The study was conducted to compare the appearance, morphology, and fighting behaviors of the Asil and American crossbred roosters. A total of 30 roosters 8-10 months of age were arranged in a completely randomized design with 2 treatments corresponding to 2 breeds: Asil and American crossbred. Each treatment was reproduced 15 times with 1 rooster per time. Each rooster was isolated in an individual cage at the household in Chau Hoa commune, Giong Trom district, Ben Tre province. The appearance characteristics were observed directly and the chicken's body indexes were measured directly. The fighting behavior was assessed by the recorded videos. The results showed that the Asil crossbred roosters had red and white neck feathers (26.67%), red-orange body feathers (33.33%), blue-black tail feathers (60%), strawberry comb (66.67%), yellow in legs (33.33%) and beak (40%), and orange eyes (46.67%). American crossbred roosters had red feathers in the neck (40%) and body (40%), blue-black tail feathers (73.33%), strawberry comb (66.67%), yellow in legs (53.33%) and eyes (73.33%), and yellow-black beak (46.67%). There was a statistically significant difference in some morphological characteristics between American and Asil crossbreds (P0.05).

Keywords: Appearance characteristics, morphology, fighting behavior, rooster