Effects of naringin supplementation on productive performance, antioxidant status and immune response in heat-stressed lambs

• We investigated the use of naringin in growing lambs under hot conditions.
• Naringin was supplemented as repeated oral administration of different levels of naringin (0, 7 or 14 g/week/lamb).
• Naringin improved the body weight and feed efficiency in treated lambs.
• Naringin reduced the adverse effects of thermal stress on antioxidant statue and immune function.

A study was conducted to evaluate the effects of naringin supplementation on antioxidant status and immune response of lambs under hot environmental conditions. Eighteen 4-month-old Awassi male lambs (initial body weight 23.8 ± 1.3 kg) were orally dosed with naringin in a 60-day trial during the summer months (July and August) in Saudi Arabia. The lambs were randomly assigned to receive 0, 7 or 14 g of naringin, administered as a weekly oral dose. Feed intake was measured weekly, and the lambs were weighed on days 1, 15, 30, 45 and 60. Rectal temperature (RT) and respiration rate (RR) were measured three times (0800, 1200 and 1600 h) on days 1, 15, 30, 45 and 60. Blood samples were collected from all lambs on days 1, 15, 30, 45 and 60 to measure enzymatic concentrations and total primary antibody level in serum, antioxidant variables in plasma and hematological variables in whole blood. Lambs were injected intradermally with 0.15 mg phytohemagglutinin (PHA) on day 45, and the immune response to this antigen was measured 0 and 24 h after injection. Oral administration of 7 g/week of naringin resulted in an increase in average daily gain (13.4%; P < 0.02) and a greater gain to feed ratio (17.1%; P < 0.05) compared to the control group. Oral administration of 14 g/week of naringin resulted in increases in plasma superoxide dismutase (6.9%; P < 0.05) and glutathione peroxidase (19.9%; P < 0.05) activities compared with those of untreated animals. In addition, lambs receiving 14 g/week of naringin also had greater total primary serum antibody titers than those of untreated lambs (P < 0.05). The mean skinfold thickness for lambs that received 7 and 14 g/week of naringin were higher (P < 0.05) than the control lambs. These results indicate that naringin supplementation improved performance traits and enhanced antioxidant status and immune response in lambs during hot environmental conditions.