Thiamin and niacin supplementation in diets of heat stressed broiler chicks

Abstract EN

Three hundred one day old Hubbard chicks were provided with a basal recommended control starter diet for 2 weeks without suppleme-ntary excess vitamins.

At beginning of the 3rd week of age, the chicks were divided into 5 equal duplicate groups.

The control group was fed the basal grower and finisher diets (2 weeks of each) without vitamins supplementation.

The other groups were fed the grower and finisher diets supplemented with thiamin (8 or 16 mg / kg) or niacin (108 or 216 mg / kg).

The dietary supplementation of vitamins was only at the periods during which the broiler chicks were exposed to high ambient temperature (above 30°C).

The chicks were vaccinated against Newc-astle and Gumboro diseases at proper time.

Body weight of the chicks and consumed diets were recorded every two weeks and the feed conversion ratio was calculated.

Blood samples were collected from the wing vein of the broilers at 25, 38 and 42 days of age and the sera were analyzed for glucose, triglycerides, cholesterol, total protein, albumin, globulin, T3¬, T4 and cortisol.

Blood smears were prepared for determination hetrophil / lymphocyte (H / L) ratios.

At end of the experiments, 5 chicks from each group were sacrificed to obtain specimens from the liver, kidney, lung, spleen and brain for studying the histopathological changes.

The results revealed that supplementing the diets with thiamin (8 mg / kg) or niacin (108 mg / kg) during the periods of heat stress significantly improved the body weight and feed conversion ratio recorded at the 4th and 6th weeks of the age and increased the plasma concentrations of T4 and decreased the plasma cortisol.

However, there were no significant differences in plasma concentrations of T3 due to feeding the heat stressed broilers on the diets supplemented with thiamin or niacin.

Supplementing the diets of the heat stressed broilers with thiamin or niacin increased the serum triglyceride; total protein; albumin and globulin and decreased the cholesterol specially at the low levels of supplementation.

The blood glucose regulating effect was more clear in serum of the broilers supplemented with niacin at 108 mg / kg followed by broilers supplemental with thiamin at 8 or 16 mg / kg diets.

Dietary supplementation with either thiamin (8 or 16 mg / kg) or niacin (108 mg / kg) reduced the H / L ratio and decreased the histopathological changes.

From the present study, it could be concluded that dietary supplement-ation of heat stressed broiler chicks with thiamin or niacin at concentr-ations of 8 or 108 mg / kg, respectively could improve the growth perf-ormance and biochemical parameters, minimize the pathological changes and could alleviate a part of the adverse effect of heat stress.