lactcurves

The goal of lactcurves is to provide parameter estimates and selection criteria for lactation curve models, cubic splines, and legendre polynomials. Start parameters for lactation curve models were optimized using milk yield test-day data across the first three lactations of ~1.7 million Holstein Friesian cows. Other data might require adjusting of the start parameters, but the lactcurve package gives a comprehensive source of models over the last 100 years.

Installation

You can install the released version of lactcurves from CRAN with:

install.packages("lactcurves")

Example

This is a basic example which shows you how to solve a common problem:

library(lactcurves)
## basic example code

create data set for 3 individuals with milk yield records on 24 days

ID=c(rep("ID123",24),rep("ID456",24),rep("ID789",24))

dim=as.integer(rep(seq(from=5, to=340, by=14),3))

mkg=as.numeric(c(23.4,28.3,30.5,31.3,31.5,31.3,30.9,30.5,30.1,29.6,29.1,28.7,28.2,27.7,27.2,26.7, 26.2,25.7,25.2,24.7,24.2,23.7,23.2,22.8, 21.3,25.7,26.9,27.2,26.9,26.5,26.1,25.6,25.1,24.6,24.1,23.6,23.1,22.6,22.1,21.6,21.1,20.6,20.1, 19.6,19.1,18.6,18.1,17.6, 22.0,26.5,28.1,28.4,28.2,27.9,27.4,26.9,26.4,25.9,25.4,24.9,24.4,23.9,23.4,22.9,22.4,21.9,21.4, 20.9,20.4,19.9,19.4,18.9))

data=cbind.data.frame(ID,dim,mkg)

run example

output=AllCurves(data,mkg,dim)

output$critall output$modeldescrip output$critbest output$bestmodel output$Error output$ModelParam output$summary17b

plot curve

set the number of days to consider

dim=c(1:340)

look up the model and its estimated parameters

output$summary17b

use model and parameters to plot curve

plot(19.293701+(31.358471-19.293701)(1-exp(1)^(-0.059874dim))-0.035495*dim)