This investigation aimed to evaluate the effect of methionine and/or betaine supplementation on performance, carcass characteristics and economic efficiency of broilers that fed low protein diets. A total numbers of 180 one day old unsexed Hubbard broiler chicks were divided into six treatments (30 birds each). Each treatment contained 3 replicates of 10 birds. Two levels of dietary crude protein (recommended, D1) control diet, and low protein (-2% crude protein, D2), treatment diets (T1-T5) and DL- methionine (MET), or betaine (BET), were added in experimental treatment diet as follows:
1- Chicks were fed control diet (D1) control
2- Chicks were fed low protein diet (-2% crude protein, D2) (T1)
3- Chicks were fed D2 + 100% MET (T2)
4- Chicks were fed D2 + 50% MET + 50% BET (T3)
5- Chicks were fed D2 + 25% MET + 75% BET (T4)
6- Chicks were fed D2 + 100% BET (T5)
All diets (control and T1-5) were equal in lysine % while MET add in the T2 diets up to control diet.
The results indicated that:
1- Body weight gain during whole experimental period were not significantly affected by different dietary treatments, where feed intake, and feed conversion ratio performance index (PI) and production efficiency factor (PEF) were significantly affected. Moreover chicks fed the high protein diets reflected the highest body weight gain value and the best in feed conversion compared with those fed the low protein diets (T1-5).
2- Carcass characteristics parameters % (carcass, liver, gizzard, heart, giblets and total edible parts) showed in some cases the highest significant figures when broiler chicks fed diets containing BET (T4 and T5) compared to other treatments.
3- Economic efficiency values were improved in chicks fed low protein diets supplemented with MET and/or BET as compared with those fed unsupplemented diets and chicks fed control diet showed the highest economical evaluation compared with the other treatments (T1-5).
Therefore, it could be concluded that MET and BET supplementation have been recommended in low-protein broiler diets to support and enhance economic efficiency.