Health and growth performance of barrows reared in all-in/all-out or continuous flow facilities with or without a chlortetracycline feed addictive

Objective-To compare health and growth performance in barrows reared in all -in/all-out (AIAO) or continuous flow (CF) management systems. Animals-400 barrows. Procedure-Barrows (approx 2 months old) were allotted to 4 replications (10 0 barrows each); barrows were housed in AIAO or CF rooms (10 pens/room), an d 50 pigs/replicate received chlortetracycline (CTC, 110 mg/kg of feed). Ba rrows from each pen were slaughtered at 3, 4, 5, and 6 months old. Results-Barrows in the AIAO room had greater total daily gain (TDG) and lea n daily gain (LDG) than did barrows in the CF room. Addition of CTC did not improve TDG or LDG in either environment. Barrows in the AIAO room reached body weight of 104.5 kg in 169.7 days, compared with 177.3 days for barrow s in the CF room. Feed-to-gain ratio was not affected by management or CTC. Lungs from barrows reared in AIAO facilities had a lower percentage of les ions than did lungs of barrows reared in CF facilities (1.74% vs 9.52%). Ad dition of CTC did not affect prevalence and extent of lung lesions. Extent of lung lesions was positively correlated with change in serum optical dens ity (OD) to Mycoplasma hyopneumoniae (r = 0.35), but not with change in ser um OD to Actinobacillus pleuropneumoniae, Lean growth and serum OD to M hyo pneumoniae and A pleuropneumoniae were not correlated. Conclusions-Health and growth performance were better for barrows in an AIA O facility, compared with a CF facility, but addition of CTC to feed failed to enhance health or performance of barrows in either facility.