Effect of dietary phenylpropanoid glycoside-based natural extracts on blood parameters and productive performance in intensively-reared young hares

Two different doses of a dietary verbascoside-based supplement were evaluated on various blood parameters and on productive performance in young weaned hares reared intensively from 28 to 90 days of age. The study lasted for 62 days and it was conducted on 210 young hares divided into three homogeneous groups of 70 animals each, consisting of a control group and two experimental groups. Each group received the dietary supplement in the feed, titrated to 0.5% verbascoside, 1 kg/t of concentrate (LVB group) and 2 kg/t of concentrate (HVB group). The experimental reliefs included the measurement of blood parameters such as triglycerides, total cholesterol, high density lipoprotein cholesterol, and bilirubin, along with some markers of oxidative status in plasma such as reactive oxygen metabolites, thiobarbituric acid-reactive substances, and vitamins A and E. Various productive parameters were also measured such as body weight and growth rate, food consumption, and feed conversion. The experimental treatment resulted in a significant decrease in triglycerides (P < 0.01) and bilirubin (P < 0.05) and an increase in high density lipoprotein cholesterol (P < 0.01) both in the low verbascoside (LVB) and high verbascoside (HVB) experimental groups. In addition, the oxidative plasma stability in blood also improved, with a significant decrease in the concentration of reactive oxygen metabolites (P < 0.01) and thiobarbituric acid-reactive substances (P < 0.01), along with increased levels of vitamin E (P < 0.05). The productive performance was not statistically influenced by the experimental treatment, except for the growth rate which increased significantly (P < 0.05) in the experimental LVB and HVB groups: 6.9% and 8.7% respectively compared with the control group.