Spray-dried plasma (SDP), a byproduct of the meatpacking industry, is commonly used in swine diets to enhance growth and optimize feed utilization. Multiple studies have shown that animals' immune responses can be improved by giving them plasma proteins like SDP orally. This study aims to highlight the importance of non-invasive dietary interventions in stimulating immune responses and enhancing immunological characteristics. A comprehensive search was conducted using the indexing databases Scopus, PubMed/Medline, ISI Web of Science, Embase, Cochrane Central, and CINAHL and out of the 541 publications initially searched, only 13 fit the specified criteria. This meta-analysis incorporated seven trials, including a total of 210 animals. The SDP group had significantly lower IL-10 levels (SMD: −1.79, 95% CI: −2.43, −1.15, I2: 60%, p = 0.04) compared to the control group.  The SDP group showed statistically higher TNF-α (SMD: 2.32, 95% CI: 0.74, 3.89, I²: 92%, p = 0.004) than the control group.  Also, the SDP group showed statistically higher IgG (SMD: 0.59, 95% CI: 0.03, 1.15, I²: 54%, p = 0.04) than the control group. SDP alters cytokine secretion, promoting an anti-inflammatory immune profile. The positive impact of SDP in this model suggests that these supplements may help enhance immune responses.