title: Heritability estimates for ages at farrowing, rebreeding interval and litter traits in swine.
abstract: Data from three commercial herds of swine located in Santa Catarina State, Brazil, were used to estimate least-squares means, variance components and heritabilities for reproductive traits. A total of 663 Landrace and Large White gilts by 155 sires provided information on first farrowing and litter traits and records on 433 sows by 118 sires were available for second farrowing traits. Age at conception and at farrowing, number born, number born alive and first to second farrowing interval were analyzed. Landrace females were younger than Large White females at first and second conception and first and second farrowing (P less than .05). Gilts born during summer months were younger at first farrowing (P less than .05) than those born during winter. Sows weaning their first litter during the summer had longer gestation periods and longer weaning to conception and farrowing intervals than sows weaning their first litter during the winter (P less than .001). Least-squares means for age at first conception and farrowing and at second conception and farrowing were 273.5, 388.3, 437.0 and 551.8 d, respectively. Average weaning to conception and farrowing intervals were 22.0 and 173.7 d, respectively. Sire variance components were usually negative or equal to zero for first and second litter traits. This was also observed for dams in some cases.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000367:Age Factors; D000818:Animals; D001938:Brazil; D005260:Female; D008098:Litter Size; D008957:Models, Genetic; D011247:Pregnancy; D012098:Reproduction; D013552:Swine / Q000235:genetics* / Q000502:physiology