Abstract

The present study was conducted to investigate the effect of dietary protein levels and citric acid on the growth performance, carcass yield, abdominal fat, chemical composition of meat, intestinal morphology, and blood parameters of broiler chickens. A total of 160 Cobb 500 unsexed one-day-old broilers were assigned to 4 dietary treatments, 4 replicates of 10 chickens each. A factorial design arrangement 2×2 was used, including two protein levels, 100% (optimal level) and 90% (low level) of recommended dietary crude protein for cobb 500 broiler chickens, each protein level supplemented with or without 20-gram citric acid /kg. The results showed that chickens fed the diet containing 100% required Crude Protein (CP) supplemented with citric acid which could significantly improve body weight gain, feed conversion ratio, carcass yield, abdominal fat, fat content in meat, intestinal morphology, cecal microbial content, and blood parameters (Albumin, haemoglobin Ac1, fructosamine, and cholesterol). Chickens fed the low CP diet supplemented with citric acid could compensate for the growth performance equivalent to those fed the optimal CP diet. Both required protein level and citric acid were significantly improved blood albumin and reduced haemoglobin Ac1 and fructosamine, which could serve as indicators of the blood protein glycation. In conclusion, citric acid addition could alleviate the negative effect of feeding broiler chickens on low CP diets through its beneficial impact on intestinal morphology, cecal bacterial counts, blood cholesterol reduction, and glycated proteins.