes involved in pig cortisol regulation, using a comparative or translational systems genetics approach. The pig data used were from a 10-yr divergent genetic selection experiment, providing data on 417 individuals. Population genetics analysis showed that cortisol is highly genetically determined with heritabilities of 0.40-0.70. Furthermore, a major gene with an additive effect of 86 ng/ml is segregating. Genetical-genomics investigations revealed two trans-acting eQTL for Crhr1 gene expression on chromosomes 2 and 13. Candidate gene search under trans-eQTL peaks yielded 63 genes for Crhr1 expression phenotypes. Functional links for Crhr1 genes with other genes/proteins in the gene network using mouse data were shown for the first 10 statistically significant genes involved. Results show translational or comparative systems genetics approaches reduce costs and time in large-scale genetics and "-omics" investigations. This is the first study to report a strong genetic basis for cortisol physiology using a systems approach.

Exercise Training Reverses the Effects of a High Fat Diet on the ACTH Response to Stress

PURPOSE: This study was conducted to determine the effects of diet and exercise on the hormone response to stress. We hypothesized that a high fat/high cholesterol diet would compromise the ACTH and cortisol response to stress, and that this decrease would be ameliorated by exercise training. We also hypothesized that exercise training, in animals on a normal control diet, would augment the ACTH and cortisol response to stress. METHODS: Twelve sexually mature, Yucatan miniature swine, aged 9-13 mo, were used for this study. Six animals were placed on a high fat/high cholesterol diet for 16-20 wks and 6 animals received a normal pig chow diet. Three animals from each group underwent treadmill training for 16-20 wks. This distribution of animals resulted in 4 groups with 3 pigs in each group (normal diet sedentary (NS); normal diet exercise training (NEX); high fat/high cholesterol diet sedentary (HFS); high fat/high cholesterol diet exercise training (HFEX)). Blood samples were collected in EDTA Vacutainers while animals were under anesthesia. Anesthesia induces an increase in both ACTH and cortisol in pigs. A two-way ANOVA test of exercise and diet interactions and t-tests were run to compare groups with significance set at P < 0.05. RESULTS: The high fat/high cholesterol diet significantly decreased the ACTH response to anesthesia-induced stress compared to the Controls (NS: 165 ± 22 pg/ml vs. HFS: 79 ± 7 pg/ml). Exercise training did not affect the ACTH response in animals on the normal diet (NEX: 127 ± 17 pg/ml), but significantly increased the ACTH response in the animals on the high fat/high cholesterol diet (HFEX: 230 ± 46 pg/ml). There is a significant interaction between diet and exercise so that the greatest ACTH response was seen in animals receiving both exercise training and a high fat/high cholesterol diet. Neither diet nor exercise affected the cortisol response to anesthesia-induced stress (NS: 116 ± 26 ng/ml; NEX: 106 ± 11 ng/ml; HFS: 140 ± 9 ng/ml; HFEX: 148 ± 30 ng/ml). CONCLUSION: In pigs on a normal chow diet, exercise training does not affect the ACTH or cortisol response to anesthesia-induced stress. A high fat/high cholesterol diet significantly compromises the ACTH response to anesthesia-induced stress and, this decrease is ameliorated by exercise training.

Effect of feed texture, meal frequency and pre-slaughter fasting on carcass and meat quality, and urinary cortisol in pigs

Carcass and meat quality traits, and urinary cortisol variation was studied in 96 barrows assigned to the following treatments: feed texture (FT; mash vs. pellets), meal frequency (MF; 2 vs. 5 meals per day) and fasting time (F; 4, 14 and 24 h) according to a 2 × 2 × 3 factorial design. Pigs fed mash, receiving feed five times a day and fasted for 24 h before slaughter had lower carcass dressing yield ( P < 0.001). A higher ( P < 0.05) bruise score was found on carcasses from pigs fasted for 14 and 24 h and fed either pelleted or mashed feed five times per day. The pH u value in the Longissimus muscle increased ( P < 0.05) with increasing fasting time, whereas in the Adductor muscle it was higher ( P < 0.05) in pigs fed with pellets in two meals per day and fasted for 24 h. Urinary cortisol tended to be higher in pigs fasted for 14 h compared to those fasted for 4 ( P = 0.10) and 24 h ( P = 0.06). The results of this study show a significant influence of pellet feeding on carcass yield in fasted pigs, while the effects of pre-slaughter fasting time on meat quality traits were limited.

Urine cortisol in pigs of different MH-genotypes

Urine cortisol concentration was evaluated in German Landrace barrows of two MH-genotypes (NN, Nn) housed in metabolic cages. Furthermore, cortisol in urine was evaluated as a substitute measure of plasma cortisol values in pigs. Three replicates were done, each including 4 animals. Altogether there were 12 animals included in the experiment. The effect of MH-genotype on urine cortisol concentration was evaluated and correlations between urine and plasma cortisol were calculated. Higher urine cortisol values in NN- in comparison to Nn-pigs indicated stronger response to stressors by stress resistant NN-genotype. The correlation between urine (12-hr urine values) and plasma (the average of 12 collections per day, taken between 8.00 a.m. and 11.00 a.m.) cortisol values was practically negligible in samples taken on the same day (r = 0.07, P = 0.71). In time-lag samples (urine taken the day after blood collection) correlation was increased (r = 0.22), but still not significant (P = 0.22). A connection between plasma and urine cortisol values was indicated, but it should be better understood before urine cortisol is used as a substitute of plasma cortisol measuring in pigs.

Temporal relationship of hippocampal liquor- and plasma-cortisol-concentrations in the domestic pig challenged with synthetical adreno-corticotrophic hormone

The concentration of plasma and intracerebral cortisol in pigs challenged with 0.5 IU adrenocorticotrophic hormone/kg body weight was simultaneously measured at a 30 min rate. The pigs ( n=5) were provided with indwelling jugular vein catheters and guide canullas for insertion of a hippocampal microdialysis probe. Every five blood samples taken at 6 min intervals were pooled to simulate the 30 min collection time of the microdialysis. Stimulation resulted in an increment of cortisol of roughly 200% in plasma and 190% in the dialysate compared to basal value. The average time lag of hippocampal to plasma peak was 48.75 min. Considering the temporal resolution of the protocol it is inferred that delays of at least 30 min occur between variations of peripheral and central nervous cortisol.

The Effects of Mixing on Behavior and Circadian Parameters of Salivary Cortisol in Pigs

Ekkel, E. D., B. Savenije, W. G. P. Schouten, V. M. Wiegant and M. J. M. Tielen. The effects of mixing on behavior and circadian parameters of salivary cortisol in pigs. Physiol Behav 62(1) 181–184, 1997.—The present study describes an experiment that was carried out to study the effects of mixing pigs once at 25 kg, preceded by transportation for 1.5 h, on the behavior and the circadian rhythmicity of salivary cortisol. The frequency of agonistic interactions was higher for mixed pigs. This was not only the case immediately after mixing, when pigs started to fight to establish a new social rank (p < 0.05), but also 5 to 6 weeks later; still more headknocks and bites towards other pigs were seen at that time among mixed pigs (p < 0.01). However, neither the basal cortisol concentration, assessed as the MESOR of the circadian rhythm of salivary cortisol, nor the amplitude of that rhythm was different between the groups.

Time course of increased plasma cytokines, cortisol, and urea nitrogen in pigs following intraperitoneal injection of lipopolysaccharide.

The emerging view is that reduced feed intake, lean muscle accretion, and growth in immunologically challenged pigs is the result of increased cytokine activity, but this has not been directly tested. To begin addressing this issue, 72 crossbred barrows and gilts (11.55 +/- .19 kg BW) were not fed for 12 h and then injected i.p. with 0, .5, or 5 micrograms/kg of Escherichia coli lipopolysaccharide (LPS). Blood was collected by jugular puncture at 0, 2, 4, 8, 12, and 24 h after injection. Plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), cortisol, plasma urea nitrogen (PUN), NEFA, and triglycerides were determined. Immunological stress was induced by LPS as indicated by increased secretion of TNF-alpha, IL-6, and cortisol. In pigs receiving 5 micrograms/kg of LPS, plasma TNF-alpha was increased 10-fold at 2 h after injection and was still elevated (P < .01) at 4 h. In these same pigs, plasma concentration of IL-6 was increased at 2 h and peaked at 4 h with levels exceeding baseline values by 200-fold (P < .01). Cortisol was elevated at 2, 4, and 8 h after injection (P < .01). The increased secretion of cytokines and cortisol in pigs injected with 5 micrograms/kg of LPS was followed by an increase in protein degradation, as evidenced by PUN values that were increased two- and threefold at 8 and 12 h after injection, respectively. However, unlike previous reports in laboratory animal species, plasma glucose, NEFA, and triglycerides were not altered by LPS. Nonetheless, as the period of feed deprivation progressed from 12 to 36 h, plasma NEFA and triglycerides increased (P < .05) and plasma glucose tended to decrease. We believe that immunological challenge induces cytokine synthesis and secretion in swine which, in turn, may induce protein catabolism.

Effects of short-term restraint stress on plasma concentrations of catecholamines, β-endorphin, and cortisol in gilts

SUMMARY The effects of short-term restraint stress, by means of snaring, on plasma concentrations of catecholamines, β-endorphin, and cortisol were studied in 6 gilts. A catheter was inserted into the jugular vein, and 2 blood samples were collected before onset of stress. Thereafter, a hog snare was applied, and blood samples were collected at 0.5,2, and 3.5 minutes after the start of snaring. Plasma epinephrine and norepinephrine concentrations increased (P &lt; 0.001) within 0.5 minute after start of restraint and decreased thereafter. Plasma concentration of β-endorphin increased (P &lt; 0.05) within 2 minutes after start of restraint, whereas that of cortisol increased (P &lt; 0.05) 3.5 minutes after start of restraint. Taken together, short-term stress, such as snaring, may increase the plasma concentration of catecholamines, β-endorphin, and cortisol in pigs.

Adrenocorticotropic hormone and cortisol response to corticotropin-releasing factor and lysine vasopressin in pigs1

Two experiments were conducted to evaluate the ability of corticotropin-releasing factor (CRF) and lysine vasopressin (LVP) to stimulate the secretion of ACTH and cortisol in pigs. In Exp. 1, barrows were blocked by weight (average BW 97 +/- 1 kg) and received an i.v. bolus of 10 (n = 4), 50 (n = 4), or 100 (n = 3) micrograms of LVP. Samples of plasma were obtained at 10-min intervals for 2 h before and for 2 h after peptide treatment. The percentage of change in plasma concentration of ACTH (average of the concentration 1 h after LVP compared with the average of the 1 h before LVP) was greater (P < .001) for 100 micrograms (452.3 +/- 4.7%) than for 10 (81.5 +/- 5.7%) or 50 micrograms (233.6 +/- 11.3%). Furthermore, the ACTH response was greater (P < .001) to 50 micrograms than to 10 micrograms. The cortisol responses to treatment (average of the concentration 2 h after LVP compared to the average of the 2 h before LVP) were similar in pigs given 50 (132.8 +/- 5.3%) and 100 (123.2 +/- 2.4%) micrograms, but both were greater (P < .001) than the response to 10 micrograms (38.2 +/- 1.4%). In Exp. 2, a dose of LVP was chosen that provided a total mass of peptide similar to the lowest dose in Exp. 1, but this time the peptide was administered at .11 nmol/kg BW. This dose of LVP was chosen because it resulted in neither maximum ACTH nor cortisol secretion in Exp. 1.(ABSTRACT TRUNCATED AT 250 WORDS)

CCK-A receptors mediate the effect of cholecystokinin on vasopressin but not on cortisol in pigs.

Bolus intravenous injections of cholecystokinin (CCK) octapeptide induce a rapid rise in plasma vasopressin and a later increase in cortisol in the prepubertal pig. To determine whether these endocrine responses involve CCK-A or CCK-B receptors, this experiment investigated the effect of CCK (1 microgram/kg) in pigs (n = 7) pretreated with the CCK-A antagonist L 364718 (70 microgram/kg) or the CCK-B antagonist L 365260 (10 ng/kg and 10 micrograms/kg). The animals were prepared with jugular vein catheters and given the antagonist vehicle, L 364718, or L 365260 10 min before administration of CCK or saline. Analysis of hormone concentrations in blood samples taken 2, 5, 10, and 20 min after the second injection indicated that an abrupt rise in vasopressin, detectable within 2 min of CCK administration, occurred after vehicle or L 365260 pretreatment but not when CCK was preceded by L 364718. In contrast, the rise in plasma cortisol that was observed approximately 15 min after CCK injection was not prevented by either antagonist. Thus peripherally administered CCK induces vasopressin release by CCK-A receptor activation, in agreement with its inhibitory effect on food intake in this species. However, the effect of CCK on cortisol secretion does not appear to involve either CCK-A or CCK-B receptors.

Effect of light intensity on circadian profiles of melatonin, prolactin, ACTH, and cortisol in pigs.

Eleven crossbred barrows were housed in environmentally controlled rooms with an 8-h photoperiod. Pigs in one room received control illumination of 113 1x (CON; n = 6), and pigs in the other room received intense illumination of 1,783 1x (INT; n = 5) fluorescent light. Pigs were given at least 20 d of exposure to the environment before blood samples were taken every 3 h for 48 h. Data were analyzed by split-plot analysis of variance. Except for prolactin, no treatment x time interactions were noted for the hormone profiles evaluated (P greater than .10). Pigs in INT had greater (P less than .05) concentrations of prolactin in serum than pigs in CON at every sampling time. Concentrations of ACTH and cortisol in plasma were similar for INT (33.9 +/- 3.2 pg/mL of ACTH and 24.4 +/- 3.4 ng/mL of cortisol, respectively) and CON (34.9 +/- 3.0 pg/mL of ACTH and 31.3 +/- 3.1 ng/mL of cortisol, respectively). Within the INT treatment, serum melatonin concentrations were more than doubled (P less than .05) during darkness (66.8 +/- 9.3 pg/mL) compared with during light (30.4 +/- 9.3 pg/mL); however, within the CON treatment, concentrations during light and darkness did not differ (38.4 +/- 9.3 pg/mL and 42.9 +/- 9.3 pg/mL, respectively). Results indicate that light of greater intensity is required to entrain circadian rhythms of melatonin in serum of pigs. Furthermore, pigs may respond to bright light with greater secretion of prolactin, even under constant duration of photoperiod.

Salivary cortisol in pigs after adrenocorticotrophin, food and water deprivation, handling, transport simulation and mixing

Salivary cortisol in pigs after adrenocorticotrophin, food and water deprivation, handling, transport simulation and mixing

Salivary cortisol in pigs following adrenocorticotrophic hormone stimulation: Comparison with plasma levels

Four prepubertal pigs were prepared with venous catheters and housed in metabolism cages. Plasma and saliva samples were taken at 15-min intervals over a 105-min period and analysed by radioimmunoassay for total (i.e. free and bound) cortisol content. Adrenocorticotrophic hormone (ACTH) was given i.v. at three different doses (0·5, 1·0 and 2·0 mg) after the second sample and the cortisol responses were compared with pretreatment values and levels observed after saline vehicle administration. Basal levels of salivary cortisol were approximately 10% of those in plasma. ACTH induced significant increases in plasma and salivary cortisol but in no case was a dose/response relationship detected. Plasma cortisol showed a maximum increase of approximately 230% whereas salivary cortisol increased only by about 130%, indicating that salivary cortisol is a less sensitive indicator of adrenal activity than plasma cortisol in this species. Estimation of salivary cortisol concentrations may offer practical advantages for the assessment of stress responses in intensively housed pigs.

Plasma Adrenocorticotropic Hormone and Cortisol in Pigs: Effects of Time of Day on Basal and Stressor-Altered Concentrations

An initial study was conducted to establish the presence in plasma of diurnal rhythms of immunoreactive porcine adrenocorticotropic hormone (pACTH) and cortisol in castrated male pigs (barrows). Fourteen barrows with jugular catheters were bled at 6-hr intervals for 24 hr. Significant changes in plasma pACTH were evident with peak levels (61 +/- 6 pg/ml) at 0100-0700 hr and a trough (38 +/- 4 pg/ml) at 1900 hr. Changes (P less than 0.05) in plasma cortisol were also present in barrows with a peak (44 +/- 6 ng/ml) at 0700 hr and a trough (21 +/- 5 ng/ml) at 1900 hr. Plasma norepinephrine and epinephrine were measured at the same time intervals and did not differ among hours. In these unstressed pigs the ratio cortisol/log10pACTH at 0700 hr (25.3 +/- 3.0) was greater than the ratio at 1900 hr (12.9 +/- 2.7). Sequential blood samples were subsequently taken on four of the barrows 12 and 26 days later. Plasma pACTH was variable among pigs and did not differ among hours. Plasma cortisol on both dates was greater (P less than 0.05) in the morning (0100 or 0700 hr) than at 1900 hr. The ratio cortisol/log10pACTH at 0700 hr was repeatedly greater than at 1900 hr. A second study was conducted to determine whether plasma pACTH and cortisol responses to mild (32 degrees C for 2 hr) or strong (20-min restraint) stressors were dependent on the time of day of stressor application (0800 hr, AM; 1600 hr, PM). Response-associated parameters (maximum concentration, maximum incremental concentration, and integrated response) for pACTH and cortisol did not differ between AM and PM. However, a qualitative difference existed between the AM and PM plasma pACTH responses to restraint +32 degrees C wherein the AM response consisted of a single prolonged surge, and the PM response of an initial major peak followed by a second significant minor peak. A suggested explanation is that the initial 20-min restraint stressor potentiated the hypothalamic-hypophyseal response to 32 degrees C. These studies are the first direct measurements which suggest the presence of diurnal changes in plasma ACTH and cortisol in barrows. The studies also indicate for barrows an absence of diurnal changes in plasma epinephrine and norepinephrine. The responsiveness of the pituitary-adrenocortical axis to stressors did not exhibit quantitative diurnal changes at the time periods measured. However, it is hypothesized that the repeatable AM-PM difference in the ratio cortisol/log10ACTH reflects a diurnal change in adrenal responsiveness to ACTH in unstressed pigs.

Metabolic clearance rate of cortisol in pigs: relationship to adrenal responsiveness

Experiments were conducted on 12 prepuberal (18- to 20-week-old) Landrace cross Large White gilts to establish if differences in adrenal responsiveness between individuals could be explained by differences in the metabolic clearance rate (MCR) of cortisol. Pigs with the highest (n = 6) and lowest (n = 6) cortisol concentration 60 minutes after challenge with ACTH were selected from a pool of 36 commercial pigs. Tritium-labelled cortisol was infused (17 to 27 ml h-1) continuously for 120 minutes to establish 'steady state' conditions. Blood samples (10 ml) were collected at 90, 100, 110 and 120 minutes. Replicate experiments were performed on some pigs. Classification of individual pigs as high or low adrenal responders to ACTH challenge was confirmed at the end of the clearance rate experiments. The MCR of cortisol in the group classed as low adrenal responders was 59.7 +/- 7.8 litres h-1 or 1.01 litres h-1 kg-1 (n = 7) which was not significantly different from the average MCR in the group classed as high adrenal responders 60.2 +/- 5.9 litres h-1 or 1.19 litres h-1 kg-1 (n = 10). These results suggest that the repeatable differences in adrenal responsiveness to ACTH that exist between individuals within a particular strain of pig depend on differences in the rate of synthesis of cortisol in response to ACTH stimulation, rather than on differences in its rate of metabolism.

Circadian variation of somatomedin and cortisol in pigs.

Circadian variation of somatomedin and cortisol in pigs.