The experimental procedures were approved by the Yangzhou University Animal Ethics Committee and complied with the China Code of Practice for the Care and Use of Animals for Scientific Purposes. A total of 120 Yangzhou male birds, 28 dold and with similar body weight, were obtained from a breeding farm. These birds were distributed to 12 pens of 10 birdsper pen. Each treatment was represented by 4 replicates (pens; 4 × 6 m; in the same room). The room temperature wasapproximately 22◦C, and no heat was provided. The birds were under natural daylight.