Influence of transport stress on serum cortisol and thyroid hormones in pigs with Halothane gene

The influence of transport stress on rectal temperature, respiratory rate and serum concentrations of cortisol, thyroxine and triiodothyronine (T3) in normal pigs (NN) and in heterozygous (Nn) pigs with Halothane gene (n), a major gene that causes the pale, soft, exudative meat (PSE), were examined in a hot environment (32–34°C). Easily releasable myofilament content of Longissimus dorsi taken by needle biopsy was also measured as an index of myofibrillar disassembly. Rectal temperature and respiratory rate were significantly increased by the transport. However, the influence was higher (P < 0.01) in Nn pigs. Serum concentration of cortisol was increased (P < 0.01) by the transport despite the genotypes. Serum concentration of T3 was not changed by the transport in Nn pigs, whereas in NN pigs it was significantly decreased after the transport (P < 0.01). Easily releasable myofilament content after the transport was higher in Nn pigs than that of NN pigs (P < 0.05). These results suggest that response of thyroid function might relate to the stimulation of muscle proteolysis and PSE in Nn pigs under stressful conditions.     

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.     

Limitations of salivary and blood cortisol determinations in pigs

Blood and saliva samples were taken from groups of pigs maintained in intensive conditions. Multiple samples were taken from two unrestrained pregnant sows fitted with jugular cannulae. Single samples were taken from groups (mixed gilts and entire males; 70–90 kg) which were lightly exercised (7) or restrained (12). The rate of salivary secretion was low and collection of adequate samples took 5 min; in a number of pigs no saliva could be obtained.In order to stimulate salivary secretion, pigs (70–80 kg) were injected with pilocarpine nitrate (25 mg, subcutaneous) which produced a copious flow of saliva persisting for at least 15 min.Resting sows had higher mean levels of cortisol in plasma, ultrafiltrate and saliva than the other groups, which did not differ from each other. Within the pilocarpine group, males had a higher ultrafiltrate level of cortisol than females. In most instances salivary cortisol was significantly greater than ultrafiltrate cortisol.Ultrafiltrate and plasma cortisol were highly correlated (r=0.883) but this correlation was low in the presence of pilocarpine (r=0.260). Salivary cortisol was poorly correlated with either plasma (r=0.167) or ultrafiltrate cortisol (r=0.278) and the correlation with plasma was even lower following the administration of pilocarpine (r=0.086).It was concluded that salivary estimates of cortisol in the pig were not usefully correlated with levels of ultrafiltrate (free) cortisol.     

Susceptibility of bacteria isolated from pigs to tiamulin and enrofloxacin metabolites

Susceptibilities to metabolites of tiamulin (TIA) and enrofloxacin (ENR) were tested using selected bacteria with previously defined minimal inhibitory concentrations (MIC). The TIA metabolites tested were: N-deethyl-tiamulin (DTIA), 2beta-hydroxy-tiamulin (2beta-HTIA) and 8alpha-hydroxy-tiamulin (8alpha-HTIA), and the ENR metabolites were: ciprofloxacin (CIP) and enrofloxacin N-oxide (ENR-N). Bacteria, all of porcine origin, were selected as representatives of bacterial infections (Staphylococcus hyicus and Actinobacillus pleuropneumoniae), zoonotic bacteria (Campylobacter coli) and indicator bacteria (Escherichia coli and enterococci). Furthermore the effects of these compounds were tested on the microbial community of active sludge to test any negative effect on colony forming units (CFU). DTIA had a potency of 12.5-50% of the potency of TIA. 2beta-HTIA and 8alpha-HTIA had potencies less than 1% of the potency of TIA. ENR-N had a potency of 0.75-1.5% of the potency of ENR, while CIP and ENR had similar potencies. Results obtained here indicate that CIP and DTIA could contribute to the selective pressure for upholding antimicrobial resistant bacteria in animals under ENR or TIA treatment. The most potent metabolites CIP and DTIA showed considerable potencies against activated sludge bacteria compared to the parent compounds. EC(50) (microg/ml) for ENR, CIP, TIA and DTIA were 0.018 [95% CI: 0.028-0.149], 0.064 [95% CI: 0.007-0.046], 6.0 [95% CI: 3.6-9.8], and 9.7 [95% CI: 5.8-16.3], respectively. This indicates that the compounds can change the bacterial population in the sludge, and hereby alter the properties of the sludge.     

Prostaglandins and reproduction in female farm animals

Prostaglandins impact on ovarian, uterine, placental, and pituitary function to regulate reproduction in female livestock. They play important roles in ovulation, luteal function, maternal recognition of pregnancy, implantation, maintenance of gestation, microbial-induced abortion, parturition, postpartum uterine and ovarian infections, and resumption of postpartum ovarian cyclicity. Prostaglandins have both positive and negative effects on reproduction; they are used to synchronize oestrus, terminate pseudopregnancy in mares, induce parturition, and treat retained placenta, luteinized cysts, pyometra, and chronic endometritis. Improved therapeutic uses for prostaglandins will be developed when we understand better their involvement in implantation, maintenance of luteal function, and establishment and maintenance of pregnancy.     

Identification of quantitative trait loci affecting reproduction in pigs

The objective of this research was to identify chromosomal regions harboring QTL affecting reproduction in pigs. A three-generation resource population was developed by crossing low-indexing pigs from a randomly selected control line (C) with high-indexing pigs of a line selected for increased index of ovulation rate and embryonic survival (I). Differences between Lines I and C at Generation 10 were 6.7 ova and 3.3 fetuses at 50 d of gestation and 3.1 fully formed and 1.6 live pigs at birth. Phenotypic data were collected on F2 females, born in three replicates, for ovulation rate (n = 423), age at puberty (n = 295), litter size (n = 370), and number of nipples (n = 428). Litter-size data included number of fully formed, live, stillborn, and mummified pigs. Grandparent, F1, and F2 animals were genotyped for 151 microsatellite markers distributed across all 18 autosomes and the X chromosome. Genotypic data were available on 423 F2 females. Average spacing between markers was 19.3 Kosambi centimorgans. Calculations of logarithms of odds (LOD) scores were by least squares, and fixed effects for sire-dam combination and replicate were included in the models. Genome-wide significance level thresholds of 5% and 10% were calculated using a permutation approach. There was evidence (P < 0.05) for QTL affecting ovulation rate on SSC9, age at puberty on SSC7 and SSC8, number of nipples on SSC8 and SSC11, number of stillborn pigs on SSC5 and SSC13, and number of fully formed pigs on SSC11. There was evidence (P < 0.10) for additional QTL affecting age at puberty on SSC7, SSC8, and SSC12, number born live on SSC11, and number of nipples on SSC1, SSC6, and SSC7. Litter size is lowly heritable and sex-limited. Therefore, accuracy of selection for litter size may be enhanced by marker-assisted selection. Ovulation rate and age at puberty are laborious to measure, and thus marker-assisted selection may provide a practical and efficient method of selection.     

生长激素在雌性动物生殖中的作用

1生长激素(GH)与性成熟正常初情期的到来往往需要GH,缺乏GH会使初情期推迟。对猴子和缺乏GH儿童的研究发现,注射GH可加快性成熟。GH的这一功能是通过激活LHRH波动发生器或增强雄激素的功能来实现的。对猪的研究也表明,GH对性成熟的影响与其作用时间有关。同时在人上也发现,当垂体促性腺激素分泌模式建立后,GH才能增加其性成熟的比例。对小母鼠的研究发现,GH免疫会推延初情期的到来。2生长激素对卵巢的作用2.1生长激素对卵巢机能的影响体内研究表明GH可作用于卵巢以影响配子的形成和类固醇的生成,然而体内注射GH会导致血液循环中…     

Effect of dietary supplementation with vitamin C or carbadox on weanling pigs subjected to crowding stress

A 2 X 3 factorial arrangement was used in each of two trials with two levels of floor space allowance (.25, .13 m2/pig) and three dietary treatments (basal, basal + 660 ppm vitamin C, basal + 55 ppm carbadox). The reduction in floor space allowance was achieved in trial 1 by doubling the number of pigs/pen from eight to 16 and in trial 2 by reducing the size of pens by half. An 18% protein starter diet was used as the basal diet. Total numbers of pigs used were 216 in trial 1 and 144 in trial 2. Pigs were weaned between 4 and 5 wk of age (7.5 kg average wt) and fed ad libitum for 28 d. Reducing floor space allowance caused a (P less than .05) reduction in weight gain of weanling pigs in both trials. When the reduction of floor space allowance was done by increasing number of pigs/pen (trial 1), pigs responded with a significantly reduced feed intake with no change in efficiency of feed utilization. However, when floor space allowance was reduced by changing the size of the pen (trial 2), feed intake of pigs was not affected but efficiency of feed utilization was reduced significantly. Neither form of crowding affected vitamin C concentration in adrenal glands and weights of adrenal glands, spleen and thymus. Dietary supplementation of carbadox, but not vitamin C, produced significantly greater weight gain, feed efficiency, and spleen weight of pigs in both trials. Although there was no interaction between crowding and dietary treatment in affecting the performance of pigs, supplemental carbadox improved the performance of crowding-stressed pigs by maintaining an adequate level of feed intake and improving feed efficiency, whether crowding was caused by increased pig density or by reduced pen size. No significant differences in phytohemagglutinin (PHA) skin test response or in the neutrophil-to-lymphocyte ratio (N/L) were observed among treatments in trial 1, while a significantly reduced response to PHA and a higher N/L were detected in crowding-stressed pigs in trial 2.     

Duration of estrus in relation to reproduction results in pigs on commercial farms.

This research was conducted to determine factors that influence duration of estrus, AI strategy, and reproduction results between and within commercial swine farms that use AI. Data from 15,186 sows and gilts on 55 farms for a period of 6.1+/-4.2 mo per farm were used in this study. The average duration of estrus was 48.4+/-1.0 h, ranging from 31 to 64 h, and was consistent from month to month within a farm (repeatability of 86%). Differences in duration of estrus between farms accounted for 23% of the total variation in duration of estrus. On most farms (n = 45), gilts showed a shorter (P < .05) duration of estrus than sows (40.8+/-1.1 h vs 48.5+/-1.0 h). The duration of first estrus after weaning was longer (P < .0001) compared with that of repeat-breeder sows (50.2+/-1.0 h vs 46.8+/-1.0 h). Duration of estrus decreased (P < .05) when interval from weaning to estrus increased from 4 to 6 d (56.0 +/- 1.2 h vs 45.8 +/-1.2 h). The regression of interval from onset to estrus to first AI and interval from weaning to estrus varied between farms and ranged from -7.4 to +1.3 h/d; four farms had a positive relationship. Farrowing rate decreased (P < .05) from 89.7+/-2.7% to 78.2+/-5.74 when the interval from weaning to estrus increased from 4 to 10 d. The litter size decreased (P < .05) from 11.7 to 10.6 pigs when the interval from weaning to estrus increased from 4 to 7 d. Compared with a single AI, double AI in sows and gilts resulted in a 4.3 and 7.0% higher (P < .05) farrowing rate, respectively. When the first AI was performed after expected ovulation, reproduction results were lower than when AI was performed before or at expected ovulation in sows. Duration of estrus was not related to farrowing rate or litter size in individual pigs. Number of inseminations per estrus, time of AI, and duration of estrus were correlated, which made it difficult to assess which of these factors was primarily related to the farrowing rate or litter size. Knowledge of average duration of estrus on farms and of factors that influence the duration of estrus on commercial farms can help to improve the efficiency of the AI strategy specific for each farm.     

Time in lairage needed by pigs to recover from the stress of transport.

Two experiments were carried out in which a total of 602 pigs were slaughtered after being held in lairage for periods ranging from less than one hour to 21 hours. In the first experiment the pigs were handled under ideal conditions and slaughtered at the University of Bristol slaughterhouse; in the second the pigs were killed at a commercial plant. Blood samples collected at exsanguination were analysed for indices of stress. There were no consistent effects of time in lairage on the levels of lactate and creatine phosphokinase. Plasma cortisol and beta-endorphin levels were reduced by lairage for three hours or more in the first experiment and cortisol was reduced by lairage for two hours or more in the second; beta-endorphin was not measured in the second experiment. A period of rest in lairage allowed the pigs to recover from transport and the associated handling and the recovery appeared to be complete within two to three hours.     

Effects of transport stress on concentrations of cortisol, corticosteroid-binding globulin and glucocorticoid receptors in pigs with different halothane genotypes

Effects of stress on concentrations of cortisol and corticosteroid-binding globulin (CBG) in blood plasma and on glucocorticoid receptor concentrations in muscle cytosol were studied in pigs representing three Halothane (Hal) genotypes (NN, Nn, nn). At 12 wk of age, animals were divided into four groups: pigs subjected to transport (5 h in a truck), pigs treated with amperozide prior to transport, pigs not transported but treated with amperozide and pigs neither transported nor given amperozide. Animals were slaughtered the week they reached 100 kg live weight (3 mo later). The Hal gene showed no major influence on the variables studied except for cortisol concentrations (P = .06) measured directly after transport at 12 wk of age (NN = 66.8 nM, Nn = 61.4 nM, nn = 69.4 nM). However, the response in each Hal genotype differed, depending on whether or not the pigs had been exposed to transport. Two weeks after transport, NN pigs developed higher cortisol concentrations than untransported animals, whereas the response was reversed in nn animals; Nn pigs showed no difference in this regard. At slaughter, the effect of transport (12 wk of age) on cortisol and CBG was still apparent. In NN pigs cortisol and CBG concentrations were elevated (P less than or equal to .05, P = .08, respectively), whereas concentrations tended to be lower in nn pigs (P = .17, P = .07, respectively) when compared with untransported pigs. Transported pigs had lower receptor concentrations at slaughter (P less than or equal to .01) than untransported pigs. However, pigs given amperozide in connection with transport had a receptor concentration comparable to that in untransported pigs. Our study shows conclusively that transport stress had long-term effects on cortisol, CBG and glucocorticoid receptor concentrations. In addition, amperozide had long-term effects on cortisol and receptor concentrations.     

The influence of restraint immobilization stress on the concentration qf bioamines and cortisol in plasma of Pietrain and Duroc pigs

Forty-five Duroc (recognized as not susceptible to stress) and 34 Pietrain (susceptible to stress) pigs were subjected to immobilization stress in a prone position for 5, 15, 30 and 60 min. Plasma concentrations of epinephrine (E), norepinephrine (NE), dopamine (DA) and cortisol (C) were determined in response to restraint stress. The concentrations of E, NE and DA were different between the two strains of pigs (some significant interactions); the highest response was seen after 5 min of stress. The concentration of plasma C increased with duration of stress and there was a significant interaction between strain of animals and the time of stress. Our data substantiate the use of E, NE, DA and C as indicators of stress in swine as early as 5 min after exposure to the stressor. It is also shown that stress-susceptible Pietrain pigs had higher plasma concentrations of E, NE and DA than Duroc pigs.     

解决猪的氧化应激

氧化应激会带来许多影响育种和饲养系统中生产性能的问题。生产者可以寻找能够应对该问题的新方法,并利用已被证明可以提高动物生产性能的替代性抗氧化剂。     

Plasma cortisol concentrations in dogs given cortisone or placebo by mouth

Fasted normal dogs (n=8) were given fixed doses of cortisone acetate orally as 5 mg and 25 mg tablets; plasma cortisol concentrations were determined, and C_max, t_max and area under the curve of plasma cortisol concentration plotted against time from zero to 12 hours were compared for the two preparations. In addition, these variables were compared when 25 mg tablets were administered with and without food. No significant difference in cortisol availability was noted for the two preparations and feeding did not apparently affect cortisone absorption. The findings in two hypoadrenocorticoid dogs were similar. Plasma cortisol concentrations in placebo-treated dogs similarly sampled showed minor fluctuations and were generally within accepted reference limits for normal dogs.