A study was conducted to evaluate effect of threonine levels on performance of Ross broiler chicks during the period of 0 to 10 days.Diets were formulated based on NRC(1994) recommendations.All diets were isocaloric and isonitrogenous.Dietary treatments consisted of 4 graduations of total threonine (0.8% = NRC recommendation, 0.87% =average of NRC recommendation and Ross recommendation, 0.94% = Ross recommendation and 1.01% = more than Ross recommendation).Each of the four treatments was fed to four replicate pens of ten male commercial broilers in a completely randomize design.Food intake and body weight significantly (p<0.05) increased in 0.87% threonine containing diet.The best feed conversion ratio was observed in the chicks fed on ration containing 0.87% threonine (p<0.05) ,whereas , the lowest feed conversion retio was observed in case of chicks fed on retion containing 1.01% threonine(1.61 vs 1.7).Mortality did not vary significantly among chicks receiving all experimental diets.These data suggest that requirements for threonine suggested by NRC(1994) are inadequate.

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