Two major components of rations are energy and protein. Protein is the second major part of a ration. It is mainly supplied by vegetable and animal protein sources. Animal protein sources are of superior quality due to its more balance profile of essential amino acids. High cost and mal-practice of adultering the animal protein sources compelled the nutritionists to use vegetable protein sources. Vegetable protein sources are cheaper and available in more quantity but deficient in certain critical amino acids. Threonine is an important amino acid in nutrition of both mammals and birds. Practically, in diets threonine is usually either second, third or fourth limiting amino acid depending on the types of diets (Radke and Lewis, 1992). Vegetable protein sources can efficiently be incorporated in poultry ration by supplementing with synthetic sources of amino acids to bring them at par or near to that of animal protein sources.

Two hundred day-old broiler chicks were randomly distributed into five groups. Each group was further sub-divided into four replicates containing 10 chicks each and were reared in battery cages. Starter rations A, B, C, D and E containing 20% crude protein, 2900 k.cal ME/kg and threonine 1eve1s 0.70, 0.75, 0.80, 0.85 and 0.90 per cent, respectively were fed upto 28th day of age. Similarly finisher rations A, B, C, D and E containing crude protein 18.5%, 3000 k.cal ME/kg and 0.66, 0.70, 0.74, 0.78 and 0.82 per cent threonine levels were fed from 29th to 35th day of age, respectively. The chicks were weighed individually at day old and also at weekly intervals upto the end of the experiment. Weekly feed consumption was recorded for each experimental units separately. At the end of the experiment, three birds from each experimental units were picked up randomly and slaughtered to record he slaughtered data.

The weight gain of the birds fed on various experimental rations A, B, C, D and E from 0-5 weeks of age were 810.50, 1935.00, 1861.25, 1802.49 and 1748.00 gms, respectively. Significantly more weight gain was observed in birds fed on ration B, C, D and E containing various levels of threonine as compared to chicks fed on ration A. However, the result revealed non-significant difference between B&C and D&E.

The results of feed consumption indicated that birds on different experimental rations A, B, C, D and E were 1423.12, 2970.22, 2924.72, 3011.22 and 3015.07 gms, respectively. Significantly more feed was consumed by the chicks fed on rations B, C, D and E as compared to chicks fed on ration A.

Feed efficiency of the birds on different experimental rations A, B, C, D and E were 1.76, 1.54, 1.57, 1.67 and 1.72, respectively. Significantly better feed utilization was noticed in birds fed on ration B, while the birds fed on ration A was less efficient in feed utilization. However, non-significant difference in feed efficiency was observed between the chicks fed on ration A&E, B&C, E&D.

The abdominal fat percentage of the birds fed on different experimental rations A, B, C, D and E were 2.25, 2.15, 2.10, 2.05 and 2.08 per cent, respectively. The birds fed on ration D deposited less, while birds on ration A was high in abdominal fat. However, nonsignificant difference were observed among the chicks fed on ration A&B, B, C, D & E.
Statistical analysis of the data revealed non-significant effect of treatment on dressing percentage and weight of giblets i.e. gizzard, heart, spleen and liver.

The data regarding economical aspect of ration revealed that the average feed cost per kg of live weight of chicks fed on rations A, B, C, D and E were 15.47, 14.00, 14.42, 15.44 and 16.00 rupees, respectively. Apparently ration B was most economical in comparison with other rations.