Replacing corn grain with dried sugar beet meal in fattening goats: effects on feed  efficiency and gastrointestinal microbiota
This study examined the effects of replacing corn grain with dried sugar beet meal on feed intake, growth performance, ruminal fermentation, blood acid-base balance, and gastrointestinal microbiota in fattening goats. Twenty-four male Murciano-Granadino kids were assigned to three diets: a control diet without sugar beet (CTRL), and two diets where 50% (SB9) or 100% (SB18) of the corn grain was replaced by dried sugar beet meal. Goats were fed ad libitum for 49 days. Feed intake and average daily gain were lower (P < 0.05) in SB-fed goats, although dry matter digestibility remained unchanged. Ruminal pH and total volatile fatty acid concentration showed no differences among diets, but butyrate and valerate proportions increased in SB-fed animals. Ruminal microbiota responded in a dose-dependent manner: SB9 enhanced bacterial richness and evenness, while SB18 decreased richness and shifted the community toward sugar-fermenting taxa (e.g., Olsenella, Candidatus Endomicrobium) and away from fibrolytic bacteria (e.g., Treponema, Rikenellaceae). Faecal and salivary microbiota remained unaffected. Blood analyses revealed lower insulin levels in SB-fed goats and slight changes in acid-base balance. These findings suggest that dried sugar beet meal influences ruminal microbial ecology and fermentation patterns and may reduce performance at high dietary levels. Moderate inclusion appears to preserve ruminal stability while supporting a more diverse microbiota.