Untersuchungen zum Umsatz von¹⁴C-¹⁵N-Azetamid bei Schafen

Abstract

4 male sheep (average weight: 53.5 kgs) were fed a semisynthetic diet containing acetamide as sole source of nitrogen. At the beginning of the trial twin-labelled 15N-14C-acetamide was administered by way of a ruminal fistula. The curve pattern of 14C activity in the TCE-soluble fraction of the ruminal fluid showed a synchronous behaviour in all animals beginning at 3 hours after the beginning of the trial. A half-life of 2 1/2 hours for the rate of absorption of 14C acetamide and deaminated 14C acetate was established from the decline in 14C activity observed in the TCE-soluble fraction of the ruminal fluid. The peak level of 14C labelling in ruminal proteins was reached after 6 hrs. The specific 14CO2 activity in respiratory air reached its maximum level after 4 hrs, and was then found to decline continuously. 56% of the administered amount of 14C was excreted over a period of up to 50 hrs after beginning of the trial. The very fact that the peak level of 14C activity was observed to appear in the TCE-soluble fraction of the blood plasma as early as after 1 hr seems to indicate that acetamide is also absorbed through the ruminal wall. The half-life of decline in the 14C activity of this fraction was 5.7 hrs. Analysis by thin layer chromatography showed that 75% of this amount of activity is present in 14C acetamide. The rate of 14C incorporation into blood plasma proteins reached a plateau region after 21 hrs, which was also maintained on the 2nd day of the experiment. 6.5% of the administered amount of 14C activity was excreted in the urine until the 7th day of experiment. 76.6% of the amount of urinary 14C activity excreted within a period of 48 hrs were voided as 14C acetamide. 3.8% of the administered amount of 14C activity was excreted with the faeces within the first 6 days of experiment.

Presence of Acetamide in Milk and Beef from Cattle Consuming AFEX-Treated Crop Residues

“…Adam et al also dosed sheep with labeled acetamide directly in the rumen and noted that peak urine accumulation of 15N occurred after only 8 h. 30 Furthermore, the acetamide appeared to be virtually eliminated from the rumen within 15 h in that study, which is also consistent with our findings of rapid reduction of acetamide from milk following removal from the diet. Likewise, labeled carbon from acetamide fed to sheep declined in the rumen with a half-life of 2.5 h. 14 Additional studies will be necessary to further delineate the metabolism and excretion of acetamide in large ruminant animals.…”

“…While acetamide can be metabolized in the rumen by amidase enzymes into acetate and ammonium, − any acetamide that is not metabolized in the rumen could enter the milk or meat, in which case the feed contaminant would also become a food contaminant. Previous research suggests that acetamide can pass through the rumen wall and thus may enter the bloodstream. Recently, it has been shown that acetamide is already present as a food contaminant in many foods, including milk, beef, roasted coffee, and chicory root …”