Growth performance, carcass characteristics, and the incidence of ascites in broilers in response to feed restriction and litter oiling

The effect of feed restriction and the application of canola oil to broiler straw litter to contain respirable dust on growth performance, carcass tra its, and the incidence of ascites was evaluated with 800 male broilers stud ied in two 6-wk periods. Two pens of birds were feed restricted. Two pens o f birds received feed ad libitum for the 6-wk trial. One restricted and one ad libitium pen received biweekly addition of canola oil to the litter. At 6 wk of age, 30 birds from each pen were killed for determination of breas t muscle, fat pad, and heart weights. All birds were scored for the inciden ce of ascites at processing. A cross sectional image of each heart was digi tally recorded and, using image analysis, the right ventricular area (RVA), left ventricular area (LVA), and total heart area (HA) were determined. Th e right ventricular wall was removed and its weight was expressed as a perc entage of total heart weight (PRVW). The 40-d BW was significantly greater in the ad libitum birds (2.07 kg) tha n in the feed-restricted birds (1.86 kg). The right ventricular weight (RVW ) (1.69 and 1.92 g) and the RVA (0.35 and 0.40 cm(2)) were also significant ly different between the two feeding treatments. The ascites score was sign ificantly correlated to the RVW (r = 0.50) and RVA (r = 0.52). The RVA was also correlated to the RVW (r = 0.63). Oiling the litter did not result in differences in carcass characteristics. Litter oiling significantly reduced the RVA of the ad libitum birds (0.36 cm(2)) compared to the ad libitum bi rds that did not have oiled litter (0.44 cm(2)). Feed restriction reduced t he incidence of ascites, but also reduced gain. Litter oiling in the feed-r estricted groups reduced the RVA, but did not reduce mortality.