Influence of diets supplemented with naturally protected or unprotected eucalyptus oil on methane production and lactating buffalo productivity
Abstract This study aimed to investigate the effects of naturally protected eucalyptus oil supplementation in a form of leaves (EUL) or mature seed capsules (EUS) compared to crude eucalyptus oil (EUO). The control group (G1) received the basal diet consisting of concentrate feed mixture, fresh berseem, rice straw, and corn silage. The G2, G3, and G4 animals were fed the basal diet with a supplement of 200 g/head/day of EUL or EUS or 4 mL EUO, respectively. Supplementation with EUL or EUS increased NH3-N, SCFA, and acetic acid concentrations in-vitro. The total count of bacterial, protozoa and cellulolytic bacteria increased (P < 0.05) with EUL and EUS supplementation. Methane production lowered (P < 0.05) with EUS, EUL, and EUO supplementation. Milk fat decreased (P < 0.05) with EUO supplementation, while an adverse trend was shown for lactose. No differences in feed conversion were found among EUS, EUL, and EUO. Total protein, albumin, and blood urea increased (P < 0.05) with supplementation of EUL or EUS compared to EUO. EUO supplementation yielded increased (P < 0.05) AST, ALT, glucose, and creatinine. Supplementation with EUL, EUS, or EUO decreased (P < 0.05) DM, OM, and CP digestibility. While digestibility of EE with supplementation by EUL, EUS, or EUO was higher (P < 0.05). Digestibility of NDF and ADF decreased (P < 0.05) with supplemental EUL, EUS, or EUO compared to the control diet. Feeding EUS increased the values of TDN and DCP compared to EUL, which was higher than EUO. Our results confirm that the naturally protected form of leaves or seeds mitigates the negative effects of directly supplementing crude eucalyptus oil.