Abstract
Transferrin polymorphisms and growth rate up to 12 weeks of age were observed in RIR. crossbreds and native chickens. $Tf^{BB}$ genotype was observed in all types of bird. $Tf^{BC}$ occurred only in crossbred and native chickens. Frequency of $Tf^B$ was the highest in all types. Mean body weights at 8- and 12- weeks of age were the highest in RIR ($292{\pm}37.77$ and $612{\pm}75.69g$ respectively) and the lowest in natives for $Tf^{BC}$ ($180{\pm}11.54$ and $308{\pm}4.94g$ respectively). The difference in 12 week body weigh t of crossbreds between $Tf^{BB}$ and $Tf^{BC}$ was found to be significant (p<0.05). The results indicate that crossbreds ($Tf^{BB}$) may be grown effectively upto 12 weeks of age under Bangladesh conditions.