An abattoir survey of pneumonia and pleuritis in slaughter weight swine from 9 selected herds. II. Enzootic pneumonia of pigs: microbiological findings and their relationship to pathomorphology

Lungs from 191 slaughter pigs with gross lesions indicative of enzootic pneumonia of pigs (EPP) and 80 grossly normal lungs, all originating from 9 different herds, were subjected to microbiological and pathological examinations. The microbiological studies included both bacterial and mycoplasmal culture and also testing for Mycoplasma hyopneumoniae antigen in tissue by indirect immunofluorescent technique. M. hyopneumoniae, Pasteurella multocida and Mycoplasma hyorhinis were detected in 83%, 43% and 37% of the pneumonic lungs, respectively. Mycoplasma flocculare was the most frequently isolated organism in the non-pneumonic lungs. The greatest amounts of macroscopic pneumonia (25.2%) were recorded in lungs with all the three agents M. hyopneumoniae, P. multocida and M. hyorhinis present. The amounts of pneumonia in lungs with M. hyopneumoniae alone and in concurrence with P. multocida, were 9.3% and 15.6%, respectively. M. hyorhinis was also, in this study, associated with higher frequency of diffuse pleuritis. These findings indicate that M. hyorhinis might be involved in the pathogenesis of pneumonia in slaughter pigs. Ninety-six per cent of the isolates of P. multocida from pneumonic lungs could be characterized as type A. In the herds which had the most severe pneumonia problems, toxin production was detected in 83% of the P. multocida strains while only 28% were toxigenic in herds with subclinical to moderate pneumonia problems.     

An abattoir survey of pneumonia and pleuritis in slaughter weight swine from 9 selected herds. I. Prevalence and morphological description of gross lung lesions

The prevalence and pathomorphology of gross lung lesions were studied in 855 slaughter weight pigs from 9 selected herds in south-eastern Norway. Pneumonic or pleuritic lesions were found in 84% of the lungs, ranging from 37% in the least affected herd to 97% in the one most affected. Bronchopneumonia indicative of a primary Mycoplasma hyopneumoniae infection was found in 70% of the lungs, ranging from 9% to 82% in the individual herds. The amount of bronchopneumonic lesions in individual lungs ranged from 0 to 69%, with an average of 7.8%. Pleuropneumonia indicative of Actinobacillus (Haemophilus) pleuropneumoniae infection was found in 29% of the lungs ranging from 0 in the least affected herd to 58% in the most affected. Diffuse pleuritis was found in 41% of the lungs and the prevalence ranged from 4% to 63%.     

An abattoir survey of pneumonia and pleuritis in slaughter weight swine from 9 selected herds. IV. Bacteriological findings in chronic pneumonic lesions.

A total of 855 pig lungs were collected at slaughter and evaluated macroscopically. Bacteriological examinations were carried out on tissue samples from chronic pleuropneumonic lesions (n = 196) and from chronic bronchopneumonic lesions with suppuration (n = 14). Samples from normal lung tissue (n = 22) were also included. Pasteurella multocida was isolated from 54%, Actinobacillus (Haemophilus) pleuropneumoniae from 11%, and Streptococcus spp. from 14% of the pneumonic lesions, respectively. From normal lung tissue P. multocida was isolated from 3 (14%) of the samples, A. pleuropneumoniae was not recovered and streptococci were isolated from only 1 (5%) of these samples. The above mentioned bacterial species were recovered either in pure cultures or mixed with various other microbes. A total of 109 P. multocida strains were further characterized by capsular serotyping and testing for production of dermonecrotic toxin. Ninety-nine (91%) of the strains were capsular type A 10 (9%) were type D. Out of the type A and the type D strains 94% and 90% were toxigenic, respectively. Most of the A. pleuropneumoniae strains were serotype 2. Strains of serotypes 1 and 7 were also identified. The majority of the streptococci were identified as either Streptococcus suis or Streptococcus dysgalactiae. Actinomyces pyogenes was isolated from 14% of the lesions and anaerobic bacteria from 18%, respectively. The significance of the various bacterial species in relation to the development of chronic pneumonic lesions is discussed. Special attention is paid to P. multocida, and it is concluded that this bacterial species is probably of importance for the development of both types of chronic pneumonias.     

Effects of dietary vitamin E and fat supplementation in growing-finishing swine fed to a heavy slaughter weight of 150 kg: II. Tissue fatty acid profile,vitamin E concentrations,and antioxidant capacity of plasma and tissue

The study aimed to assess the effects of vitamin E (VE) supplementation and fat source on fatty acid (FA) composition, VE concentrations, and antioxidant capacity in plasma and tissues of pigs fed to a heavy slaughter weight (150 kg). A total of 64 pigs (32 barrows, 32 gilts; 28.41 ± 0.83 kg) were blocked by sex and weight, and randomly assigned to one of eight dietary treatments (n = 8 per treatment) in a 4 × 2 factorial arrangement. Fat sources included corn starch (CS), 5% tallow (TW), 5% distiller’s corn oil (DCO), and 5% coconut oil (CN); VE supplementation levels were 11 and 200 ppm. Five-phase diets were formulated to meet requirement estimates of NRC (2012) and fed to pigs for each period of 25 kg from 25 to 150 kg. Increasing VE supplementation level increased C16:1 (P < 0.05) content but decreased C20:0 (P < 0.05) content in backfat and belly fat, while in liver, it increased C17:0 (P < 0.05) but decreased C18:0 (P < 0.05). Compared to the pigs fed the CS diet, the pigs fed the CN diet had greater (P < 0.05) content of total saturated FA, the pigs fed the DCO diet had greater (P < 0.05) content of total polyunsaturated FA content and iodine value, and the pigs fed the TW diet had greater (P < 0.05) content of total monounsaturated FA in backfat, belly fat, and liver. Plasma VE concentrations increased linearly (P < 0.05) with increasing length of feeding but faster (P < 0.05) in the pigs fed the CN and TW diets compared with the CS and DCO diets within the 200 ppm VE level; the pigs fed the DCO diet had the highest plasma VE concentrations (P < 0.05) from Phase 2 to Phase 5 within the 11 ppm VE level. The VE concentrations in liver and loin muscle (P < 0.05) increased with increasing dietary VE level from 11 to 200 ppm, but it was not affected by dietary fat source. There was no effect of VE supplementation and fat source on antioxidant capacity in plasma and liver except that pigs fed the DCO diet had greater liver SOD activity (P < 0.05) than the pigs fed the CN diet. In conclusion, dietary VE supplementation did not affect FA profile in backfat, belly fat, and liver consistently, while dietary FA composition with different fat sources affected much of the FA profile in backfat, belly fat, and liver. The higher level of VE supplementation increased liver and muscle VE concentrations and dietary fat sources affected plasma VE concentrations differently (P < 0.05), wherein the TW and CN diets increased the VE absorption greater than the DCO diet.