<i>Caesalpinia sappan</i> and <i>Tiliacora triandra</i> powder as a novel feed additive to mitigate PRRSV infection in weaned pigs

This study aimed to determine the antiviral effects of Caesalpinia sappan and Tiliacora triandra powders on weaned pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV). The C. sappan and T. triandra powders were mixed in various ratio (CT) to assess their antiviral activity against PRRSV in vitro. The promising in vitro findings resulted in the subsequent phase of the trial, in which 24 weaned pigs were randomly allocated to four treatments using a completely randomised approach. The four dietary treatments employed were a basal diet (CON) and supplementation with CT in the basal diet at concentrations of 0.5 g/kg (CT0.5), 1.0 g/kg (CT1.0), and 5.0 g/kg (CT5.0), respectively. Each piglet was intranasally administered 2 mL of the US PRRSV strain at 1 × 104 a median tissue culture infective dose (TCID50)/mL. Productive performance assessments were conducted, blood samples were taken weekly for haematology, viral load, and antibody titre analysis. Lung tissue was assessed using immunohistochemistry. In the CT5.0 group, pigs had significantly decreased virus loads in their serum compared to the CON group (p < 0.05). All CT groups had greater PRRSV antibody titres than CON groups. In the CT5.0 group, D14 and D28 lymphocyte levels were higher than in the CON group (p < 0.05). Lungs of pigs in the CT0.5 group had higher secretory IgA levels than those in the CT1.0 and CT5.0 groups (p < 0.05). Lastly, CT powder possess the potential to be used as feed additives for pig to inhibit the PRRSV virus infection.