The effect of melatonin implants on shedding of cashmere in goats

Abstract

In the study of the effect of exogenous melatonin on shedding of cashmere fibre, 10 pregnant feral goats received two subcutaneous implants, each containing 18 mg of melatonin. Five does were implanted on 2 July 1987 and the remainder received the implants on 23 July 1987. A further 5 contemporary does served as herd mate controls. Five rising l-year-old bucks were treated in the same manner on 23 July with 4 contemporary bucks serving as controls. Blood samples were collected weekly for 13 weeks for determination of plasma melatonin levels and mid-fleece samples were plucked weekly to detelmine the percentage of brush end formation. In the treated goats plasma melatonin levels rose within 24 hours of implantation. In the bucks plasma melatonin concentrations returned to basal levels 10 weeks after implantation, whereas in the treated does plasma melatonin levels did not return to basal levels within the experimental period. Also does treated on 23 July took longer to attain peak melatonin levels and these were maintained for longer than in the does treated on 2 July 1987. No significant treatment differences in brush end formation were detected (P >0.05), however the trends observed indicated that melatonin delayed shedding of cashmere. Does treated on the 2 July and 23 July obtained maximum percentage of brush ends three and five weeks respectively after that of the control does. Melatonin treatment appeared to have no harmful side-effects on productivity (e.g. rearing of kids) of these does.