The Impact of Dietary Yeast Fermentation Product Derived from Saccharomyces cerevisiae on Semen Quality and Semen Microbiota of Aged White Leghorn roosters

Abstract

The objective of this study was to determine the effects of feeding different levels of yeast fermentation product (YFP) on rooster semen quality and semen microbiota (yeast and bacteria). A commercially available YFP was included at either 0%, 0.5%, or 1.0% of the diet. Individually caged White Leghorn roosters (n = 63), 60 wk of age, were equally divided among the 3 diets. Feed intake and individual semen samples were obtained weekly (8 wk). Semen samples were analyzed for the sperm quality index (SQI), semen volume, sperm concentration, and sperm viability. Biweekly, body weight and body weight gain were determined, and semen samples were serially diluted and spread plated to detect yeast as well as total aerobic bacteria. Dietary YFP did not impact feed intake, body weight, or body weight gain. However, as the dietary levels of YFP increased, SQI linearly decreased but bacteria per billion sperm and yeast per billion sperm linearly increased. Additionally, yeast per billion sperm was positively correlated with bacteria per billion sperm. The decrease in SQI may be a result of the increase in bacteria per billion sperm and yeast per billion sperm with supplementation of YFP, because the SQI was negatively correlated with bacteria per billion sperm and yeast per billion sperm. These data suggest the increased number of bacteria and yeast per sperm resulted from supplementation and is detrimental to semen quality.