An experiment was conducted to determine the effect of partial or total switching soybean meal (SM) by Guar meal (GM) in broiler diets (started, grower, and finisher1) 7-35 days of age and feed all birds (SM) in (finisher2) diet 36-42 days of age on productive performance, carcass characteristics, and economical evaluation of broiler chicks.  Five levels of GM representing [control (100% SM + 0.00% GM), T1= 87.5% SM+12.5% GM, T2=75% SM+25% GM, T3=50% SM+50% GM and T4=0.00% SM+100% GM] during starter (7-21 days), grower (22-28 days) and finsher1 (29-35 days) stages then all broiler chicks fed on finsher2 diets (36- 42 days, 100% SM). 7 days- old 125 Ross broiler chicks (housed 5 birds/cage) were allotted into the five treatments, each containing 25 chicks in 5 replicates per treatment. Body weight (BW) and feed intake (FI) were recorded and body weight gain (BWG) and feed conversion ratio (FCR) were calculated. Feed and water were supplied ad-libtum. At the end of experiment, 3 birds from each treatment were randomly selected and slaughtered for carcass measurements.
The results showed that:

Body weight (BW), Body weight gain (BWG) and feed intake (FI) linear decrease with increase GM concentration in diets during experimental period (7-42) days of age and, in turn, caused whole linear increase in feed conversion ratio (FCR) values.
Dietary supplementation of GM had no effects on the relative weight of carcass characteristics except gizzard% and giblets%.
Dietary supplementation of (GM) had significant effects on the figures of tibia and plasma parameters except Albumin and GOT.
Price of kg feed and feed intake cost liner decrease with increase GM concentration, however; relative economic efficiency (REE) was decreased with increasing the levels of GM in broiler diets.
Broiler chickens fed (87.5% SM+12.5%GM, T1) gave the best results of BW, BWG, FI, FCR and REE, without any adverse effect on carcass and bone traits and some blood plasma parameters.
Conclusion: Guar meal can be used as a replacement for soybean meal at level of (87.5% SM+12.5%GM) in broiler diets from (7-35) days then fed on (0.00 GM) up to 42 days of age for better performance, carcass characteristics and relative economic efficiency.