Metabolic effects of fasting in steers

The effect of starvation for five days on blood levels of various hormones and metabolites was studied in seven steers. There was a significant decrease (P less than 0.05) in thyroxine (free and total), 3,5,3'-triiodothyronine (free and total), immunoreactive insulin, propionic acid, butyric acid and glucose, 3,3',5'-triiodothyronine and alpha-aminoacid-N levels did not change. Free fatty acids, beta-hydroxybutyrate, acetoacetate, urea, isobutyrate, alpha-methylbutyrate and isovalerate, total protein and albumin significantly (P less than 0.05) increased.