Quantification of melamine absorption, distribution to tissues, and excretion by sheep1

Abstract

Eight Döhne Merino rams were used to quantify apparent absorption, distribution to tissues, and excretion of dietary melamine in sheep. Two batches of concentrate pellets were made; one (CON) contained corn gluten meal with no detectable melamine and the other (MEL) contained corn gluten meal that was previously found to be highly contaminated with melamine at 15,117 mg/kg. The MEL pellets contained 1,149 mg/kg of melamine. During a 10-d adaptation period, all the animals received a forage-based diet supplemented with 600 g/d of the CON pellets. This was followed by an 8-d collection period during which 6 of the animals received MEL pellets and 2 received CON pellets. Melamine intake of sheep that received MEL pellets was 0.69 g/d. Blood samples were taken before first ingestion of MEL pellets on d 1 and again on d 3, 6, and 8 of the collection period for melamine and serum creatinine analyses. Feces and urine were collected quantitatively over the 8 d for proximate and melamine analyses. All the animals were slaughtered at the end of the trial, and samples of the LM, liver, kidneys, and abdominal fat were taken for melamine analysis. Data of the 2 sheep that received CON pellets for the duration of the trial confirmed that no melamine was detected in any of the samples, and no statistical analyses were performed on these data. The apparent digestibility or efficiency of absorption of ingested melamine was 76.7%. Melamine was detected in the urine, blood, muscle (LM), and fat tissue of all the sheep that received MEL pellets. Serum melamine concentrations reached 5.4 mg/kg on d 8 of the collection period, and the meat (LM) contained 9.6 mg/kg of melamine. Calculations on the partitioning of ingested melamine suggested that urine is the major excretion route accounting for 53.2%, whereas feces accounted for 23.3% of ingested melamine. Approximately 3.5% of the ingested melamine was detected in muscle. It was concluded that ingested melamine is highly absorbable from the small intestine and that a pathway exists for the distribution of dietary melamine to meat.

Melamine in eggs, plasma and tissues of hens fed contaminated diets

“…Melamine in eggs Different authors reported an indirect melamine contamination of animal products, such as milk, cheese, meat and eggs, when animals were exposed to melamine-contaminated diets (Cruywagen et al, 2009;Dong et al, 2010;Cruywagen et al, 2011;Sun et al, 2011). The existence of an excretion pattern from feed to eggs was also reported (Bai et al, 2010;Chen et al, 2010;Dong et al, 2010;Valat et al, 2011;Yang et al, 2011).…”

“…Recently, a pathway of melamine accumulation in various tissues (i.e. muscle, kidney, liver and abdominal fat) was reported in sheep, with a reported efficiency of melamine deposition in meat equal to ,3.5% (Cruywagen et al, 2011).…”

Investigation of melamine and cyanuric acid deposition in pig tissues using LC-MS/MS methods

“…The carry-over of MRC from feed to edible tissues of animals has been investigated in pig, chicken, lamb, sheep and fish (Andersen et al, 2011;Cruywagen et al, 2011;Li et al, 2010;Lv et al, 2010;USFDA, 2007;Wang et al, 2014). The data reported suggest that multiple factors determine MRC depositions in tissues and more data are needed to fully evaluate human health risks associated with consumption of products derived from animals exposed to MRC.…”

<i>In Vitro</i> Degradation of Melamine by Ruminal Microorganisms

“…The estimated effective ruminal melamine degradability of between 3.7% and 7.2% may explain part of the 18% unaccounted for melamine observed in the trial of Cruywagen et al (2011) who investigated excretion routes of melamine in sheep receiving a melamine-tainted concentrate supplement. McDonald (1981) reported that protein degradation is affected by retention time in the rumen and inversely related to passage rate.…”

“…In a study with sheep to quantify the partitioning of absorbed dietary melamine to various tissues and excretion via faeces and urine, Cruywagen et al (2011) found that 53.2% of ingested melamine was excreted via urine and 23.3% via faeces. They reported that the melamine residue in muscle tissue accounted for approximately 3.6% of ingested melamine.…”