Effect of in ovo Feeding of Graded Levels of L-glutamine on Blood Biochemistry, Colour and Texture of Selected Muscles, Carcass Quality Traits of Coloured Chicken during Heat Stress

Abstract

Glutamine (Gln) has gained attention as a promising feed additive due to its ability to promote the growth of intestinal villi. Glutamine, a non-essential amino acid is found predominantly in the blood and intracellular space, serves as a vital energy source for rapidly dividing cells, particularly enterocytes. Early in ovo supplementation with glutamine (Gln) has been found to promote the development and maturation of the intestinal epithelium and skeletal muscle, offering both immediate and long-term benefits after hatching. The present study was designed to study the effect of in ovo feeding of graded levels of L-Gln supplementation on blood biochemistry, colour and texture of selected muscles and carcass quality traits of coloured chicken. Four hundred and eighty six fertile eggs of coloured chicken (Chabro) were set for incubation. On 18th day of incubation, fertile eggs were divided into five treatment groups – un-injected control (T1), injected with distilled water (Sham Control) (T2), injected with 0.5 ml of 0.5% L-glutamine (Gln) (T3), injected with 0.5 ml of 1% Gln (T4) and injected with 0.5 ml of 2% Gln (T5). After hatching, three hundred sixteen day-old straight-run colored chicks were further sub-divided into three replicates with fifteen birds in each replicate. Birds were reared for 8 weeks and kept on a Basal or Control diet (BIS, 2007; broiler starter diet, 22% CP and 3100 ME till 4 weeks and thereafter broiler finisher diet, 20% CP and 3200 ME till 8 weeks of age). Average temperature, RH and THI during the experiment was 34.340C, 64.14% and 86.76 respectively. After 4 weeks of age, serum AST was significantly lower (P<0.001) in T3, T4 and T5 compared to control group birds. However, serum total protein, cholesterol and HDL were significantly higher (P<0.001) in T3 compared to T1.  After 8 weeks of age, serum AST was significantly lower (P<0.001) in birds of T4 compared to T5 and comparatively lower than other treatment groups. Further, cholesterol and HDL were significantly lower (P<0.001) in T4 and serum total protein was significantly higher (P<0.001) in T3 compared to T1 birds. Percent liver weight was significantly higher (P<0.001) in T2 and T3 compared to T1 birds. No significant difference was found in the development of digestive and lymphoid organs among the birds of different treatment groups. Further, no significant difference was found in colour and texture of breast and thigh meat and other carcass quality traits. Hence, it may be concluded that serum total protein was significantly higher in 0.5% L-glutamine and serum AST was lower in 1 % L-glutamine in ovo supplemented groups respectively than the control group birds without affecting the development of digestive and lymphoid organs as well as carcass quality traits in coloured chicken reared during heat stress.