Toxicity and tissue distribution of methylsulfonylmethane following oral gavage in broilers

An experiment was conducted to investigate the toxicity and tissue distribution of methylsulfonylmethane (MSM) following oral gavage in broilers. A total of four hundred and thirty-two 15-day-old Ross 308 male broilers were allotted to 6 treatments with 6 replicates of 12 birds per replicate and administered a single oral dose of MSM at 0, 50, 100, 300, 1,000, or 2,000 mg/kg BW (Study 1). Another one hundred and sixty-eight 3-day-old chicks were allotted to either control or test group (Study 2) and administered a daily oral gavage of either 0 or 1, 500 mg/kg BW of MSM for 21 D consecutively. Blood and tissue samples were collected over a 48 h (Study 1) or 21 D (Study 2) period and analyzed for MSM concentrations. Toxicity was assessed through changes in hematology and clinical blood chemistry. In Study 1, plasma MSM concentrations were below 167 μg/mL at all time-points in birds receiving up to 300 mg/kg BW, and were significantly higher (P < 0.05) in birds receiving 1,000 or 2,000 mg/kg BW. Similarly, only the highest 2 MSM dosages elicited increased lymphocyte and decreased heterophil counts at 8 h (P < 0.003) and decreased hematocrit at 48 h (P = 0.015). Growth performance variables were unaffected by MSM in Study 2, and plasma and tissue MSM concentrations were highest on study day 21, with MSM-dosed birds always exhibiting higher (P < 0.03) concentrations compared with the control. Birds in Study 2 that were dosed with MSM had decreased liver enzyme concentrations at day 7 and 21 and decreased glucose and phosphorus at day 7. Importantly, MSM was detected in plasma and all tissues of control groups, confirming that MSM is synthesized de novo in chickens. In conclusion, oral MSM at either acute (single dose at 1,000 to 2,000 mg/kg BW) or sub-chronic (1,500 mg/kg BW daily for 21 D) concentrations did not cause any adverse effects on growth or clinical outcomes and appeared to be absorbed and distributed throughout the body.