Abstract :

T

he objective of the present study was to evaluate the effect of fasting regimen and dietary zinc (Zn) supplementation on hematological parameters, blood biochemical components, hormonal profiles and the antioxidative properties in males of growing rabbits. A  total of 60 weaned male V-Line rabbits (35 days old) were randomly divided into six experimental treatments (10 each): (1) control (basal diet ad labium without any supplementation of Zn); (2) Ad+Zn (basal diet ad labium +100 mg Zn/kg diet); (3) F24 (24 hr fasting regimen per week); (4) F48 (48 hr fasting regimen per week); (5) F24+Zn (24 hr fasting regimen per week+100 mg Zn/kg diet) and (6) F48+Zn (48 hr fasting regimen per week+100 mg Zn/kg diet). All experimental treatments were provided from 35 to 84 day of age. The obtained results showed that fasting regimen (in experimental groups F24 and F48) decreased significantly red blood cells (RBCs) compared with those of control (Ad) or Ad+Zn groups in growing rabbits (P≤ 0.0001). While, group F48 recorded the lowest value of blood hemoglobin concentration (Hb) and packed cell volume (PCV). Dietary Zn supplementation relieved the effect of fasting in groups F24+Zn and F48+Zn. Regarding to white blood cells (WBCs) count, the lowest WBCs number was observed in F48 group compared with other treatments. The highest neutrophils percentages were recorded in groups supplemented with Zn (in groups Ad+Zn, F24+Zn and F48+Zn) compared with the other groups. No significant differences were observed in lymphocytes (%) monocytes (%) eosinophils (%) and basophils (%) among the experimental groups. Feeding growing rabbit's ad libitum diet supplemented with Zn (Ad+Zn) increased significantly blood plasma total protein and albumin concentration comparing with the other experimental groups. However, fasting regimen groups with or without Zn supplementation decreased significantly plasma total protein, albumin, glucose, total lipids, cholesterol and numerically triglycerides concentrations comparing with those fed ad libitum diet with or without Zn supplementation. Growing rabbits exposed to fasting (F24, F48, F24+Zn and F48+Zn groups) had a significant increase in blood plasma aspartate aminotransferase (AST), while, growing rabbits exposed to fasting with Zn (F24 and F48 groups) had a significant increase in blood plasma alanine aminotransferase (ALT) compared with those fed ad libitum diet with or without Zn supplementation (Ad and Ad+Zn groups). Total antioxidant capacity (TAC) was significantly increased in the group fed ad libitum diet supplemented with Zn (Ad+Zn) compared with the other experimental groups. However, TAC was significantly reduced in growing rabbit subjected to fasting regimen (24 or 48 h) and dietary Zn supplementation alleviated this effect and improved TAC significantly. Growing rabbits exposed to fasting (F24, F48, F24+Zn and F48+Zn groups) had a significant increase in plasma malonylaldhyed (MDA) concentration, cortisol, corticosterone and significantly decrease in blood plasma triiodothyronine (T₃), thyroxin (T₄) compared with those fed ad libitum diet (Ad) and ad libitum diet + Zn (Ad+Zn). It could be concluded that growing rabbits exposed to fasting and fed diet supplemented with or without Zn had a significantly decrease in RBCs, Hb concentration, PCV, plasma total protein, albumin, glucose, total lipids, cholesterol, triglycerides, T₃ and T₄ concentrations. Interestingly, dietary Zn supplementation improved the antioxidative properties and reduced the rate of lipid peroxidation in growing rabbits subjected to fasting regimen.

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