title: Health and growth performance of barrows reared in all-in/all-out or continuous flow facilities with or without a chlortetracycline feed additive.
abstract: OBJECTIVE
  To compare health and growth performance in barrows reared in all-in/all-out (AIAO) or continuous flow (CF) management systems.
  
  
  METHODS
  400 barrows.
  
  
  METHODS
  Barrows (approx 2 months old) were allotted to 4 replications (100 barrows each); barrows were housed in AIAO or CF rooms (10 pens/room), and 50 pigs/replicate received chlortetracycline (CTC, 110 mg/kg of feed). Barrows 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 lean 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 barrows 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 lesions than did lungs of barrows reared in CF facilities (1.74% vs 9.52%). Addition of CTC did not affect prevalence and extent of lung lesions. Extent of lung lesions was positively correlated with change in serum optical density (OD) to Mycoplasma hyopneumoniae (r = 0.35), but not with change in serum OD to Actinobacillus pleuropneumoniae. Lean growth and serum OD to M. hyopneumoniae and A. pleuropneumoniae were not correlated.
  
  
  CONCLUSIONS
  Health and growth performance were better for barrows in an AIAO facility, compared with a CF facility, but addition of CTC to feed failed to enhance health or performance of barrows in either facility.
mesh_terms: D000821:Animal Feed; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D019072:Antibiotic Prophylaxis / Q000662:veterinary*; D001424:Bacterial Infections / Q000517:prevention & control / Q000662:veterinary*; D002751:Chlortetracycline / Q000008:administration & dosage / Q000627:therapeutic use*; D005503:Food Additives; D006799:Housing, Animal; D007559:Ivermectin / Q000008:administration & dosage / Q000627:therapeutic use; D008099:Liver / Q000187:drug effects / Q000473:pathology; D008168:Lung / Q000187:drug effects / Q000473:pathology; D008297:Male; D009919:Orchiectomy; D010273:Parasitic Diseases, Animal / Q000517:prevention & control; D013552:Swine / Q000254:growth & development*; D013553:Swine Diseases / Q000517:prevention & control*; D015430:Weight Gain / Q000187:drug effects