Metabolic Profile of Steers Subjected to Normal Feeding, Fasting, and Re-Feeding Conditions.
Vet Sci 2020;
7:vetsci7030095. [PMID:
32708177 PMCID:
PMC7558577 DOI:
10.3390/vetsci7030095]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/11/2020] [Accepted: 07/17/2020] [Indexed: 12/02/2022] Open
Abstract
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.
Collapse