Epidemiological investigation of swine tuberculosis in Arizona.

Swine tuberculosis occurred in thirteen herds of swine in Arizona. Mycobacterium avium serotypes 1, 2, 4, 5 and 8 were isolated from tissues of affected animals. These serotypes are responsible for approximately 85% of the mycobacterial infections found in swine in the United States. Based on tuberculin skin test responses and examinations of tissues collected at slaughter, the source of infection in at least one of these herds, Herd A, was found to be infected sawdust and wood shavings used as bedding. This finding concurs with the reports of others. Tuberculin skin tests performed on slaughter pigs in Herd A showed a 97.1% correlation between the number of pigs responding to tuberculin and the number found to have tuberculous lesions at slaughter. No correlation of skin test response and presence of lesions was possible for individual pigs, but these results imply that the test may have value when used to determine prevalence of the disease in a herd of pigs.     

应激对猪生产性能、行为及血液理化指标影响的研究进展

应激条件下会影响猪的生产性能、行为及血液生理生化指标,对动物机体造成危害。因此,在畜牧生产实践中应尽一切努力防止应激特别是严重应激的发生,以免影响生产的有序进行,损害动物福利,降低经济效益。作者主要综述了断奶、冷、热、运输、屠宰等常见应激因素对猪的生产性能、行为及血液生理生化指标的影响。     

Comparison of muscle fluid and serum for detection of antibodies against hepatitis E virus in slaughter pigs

Muscle fluid was investigated as an alternative to serum for detecting anti-hepatitis E virus (HEV) antibodies in slaughter pigs. Samples of serum and diaphragmatic muscle juice from 67 pigs were analysed by anti-HEV IgG ELISA. Compared to the serum ELISA, the ELISA on diaphragmatic muscle fluid had a sensitivity of 93%, a specificity of 91.7%, a κ value of 0.84 and a determination coefficient (R(2)) of 0.77; both tests had global agreement of results. Muscle fluid can be used as an alternative to serum for serological detection of HEV antibodies in slaughter pigs.     

Effect of hCG Stimulation on Plasma Androstenone Concentrations and Cytochrome b5 Levels in Testicular Tissue

The effect of Human chorionic gonadotropin (hCG) stimulation on the concentrations of free and conjugated androstenone in plasma was studied in 34 crossbred entire male pigs (Landrace x Swedish Yorkshire). Seventeen pigs were treated with hCG 4 days prior to slaughter and the remaining pigs were treated with sterile saline and served as controls. Blood samples were taken prior to hCG or saline injection and on the day before slaughter and analysed for concentrations of free and conjugated androstenone. Testicular tissue samples were taken at slaughter and analysed for the levels of cytochrome b5 (cyb5) protein. Here we have demonstrated for the first time that hCG stimulation causes an increase in the plasma levels of both free and conjugated androstenone. Not all animals responded in the same way to hCG treatment regarding levels of free and conjugated androstenone demonstrating that individual animals can have differences in their capacity to produce free and conjugated androstenone. We suggest that hCG treatment is a good way to determine the potential for androstenone conjugation when androstenone synthesis in the testis is high. The levels of cyb5 protein in the testis were slightly related (r=0.41, p < 0.10) to free androstenone levels in the pigs after hCG administration, although levels of cyb5 protein were not affected by hCG treatment.     

Effect of transportation and feed withdrawal on shedding of Salmonella typhimurium among experimentally infected pigs.

OBJECTIVE: To determine whether stress associated with transportation or feed withdrawal increased fecal shedding of Salmonella Typhimurium among pigs experimentally infected with the organism. ANIMALS: 86 healthy pigs. PROCEDURE: Pigs were challenge exposed with Salmonella Typhimurium at 4 weeks old and reared conventionally. When pigs reached market weight, they were assigned to groups and subjected to various combinations of transportation and feed withdrawal. Ileocecal contents were collected after slaughter and tested for Salmonella Typhimurium. RESULTS: Salmonella Typhimurium was not detected in feces collected from pigs just prior to slaughter. When feed was withheld for 24 hours prior to slaughter, the proportion of transported pigs with Salmonella Typhimurium in ileocecal contents at the time of slaughter was not significantly different from the proportion of nontransported pigs. However, when feed was not withheld prior to slaughter, the proportion of transported pigs with Salmonella Typhimurium in ileocecal contents at the time of slaughter was significantly higher than the proportion of nontransported pigs. CONCLUSIONS AND CLINICAL RELEVANCE: When carrier pigs remained on feed, transportation stress increased the proportion positive for Salmonella sp. On the basis of results reported here, it is suggested that producers withhold feed from pigs for 24 hours prior to transportation to a slaughter plant.     

Muscle meat quality in swine. 4: Response of fattening pigs to removal from pigsty and transport to slaughterhouse

Blood was sampled through indwelling catheters from pigs taken to places for slaughter by various means of transport. Sampling took place at different measuring points between removal from pig pens and actual slaughter. The blood was tested for haemoglobin, haematocrit, glucose, and lactate. The following results were obtained: Removal and transport led to strong Hb and medium Hk rises. The levels, however, returned to normal after one-and-a-half to two hours rest. Stresses caused prior to and during anaestheria led to considerable rise of Hk and Hb as well as to maximum lactate deflection. The latter excitations superimposed all the preceding reactions of the organism. The increased of Hb, Hk, and lactate recorded from animals slaughtered as little as 20 minutes after arrival were higher than those established from animals that had been allowed some rest in between. Transport losses were reduced when the animals were moved in containers due to less motoric stress. However, no mitigation of pork quality setback can be expected as long as strong excitation continues to be caused in the animals before slaughter.     

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.     

Longitudinal study of hepatitis E virus infection in Spanish farrow-to-finish swine herds

Hepatitis E is a zoonotic disease and is highly prevalent in European swine livestock. There is a need to compare the infection dynamics of hepatitis E virus (HEV) between herds with the same production system and determine the percentage of animals that could arrive infected at slaughter age. Therefore, a longitudinal study was performed in six Spanish farrow-to-finish affected farms. Twenty piglets per farm were monitored from nursery to slaughter. RT-PCR and serology techniques were applied to analyze longitudinally collected sera and/or faecal samples. Liver and bile samples were also taken at the abattoir. Anti-HEV IgM were firstly detected at 7 weeks of age in 5 farms whereas at 13 weeks of age in 1 farm (farm 2). At slaughter age 50–100% of pigs had seroconverted to anti-HEV IgG in the former 5 farms whereas in the other herd only 5% of pigs were IgG seropositive (farm 2). Six out of 96 livers and 5 out of 80 biles analyzed were HEV positive at the abattoir (total percentage of infected animals: 11.5%). All these positive animals had already seroconverted except 2 pigs of farm 2. Hence, pigs can be seronegative at slaughter age being infected during the latest fattening period. Manipulation of HEV-infected livers or other organs from pigs could be considered a possible route of transmission in Spanish abattoirs. This study represents the first longitudinal survey on swine HEV infection dynamics conducted in different herds.     

Naturally acquired Lawsonia intracellularis infection in pigs studied from weaning to slaughter by indirect immunofluorescence antibody test and polymerase chain reaction on faeces

The course of naturally acquired Lawsonia intracellularis infection was studied in 41 pigs by testing blood and faeces samples collected four to seven times from before weaning to slaughter 5 months old. At slaughter, a sample of ileum was taken for histopathology. In the first sampling when the pigs were 2-4 weeks old maternally derived IgG against L. intracellularis was demonstrated by immunofluorescence antibody test in nine pigs whereas the bacterium was detected by PCR in faeces from six pigs. The maternally derived antibodies did not prevent pigs from becoming infected as seven pigs later on shed and/or were seropositive for L. intracellularis. The lowest prevalence of L. intracellularis was observed in 6-13 weeks old pigs and it seemed as though L. intracellularis in early infected pigs only activates a minor antibody response. At slaughter 66% of the pigs were found positive by immunofluorescence antibody test compared to 24% by immunohistochemistry on ileal samples. Thus, applied at the time of slaughter the antibody test appeared to be a highly sensitive ante-mortem diagnostic tool for identifying L. intracellularis exposed pigs with or without current proliferative enteropathy.     

Muscle glycogen stores and meat quality as affected by strategic finishing feeding of slaughter pigs

The aim of the present study was to investigate whether muscle glycogen stores in slaughter pigs could be decreased through strategic finishing feeding before slaughter. Moreover, preliminary meat quality traits were measured to see whether such a regulation of muscle glycogen stores affected ultimate pH, color, and tenderness in the meat. The strategic finishing feeding was carried out the last 3 wk prior to slaughter. Seven experimental groups with eight animals per group were fed diets low in digestible carbohydrates. A control group with four animals was fed a traditional grower-finishing diet. The muscle glycogen stores were reduced in longissimus muscle (LM) 11 to 26% at the time of slaughter in pigs that were fed the experimental diets compared with the control group. Meat quality measured as ultimate pH and color on LM muscle in half the pigs 24 h postmortem showed that ultimate pH in LM was not affected by the reduction in glycogen stores in the muscles from pigs fed any of the experimental diets. However, the meat from pigs fed the experimental diets was darker than the meat from pigs that were fed the control diet with two of the experimental diets, resulting in significantly lower L* values. Activities of key enzymes in the glycolytic pathway, glycogen phoshorylase a and b, phosphofructokinase, and the fatty acid oxidative pathway, beta-hydrozyacyl-CoA-dehydrogenase, were not affected by the strategic feeding. In contrast, the activity of the proteolytic enzyme calpain as well as its inhibitor calpastatin was influenced by the strategic feeding. Lower activity of mu-calpain and greater activity of calpastatin in the muscle samples from the strategically fed pigs indicate a lesser muscle protein degradation in the muscles compared with muscles of control animals. The present study showed that the muscle glycogen stores in slaughter pigs can be reduced at the time of slaughter through strategic finishing feeding with diets low in digestible carbohydrate without compromising growth rate.     

The effect of high pre‐slaughter environmental temperature on meat quality traits of Italian autochthonous pig Suino Nero Lucano

The aim of the present study was to evaluate the effect of high pre‐slaughter environmental temperature on meat (Longissimus lumborum muscle) quality traits of Italian autochthonous pigs Suino Nero Lucano (SNL). High pre‐slaughter environmental temperature influenced the meat quality of autochthonous pigs. In particular, the meat from SNL pigs exposed to heat stress (H) showed significantly lower pH values at 24 and 48 hr post mortem, haem iron content and redness (a*) value, and a significantly higher shear force, drip loss and lightness (L*) values, compared to meat from SNL pigs reared under comfortable environmental temperature (C). Moreover, H meat showed a significant reduction of vitamin A, vitamin E, creatine and carnosine content, compared to C meat. Despite this, no pale‐soft‐exudative pork was found in our study, and no significant difference was detected between two studied groups for intramuscular fat and protein content of meat. In addition, despite the meat from SNL pigs exposed to heat stress has suffered a qualitative decrease, it showed a good endogenous antioxidants content.     

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.     

Influence of long-time transportation stress on re-activation of Salmonella typhimurium DT104 in experimentally infected pigs

In this study a Salmonella Typhimurium infection model in swine was used in order to investigate the influence of pre-mortal stress induced by long time period transportation on the re-activation of Salmonella in experimentally infected pigs. Salmonella free pigs were exposed to a highly virulent strain of Salmonella Typhimurium DT104 by direct intragastrical administration. Clinical parameters were monitored and the shedding rate in faeces was qualitatively and quantitatively determined by standard bacteriological procedures for 21 days. The distribution of the challenge organism in 14 different internal organs of transported and nontransported animals was determined. All infected animals developed clinical signs of salmonellosis 12 to 24 hours post infection. About 88 to 100% of the fecal samples were culture-positive up to post exposure day 6, and then varied from 71 to 92% until slaughter, respectively. At necropsy S. Typhimurium was recovered most frequently from caecum and ileocolic lymph nodes (83%), colon (79%), palatine tonsils (71%) and mandibular lymph nodes (62.5%). A negative impact of transportation stress on the shedding rate and the general condition of the animals was observed.     

Pleuropneumonia in swine caused by Haemophilus parahaemolyticus. A study of the epidemiology of the infection

Haemophilus parahaemolyticus infection was studied in a herd with continuous production, i.e., continuous introduction of stock to replace animals delivered for slaughter. None of 30 seronegative pigs contracted the infection when exposed to contact with two pigs that were seropositive after inoculation with H. Parahaemolyticus three weeks earlier. After aerosol infection had been applied in the building an acute outbreak with a morbidity rate of 100 per cent developed in less than 24 hours. Following recovery the majority of the 16 pigs present became seropositive, and when 30 seronegative pigs were introduced 7 weeks later, antibody response occurred in three of them. The persistence of H. parahaemolyticus in pigs that had been infected during the acute outbreak was confirmed at slaughter, in that the organism was re-isolated from the tonsils of 2 of these pigs. Most serum titres persisted for several months, but some animals showed just a transient antibody response.     

Evaluation of the antibacterial residue surveillance programme in Danish pigs using Bayesian methods

Residues of pharmacological active substances or their metabolites might be found in food products from food-producing animals. Maximum Residue Limits for pharmacological active substances in foodstuffs of animal origin are established to assure high food safety standards. Each year, more than 20,000 samples are analysed for the presence of antibacterial residues in Danish pigs. This corresponds to 0.1% of the size of the slaughter pig population and more than 1% of the sows slaughtered. In this study, a Bayesian model was used to evaluate the Danish surveillance system accuracy and to investigate the impact of a potential risk-based sampling approach to the residue surveillance programme in Danish slaughter pigs. Danish surveillance data from 2005 to 2009 and limited knowledge about true prevalence and test sensitivity and specificity were included in the model. According to the model, the true antibacterial residue prevalence in Danish pigs is very low in both sows (～0.20%) and slaughter pigs (～0.01%). Despite data constraints, the results suggest that the current screening test used in Denmark presents high sensitivity (85-99%) and very high specificity (>99%) for the most relevant antibacterial classes used in Danish pigs. If high-risk slaughter pigs could be identified by taking into account antibacterial use or meat inspection risk factors, a potential risk-based sampling approach to antibacterial residue surveillance in slaughter pigs would allow reducing the sample size substantially, while increasing or maintaining the probability of detection. Hence, the antibacterial residue surveillance programme in Danish pigs would be more cost-effective than today.     

Sensory and processing properties of cured semimembranosus muscle from stress-susceptible pigs treated with porcine somatotropin.

Forty-eight Yorkshire cross pigs of three stress susceptibility classes (stress positive, stress-carrier, and stress negative) were injected daily with porcine somatotropin (pST; 4 mg/d) or placebo. Each pig was injected in the neck once daily until taken off test, starting when the pigs weighed 59 kg. Porcine somatotropin treatment was terminated at weekly intervals as individual pigs reached 109 kg, but animals continued to be fed for six additional days to allow for required withdrawal time. The effect of pST and stress classification on the sensory, physical, chemical, and processing characteristics of cured semimembranosus (SM) muscle was evaluated. Treatment of animals with pST had no effect on the sensory scores, lipid and protein content, cooking yields, or color values of SM muscle slices. Semimembranosus muscles from stress-positive animals, however, had reduced sensory scores for texture, flavor, and overall palatability. Semimembranosus muscles from stress-positive pigs also had smaller cooking yields and greater Hunter a and b values of processed slices. The greater Hunter a and b values suggested that the color of these slices were redder and yellower than the color of SM muscle slices from negative and carrier animals. Semimembranosus muscles from stress-susceptible animals also had a significantly lower lipid content. Treatment of animals with pST did not significantly alter sensory, chemical, or processing characteristics of SM muscle slices from these animals.     

Territorial dissemination of antibodies against leptospirae at individual farms throughout a district, detected on the basis of serological testing of slaughter cattle and pigs

The serological reaction of microagglutination-lysis (RMAL) was performed to examine 4995 head of slaughter cattle and 8211 slaughter pigs for the presence of antibodies to leptospirae. The animals came from 33 farms of the Strakonice district. Antibodies to leptospirae were found in slaughter cattle from 25 (75.75%) farms and in slaughter pigs from 24 (72.72%) farms. As suggested by the examination, the antibodies to leptospirae occur in animals throughout the territory of the district, irrespective of the nature of the landscape. The occurrence of the above-mentioned antibodies on farms occurred within the range from 0.52% to 8.33% in slaughter cattle and from 0.32% to 8.10% in slaughter pigs; only rarely did it exceed 9.0%. The most frequent reactions were those with the leptospirae of the L. grippotyphosa serovar.     

Slaughter value, meat quality, creatine kinase activity and cortisol levels in the blood serum of growing-finishing pigs slaughtered immediately after transport and after a rest period

The experimental materials comprised 44 hybrid [female (Polish Large White x Polish Landrace) x male Duroc] growing-finishing pigs. The animals were randomly divided into two groups: 24 pigs were slaughtered immediately after transport and 20 pigs were slaughtered after a 24-hour rest period in the lairage. The meat content of pork carcasses, carcass dressing percentage, the proximate chemical composition, physicochemical and sensory properties of meat and shear force values were determined. Serum creatine kinase activity and cortisol levels were determined in blood samples collected before transport and during carcass bleeding. Pigs slaughtered immediately after transport, compared with those slaughtered after a 24-hour rest period, were characterized by a higher meat content of the carcass and a higher carcass dressing percentage. Pre-slaughter handling had no effect on pork quality. The incidence of normal-quality meat, partially PSE (pale, soft, exudative) meat and PSE meat was similar in both groups. Chemical analysis showed that the content of dry matter, total protein, fat and minerals in meat was comparable in both groups. As regards the functional properties of the pork, samples from the carcasses of pigs that had rested before slaughter had a higher contribution of the red color component. Meat from pigs slaughtered immediately after transport had more desirable sensory properties. Pre-slaughter resting had a significant effect on those analyzed physiological parameters which were found to be good indicators of pre-slaughter stress. Serum creatine kinase activity and cortisol levels were higher in blood samples collected after transport (during carcass bleeding) than in samples collected before transport, pointing to a strong stress response of animals to pre-slaughter treatment. The decrease in serum cortisol levels in blood samples collected during bleeding from the carcasses of pigs slaughtered after a 24-hour rest period, compared with samples collected from animals slaughtered immediately after transport, suggests that rest before slaughter alleviated stress induced by pre-slaughter handling operations.     

Relationship between serum acute phase protein concentrations and lesions in finishing pigs

To establish the relationship between serum levels of three acute phase proteins, haptoglobin (Hp), C-reactive protein (CRP) and serum amyloid A (SAA), and the occurrence and severity of lesions at slaughter, a study was carried out using 70 fattening pigs from a finishing unit. Pigs were divided into three groups: Group 1 (25 pigs with clinical signs of disease), Group 2 (25 apparently healthy pigs with lesions at slaughter) and Group 3 (20 apparently healthy pigs with no lesions at slaughter). Serum levels of CRP, SAA and Hp were significantly higher in pigs with clinical signs of disease than in apparently healthy animals. Additionally, in apparently healthy pigs, serum levels of Hp and CRP were significantly higher in animals with lesions than those without lesions. The extent and severity of lung lesions were related to serum levels of Hp.     

Danish investigations concerning body composition of pigs in relation to nutrition,sex and slaughter weight

Several Danish investigations were carried out in order to elucidate the influence of nutrition, sex and slaughter weight on the body composition in pigs. In this paper we discuss whether selection of breeding animals should be based mainly on: (1) per cent meat in the carcass, (2) a combination of per cent meat, daily gain and feed consumption per kg live weight gain, or maybe better, (3) a combination of per cent meat and feed consumption per kg meat produced.Investigations comprising five different energy and protein levels and 1100 pigs slaughtered at live weights varying from 80 to 120 kg showed that both feeding intensity and slaughter weight influenced the carcass composition. Increasing feeding intensity and increasing slaughter weight caused a deterioration in the ratio between meat and subcutaneous fat. The feeding intensity had only little influence on kg meat produced whereas increasing feeding intensity caused an increase in kg subcutaneous fat produced.The females contained more meat than did the male castrates. Besides, the deterioration in carcass composition due to increasing slaughter weight and feeding intensity were lower in the females than in the male castrates. Daily gain increased with increasing feeding intensity. The investigations indicate maximal protein synthesis to take place within the live weight area of 90–100 kg.High correlations were found between the chemical composition of the different anatomical fractions in 90-kg pigs. The empty pigs (live weight minus the content of the digestive tract) weighed on average 80.8 kg, of which 42.0% was dry matter. The dry matter contained 41.1% protein, 51.1% chemical fat, 7.7% ash and 7080 kcal per kg. The meat fraction contained 55% of the protein, 30% of the chemical fat and 38% of the energy in the empty pigs.