Relationships among treatment for respiratory tract disease, pulmonary lesions evident at slaughter, and rate of weight gain in feedlot cattle.
OBJECTIVE
To quantify the effects of treatment for clinical respiratory tract disease and pulmonary lesions identified at slaughter on rate of weight gain in feedlot cattle.


METHODS
Prospective longitudinal study.


METHODS
469 feedlot steers.


METHODS
Clinical respiratory tract disease was monitored between birth and slaughter. Steers were weaned at approximately 6 months old and entered into the feedlot for a mean of 273 days. Mean daily weight gain (MDG) was monitored during the feeding period. Lungs were collected at slaughter and evaluated for gross lesions indicative of active or resolved pneumonia.


RESULTS
Mean daily weight gain during the feeding period was 1.30 kg, and ranged from 1.16 to 1.46 kg within individual pens. Thirty-five percent of steers received treatment for respiratory tract disease between birth and slaughter, whereas 72% had pulmonary lesions evident at slaughter. Among steers treated for clinical respiratory tract disease, 78% had pulmonary lesions, whereas 68% of untreated steers had pulmonary lesions. Pulmonary lesions at slaughter were associated (P < 0.01) with a 0.076-kg reduction in MDG during the feeding period. Treatment for clinical disease was not associated with MDG after adjustment for the effect of pulmonary lesions.


CONCLUSIONS
Treatment of clinically affected feedlot cattle may be inadequate to prevent significant production losses attributable to respiratory tract disease.
Wittum
T E
TE
USDA, ARS, US Meat Animal Research Center, University of Nebraska-Lincoln, Clay Center 68933, USA.
Woollen
N E
NE
Perino
L J
LJ
Littledike
E T
ET
D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D008137:Longitudinal Studies; D008168:Lung / Q000473:pathology*; D008297:Male; D011446:Prospective Studies; D012140:Respiratory Tract Diseases / Q000378:metabolism / Q000628:therapy / Q000662:veterinary*; D015430:Weight Gain