Camargo, Ederson Gomes creator Marques, Daniele Botelho Diniz creator Figueiredo, Elsio Antonio Pereira de creator Silva, Fabyano Fonseca e creator Lopes, Paulo Sávio creator text periodical abstract or summary bl. continuing eng ABSTRACT - We aimed to estimate litter size and litter uniformity genetic parameters and genetic trends of Landrace pigs at birth and at three weeks by using multitrait analyses for 2,787 litters. The following litter traits were evaluated: number of piglets born alive (NBA), within-litter weight mean at birth (MBW), within-litter weight standard deviation at birth (SDB), within-litter weight coefficient of variation at birth (CVB), number of piglets at three weeks (NT), within-litter weight mean at three weeks (MT), within-litter weight standard deviation at three weeks (SDT), and within-litter weight coefficient of variation at three weeks (CVT). Heritability estimates for NBA, MBW, SDB, and CVB were 0.09±0.04, 0.31±0.08, 0.01±0.04, and 0.07±0.05, respectively, greater than those obtained at three weeks (0.06±0.04, 0.10±0.06, 01±0.04, and 0.02±0.04 for NT, MT, SDT, and CVT, respectively). The genetic correlations between NBA and MBW and between MBW and CVB (−0.73±0.20 and −0.93±0.21, respectively) were of moderate to high magnitudes, as well as the genetic correlations between CVT and SDT (0.85±0.39). Genetic correlations between MBW and MT, SDB and SDT, CVB and CVT, and NBA and NT were 0.73±0.16, 0.69±0.54, 0.36±0.80, and 0.95±0.06, respectively. The genetic trends were linear for NBA and CVB and quadratic for MBW and SDB, whereas for all traits at three weeks, they were close to zero. Within-litter weight coefficient of variation (CV) may be the most appropriate variation measure for application in breeding programs, especially at birth, due to its greater heritability estimate and high and negative genetic correlation with MBW. The genetic trends show that NT does not follow the increase in NBA, emphasizing the need to review the breeding goals. Keywords: coefficient of variation, genetic parameters, genetic trends, piglet, variation Publicação on-line; 32 ref.; 4 illus; 6 tables; Sumaries (En) LEITÃO NINHADA PARÂMETRO GENÉTICO PRODUÇÃO ANIMAL Viçosa-MG Sociedade Brasileira de Zootecnia 1997 2024-4310 1516-3598 BR2024000505 v. 49 p. 1-12 ; (2020) https://www.scielo.br/j/rbz/a/pC9P5PJ6MVNMfvXgsK4QzpQ/?format=pdf&lang=en https://www.scielo.br/j/rbz/a/pC9P5PJ6MVNMfvXgsK4QzpQ/?format=pdf&lang=en BR-BrBNA 250402 20250402171116.0 eng