Effect of Age and Sex on Medullation Types and Fiber Characteristics in Huacaya Alpacas

Background: Fiber is a distinctive attribute of the alpaca due to its softness qualities; it contains less grease and has a finer cuticle compared to sheep's wool. Therefore, the types of medullation were estimated: non-medullated fibers (NoMed), fragmented medulla (FragMed), discontinuous medulla (DiscMed), continuous medulla (ContMed) and strongly medullated fibers (StrMed), considering the age and sex of Huacaya breed alpacas (Vicugna pacos) under extensive management conditions in high Andean pastures. Methods: Six grams of fiber samples were collected from the mid-side region (located above the third last rib, halfway between the midline of the belly and the midline of the back) of 240 Huacaya alpacas from the district of Macusani, province of Carabaya, Puno, during the year 2022. They were then processed in the Fiber Laboratory of the Faculty of Textile Engineering and Garments at the National University of Juliaca using the FIBER EC V4.0 and FIBER MED V1.0 equipment. Result: The results obtained show that the percentage of non-medullated fibers decreases as the animal’s age increases (1 year= 75.60%, 2 years=69.43%, 3 years=69.05% and greater than 4 years=66.25%) (P≤0.05). The percentage of medullated fibers in animals of 1 year was 24.40%; 2 years, 30.57%; 3 years, 30.95% and greater than 4 years, 33.59% (P≤0.05). The mean fiber diameter in 1-year-old alpacas is 17.32 mm, 2 years=19.49 mm, 3 years = 19.91 mm and 4 years=20.10 mm (P≤0.05). The comfort factor in 1-year-old animals is 99.47%, 2 years with 98.02%, 3-year-olds with 97.01% and those older than 4 years with 96.45% (P≤0.05). Regarding the curvature index, values of 55.86 °/mm were obtained for 1-year-old animals, 53.43 °/mm for 2-year-olds, 53.99 °/mm for 3-year-olds and 52.23°/mm for those older than 4 years (P≤0.05). In conclusion, Huacaya alpacas exhibit low values for the percentage of strongly medullated fibers due to the age and sex of the animal, demonstrating very good fleece uniformity.