Biometric characteristics in vicuñas (Vicugna Vicugna mensalis)
Introduction
Among the 4 species of South American camelid family (llama, alpaca, vicuña, guanaco), the vicuñas (Vicugna vicugna) are wild camelids that live in Peru (Wheeler, 1998; Wheeler et al., 2001). Vicuñas inhabit the high Andes regions between 3800 and 4800 masl (Zuñiga, 2007), between 9°30′ S and 29°00′ S in Ecuador, Bolivia, Peru, Chile and Argentina (Torres and Puig, 2012). Among these countries, vicuñas generate an annual production value of more than $ US 3 million (CONACS, 2006) with the largest population in Peru (FAO, 2005). Two geographical subspecies are recognised: one to the south (Vicugna vicugna vicugna); the other in the north (Vicugna vicugna mensalis). The southern subspecies is larger and lighter in color with respect to the northern subspecies. However, the most studied is the northern subspecies (Wheeler, 2006).
In the community of Huachocolpa (Huancavelica) the vicuñas (Vicugna vicugna mensalis) are raised in semi-captivity. Given the difficult conditions for managing vicuñas in the Andes region it is necessary to determine the different zoometric measurements and their relationship through indices for the characterization of the species and estimation of body weight. Knowledge of the growth rate and body weight (BW) are important for animal production and animal health management and are known to affect fibre quality in Merino sheep, Angora and cashmere goats (McGregor and Butler, 2008; McGregor et al., 2012; McGregor and Butler, 2016). Mercedes et al. (2011) reported no differences in the zoometric indices of females and males Vicugna vicugna mensalis. Schmidt-Nielsen (1984) has described the allometric relationships between the body measurements of a range of growing animals with their BW but there is little information on this subject for vicuñas.
The objectives of this study are to evaluate the relationships between the BW and sex of the vicuñas and biometric characteristics, and to obtain predictive functions for BW at shearing in the vicuñas managed in semi-captivity by the Campesino Community of Huachocolpa district, Huancavelica region of Peru.
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Study location
The study was conducted in the community of Huachocolpa, located in the district of the same name, province and region of Huancavelica at 4875 m altitude (12°46′57″ S; 74° 58′21″ W). The annual average temperature is 10 °C. The mean annual rainfall is 928 mm, with two defined periods, rainy (November - March) and dry (April - October). The climatic type is humid and cold wasteland. The geomorphology is constituted by dissected highlands, local erosion soils and mountain slopes (ONER, 1984). The
Animal population
The mean and range in the measured biometric characteristics of the vicuñas are provided in Table 1. BW varied between 20.8 and 52.3 kg. In general, the variability of HL, NL, WHT, BHT, RHT, GIRTH, BL and MP can be considered as low (5.6–9.2%).
Effect of sex and age
There were no significant interactions of sex × age on any measurement. There was an effect of sex on the BW and BL (P < 0.05) but not other measurements (Table 2). Age affected BW, BHT, RHT, GIRTH and LA (P < 0.001), MP (P < 0.01) and BL (P < 0.05).
Population characteristics
In this sample of vicuñas, males were heavier and longer than females. Mercedes et al. (2011) previously found no differences between the sexes in body measurements. As might be expected, adult vicuñas were heavier, higher, longer and had a greater girth compared with juvenile vicuñas. The difference in BW between adult and juvenile vicuñas was only 3.6 kg, about 10%, which indicates that by three years of age these vicuñas have almost obtained their mature size. The mean girth of 92.1 cm for
Conclusions
Male vicuñas were heavier and longer than females, and adult vicuñas were heavier, higher, longer and had a greater girth compared with juvenile vicuñas. The best predictive model for body weight, accounting for 64% of the variance in body weight, included terms only for body volume (obtained using girth and body length measurements) and wither height. Sex and age were not significant in the best model. The model was: log10 (body weight) = –19.48 + 8.36 × log10(body volume) –0.83 × (log10(body
Acknowledgments
The authors thank the community of Huachocolpa district Huachocolpa, province and region of Huancavelica, Peru, for the facilities provided and for the authorization for the handling of the vicuñas. We also thank the representatives of the regional leadership of South American Camelids, in the Regional Government of Huancavelica.
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