Papaya extract upregulates the immune and antioxidants-related genes, and proteins expression in milk somatic cells of Friesian dairy cows.

Carica papaya is a perennial plant containing bioactive constituents with free radical-scavenging and immune-modulating activities. In contrast, the immune suppression is predominant in the periparturient period, where oxidative stress has a substantial impact on the mammary gland health. The aim of the experiment reported here was to determine the potential effect of C. papaya aqueous extract (CPE) on milk production traits, and expression of genes and proteins related to immune and antioxidant status in dairy milk somatic cells (MSCs). Forty Friesian dairy cows were divided equally between a control and CPE-treated groups (orally drenched 250 µg/kg bwt, once weekly a month before expected parturition and continued until 5 months post-partum). CPE did not affect milk yield or composition but upregulated the expression of β13-defensin (DEFB13), cathelicidin 2 (CATHL2), cathelicidin antimicrobial peptide (CATHL3), hepcidin (HAMP), lysozyme (LYZ), catalase (CAT) and glutathione peroxidase (GSH-Px) in MSCs. The environmental micro-organisms did not influence the levels of the transcripts. The DEFB13, CATHL2, CATHL3, HAMP and LYZ, but not β1-defensin (DEFB1) transcripts and proteins were constitutively expressed in MSCs obtained from pathogen-free udders. It could be concluded that CPE has immunostimulant and antioxidant activities; thereby, it could be utilized to minimize the occurrence of mastitis.