Effect of photo-translation on fleece growth in cashmere goats

Abstract

Cyclical changes in fleece parameters were studied in mature feral doe goats exposed to either natural light (NL) followed by continuous light (CL) then NL, or CL followed by NL then CL.Results show that both initial translocations (NL-CL and CL-NL) were recognized immediately and reflected in changes in volume growth rate, length, diameter, brush end fibres of cashmere and cashmere : hair ratio. Cyclic activity continued after the change in photoperiod. Progressive alterations in cycle amplitude, period and frequency appeared in CL following the initial NL-CL change. Following the initial CL-NL change, cycles of some cashmere fleece parameters continued to be influenced by previous CL exposure and did not immediately adopt NL cyclicity. Mean cycle periods of 252-261 days were common to all CL photoperiods and to NL following CL. This suggests that CL exposes a unique cycle of fleece growth, which is independent of photoperiod and retained for some time after the cessation of CL, owing to transient modification of pineal function. Differences between the response to the first and second translocation may be a function of interactions between the cycle status and translocation, rather than solely the change from one photoperiod to another.The NL-CL change resulted in two cycles of cashmere growth in the 392 days following the initial translocation. This would allow two fleeces to be harvested during that time compared with the one expected in NL alone. Exploitation of this principle may represent an opportunity to increase cashmere production.