This study was aimed at determining the effective ingredients of yeast culture (YC) for animal breeding. First, the contents of YCs obtained from various fermentation times were detected using gas-chromatography. A total of 85 compounds were identified. Next, 336 Arbor Acres (AA) broilers were randomly divided into seven experimental groups and fed a basal diet, diets supplemented with YCs obtained at various fermentation times, or SZ1 (a commercial YC product). A significant increase in body weight gain (BWG) and a significant decrease in feed conversion ratio (FCR) of AA broiler chicks were observed with YC supplementation. Additionally, most of blood and immunological indices were improved with YC supplementation. According to the production performance and the results of multivariate analysis, glycine, fructose, inositol, galactose, and sucrose were found as the potential effective compounds of YC and were involved in metabolic pathways including glycine, serine, and threonine metabolism. Supplementation with diets based on combinations of effective compounds improved weight gain, feed efficiency, serum immunoglobulin A, and immunoglobulin G, but decreased blood urea concentration. These findings suggest YCs as effective and harmless feed additives with improved nutritional properties for broiler chicks.

Background:In highly intensive dairy farms, cows often suffer from metabolic disorders that cause severe oxidative stress.Objectives: This study aimed to observe correlations and associations of oxidative stress-related indicators with milk compositions and metabolites.Methods: Twenty-two multiparous Holstein dairy cows in early lactation were randomly selected from a commercial dairy farm. The morning milk was collected for composition and metabolites analysis. Blood was sampled via the tail vein to analyze oxidative stress-related indicators (reactive oxygen species, ROS; catalase, CAT; superoxide dismutase, SOD; glutathione peroxidase, GPX; malondialdehyde, MDA) and metabolites.Results: Results showed that ROS were positively correlated with CAT, GPX, SOD, and MDA. However, the levels of CAT, GPX, and SOD were negatively related to milk fat (P < 0.05). Nineteen serum and 7 milk metabolites were selected from detectable metabolites according to their correlations with ROS, CAT, GPX, and SOD (P < 0.05). Metabolic pathway analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database revealed that these metabolites are primarily involved in the metabolic pathways of carbohydrates and amino acids. Conclusions:This study gave us a better understanding on oxidative stress that ROS not only increased oxidative damage (MDA) in dairy cows, but also altered some metabolites involved in amino acid and carbohydrate metabolism.

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