RT Journal Article T1 Genetic parameters of fiber density traits and their relationship with textile traits in alpacas A1 Cruz, Alan A1 Quispe, Edgar A1 Yucra, Alex A1 Morante, Renzo A1 Burgos, Alonso A1 Quispe, Max David A1 Gutiérrez García, Juan Pablo A1 Gutiérrez Reynoso, Gustavo AB 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 PB Elsevier SN 1871-1413 YR 2025 FD 2025 LK https://hdl.handle.net/20.500.14352/122664 UL https://hdl.handle.net/20.500.14352/122664 LA eng NO Cruz, A., Quispe, E., Yucra, A., Morante, R., Burgos, A., Quispe, M. D., Gutiérrez, J. P., & Gutiérrez-Reynoso, G. (2025). Genetic parameters of fiber density traits and their relationship with textile traits in alpacas. Livestock Science, 299. https://doi.org/10.1016/J.LIVSCI.2025.105754 NO Contribución de autores: Alan Cruz: Writing – original draft, Validation, Investigation, Formal analysis, Conceptualization. Edgar Quispe: Writing – review & editing, Investigation, Funding acquisition, Formal analysis. Alex Yucra: Data curation. Renzo Morante: Writing – review & editing, Data curation. Alonso Burgos: Data curation. Max David Quispe: Investigation, Funding acquisition. Juan Pablo Gutierrez: ´ Writing – review & editing, Visualization, Validation, Supervision, Methodology. Gustavo Gutierrez-Reynoso: ´ Writing – review & editing, Visualization, Validation, Funding acquisition, Conceptualization.Contrato: N.° 451-PROINNOVATE-PIEC2-2023 NO Universidad Nacional Agraria La Molina DS Docta Complutense RD 25 dic 2025