Non-genetic factors affecting morphometric and fleece traits in guanaco (Lama guanicoe guanicoe) populations from Argentinean Patagonia

Lama guanicoe guanicoe is the guanaco subspecies located in the Argentinean Patagonia. It is of particular interest to characterize these populations as it is a native species and a high quality fibre production genetical resource. With the aim of describing phenotipically Lama guanicoe guanicoe populations, 262 specimens were sampled. The animals came from four different ecological regions, both wild and bred in captivity, from 5 ranches. Three age classes were established: calves (0–1 year), yearlings (1–2 years) and adults (more than 2 years). Morphometric variables measured were: body length (BL), thoracic depth (TD), half thoracic perimeter (HTP), head length (HL), shin length (ShL) and metacarpal circumference (MC). Fleece samples were evaluated on two ranches (n = 115) for: fleece total weight (FTW) and mean diameter of down (MDFD). Relationships between variables were studied and differences between morphostructures considering sex, age and ranch were analyzed. Age was the most important differencing factor (p < 0.05) for all morphometric traits (except for the ShL between yearlings and adults). Calves had finer MDFD (14.2 ± 0.6 μm) and less FTW (159 ± 47 g) than yearlings (15 ± 5.8 μm and 254 ± 57 g). Sexual dimorphism was not found in calves nor in yearlings for any of the morphometric characters considered. Adult females presented greater significant values (p < 0.05) for TD (42.7 ± 2.1 cm) and HTP (55.4 ± 3.2 cm) than males (41.6 ± 2.3 cm and 53 ± 2.9 cm, respectively). Only calf males presented higher significant values than females for the FTW (169 ± 42 g and 147 ± 51 g, respectively). FTW and MDFD were positively correlated between them (0.42) and with the thoracic measures (TD and HTP), these data imply an inverse relationship between quality and quantity of the fleece and suggest that the thoracic variables are good indicators of the fleece animal production in these Patagonian populations.