J. Anim Sci.
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J. Anim Sci. 1984. 59:67-73.
© 1984 American Society of Animal Science
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Heritability Estimates for Ages at Farrowing, Rebreeding Interval and Litter Traits in Swine1

R. Irgang2 and O. W. Robison3

Empresa Brasileria de Pesquisa Agropecuária, EMBRAPA, CNPSA, Concórdia, Santa Catarina, Brazil and and North Carolina State University, Raleigh 27695-7621

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<.05). Gilts born during summer months were younger at first farrowing (P<.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<.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. Estimates of heritability from paternal and maternal half-sibs were, respectively, .47 ± .26 and .49 ± .35 for age at first conception, .49 ± .26 and .49 ± .35 for age at first farrowing, .09 ± .32 and .91 ± .43 for age at second conception, .13 ± .32 and .87 ± .43 for age at second farrowing, .24 ± .34 and .03 ± .53 for weaning to conception interval and .27 ± .34 and .24 ± .50 for farrowing interval. Additive genetic correlations between age at first conception and weaning to conception and farrowing intervals were small but positive. These results suggest that selection for age at first conception should be effective in increasing pigs •sow-1 •year-1.

Footnotes

1 Paper No. 8945 of the Journal series of the North Carolina Agricultural Research Service, Raleigh.

2 Researcher, EMBRAPA, Concórdia, Santa Catarina, Brazil, at Dept. of Anim. Sci., North Carolina State Univ.

3 Dept. of Anim. Sci., North Carolina State Univ.






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Copyright © 1984 by the American Society of Animal Science.