Effects of mimosine on plasma amino acid concentrations in Angora goats

Abstract

Effects of mimosine intravenously infused for 2 days or orally dosed on plasma amino acid concentrations in Angora goats were determined. In one experiment, 20 mature Angora wethers (36 ± 1.9 kg BW) were infused for 2 days with 79, 102 and 135 mg/(kg BW/day) of mimosine, 90 mg/(kg BW/day) of 2,3-dihydroxypyridine (2,3-DHP) or saline; plasma was sampled before infusion and 24 and 48 h later. At 7 days after infusion began, fleece shedding was observed in all goats receiving mimosine, but not in any goats infused with 2,3-DHP or saline. Mimosine depressed ( p < 0.05) plasma concentrations of Gly, Thr, Arg and Lys, with mimosine level having no effect. Conversely, amino acid concentrations in goats infused with 2,3-DHP were similar ( p > 0.10) to levels in Control goats. In another experiment, Angora bucklings (23 ± 0.5 kg BW) were orally dosed with 400 or 600 mg/kg BW of mimosine; plasma samples were collected before dosing and 22 and 46 h later. At 9 days after oral doses of mimosine, no fleece shedding was noticeable; however, at 31 days changes in fleece status of some goats were observed. For Thr and Arg, mimosine dosing decreased plasma concentrations at 22 h compared with concentrations before dosing ( p ≤ 0.05), and for Thr, Arg and Lys mimosine dosing increased amino acid concentrations at 46 h ( p ≤ 0.05). The increase in Val concentration due to mimosine dosing was greater than 0 for 400 mg/kg BW of mimosine ( p < 0.05) and at 46 h ( p < 0.01), and was greater ( p < 0.05) at 46 than 22 h. The increase in Leu concentration due to mimosine dosing differed from 0 for 400 ( p < 0.05) and 600 mg/kg BW of mimosine ( p < 0.05) and at 46 h ( p < 0.01), and was greater ( p < 0.05) at 46 versus 22 h. In conclusion, 2-day infusion of mimosine to defleece altered plasma concentrations of some amino acids.