Health classification of multisource feeder pigs—a field trial

Health classification of purchased multisource feeder pigs was tested in a field trial. Feeder pigs transported to the all-in all-out finishing units were classified according to the health status of the source herd. Health class (HC) feeder pigs originated from the farrowing units which were free of clinical signs of respiratory diseases and swine dysentery, and free of Mycoplasma hyopneumoniae antibodies. Performance and meat inspection results of 20 HC and 384 conventional control batches (health status unknown) were analysed. Previous batches from the same herds were used to adjust the differences between HC and conventional batches by herd effect. Mean average daily gain (ADG) was 839 g in the HC group and 803 g in the conventional group. ADG improvement from previous batch to test batch was 28 g better (P < 0.01) in the HC group than in the control group. After adjusting the results for slaughter weight, supply district and herd effect, the obtained difference in ADG between the HC and the conventional batches was 24 g. Mortality in the HC batches was 20% less (P < 0.1) than in the control batches. Organ condemnations were about 40% less frequent in the HC group than in the control group (P < 0.01). There were no significant differences in whole carcass or liver condemnations. Partial carcass condemnations (PCC) were 1.4 times more frequent in the HC group than in the control group (P < 0.01). Joint infections were the specific reason for increased PCC. Abscesses (another usual cause of PCC) did not differ between the HC and the conventional batches. The greatest differences were found in pneumonia and pleurisy. Pneumonia findings were almost nine times more frequent (P < 0.01) in the control group (11.1%) than in the HC group ( 1.3%). Pleurisy findings were nearly twice as common iii the control group than in the HC group (P<0.01).