AIR VELOCITY AND HIGH-TEMPERATURE EFFECTS ON BROILER PERFORMANCE

Three trials, using a total of 1,320 male broilers, were conducted to study the effect of air velocity at 125 m/min on body weight gain and feed: gain. The broilers were placed on litter in pens in a wind tunne l or on litter in floor pens with conventional cross ventilation when 4 wk old. Except for air velocity, the conditions in the floor pens an d the tunnel were the same. In Trials 1 and 2, only nipple waterers we re used. In Trial 3, one-half of the pens on the floor and one-half of the pens in the tunnel were equipped with trough waterers; the remain ing pens were equipped with nipple waterers. When compared with conven tional ventilation, tunnel rearing improved body weight gain and feed: gain in all three trials. In Trial 3, waterer type did not significant ly affect body weight gain or feed:gain in the tunnel. However, body w eight gain and feed:gain were reduced in floor-reared birds using nipp le waterers as compared with birds using trough waterers. The increase d panting of the conventionally ventilated birds, as compared with the tunnel-ventilated birds, may have contributed to their decreased body weight gain and improved feed:gain. The lower body weights may occur because of the difficulty the birds experience when drinking from nipp les while panting.