THE EFFECT OF ZINC BACITRACIN ON THE PHYSIOLOGY OF BROILERS FED PLANT AND ANIMAL PROTEIN DIETS
This study presents the influence of zinc (Zn) bacitracin, a growth promoter on the physiology of broiler chickens fed plants and animal protein diets. The differential effect of the two diets on plasma lipid profiles (total cholesterol, triglycerol, high-density lipoprotein, (HDL) and low-density lipoprotein (LDL), mineral profiles, (including calcium to phosphorus ratio in the broiler chicken bones) and the plasma hormone profile (testosterone, oestrogen and progesterone levels) were investigated. Results showed a significant difference (P<0.05) in the broiler plasma, total cholesterol, HDL, and LDL cholesterol, while there was a non-significant difference in the triglyceride levels. Broilers fed with animal protein diet induced higher levels of cholesterol, but on addition of Zn bacitracin, the cholesterol level was reduced, same was the case with those fed plant protein diets although not significant. Cholesterol levels in plasma were reduced due to addition of Zn bacitracin and could indicate cholesterol deposition in the tissues. Hormonal analysis (oestradiol) showed a significant difference (P<0.05) between plant protein diets and animal protein diets, indicating increase in hormonal plasma with a decrease in oestradiol levels when Zn bacitracin was added especially to plant protein diets. Progesterone levels in plasma were significantly higher in the animal protein diet than in the plant protein diet, but were reduced when Zn bacitracin was added, while Progesterone levels showed a similar decrease (P<0.05) when Zn bacitracin was added in plant protein diet. Testosterone levels in plasma did not increase (P>0.05) when Zn bacitracin was added to the plant protein diet, while there was an increase in testosterone when Zn bacitracin was added to the animal protein diet. Broiler chickens fed with plant protein diet showed significantly higher Calcium levels in bones and claws (P<0.05). The inclusion of Zn bacitracin significantly lowered Ca levels in both diets. Phosphorus levels in bones and claws showed no significant differences. These results indicate that some parameters changed in tissues on inclusion of Zn bacitracin, but its negative effect on the physiology of broilers and the possible effect on humans need to be further investigated.
Key words: Zinc bacitracin, Hormone, Minerals, Cholesterol