Evaluating portable wire-flooring models for inducing bacterial chondronecrosis with osteomyelitis in broilers

Rearing broilers on flat or sloping wire flooring is an effective method for consistently triggering lameness attributable to bacterial chondronecrosis with osteomyelitis (BCO). Portable obstacles known as speed bumps (SB) also consistently trigger modest incidences of BCO when they are installed between feed and water lines in litter flooring facilities. Two experiments were conducted to determine the most effective broiler age for introducing the SB into litter flooring pens, and to evaluate alternative configurations of the traditional SB with the expectation that amplified mechanical challenges to the legs of broilers should increase the incidence of BCO. Broiler chicks obtained from commercial hatcheries (lines B and D in experiment 1, lines A and B in experiment 2) were reared in floor pens with ad libitum feed and water and a 23L:1D photoperiod. In experiment 1, the 5 floor treatments included wood shavings litter only (L), flat wire only (W), or litter plus SB installed at 14, 28, or 42 d of age. Line B was more susceptible to lameness than line D (25.9 vs. 15.3% for all treatments combined; P = 0.001). Both lines developed low incidences of lameness on L (11 to 13%), intermediate incidences on SB regardless of day of installation (12 to 23%), and high incidences on W (21 to 39%). In experiment 2, broilers were reared with 7 floor treatments, including L, W, SB with a 50% slope (SB50%); SB50% with a limbo bar installed over the apex; SB with a 66% slope and limbo bar; SB50% with a nipple water line suspended over the apex; and a pagoda-top SB. All SB were inserted on d 28. Line B was more susceptible to lameness than line A (20.2 vs. 16.1% for all treatments combined; P < 0.05), and for both lines combined the lameness percentages averaged 7.7 (L), 29.2 (W), 17.3 (SB50%), 16.2 (SB50% with a limbo bar), 21.5 (SB with a 66% slope and limbo bar), 20.8 (SB50% with a nipple water line), and 11.5% (pagoda-top). These studies demonstrate the portable SB can be effectively used to experimentally trigger BCO in broilers.