Effects of grape pomace on ruminal and rectal microbiota and urinary nitrogen emissions in Angus bulls

The primary components of grape pomace (GP) include grape seeds, skins, and stalks, constituting a by-product of the wine industry. This study aimed to examine the impact of grape pomace on the growth performance and nitrogen utilization efficiency of Angus cattle through rumen and rectal microorganisms. Thirty Angus bulls were allocated to three dietary treatments according to a completely randomized design: 0% (G0), 10% (G10), and 20% (G20) dry matter corn silage replacement to dried GP as dry matter. The results showed that the average daily gain (ADG) of G0 and G10 was significantly higher than that of G20 (P Overall, based on this study, it can be concluded that adding to 10% GP in Angus bulls rations had no negative effects on growth performance and apparent digestibility, linearly reduced emissions of urinary nitrogen and better microbial community complexity and stability by interaction network diagrams. These findings offer valuable insights into the potential benefits of incorporating GP into the diet of ruminants.