Differences in fibre diameter profile between shearing periods in white Huacaya Alpacas (Vicugna pacos)

A total of 153 midside fibre samples, one per animal at left side, were obtained in two shearing periods (I Period: December 2009, n=109; II Period: March 2010, n=44) from white Huacaya alpacas belonging to CIPCS - Lachocc herd of National University of Huancavelica. Fibre diameter profiles (FDP) were obtained using the OFDA 2000 instrument, measuring fibre diameter every 5 mm along the entire length of staples (Brims et ah, 1999), in a subsample of between 400-800 fibres per animal. Different fibre diameter profile variables were calculated and compared between shearing periods taking into account differences due to sex and age. The variables were the following: average fibre diameter (AFD), maximum and minimum fibre diameter (FDMax, FDMin), its respective positions (PMax, PMin), fibre diameter change along the staple (TACA, calculated as the absolute value of (FDMax - FDMin), and fine ends (FE; calculated as the difference between the mean diameter of fibres in the first (f) and last (1) 5 mm of the staple, and FD: FE=[(f+l)/2]-FD). Results show different FDP for the two shearing periods, being significantly different PMax PMin and FE (P<0.05). No differences for sex were observed, but age affected AF, FDMax, FDMin, PMax, PMin, TACA and FE (P<0.05). These results showed, in terms of the needs of textile industry in processing performance, a better quality of fibre obtained during the shearing ofDecember 2009.