becker.chicken {agridat} | R Documentation

## Mating crosses of chickens

### Description

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

    data(becker.chicken)
    dat <- becker.chicken

    if(require(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))
    }

    ## Not run:
      # Sums match Becker
      sum(dat$weight)
      aggregate(weight ~  male + female, dat, FUN=sum)

      # Variance components
      require(lme4)
      require(lucid)
      m1 <- lmer(weight ~  (1|male) + (1|female), data=dat)
      as.data.frame(lme4::VarCorr(m1))
      ## grp        var1 var2      vcov    sdcor
      ## 1   female (Intercept) <NA> 1095.6296 33.10030
      ## 2     male (Intercept) <NA>  776.7543 27.87031
      ## 3 Residual        <NA> <NA> 5524.4000 74.32631

      # 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

    ## End(Not run)

[Package agridat version 1.16 Index]