ENADE Zootecnia Practice Questions - ENADE Zootecnia - Exame Nacional De Desempenho Dos Estudantes Exam

Acetate is converted directly into glucose in the liver via the pyruvate carboxylase pathway, serving as the sole precursor for systemic gluconeogenesis during early lactation in high-yielding dairy cows receiving balanced total mixed rations in modern confinement systems. Propionate is absorbed through the ruminal epithelium and transported to the liver, where it serves as the major substrate for gluconeogenesis, while acetate is the primary precursor for de novo lipogenesis in adipose tissue and the mammary gland. Butyrate is completely absorbed unchanged into the portal bloodstream and oxidized directly in skeletal muscle without prior conversion to beta-hydroxybutyrate within the metabolically active rumen epithelial lining during active ruminal digestion in grazing steers. Propionate and butyrate are converted into storage glycogen within the rumen wall, preventing their entry into hepatic intermediary metabolism during periods of severe postpartum negative energy balance in lactating dairy cattle managed under pastoral conditions.