An Epidemiologic and Economic Study of Respiratory Diseases in Two Conventional Danish Swine Herds. II: Associations Between Lesions Present at Slaughter and Mean Daily Gains During Specific Intervals of the Growth Period

A total of 578 slaughter pigs from 2 Danish conventional farrow-to-finish operations (Herds a and B) were followed from an age of 14 days to slaughter. Pigs were weighed at 3 weeks intervals and at slaughter and extended post mortem examination of the plucks was done. Regression models with second and third order interaction terms demonstrated that Mycoplasma-like pneumonia, complicated pneumonia, anterio-ventral pleuritis, pericarditis, fissures and atrophic rhinitis, separately and through interactions with other lesions, significantly reduced mean daily gains during specific intervals of the growth period in 2 conventional swine herds. It is likely that the periods of reduced growth reflect the times when the diseases were in the acute and early recovery stages. Maximum estimated reductions in daily gains associated with the combined lesions were 82 grams and 283 grams during the interval 120-140 days in Herds A and B, respectively. Although dorso-caudal pleuritis and parietal pleuritis had minor negative effects during 2 intervals neither had a significant adverse effect on total growth rate in either herd (Paisley et al. 1993). R² values for the regression models were less than 0.27 showing that the lesions present at slaughter explained less than 27% of the variation in herd mean daily gains during any interval.     

Relationship of growth performance to pneumonia and atrophic rhinitis detected in pigs at slaughter

Three commercial swine herds were selected for study, because pigs at slaughter consistently had lung lesions typical of bronchopneumonia and snout lesions consistent with atrophic rhinitis. Pigs were reared in the conventional system for each herd except that they were identified at birth and weighted at various intervals. At slaughter, individual pig lungs and snout were examined for lesions of pneumonia and atrophic rhinitis, respectively. Lesions were scored and correlated with growth indicators for each pig. Included in the growth indicators were: average daily gain (growing phase), average daily gain (finishing phase), average daily gain (total), and days to reach 104.5-kg body weight. Additionally, for each pig, scores for lung lesions were correlated to grades for snout lesions. Three correlation coefficients for measurements of pigs within herd B were significant and included days to 104.5-kg body weight and grades for snout lesions, -0.15 (P less than 0.02); average daily gain (finishing) and grades for snout lesions, 0.17 (P less than 0.01); and average daily gain (total) and grades for snout lesions, 0.16 (P less than 0.01). Contrary to findings in other investigations, pigs that attained market weight at the youngest age did not have the lowest score for lung lesions, the lowest grade for snout lesions, or the least extensive or severe lesions. Combining data from all 3 herds, the mean scores for lung lesions and mean grades for snout lesions decreased significantly (P less than 0.05) as the age of pigs at slaughter increased. All other statistical correlations were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of the effects of enzootic pneumonia in pigs on weight gain and days to slaughter under New Zealand conditions

The effects of enzootic pneumonia on average daily weight gain and number of days taken to reach slaughter weight was studied in 333 bacon-weight pigs. Each 1% of lung volume affected by enzootic pneumonia was shown to reduce average daily gain by 2.2 grams and increase the numbers of days to slaughter by 0.61 days. The cost of these reductions in performance was calculated to be about NZD 1 for each 1% of lung affected.     

Relationship to growth performance of pneumonia and atrophic rhinitis lesions detected in pigs at slaughter among four seasons.

A commercial swine herd was selected for study, because pigs at slaughter repeatedly had lung lesions consistent with enzootic pneumonia and had snout lesions typical of atrophic rhinitis. Pigs born during various seasons of the year were allotted to 4 investigations and were evaluated from birth to slaughter. Individual lungs and snouts were identified and collected at the slaughter plant and later examined for gross lesions of bronchopneumonia and atrophic rhinitis, respectively. Each lesion was scored, and the following comparisons were made within investigations: prevalence and mean scores for lung lesions; prevalence and mean grades for snout lesions; correlations between lung lesion scores and growth indicators; correlations between snout lesion grades and growth indicators; and correlations between lung lesion scores and snout grade scores. Included in the growth indicators were average daily gain during the growing phase, average daily gain during the finishing phase, average daily gain during growing and finishing phases, and days to attain 104.5 kg of body weight. Prevalence of lung or snout lesions, mean values for lung lesion scores, mean values for snout lesion grades, and mean values for the various growth indicators were tested for statistical differences among the 4 investigations. Prevalence of lung lesions was highest (96%) for winter-slaughtered and lowest (81%) for autumn-slaughtered pigs. Mean scores for lung lesions were 7% (summer), 5% (autumn), 9% (winter), and 16% (spring). Prevalence of snout lesions was highest (85%) for spring-slaughtered pigs and lowest (42%) for autumn-slaughtered pigs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of atrophic rhinitis on growth rate in Illinois swine herds

Influence of atrophic rhinitis (AR) on mean daily weight gain (MDG) was studied in hogs randomly selected from 7 farrow-to-finish herds in Illinois. Herds were selected to obtain a wide range of clinical signs and lesions of the disease; thus, prevalence of clinical signs of AR in finishing hogs ranged from 0% to 20% among herds, and in hogs examined at slaughter the proportion of hogs with turbinate lesions ranged from 5% to 92%. None of the herds investigated had any obvious problems with pneumonia; nevertheless, hogs with moderate to severe pneumonic lesions were excluded from the study, to minimize any combined effect of AR and pneumonia. In 3 herds, MDG in AR-free pigs was 15% to 18% better than in pigs with severe AR lesions. Prevalence of clinical signs ranged from 5% to 20%, and of turbinate lesions, from 66% to 92%. In 4 herds in which MDG appeared to be unaffected by AR, prevalence of clinical signs of the disease ranged from 0% to 5%, and of turbinate lesions, from 5% to 74%. No consistent pattern of influence on AR lesions was found for bacterial infections, as determined by culturing of nasal swab specimens on MacConkey agar and blood agar.     

Association between growth indicators and volume of lesions in lungs from pigs at slaughter.

Conflicting findings exist among studies on the effect of pneumonia on growth in pigs. We determined the extent of pneumonia in market-weight pigs by use of an objective, volumetric method and linear regression analyses of mean daily gain and days-to-slaughter weight on the percentage of pneumonic lung. In a range of extent of pneumonia between 1.33 and 70.44%, a 10% increase in the volume of pneumonic lung was associated with a decrease in mean daily gain by 41.1 g and a 16.7-day increase in number of days to a slaughter weight of 104.5 kg.     

Non-infectious factors associated with macroscopic and microscopic lung lesions in slaughter pigs from farrow-to-finish herds

A cross-sectional epidemiological study was conducted in 150 randomly selected farrow-to-finish herds to investigate which non-infectious factors might act as risk indicators for the prevalence and severity of macroscopic and microscopic lung lesions in slaughter pigs. Data were collected during herd visits through inspections of the pigs and through interviews with the farmers. Macroscopic lung lesions of pneumonia and pleuritis were recorded at slaughter from 25 pigs per herd, and microscopic lung lesions of lymphohistiocytic infiltration were recorded from 10 pigs per herd. The median herd level prevalences were 24 per cent for pneumonia, 16 per cent for pleuritis and 60 per cent for lymphohistiocytic infiltration. Pneumonia lesions were negatively associated with pleuritis lesions and positively associated with lymphohistiocytic infiltration. Pleuritis lesions were negatively associated with lymphohistiocytic infiltration. The prevalence and the severity of pneumonia lesions were increased by a high frequency of purchasing gilts and by a slaughter date in January to February. The presence of a growing unit also increased the severity of pneumonia. The prevalence and the severity of pleuritis lesions were higher when there were more pig herds in the municipality, and when there were poor biosecurity measures, and their prevalence was increased by a slaughter date in January to February, and their severity by a slaughter date in March to April. An increase in the airspace stocking density in the finishing unit also increased the prevalence of pleuritis. The prevalence and the severity of lymphohistiocytic infiltration in the lung tissue were higher in herds purchasing gilts. Pigs raised in pens with slatted floors were also at higher risk of more severe lesions of lymphohistiocytic infiltration.     

The effects of health classification and housing and management of feeder pigs on performance and meat inspection findings of all-in-all-out swine-finishing herds

The effects of health classification and of housing and management on performance and meat inspection findings were studied in 166 all-in-all-out finishing herds in Finland in 1995 and 1998. Producers could buy either health-classified (certified free of certain diseases) or standard-class pigs for their farms. Herds that had attained a certain level of housing and management were eligible to join the LSO 2000 management system for finishing herds. In 1995, none of the study herds were LSO 2000 units. In 1998, 76 of them had become LSO 2000 units, while 90 had remained as non-LSO 2000 units. Continuous outcome variables (daily gain and time in the finishing unit) were analysed with a mixed-model procedure with repeated measurements from the same farms. Discrete variables were analysed either with Poisson regression (mortality, whole- and partial-carcass condemnations, organ condemnations, arthritis, abscesses) or logistic regression (liver condemnations, pneumonia, pleuritis). The models were adjusted for the year, size of the herd and the average slaughter weight of the batch.The benefits obtained by the health classification of the feeder pigs included a substantial increase in daily gain (37g, about 5%) and decrease in time in the finishing unit (4 days, about 4%), decrease in mortality (odds ratio, OR 0.68), a substantial decrease in pneumonia (OR 0.37) and pleuritis (OR 0.60), and a substantial decrease in liver (OR 0.45) and organ (OR 0.72) condemnations. Classification of the pigs did not have an effect on the prevalence of whole-carcass condemnations, arthritis or abscesses. The health-classified pigs had, unexpectedly, more partial-carcass condemnations (OR 1.15) than the standard-class pigs. The obtained benefits of the LSO 2000 units were an increase in daily gain (14g, about 2%), decrease in time in the finishing unit (2 days, about 2%), a decrease in mortality (OR 0.69) and a decrease in whole-carcass (OR 0.69) and partial-carcass (OR 0.81) condemnations. The LSO 2000 units did not have any advantage over the non-LSO 2000 units in their prevalence of liver or organ condemnations, arthritis, abscesses, pneumonia or pleuritis.     

Noninfectious factors associated with pneumonia and pleuritis in slaughtered pigs from 143 farrow-to-finish pig farms

A cross-sectional study involving 143 farrow-to-finish herds was carried out to identify herd-level noninfectious factors associated with pneumonia and pleuritis in slaughter pigs. Data related to herd characteristics, biosecurity, management and housing conditions were collected by questionnaire during a farm visit. Climatic conditions were measured over 20 h in the post-weaning and finishing rooms where the slaughter pigs were kept. After these on-farm investigations, the finishing pigs were examined at slaughter for lung lesions. A sample of 30 randomly selected pigs per herd was scored for pneumonia and pleuritis. Herds were grouped into three categories according to their pneumonia median score (class 1: ≤ 0.5; class 2: 0.53.75). For pleuritis, a herd was deemed affected if at least one pig had a high pleuritis score (≥ 3). A multinomial logistic regression model was used to identify factors associated with pneumonia classes 2 and 3. A logistic regression for binary outcome was used to identify risk factors for severe pleuritis. An interval of less than four weeks between successive batches (OR=4.5, 95% confidence interval (95% CI): 1.5-13.6, p<0.01), large finishing room size (OR=4.3, 95% CI: 1.6-11.6, p<0.01) and high mean CO(2) concentration in the finishing room (OR=4.2, 95%CI: 1.6-11.3, p<0.01), significantly increased the odds for a herd to be in class 2 for pneumonia. The same risk factors were found for class 3 and, in addition, a direct fresh air inlet from outside or from the corridor in the post-weaning room vs an appropriate ceiling above the pigs (OR=5.1, 95% CI: 1.4-18.8, p=0.01). The risk for a herd to have at least one pig with a high pleuritis score was increased when the farrowing facilities were not disinsected (OR=2.7, 95% CI: 1.2-5.8, p=0.01), when tail docking was performed later than 1.5 days after birth (OR=2.6, 95% CI: 1.2-5.7, p=0.01) and if the piglets were castrated when more than 14 days old (OR=2.7, 95%CI: 1.1-6.8, p=0.03). A temperature range of less than 5°C for the ventilation control rate in the farrowing room (OR=2.7, 95% CI: 1.2-5.9, p=0.01), a mean temperature in the finishing room below 23°C (OR=3.0, 95% CI: 1.3-6.8, p<0.01) and large herd size (OR=3.1, 95% CI: 1.4-6.9, p<0.01) were also associated with increased risk of pleuritis. The factors affecting pneumonia and pleuritis seemed to be different. All rearing steps from farrowing to finishing must be taken into account in any health programme aimed at controlling pneumonia and pleuritis and lung health may be improved through several pathways, i.e. correcting managerial and hygienic factors, implementing an appropriate and well-functioning ventilation in order to offer favorable climatic conditions.     

Infections with Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae in fattening pigs. Influence of piglet production systems and influence on production parameters

Two hundred and sixty-four feeder pigs from an age-segregated herd (A-pigs) and 264 feeder pigs from a continuous production system (C-pigs) were transferred into identical but separate rooms in a fattening herd employing all-in all-out production. On arrival, none of the A-pigs and 39% of the C-pigs were seropositive to Mycoplasma hyopneumoniae (M. hyo). At slaughter 30% of the A-pigs and 99% of the C-pigs were seropositive to M. hyo. Pigs with acute swine enzootic pneumonia (SEP) at slaughter and pigs that seroconverted to M. hyo late in the rearing period showed a lower growth rate compared with pigs with chronic SEP or pigs that seroconverted to M. hyo early or not at all. No A-pigs and 12% of the C-pigs were seropositive to Actinobacillus pleuropneumoniae 2 (A. pp 2) at arrival to the fattening herd. At slaughter, 10% of the A-pigs and 13% of the C-pigs were seropositive to A. pp 2. On arrival, the prevalence of pigs seropositive to A. pp 3 was lower among A-pigs than C-pigs. During the fattening period the situation was reversed. The prevalence of pleuritis at slaughter was low (2.7-4.2%) and there were no associations between pleuritis at slaughter and developments of antibodies to A. pp 2 or 3. However, pigs with pleuritis developed antibodies to M. hyo to a greater extent than pigs without pleuritis. Pigs with pleuropneumonia at slaughter and pigs that seroconverted to A. pp 2 or 3 had, during certain periods of the rearing, higher growth rates compared with pigs without pleuropneumonia or pigs that did not seroconvert to A. pp 2 or 3.     

Pleuritis in slaughter pigs: Relations between lung lesions and bacteriology in 10 herds with high pleuritis

Pleuritis in slaughter pigs has increased in recent years in the Netherlands. The aim of the present study was to determine what respiratory pathogens were involved in pleuritis.In total, lungs of 968 slaughter pigs from 10 herds with high prevalence of pleuritis were morphologically examined for size, location, and type of lesions. Moreover, histology and bacteriology were performed.Examination of gross lung lesions showed 45% pleuritis, 14% pleuropneumonia and 38% catarrhal pneumonia. Peribronchiolar cuffing was found in 61 of 142 samples. Actinobacillus pleuropneumoniae was cultured from 22 lung samples from four herds. Pasteurella multocida was cultured from 55 lung samples in eight herds. No specific pattern with respect to the causal pathogens was found.In conclusion, no single infectious cause of pleuritis was found. A variety of infectious agents combined with environmental factors should be considered as a cause of pleuritis.     

Efficacy of an inactivated aqueous vaccine for the control of enzootic pneumonia in pigs infected with Mycoplasma hyopneumoniae

The efficacy of an inactivated aqueous vaccine against Mycoplasma hyopneumoniae was evaluated at two M hyopneumoniae-infected farrow-to-finish commercial farms (A and B) in Greece. In a prospective, randomised double-blind study, two groups on each farm received intramuscular doses of either the vaccine or the adjuvant when they were one and four weeks of age. The pigs were observed daily for clinical signs of disease; morbidity and mortality were recorded; and bodyweight was recorded at intervals. At slaughter, the lungs of the animals were examined and the chest cavities were examined for signs of pleuritis. No adverse reactions to the treatments were observed in any of the pigs. On farm A the vaccinated pigs were on average 6 kg heavier at slaughter, and on farm B they were on average 4 kg heavier; on both farms the average daily gain of the pigs was greater than that of the unvaccinated pigs. The prevalence and severity of enzootic pneumonia in the affected lungs were significantly lower in the vaccinated than in the unvaccinated pigs.     

Host determinants of pneumonia in slaughter weight swine

A prospective cohort study was undertaken in a farrow-to-farrow swine herd to describe patterns of pneumonia, and to identify host risk factors associated with the extent of pneumonic lesions in 2 weight groups of slaughter swine. The risk of coughing and pneumonic lesions increased with increasing age of pigs within the herd (P less than 0.0001). The age-specific prevalence of pneumonic lesions was low (2.7%) in pigs less than 16 weeks old at slaughter, but increased rapidly when pigs were between 16 and 22 weeks old (8.6 to 67.9%). After 22 weeks, the prevalence remained relatively constant at about 80%. Associations between possible risk factors and pneumonia were investigated by use of multiple-regression models. Age at weaning (less than 24 days) and birth weight (less than 1 kg) exerted small, but significant (P less than 0.002), effects on the extent of pneumonic lesions in pigs slaughtered at 30 to 50 kg live weight. For pigs slaughtered at 90 to 110 kg, pneumonic lesions were more extensive (P = 0.007) in pigs sired by Yorkshire boars than pigs sired by non-Yorkshire sires (Duroc, Hampshire, Chester White, or American Spotted). Other host factor variables including weaning weight and clinical diseases (atrophic rhinitis, diarrhea, and arthritis) were not associated with pneumonia extent in either weight group. Higher pneumonia percentages were also associated with reduced growth rates in the grower/finisher phase. Pigs sired by Yorkshire boars grew significantly (P less than 0.0001) more slowly from entry into shed 2 (mean, 38 kg) until about the time of exit (mean, 92 kg) than pigs sired by other breeds (747 g/d and 795 g/d, respectively).     

Field efficacy of a combined use of Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae vaccines in growing pigs

The effectiveness of simultaneous administration of commercial Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae vaccines was tested in an indoor commercial piggery which had experienced continuing respiratory-disease problems confirmed as due to both of these pathogens. Piglets were randomly assigned in equal numbers to vaccination and control groups, and each vaccine was administered at a separate site to assigned piglets at two and four weeks of age. Live weight of vaccinates immediately prior to slaughter was 2.49 kg higher (p = 0.04) than for controls at equal mean slaughter age of 132 days. Average daily gain (ADG) from 16 weeks to slaughter of vaccinates was also significantly higher (33 g/day) than in controls (p = 0.05). Daily gain was not significantly different in younger age groups. Active enzootic pneumonia lesions were more likely in control than in vaccinated pigs. There were no significant differences between vaccination groups with regard to severity of pleurisy or presence of pleuropneumonia lesions at slaughter. Log-linear modelling was used to test the statistical association between vaccination, enzootic pneumonia lesions, pleurisy lesions and pleuropneumonia lesions. It showed a reduction in the severity of enzootic pneumonia lesions for vaccinated pigs, and the presence of pleuropneumonia lesions increased the likelihood of pleurisy lesions. No other association was significant, and no evidence of synergy between the vaccines in influencing lesion severity for pleuropneumonia was detected (within the limitations set by the trial design).     

Survey of pleuritis and pulmonary lesions in pigs at abattoir with a focus on the extent of the condition and herd risk factors

Cranioventral pulmonary consolidation (enzootic pneumonia-like lesions) and chronic pleuritis (CP) are common findings in slaughtered pigs. Pleural lesions involving dorsocaudal lobes are suggestive of pleuropneumonia due to Actinobacillus pleuropneumoniae. In this report the results of an abattoir survey of pleuritis and pulmonary lesions in pigs is presented with a focus on herd risk factors. A total of 4889 animals, ranging in age from 9 to 10 months, from 48 batches of pigs belonging to an equal number of herds, were included in the study. Bronchopneumonic lesions suggestive of enzootic pneumonia (EP-like lesions) were detected in 46.4% of the examined lungs. The EP-like lesion average value for all lungs was 1.03 (95% CI 0.98-1.08), ranging from 0.17 to 2.56 among the 48 batches; 47.5% of lungs showed chronic pleuritis. Dorsocaudal pleuritis suggestive of recovered pleuropneumonia (SPES score ≥2) was found in 25.1% of the lungs. The mean SPES (slaughterhouse pleuritis evaluation system) value of the overall 4889 lungs was 0.83 (95% CI 0.78-0.86). The mean SPES value of the batches ranged from 0.04 to 1.87. The mean Actinobacillus pleuropneumoniae index of all studied batches was 0.61 (95% CI 0.51-0.71), ranging from 0 to 1.84. Blood samples were collected from each herd to evaluate antibody titres to Mycoplasma hyopneumoniae, A. pleuropneumoniae, Aujeszky's disease virus, porcine reproductive and respiratory syndrome virus (PRRSV), and swine influenza virus. Herd characteristics were recorded using a questionnaire given to the farmers. A multivariable analysis was conducted to identify risk factors for pleuritis and EP-like lesions. High dorsocaudal pleuritis was associated with A. pleuropneumoniae seroprevalence and history of A. pleuropneumoniae isolation from pneumonic lungs of dead animals. Vaccination of weaners at 3-5 weeks of age against PRRS using a modified live vaccine was associated with a reduction in the percentage of cranioventral pulmonary consolidation (EP-like lesions).     

Growth performance of pigs fed diets with and without tylosin phosphate supplementation and reared in a biosecure all-in all-out housing system

Three hundred and eighty-four pigs, mean initial live weight of 20.8 kg, were assigned randomly to groups of 24 (12 females, 12 castrated males). Each group was randomly assigned to 1 of 2 dietary treatments consisting of the same commercial barley-based diet, with or without the addition of tylosin phosphate. The barn where the animals were housed operates as an all-in all-out facility, and all pigs arrived on the same day as part of a group of 960 pigs. No new pigs were introduced into the facility during the period of this trial and pigs were sent to market over a 4-week period upon achieving a live weight of 110 kg. The pigs were weighed at the beginning of the trial and when they left the facility for slaughter. Feed consumption and incidence of disease, mortality, or both were recorded daily. At slaughter, carcass backfat depth over the last rib, 6.5 cm ventral to the dorsal midline (P-2 site); loin depth; carcass weight; predicted lean yield; and grade index were recorded. The sow herd supplying pigs to the unit was known to be free of the major swine diseases such as swine influenza, mycoplasma pneumonia, porcine reproductive and respiratory syndrome (PRRS), necroproliferative enteritis, and ascarids. A strict biosecurity protocol was employed to minimize the risk of introducing disease organisms into the unit. Prior to this study, no subtherapeutic antibiotics had been used in this facility. Tylosin phosphate supplementation had no significant effect on final weight, days on test, total gain, and daily gain. In both treatments, the pigs reached a mean market weight of 110.2 kg within 94.1 days, resulting in daily gains of the order of 950 grams per day. Due to the design of the trial, it was difficult to measure significant feed consumption effects. Feed consumption and conversion appeared to be similar for pigs in both treatment groups. At slaughter, tylosin phosphate supplementation appeared to significantly increase lean muscle content of the carcass as measured by loin muscle depth (P = 0.04). Mortality rates and the number of underweight pigs sent to market were low for this trial. Mortality was similar for both treatments; however, more of the control pigs than of the tylosin phosphate fed pigs were underweight when sent to market. From the results of this study, it appears that pigs of fast growing genotypes fed adequate diets and housed in a biosecure environment do not require dietary tylosin phosphate supplementation in order to maximize growth. There is some indication that tylosin phosphate supplementation may improve lean content of the carcass in pigs housed in such an environment.     

Measurement of conchal atrophy and pneumonic lesions and their association with growth rate in commingled feeder pigs

A group of 85 commingled feeder pigs was fed on a totally confined feeding floor until slaughter. Mean daily weight gain was calculated for each pig. At slaughter, the nose of each pig was cross-sectioned and scored for conchal atrophy by use of 2 methods. One method ascribed a score based on a linear measurement of the distance between the ventral scroll of the ventral conchae and the ventral floor of the nasal cavity. The other method ascribed a score based on a subjective evaluation of the degree of conchal degeneration according to previously published guidelines. The amount of pulmonary consolidation attributable to pneumonia was also estimated for each pig. Association was not found between growth rate and conchal atrophy, as determined by linear measurement scores. A negative correlation existed between growth rate and conchal atrophy, as determined by subjective evaluation scores. Pigs with extensive pneumonic lesions (consolidation of 20 to 30% of total lung volume) grew slower than pigs with milder pneumonic lesions. Results of this study indicate that subjective evaluation scores of conchal atrophy may be more useful in predicting growth rate than are linear measurement scores.     

Association of growth performance with atrophic rhinitis and pneumonia detected at slaughter in a conventional pig herd in Hungary

The influence of atrophic rhinitis (AR) and pneumonia on growth performance was assessed in a conventional farrow-to-finish pig farm affected by both diseases. All tested pigs (n = 138) were individually weighed at birth, at weaning, at moving to the growing/finishing unit, and at slaughtering. The extent (grade) of turbinate atrophy and lung consolidation attributable to pneumonia was determined in each pig at slaughter. A negative correlation was found between birth weight and the prevalence of nasal lesions at slaughter, suggesting that pigs born with smaller weight may be more susceptible to AR. The growth performance of the pigs also showed a negative correlation with the degree of turbinate atrophy. In the nursery period, the average daily gain (ADG) of pigs with moderate/severe turbinate atrophy was 13.3% lower than that of animals with healthy snouts. In the finishing period, pigs with mild AR lesions had an ADG reduction of 6.2%, while pigs with severe AR lesions had a significant, 9.4% reduction in ADG as compared to the AR-free pigs. The extent of weight gain reduction over the whole life cycle was very similar (approximately 6%) in the pigs having either AR or pneumonia alone. In those pigs where both respiratory diseases were present, their effects seemed to be added up (11.5%); however, nasal lesion scores and percentage of lung consolidation did not show statistically apparent interactive effects on growth performance.     

Comparison of the effect of pneumonia detected during lifetime with pneumonia detected at slaughter on growth in swine

Pneumonia in swine has been studied mainly at slaughter or necropsy. However, when performing slaughter or postmortem examinations, assessment of the true prevalence or lifetime extent of pneumonia is at best speculative. Radiography was used to evaluate lungs from pigs 21 to 150 days old. Follow-up slaughter examination was performed on pigs 180 days old. Individual percentage of pneumonia observed over the life of each pig and at slaughter were added to yield lifetime pneumonia scores. A significant (P = 0.0001) negative effect of lifetime pneumonia on growth rate was found. By comparison, slaughter examination proved to be a poor indicator of lifetime pneumonia; lesions were found to progress and regress dynamically throughout the life of pigs.     

The relationship between infectious and non-infectious herd factors with pneumonia at slaughter and productive parameters in fattening pigs

This paper explores the relationship between infectious and non-infectious herd factors with the occurrence of pneumonia at slaughter and productive parameters in fattening pigs on 39 fattening herds. A questionnaire was used to obtain environmental and management factors (non-infectious factors). Blood samples and lungs were obtained from 35 pigs in each herd at slaughter. Serological testing was performed for antibodies against three respiratory pathogens (infectious factors): porcine reproductive and respiratory syndrome virus (PRRSV), Mycoplasma hyopneumoniae (Mh) and Aujeszky's disease Virus-gE protein (ADV-gE). Lung lesion classifications were catarrhal-purulent bronchopneumonia (CPBP), pleuropneumonia (PLP) and pleuritis. A mean lesion value (MLV) was calculated for each lesion. ANOVA and logistic regression assessed statistical associations among MLV, average daily gain (ADG) and feed conversion ratio (FCR) (dependent variables) with infectious and non-infectious factors (independent variables). Mh vaccination was associated with a significant decrease in CPBP; high Mh seroprevalences was associated with an increased level of CPBP. FCR was negatively related with high seroprevalences for ADV-gE and Mh. No significant associations were seen for ADG.