Melatonin implantation from winter solstice could extend the cashmere growth phase effectively

The effects of melatonin on cashmere growth in Liaoning cashmere goats were studied by treatment with melatonin implants from December (winter solstice) to June. Thirty-two castrated Liaoning cashmere goats were randomly allotted to 2 treatment groups, with 8 replicates of 2 goats per treatment group. In the experimental (E) group the goats were given melatonin implants subcutaneously with 2 mg per kilogram of BW, while in the control (C) group goats had no implant. All goats were fed a balanced diet under the same environmental conditions. Feed intake and live weight were recorded. Plasma melatonin concentration, cashmere growth rate, cashmere fibre diameter and secondary follicle activity were determined on samples taken monthly from December to June. There was no significant effect of melatonin implantation on feed intake and live weight. Plasma melatonin concentrations declined significantly with time in C but not in E, so that levels in E were significantly higher than in C from January to June. Cashmere growth rate decreased significantly with time in both E and C, but growth in C was less than in E from January to March, when it ceased completely in C. Cashmere fiber diameter was unaffected by time or treatment. Secondary follicle activity decreased significantly in both groups, but more rapidly in C than in E. Melatonin implants could be an effective way to increase cashmere production after the winter solstice.