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ABSTRACT This study used a pedigree analysis to monitor trends in the genetic structure of the Mangalarga breed and identify factors that could impact its genetic variability. For this, genealogical information was used from the Associação Brasileira dos Criadores de Cavalo da Raça Mangalarga, considering as total population (TP) the animals born between 1919 and 2018 (n = 206,426) and as reference population (RP) those born between 2009 and 2018 (n = 20,539), which is the most recent generation according to the average generation interval calculated for the breed of 9.37 years. We evaluated the number of male and female births per year, foals produced by Mangalarga breeding animals, using the ENDOG 4.8, generation interval, proportion of known ancestors per parental generation, number of equivalent generations known per animal, inbreeding coefficient, increase in inbreeding, average relatedness (AR), effective population size, effective number of founders, effective number of ancestors, and founder genome equivalent. The number of equivalent generations known per animal increased over time, reaching an average of 2.75 in TP and 4.88 in RP. The calculated F was 2.26% for TP and 5.57% for RP, while AR was 2.41% for TP and 4.10% for RP. The effective population size was 40.85 for TP and 38.89 for RP. The 206,426 registered Mangalarga horses (TP) were derived from the genetic contribution of 9,011 founders and 8,908 ancestors, whereas those registered in or after 2009 (RP) originated from 2,662 founders and 2,193 ancestors. The effective number of founders represented 1.11 and 1.35% of the total number of founders in TP and RP, respectively. For RP, 11 animals accounted for 29.21% of the genetic pool of the breed. The analysis of population parameters estimated in the present study indicates that the Mangalarga horse population was formed through uneven contributions from founders and ancestors; therefore, genetic management of the breed is required to restrict average inbreeding from increasing over generations. variability this (TP 191 201 n 206426 206 426 RP (RP 200 20,539, 20539 20,539 , 20 539 20,539) 937 9 37 9.3 years year 48 4 8 4.8 coefficient AR, (AR) time 275 2 75 2.7 488 88 226 26 2.26 557 5 57 5.57 241 41 2.41 410 10 4.10 4085 40 85 40.8 3889 38 89 38.8 206,42 9011 011 9,01 8908 908 8,90 2662 662 2,66 2193 193 2,19 111 1 1.1 135 35 1.35 respectively 2921 29 21 29.21 therefore 19 20642 42 2053 20,53 53 93 3 9. 4. (AR 27 7 2. 22 2.2 55 5.5 24 2.4 4.1 408 40. 388 38. 206,4 901 01 9,0 890 90 8,9 266 66 2,6 219 2,1 1. 13 1.3 292 29.2 2064 205 20,5 5. 206, 0 9, 8, 6 2, 29. 20,