Effects of air velocity applied from 11 to 21 days of age on growth performance, body size traits, serum biochemical variables, and intestinal digestive enzyme activities of Pekin ducks at 42 days of age.

This study was conducted to determine whether air velocity applied during the brooding period exerts carryover effects on subsequent growth performance, body size traits, serum biochemical variables, and intestinal digestive enzyme activities of Pekin ducks at 42 d of age. A total of 90 healthy 7-d-old male ducks with similar initial body weight were randomly assigned to 3 air velocity treatments (0, 0.5, and 1.0 m/s), with 3 replicates per treatment and 10 ducks per replicate. Air velocity treatments were applied from 11 to 21 d of age, after which all ducks were reared under the same conventional conditions until 42 d. Feed intake and body weight were recorded throughout the experiment, whereas body size traits, slaughter traits, serum biochemical variables, and intestinal digestive enzyme activities were determined at 42 d of age. As a result, air velocity significantly affected BW, ADG, ADFI, and FCR at 42 d of age (P=0.001 for each variable). Ducks exposed to 1.0 m/s during brooding had the highest BW, ADG, and ADFI and the lowest FCR among the three treatments. Oblique body length, keel length, chest depth, chest width, and hip width were also greater in the 1.0 m/s group, whereas several other body size traits were unaffected. Breast muscle yield (P=0.260) and leg muscle yield (P=0.088) were not affected by treatment, whereas abdominal fat weight (P=0.024) and abdominal fat yield (P= 0.020) were higher in the 1.0 m/s group. Among the serum biochemical variables, only UA differed among treatments (P=0.0013), whereas GLU, TP, LDH, AST, ALT, LDL-C, HDL-C, TG, and CHOL were unaffected. Activities of lipase, trypsin, amylase, sucrase, maltase, and alkaline phosphatase were generally higher in ducks exposed to 1.0 m/s during brooding, with significant treatment effects observed in the duodenum, jejunum, and ileum, whereas no significant differences were detected in the cecum. These findings indicate that air velocity applied from 11 to 21 d of age can exert carryover effects on subsequent growth, body development, carcass fat deposition, and luminal digestive enzyme activity in Pekin ducks.