Mating crosses of chickens

Usage

data("becker.chicken")

Format

A data frame with 45 observations on the following 3 variables.

male: male parent
female: female parent
weight: weight (g) at 8 weeks

Details

From a large flock White Rock chickens, five male sires were chosen and mated to each of three female dams, producing 3 female progeny. The data are body weights at eight weeks of age.

Becker (1984) used these data to demonstrate the calculation of heritability.

Source

Walter A. Becker (1984). Manual of Quantitative Genetics, 4th ed. Page 83.

References

None

Examples

if (FALSE) { # \dontrun{

  library(agridat)
  data(becker.chicken)
  dat <- becker.chicken
  
  libs(lattice)
  dotplot(weight ~ female, data=dat, group=male,
          main="becker.chicken - progeny weight by M*F",
          xlab="female parent",ylab="progeny weight",
          auto.key=list(columns=5))

  # Sums match Becker
  # sum(dat$weight)
  # aggregate(weight ~  male + female, dat, FUN=sum)

  # Variance components
  libs(lme4,lucid)
  m1 <- lmer(weight ~  (1|male) + (1|female), data=dat)
  # vc(m1)
  ## grp        var1 var2      vcov    sdcor
  ## 1   female (Intercept) <NA> 1096   33.1
  ## 2     male (Intercept) <NA>  776.8 27.87
  ## 3 Residual        <NA> <NA> 5524   74.32

  # Calculate heritabilities
  # s2m <- 776  # variability for males
  # s2f <- 1095 # variability for females
  # s2w <- 5524 # variability within crosses
  # vp <- s2m + s2f + s2w # 7395
  # 4*s2m/vp # .42 male heritability
  #4*s2f/vp # .59 female heritability

} # }