Abstract
The current study investigated the impact of different concentrations of purified egg yolk immunoglobulin Y (IgY) supplemental food on the growth performance, behaviors, cecal contents of
Escherichia coli
, and the meat quality of broiler chicks. Four dietary groups were given to 180 female Ross broiler chicks at random (
n
= 45 for each). The control group was fed a standard diet only, whereas the other three experimental groups were fed the same basic diet supplemented with 1,500, 3,000, and 4,000 μg/ml IgY for a duration of 42 days. Significant greater behavioral activities, including, feeding, drinking, and dust bathing (
p
< 0.05), in the birds fed 4,000 μg/ml of IgY compared to the control group were observed. Greater weight gains of the crop, proventriculus, gizzard, and intestine (
p
< 0.05) were observed for broiler chicks fed 4,000 μg/ml of IgY when compared to the control group. After 3 weeks of feeding, the groups fed 3,000 and 4,000 μg/ml IgY had significant lower
E. coli
counts in the muscle and cecal contents (
p
< 0.05) when compared to the control group. Moreover, dietary supplementation with 4,000 μg/ml IgY in the third week and 3,000 μg/ml IgY in the sixth week resulted in greater weight gain (
p
< 0.01) when compared to the control group. Also, at week 3, chicks fed 4,000 μg/ml of IgY had a lower feed conversion ratio (FCR) when compared to the control group (
p
< 0.05). At week 6, chicks fed 3,000 μg/ml of IgY had lower FCR than the control (
p
< 0.05). The circulating heterophile/lymphocyte ratio was simply altered in birds fed variable IgY concentrations (1,500, 3,000, and 4,000 μg/ml), with no significant differences compared to the control group due to the individual resistance of each bird to physiological stress. The addition of 4,000 μg/ml IgY to the diet enhanced the nutritive value of meat, including protein, fat, and ash content (
p
< 0.05). Our study concluded that dietary supplementation of 3,000 and/or 4,000 μg/ml IgY improved the growth rates, behavioral activities, intestinal health indices, and meat quality of broiler chicks.