A Survey of the relationship between management practices and risk of acute interstitial pneumonia at US feedlots
Keywords:animal husbandry, feedlots, morbidity, mortality, pneumonia, risk, vaccination
Acute interstitial pneumonia (AIP) is a recognized cause of feedlot morbidity and mortality, but the cause is unknown. Management practices have been suggested to contribute to the pathogenesis of AIP, but little supportive data exists. A cross-sectional survey of US feedlots evaluated the relationship between management practices and subjective and objective measures of AIP risk. Of 65 respondents, 75.4% recognized AIP as a cause of morbidity or mortality in their feedlot. Managers reported that 80.5% of AIP deaths occurred in cattle on feed over 60 days, 62% of AIP deaths occurred in the summer and 62.2% of AIP deaths were heifers. Thirty-three feedlots reported the percent of placements that died of AIP, which ranged from 0.001-0.75%. Feedlots in northern states were less likely to report AIP as a cause of morbidity/mortality, while larger feedlots and feedlots placing higher proportions of yearlings more often recognized AIP as a cause of morbidity/mortality. Although heifers were recognized to account for 62% of AIP deaths, feedlots placing a large proportion of heifers were not more likely to recognize AIP as a cause of morbidity/mortality than feedlots placing a small proportion of heifers. Feedlots that vaccinated over 95% of cattle for Mannheimia haemolytica/Pasteurella multocida were less likely to recognize AIP as a cause of morbidity/mortality than feedlots who vaccinated less than 95% of cattle for these pathogens. The percent of cattle dying of AIP in feedlots that vaccinated over 95% of cattle for Mannheimia/Pasteurella was 0.06%, compared to 0.14% for feedlots vaccinating less than 95% of cattle for these pathogens. Although these data must be interpreted in light of the limitations of a survey as a data collection device, results suggest the impact of feedlot location and size, animal gender and vaccination strategy merit further scrutiny in research to determine the cause of feedlot AIP.