Effect of Immunization Against Melatonin on Seasonal Fleece Growth in Feral Goats

In 1992, a study investigated the impact of immunization against melatonin on the cashmere growth cycle in Australian feral goats using four different vaccination protocols. The study found that goats with a significant immune response to the vaccinations experienced an accelerated cashmere growth cycle, with two cycles of cashmere length growth within the first 16 months and an increase in annual cashmere production during the first year. However, these effects were not observed in the second year, suggesting possible desensitization to melatonin or a reduced antibody response. The immunization affected both sexes, with a greater impact on cashmere length in wethers (castrated males) than in does (females). Continuous decline in specific antibody levels led to more frequent but smaller cashmere growth cycles, while guard hair growth was less affected. Small peaks in specific immunity during solstices had no significant effect on cashmere growth. Immunization timed at the winter solstice significantly increased greasy fleece weight, cashmere yield, and mass of cashmere produced without affecting fiber diameter. The study concluded that the timing of cashmere growth cycles in goats could be transiently altered by appropriately timed immunization against melatonin, suggesting that melatonin may regulate cashmere growth cycles by either entraining an endogenous rhythm or altering follicle sensitivity seasonally.