Responses of dairy cows to dietary aflatoxin: Concentration of blood serum constituents and hormones associated with liver-kidney dysfunction and maintenance of lactation

Abstract

In the first part of this study, two fistulated Holstein cows in mid-lactation were given 13 mg of impure aflatoxin B1 (AFB1) (aflatoxin B1 plus other aflatoxins and metabolites produced by Aspergillus parasiticus in culture) for 7 days. Animals were bled daily and their blood was analyzed for serum glutamate-oxaloacetate transaminase, serum glutamate-pyruvate transaminase, alkaline phosphatase, gamma-glutamyl transpeptidase, bilirubin, cholesterol, triglycerides, total protein, blood urea nitrogen, creatinine, and uric acid. Concentrations of these constituents remained relatively unchanged during treatment. In the second part of the study, seven fistulated Holstein cows in mid-lactation were given daily doses of 13 mg of AFB1 for 7 days. Six animals received pure AFB1; one animal received impure AFB1. Amounts of four hormones [cortisol, insulin, thyroxine (T4), and triiodothyronine (T3)], hormone binding capacity for T3 (T3U), and glucose in serum were monitored. The amount of T3 and percent of T3U increased (12%) and decreased (4%), respectively, during treatment. No discernible changes in amounts of T4, cortisol, insulin, and glucose were observed in the animals receiving pure AFB1. However, glucose levels in serum of the animal receiving impure AFB1 decreased by 9% during treatment. This decrease in serum glucose level was accompanied by a reduction in the amount of milk produced. Overt signs indicative of ill-health were not apparent, and thus could not be related to changes in blood constituents measured.