Effects of distance and barriers between resources on bone and tendon strength and productive performance of broiler chickens

Lameness or leg weakness is becoming an important problem in broilers selected for rapid growth, and although the causes are not known, sedentary behavior could be a cause. Two experiments were conducted to study the effects of distance and the presence of ramps between resources (feed and water) on bone and tendon strength, ability to stand, and productive performance. In experiment 1, straight run Ross 708 chicks (n = 1,260) were randomly assigned to 1 of 3 treatments: 1.0, 3.3, or 6.6 m between resources (6 pen replicates/treatment). In experiment 2, Cobb 500 male chicks (n = 864) were randomly assigned to 1 of 4 treatments (2 x 2 factorial, 4 pen replications/treatment) consisting of 2 distances (3 or 8 m) with (WR) or without (NR) a ramp (a triangular prism 31 cm high and 132 cm wide at the base). At d 21, 45, and 56 (experiment 1), or at d 28, 35, 42, and 49 (experiment 2), birds were weighed, killed, and tibias collected to measure breaking strength (BBS), and abdominal fat (AbF) content. At d 49 (experiment 2), calcaneus ten-dons were also collected to measure breaking strength (TBS). Foot pad lesions and latency to lie (LTL) were determined before killing the birds. In experiment 1, distance did not affect BBS, LTL, foot pad lesions, or BW, but at d 49, birds in the 6.6 m treatment had lower AbF than birds in the other treatments. In experiment 2 at d 49, birds in the 8 m treatment tended to have a higher BBS than birds in the 3 m treatment (P = 0.09), whereas WR birds had lower tendon breaking strength than NR birds (P < 0.01); however, LTL was highest in 8-m NR birds. Final BW was not affected by distance, but birds in the NR group were heavier than birds in the WR group. Furthermore, AbF was lower in 8 m than in 3 m birds. Our results suggest that longer distances between resources have limited effects on bone strength, but increase the LTL, and may change feeding patterns and carcass characteristics, as evidenced by the lower AbF content. Ramps or inclination affected tendon breaking strength.