Genetic parameters of fiber density traits and their relationship with textile traits in alpacas

Abstract

Genetic improvement programs for alpacas that focus on reducing fiber diameter have succeeded in enhancing fiber quality but they have also decreased fleece weight. Fiber diameter and fleece weight have an unfavorable genetic correlation, which makes it difficult to improve both traits simultaneously. This study aimed to estimate the genetic parameters of fiber density traits, and their genetic correlations with fleece weight (FW), fiber diameter (FD), density score (DS) and percentage of medullation (PM), as well as to evaluate their incorporation as selection criteria to increase fleece weight. The density traits were the number of hair ducts per mm²(HD), number of fibers per mm² (NF) and the NF/HD ratio (RT). Fiber density traits were objectively measured by using high-resolution skin images taken from 402 Huacaya alpacas. Animal model was used to estimate genetic parameters. Pedigree (15,360 alpacas) and phenotype records for FW (11,271), DS (5,752), FD (8,763) and PM (8,763) were retrieved from the Pacomarca database. The heritability was 0.40±0.05, 0.47±0.03, 0.37±0.05, 0.34±0.02, 0.31±0.01, 0.28±0.01 and 0.16±0.01 for HD, NF, RT, DS, FD, PM and FW respectively. Favorable genetic correlations were found between NF-FW, NF-FD and DS-FW, with values of 0.36, -0.50 and 0.50, respectively. However, unfavorable genetic correlations were also found between FD-FW and PM-FW, with values of 0.35 and 0.24 respectively. NF is an appropriate selection criterion for improving fiber diameter, percentage of medullation and fleece weight simultaneously in Huacaya alpacas.