ARTICLE 84 FEED & ADDITIVE MAGAZINE August 2025 IMMUNOLOGICAL BENEFITS Fathima et al., (2024) demonstrated the immunological modulating effects of arginine during gastrointestinal challenge as an increase in dietary arginine decreased the CD8+:CD4+ T-cell ratio and down regulated the expression of inflammatory cytokines and enzymes preventing inflammatory injury to the tissues during necrotic enteritis challenge in broilers. The beneficial immunological impacts of elevated arginine ratios were also documented by Yazdanabadi et al., (2020), who reported that increasing the dietary arginine concentration to 125% of recommended levels increased nitric oxide and decreased pro-inflammatory cytokines in coccidiosis challenge broilers. This immunomodulation effects of arginine resulted in improved growth performance compared to 100% recommended arginine levels (Yazdanabadi et al., 2020). This downregulated expression of inflammatory cytokines and enzymes could prevent inflammatory tissue injury during enteric intestinal challenge. Anderson et al., (2023) also observed effects on the immune system when feeding increasing levels of digestible arginine in addition to improvements in growth performance. In a dose response study with dArg:dLys ratios between 80% and 133%, quadratic analysis determined that the optimal ratio to maximize body weight gain and feed conversion ratio (95% of vertex) in Cobb 500 broilers was 116%. Additionally, following an LPS challenge, the infiltration of heterophils, production of nitric oxide and the ratio of heterophils to lymphocytes increased linearly with increasing arginine concentration. These data support the fact that arginine plays a pivotal role in the initiation of the immune response against a foreign antigen. These immunomodulatory effects of arginine could benefit production animals during times of enteric challenge and allow improved growth performance and ability to effectively fight and clear a pathogenic infection. Necrotic enteritis is an economically important disease in broiler chickens causing intestinal damage and loss of performance. Zhang et al., (2019) demonstrated the antipathogenic properties of arginine in a necrotic enteritis model. Intestinal infection via a direct challenge resulted in significant lesion development and Clostridium perfringens recovery in the liver. The addition of L-arginine to increase the ratio to 123% of dLys significantly decreased Clostridium perfringens recovery in the liver, as well as observed lesion score in challenged broilers (Figure 2 -adopted from Zhang et al., 2019). Wang et al., (2024) reported the benefits of increasing arginine concentration on Clostridium perfringens’ α toxin-induced intestinal injury in broilers. Feeding Photo: CJ-BIO
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