Effects of Dietary Gum Arabic Supplementation on Serum Biochemical Indices and Endocrine Profile of Older Laying Hens

Abstract

Gum Arabic is a natural polysaccharide with potential physiological benefits as a functional feed additive in poultry, but information on its effects on serum biochemical and hormonal parameters in older laying hens remains limited. This study evaluated the effects of dietary supplementation with Gum Arabic on serum biochemical indices, liver enzyme activities, and thyroid and reproductive hormone profiles in older laying hens. A 140-day feeding trial was conducted using 105 Lohmann Brown laying hens aged 65 weeks. Birds were randomly assigned to five dietary treatments with three replicates of seven hens each: a control diet (T1) and diets supplemented with 15 (T2), 20 (T3), 25 (T4), or 30 g/kg (T5) Gum Arabic powder. Serum biochemical parameters, liver enzymes (AST, ALT, and ALP), thyroid hormones (T3 and T4), and reproductive hormones (estrogen, progesterone, LH, and FSH) were determined during the final experimental period (81–84 weeks of age). Gum Arabic supplementation significantly increased serum total protein in all supplemented groups compared with the control group. Albumin was significantly higher in T4 and T5, while globulin generally improved in supplemented groups. Serum AST and ALT activities decreased, whereas ALP activity increased following supplementation. Birds receiving 25 and 30 g/kg Gum Arabic showed higher serum T3 and T4 concentrations than controls. Reproductive hormones, including estrogen, progesterone, LH, and FSH, were also improved, particularly at higher supplementation levels. These findings indicate that dietary Gum Arabic positively influenced selected serum biochemical, hepatic enzyme, and endocrine indicators in older laying hens under the conditions of this study. Further research is needed to clarify the underlying mechanisms and evaluate effects on productive performance and other physiological traits.