Fennel seed powder in the diet of dairy buffalo affects milk VOCs profile, antioxidant activity and SCD1 mRNA level

The aim of this study was to assess the influence of dietary fennel seed powder (FSP) supplementation on milk production, antioxidant properties, volatile organic compounds (VOCs), and gene expression in dairy buffaloes. Twenty animals, homogenous for parity (2.6 ± 1.7), days in milk (DIM: 41.1 ± 7.17), body condition score (BCS: 6.8 ± 0.2) and daily milk yield (DMY: 13.6 ± 1.8 kg), were randomly assigned to two groups fed total mixed ration (TMR): a control group (CON) and a treated group (FEN), which received an additional 100 g/day of FSP to the diet. Over a four-week period, the milk yield, composition (Milkoscan), fatty acid (FA) profile (Gas Chromatography), antioxidant activity (superoxide dismutase: SOD, catalase: CAT, glutathione peroxidase: GPx, total antioxidant capacity: TAC, 2,2-diphenyl-1-picrylhydrazyl: DPPH), and volatile organic compounds (Gas Chromatography -Mass Spectrometry) were analyzed, along with the gene expression related to lipid metabolism and antioxidant responses (Real time-qPCR).The treatment had no effect on milk yield or chemical composition. However, FSP supplementation resulted in alterations of the milk FA profile. The milk of the FEN group exhibited significantly higher (P < 0.05) mixed FA content (C16:0-C16:1), particularly C16:1 and also C18:1 isomers, accompanied by a significant reduction (P < 0.05) in de novo synthesized FA (< C16:0). Gene expression analysis revealed a reduction in the expression of stearoyl-CoA desaturase 1 (SCD1) in the treated group (P < 0.05). The milk cholesterol content was found to be significantly lower (P < 0.001) in the FSP group milk, while antioxidant parameters demonstrated enhanced oxidative stability, with significantly higher (P < 0.001) levels of SOD, CAT, TAC, DPPH observed in the treated group. The analysis of VOCs revealed higher levels (P < 0.001) of fennel-derived compounds, such as limonene, fenchone, estragole and anethole, and significantly (P < 0.001) lower concentrations of acids, including acetic and butanoic acids, in the milk of the FEN group. The findings of this study indicate that FSP has the potential to enhance the nutritional and functional properties of buffalo milk by increasing its antioxidant capacity and modulating its FA and VOC profiles, while maintaining the yield and cheese-making potential of the milk. Further research is required to investigate the sensory and health implications of this dietary treatment.