Wine by-products, generated in large quantities and wasted with serious environmental and economic consequences, are an exceptional alternative to conventional and non-sustainable food sources. The aim of the study was to understand if these by-products could be reused in feed for broiler chickens, improving certain blood parameters important in immune responses, by testing different concentrations and administration times. The effects of the grape-seed and pomace flour of red-wine waste were evaluated. Three different diets were tested containing pomace (0%, 3%, and 6%), grape seeds (0%, 3%, and 6%), and a mix of pomace and grape seeds (0 and 3%) for 7, 21, and 42 days. Esterase, alkaline phosphatase, and peroxidase activity, along with glucose, reactive oxygen species, and glutathione levels, were evaluated in blood samples. The results showed significant changes in the parameters analyzed, especially after 21 and 42 days of administration. All diets administered showed significant effects based on exposure time and by-product concentration used. The greatest effects seem to have come from grape-seed flour. All the by-products of wine production analyzed in this study showed important antioxidant activities and can be included in the food context of farm animals in different growth phases at different concentrations.