Three experiments were conducted to investigate the use of supplemental sulfur amino acids and reduce protein level in diets for broiler breeder hens. The first experiment studied the effect of genotype (meat-type or egg-type) on the AME digestibility of selected ingredients. The ingredients included samples of cereals (corn, wheat and barley), one sample of plant protein (soybean meal) and one cereal by-product (wheat bran). Forty adult males (20 per breed) were randomly assigned to five feedstuffs. The AME of each feed ingredient was calculated from the difference between GE intake and GE losses in the droppings. The results showed the average AME n digestibility in wheat and barley samples were similar in two breeds. However, the AME n digestibility in White Leghorn birds was significantly greater for corn, soybean and wheat bran compare to the broiler strain. These results suggest that broiler breeder hens derived less metabolizable energy from feedstuffs than White Leghorn birds. In second experiment, eight hundred females and 100 males commercial strain breeders (Hubbard × Hubbard) were individually weighed. Eight hens with one male transferred to breeding pens. Hens were randomly sorted into 25 treatment groups. Treatments were involved different feeding levels of CP (17.5, 16.0, 14.5, 13.0 and 11.5%) and sulfur amino acids (0.69, 0.66, 0.63, 0.60 and 0.57%). Diets were isoenergetic and all birds received the same quantity of feed daily. Birds fed 14.5% CP had higher egg production. Settable eggs from birds fed 11.5 and 16.0% were higher than other groups (p 0.05). Dietary sulfur amino acids had no effect on egg production. Birds fed 11.5% CP had lighter weight than other groups. Eggs from birds fed 11.5 and 13.0% CP, and 0.57 and 0.60% sulfur amino acids were significantly smaller and resulted in reduce chick weight at hatching. Breeders fed 11.5% CP had higher efficiency for producing one settable egg or day-old-chick. The lowest liver weight and highest fat pad weight related to hens fed 17.5% CP. Birds fed 0.69% sulfur amino acids had lowest fat pad. In third experiment, the effect of dietary protein and sulfur amino acids of broiler breeder diets, on offspring performance. Forty broiler day-old-chicks were produced from each treatment at 39 weeks, weighed and transferred to hundred group pens. Each treatment included four replicates and ten broiler chicks per replicate. Breeder’s dietary protein had no effect on body weight and feed conversion ratio at 49 days. Also, dietary sulfur amino acids of broiler breeders had no significant effect on these t
