Growth Performance, Liver and Kidney Function, Lipid Metabolism and Thyroid Hormones of Growing Rabbits Treated with Different Types of Metabolic Agents

Abstract

Aim of the present study was to evaluate the effect of treatment of L-carnitine or coenzyme Q10 on growth performance, liver and kidney functions, thyroid hormones, and economic feed efficiency of growing rabbits fed diet supplemented with propolis. Total of 60 weaned New Zealand white rabbits (5 wk of age and 702.58±12.70 g live body weight) were divided into 3 similar groups (20 in each, 10 from each sex). Rabbits in the 1st group were fed commercial pelleted diet (CPD) without any treatment and served as control (G1). While, rabbits in the 2nd and 3rd groups were fed CPD (18% CP, 13% CF and 2800 Kcal/kg) supplemented with 0.5 g propolis (PR)/kg and orally administrated with 10 mg CoQ10/kg LBW (G2) and 40 mg L-carnitine (LC)/kg LBW (G3), respectively. Feeding rabbits was ad. Libitum, while drinking water nipples were present in each cage. From 5-13 wk of age as an experimental period, rabbits were treated by each combination twice weekly. Average of body weight (LBW), feed intake (FI) and daily gain (ADG), rate of feed conversion (FC) and viability, relative growth rate (RGR) and performance index (PI) were determined. At 13 weeks of age (end of experiment), blood samples were taken from 3 slaughtered males in each group to determine total proteins (TP), albumin (AL), creatinine (CR), urea (UR), cholesterol (CH), HDL, LDL and triglycerides (TG) concentrations, AST and ALT activity and T3 and T4 concentrations. Weights of liver, kidney and body fat were recorded. Small samples from liver and kidney tissues were taken to examine the histological structure. Results showed that final LBW, ADG, FI, RGR and FCR were not significantly affected by treatment, although these parameters tended to be the highest in G2, moderated in G3, and the lowest in G1, being higher in male than female rabbits. All growth performance parameters was not significantly affected by the interaction between treatment and sex of rabbits. Effect of treatment was not significant on absolute and relative weight of the liver and kidney. Effects of treatment on concentrations of TP, AL, GL, CR, UR, CH, HDL, LDL, TG, T3, T4, AL/GL ratio and ALT activity in blood serum were not significant, while AST activity reduced (P<0.05) in G2 and G3 than in G1. Based on the histological examination, rabbits in treated groups (G2 and G3) showed normal liver and kidney functions. Average weight of abdominal fat was higher (P<0.05) in G1 than in G2 and G3. Subcutaneous fat as absolute or relative weight of total fat was not significant. In conclusion, treatment of growing rabbits during marketing period (5-13 wk of age) with a combination of propolis and coenzyme Q10 or L-carnitine twice/week led to functional liver and kidney with normal lipid profile. These findings were associated with remarkable improvement in growth performance parameters