Effects of Yeast Culture Supplementation on Growth Performance, Nutrient Digestibility, Blood Metabolites, and Immune Response in Geese

SIMPLE SUMMARY: Antibiotics benefit animal growth performance and health. However, an overuse of antibiotics can lead to antibiotic residue and the development of drug-resistant bacteria. Considering the possible serious consequences of antibiotic overuse, non-antibiotic alternatives, such as yeast and yeast products, are widely used in animal diets to improve growth and productive performance. Geese are important poultry, and their meat provides high-quality protein to humans, but studies showing how yeast culture affect geese are limited. On this basis, the effects of dietary yeast culture supplementation on growth performance, nutrient digestibility, blood metabolites, and immune functions of geese were studies. The results showed that the dietary addition of yeast culture could improve growth performance and nutrient digestibility and can modulate the immune response of geese. This dietary strategy based on feed additives is an effective method for improving the growth efficiency of the geese. ABSTRACT: The present study was conducted to investigate the effects of dietary yeast culture (YC) supplementation on growth performance, nutrient digestibility, blood metabolites, and immune functions in geese. One-day-old Sichuan white geese (n = 300) were randomly divided into five groups containing 0 (control), 0.5%, 1.0%, 2.0%, and 4.0% of YC in the diet for 70 days. In general, the dietary supplementation of YC significantly increased the average daily gain and feed conversion ratio (p < 0.05) in which the 1.0% or 2.0% levels were better and significantly reduced the average daily feed intake at the 2.0% level (p < 0.05). YC supplementation increased digestibility of P (quadratic, p = 0.01) and gross energy (quadratic, p = 0.04) from days 23 to 27 and crude protein from days 23 to 27 and days 64 to 68 (quadratic, p ≤ 0.05), with the 2.0% level being the most effective. Serum metabolites were significantly affected by dietary YC (p < 0.05). Supplemental YC increased IL-2 on day 28 (linear, p = 0.01; quadratic, p = 0.04) and lysozyme on day 70 (quadratic, p = 0.04) and decreased complement C4 on day 70 (linear, p = 0.05). Interferon-γ, interleukin-2, and tumor necrosis factor-α genes were mostly up-regulated after YC supplementation, and interferon-γ and interleukin-2 gene expression levels were significantly increased at the 2.0% level (p < 0.05). Taken together, dietary YC supplementation improved growth performance and affected nutrient digestibility, serum metabolites, and immune function in geese, which was optimized at the 2% YC level in the present study.