EFFECT OF DIETARY SUPPLEMENTAL ZINC SOURCE AND LEVEL ON GROWTH PERFORMANCE, DIGESTIBILITY COEFFICIENTS AND IMMUNE RESPONSE OF NEW ZEALAND WHITE RABBITS

Document Type : Original Article

Authors

1 Animal Production Research Institute, Agricultural Research Centre, Giza, Egypt.

2 Animal Production Department, Faculty of Agriculture, Cairo University, Giza, Egypt.

Abstract

This study was carried out to investigate the effect of dietary zinc (Zn) supplementation in inorganic (zinc sulfate, ZnSO4) and organic (zinc methionine, Zn-Met) forms at two levels (100 or 200 mg/kg diet) on growth performance, digestibility coefficients and immune response of New Zealand White (NZW) male rabbits. One hundred male NZW rabbit (at 6 weeks of age, 808 ± 11g average body weight) were divided into five homogenous groups. The 1st group was fed basal diet including vitamins & minerals premix which contained 58 mg Zn as a control, the 2nd and the 3rd groups were fed on the same diet supplemented with 100 or 200 mg Zn/kg diet as zinc sulfate (ZnSO4, inorganic form) and the 4th and the 5th groups were fed on the same diet supplemented with 100 or 200 mg Zn/kg diet as zinc methionine (Zn-Met, organic form). Results showed that live body weight at 22 wks of age and total body weight gain of rabbits fed diets supplemented with Zn was significantly (P<0.01) higher than those fed diet without supplementation. Rabbits fed diet supplemented with 200 mg Zn-Met/kg diet had significantly heaviest body weight, followed by rabbits fed diet supplemented with 100 mg Zn-Meth/kg diet than groups fed diet supplemented with 200 and 100 mg ZnSO4. Rabbits fed diets supplemented with Zn-Met or ZnSO4 converted feed better than those fed diets without supplementation. Rabbits fed diets supplemented of Zn-Meth at 200 or 100 mg/Kg diets improved nutrients digestibility and nutritive values expressed as TDN and DCP of diets. Zn supplementation (Zn-Meth or ZnSO4) to rabbit diets significantly (P<0.01) affected cell-mediated immune response at different hours post injection of phytohemoagglutinins (PHA). Zn from Zn-Meth (200 or 100 mg/kg diets) significantly increased heighten cellular immunity than zinc from ZnSO4. Rabbits fed diets supplemented with Zn (Zn-Meth or ZnSO4) with any levels had significantly (P<0.01) higher antibody titer against sheep red blood cell (SRBC) at different weeks post immunization than those fed control diets. Zn-Meth improved significantly antibody titer against SRBC than zinc from ZnSO4. Inclusion 200 mg Zn-Met/kg diet significantly improved antibody titer post three weeks of SRBC injection than 100 mg Zn-Met. It can be concluded that dietary Zn methionine (organic form( at level of 200 mg/kg of rabbit diet improved nutrients digestibility and nutritive values of diets, which could be associated with better growth performance and immune efficiency.

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