Dietary supplementation of a novel phytogenic feed additive: effects on nutrient metabolism, antioxidant status and immune response of goats

Abstract

Fifteen adult Jamunapari goats (12–14 months; 18.83 ± 0.83 kg) were used to ascertain the effect of a phytogenic feed additive (PFA) on nutrient utilisation, metabolic profile, antioxidant status and immune response. The goats, randomly assigned to three groups, were fed a standard diet supplemented with the PFA at 0 (CON), 2 (PFA-2) and 3 (PFA-3) % of feed intake for a period of 60 days. Bodyweight and feed intake were recorded. At the end of the experiment, a metabolism trial was conducted. Blood was collected at fortnightly intervals and used to assess blood metabolites, select hormones and erythrocytic antioxidant status. Humoral and cell-mediated immune responses were also assessed. Although dietary use of PFA improved (P < 0.05) the digestibility of all the nutrients, supplementation of PFA did not impart any significant effect (P < 0.05) on dry matter intake or bodyweight changes. Nitrogen balance was higher (P < 0.05) in both the PFA groups compared with the CON. Most of the blood metabolites showed comparable values except for a lower (P < 0.05) aspartate aminotransferase activity in PFA-3. Serum cortisol reduced (P < 0.05) with PFA supplementation in a dose-dependent manner. The supplementation of PFA increased (P < 0.05) the activity of antioxidant enzymes viz. glutathione peroxidase, catalase and glutathione-S-transferase at higher doses (PFA-3), but did not alter the non-enzymatic antioxidant indices. There was no influence of PFA on the cell-mediated or humoral immune responses. Overall, the results indicated the potential of the PFA for improvement in nutrient utilisation and antioxidant status in adult goats.