Metabolic Profile of Steers Subjected to Normal Feeding, Fasting, and Re-Feeding Conditions

• Published in: Veterinary sciences Vol. 7; no. 3; p. 95
• Main Authors: Ortolani, Enrico, Maruta, Celson, Barrêto Júnior, Raimundo, Mori, Clara, Antonelli, Alexandre, Sucupira, Maria, Minervino, Antonio
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 21-07-2020; MDPI
• Subjects: Amino acids; Animals; Anorexia; Anticoagulants; Aspartate aminotransferase; Beef; Cattle; Cholesterol; Creatinine; Fasting; Fatty acids; Feeding; Food; Food supply; Glucose; Hypoglycemia; Ketogenesis; Laboratories; Lipolysis; metabolic profile; Metabolism; Metabolites; Plasma; Plasma levels; Proteins; Proteolysis; re-feeding; Regression analysis; Studies; Urea; Urine; Variables; Veterinary medicine; Brazil; United States > US
• ISSN: 2306-7381; 2306-7381
• DOI: 10.3390/vetsci7030095

The effects of feeding, fasting, and re-feeding on the metabolic profile of growing cattle were studied. Blood and urine samples were obtained from 12 crossbred steers weighing approximately 300 kg during the following periods: 11 h of normal feeding (postprandial period), 48 consecutive hours of fasting, followed by 48 h of re-feeding. Compared with the postprandial period, fasting caused the following modifications: moderate hypoglycemia accompanied by remarkable lipolysis detected by the increase in plasma levels of free fatty acids (FFAs); absence of hepatic lipidosis, as there were no changes in aspartate aminotransferase activity or serum cholesterol levels; mild ketogenesis, confirmed by the slight increase of β-hydroxybutyrate (βHB); increased amino acid burn for energy production, verified by the increase in serum urea contents. There were strong positive correlations between the plasma levels of FFAs and βHB (r = 0.68; p < 0.001), fasting duration and FFA concentration (r = 0.92; p < 0.00001), and fasting duration and serum urea (r = 0.52; p < 0.001); there was a negative correlation between fasting duration and blood glucose (r = −0.52; p < 0.0001). During this same period, mild hypovolemia characterized by an increase in intravascular volume deficit was observed. The metabolic condition observed during fasting was completely reversed during re-feeding, except for the temporarily higher proteolysis.