Effects of mimosine on fiber shedding, follicle activity, and fiber regrowth in Spanish goats

Ten 2-yr-old Spanish wethers (58.2, +/- 7.21 kg BW) were used to determine effects of 2-d intravenous infusion of mimosine (beginning on January 8) on fiber shedding, follicle activity, and fiber regrowth. Primary and seconda ry follicle activity on d 0 were 43 +/- 6.2% and 96 +/- 1.7%, respectively. Five wethers were infused with mimosine at 120 mg/(kg BW.d) and the other five received saline. At 7 to 10 d after the start of infusion, all five go ats infused with mimosine exhibited shedding, whereas shedding by controls was not observed. Cashmere fiber shedding score (5-point scale: 1 = no shed ding, 5 = excessive shedding) on d 4 was greater for mimosine goats than fo r controls (1.2 vs 2.0; P < .001), and shedding score for wethers receiving mimosine was greater (P < .05) on d 12, 16, and 20 than on d 0 and 4 (4.1 to 4.6 vs 1.4 and 2.0). Guard hair shedding score for goats receiving mimos ine was greatest (P < .01) among the days after infusion for d 12 and great er (P < .01) on d 16 than on d 0 and 4. Nonetheless, cashmere fiber yield f rom combed fleece of mimosine goats (average of 73%) was much greater than for a clipping of the uncombed side (average of 28%) when the cashmere fibe r shedding score exceeded 4.0. Secondary follicle activity on d 12 was lowe r (P < .01) for mimosine than for control wethers (6.8 vs 67.7%), and secon dary follicle activity for mimosine-infused goats on d 12 was lower (P < .0 1) than on d 0 (98.9 %), 4 (98.3%), and 20 (99.5%). Mimosine infusion resul ted in no detectable fiber regrowth in wk 4 to 7 after the start of infusio n, but regrowth rate in the following two 4-wk periods was similar for mimo sine and control wethers. In conclusion, 2-d intravenous infusion of mimosi ne at 120 mg/(kg BW.d) in the winter induced cashmere shedding but had less effect on guard hairs, suggesting future potential use of chemicals such a s mimosine to remove cashmere fiber.