Effects of season on fleece traits of Angora does in the US.

Twenty nonpregnant Angora does were used to determine seasonal effects on fleece traits, including fiber growth and follicle activity. Does grazed pastures and were supplemented with a 50% concentrate diet at a level near that required for BW maintenance. Clean fiber growth rate was greatest (p<0.05) among seasons in summer and lowest (p<0.05) in winter (1.13, 0.85, 0.98 and 1.20mg/cm(2) per day for autumn, winter, spring and summer, respectively); seasonal differences in fiber diameter were similar (34.9, 31.7, 33.7 and 36.5µm for autumn, winter, spring and summer, respectively). Fleece fiber medullation was greatest (p<0.05) in summer (0.48, 0.32, 0.40 and 0.76%), and medullated fiber diameter was greater in spring and summer than winter (69, 65, 73 and 71µm for autumn, winter, spring and summer, respectively). Primary follicle activity varied with season more than did activity of secondary follicles (primary: 74, 23, 79 and 99%; secondary: 97, 86, 94 and 99%; for autumn, winter, spring and summer, respectively). In summary, Angora goats in the US appear to exhibit seasonal follicle and fiber growth cycles, the knowledge of which may improve future nutritional management for efficient feed use in mohair production. The optimal time of shearing US Angoras for minimal contamination with medullated fibers may be just before spring and autumn equinoxes when it is likely that medullated fibers have been recently shed.