The Markhoz goat is an endangered Iranian mohair-producing breed, raising concerns about genetic diversity and inbreeding depression. This study examined the effects of inbreeding and key environmental factors (sex, age, coat color) on fleece traits in 323 goats. Fiber diameter, staple length, fiber type composition, fleece weight, fat percentage, and clean yield were measured using standard procedures. Inbreeding coefficients, calculated from pedigree records, averaged 2.78% overall and 5.17% among inbred animals. Comparisons between inbred and non-inbred goats showed no significant differences (p > .05) in fiber diameter (28.46 vs. 28.78 µm), staple length (13.93 vs. 13.77 cm), true fiber percentage (91.89 vs. 92.21%), fleece weight (493.21 vs. 514.45 g), or yield (76.86 vs. 77.21%). Regression analysis indicated no significant effects of inbreeding on any fleece trait. In contrast, environmental factors strongly influenced fleece characteristics. Males had coarser fibers (29.16 vs. 28.35 µm), higher medullation, and higher yield (p < .01). Age significantly affected fiber diameter, staple length, fleece weight, and kemp percentage, with peak fleece weight at 3–5 years (580–639 g). Coat color also influenced most traits, with black goats showing the finest fibers (27.87 µm) and highest true fiber percentage (96.33%).
