epiR (version 2.0.75)

epi.ltd: Lactation to date and standard lactation milk yields

Description

Calculate lactation to date and standard lactation (that is, 305 or 270 day) milk yields.

Usage

epi.ltd(dat, std = "305")

Value

A data frame with nine elements: ckey cow identifier, lact lactation number, llen lactation length, vltd milk volume (litres) to last herd test or dry off date (computed on the basis of lactation length, fltd fat yield (kilograms) to last herd test or dry off date (computed on the basis of lactation length, pltd protein yield (kilograms) to last herd test or dry off date (computed on the basis of lactation length, vstd 305-day or 270-day milk volume yield (litres), fstd 305-day or 270-day milk fat yield (kilograms), and pstd 305-day or 270-day milk protein yield (kilograms).

Arguments

dat

an eight column data frame listing (in order) cow identifier, herd test identifier, lactation number, herd test days in milk, lactation length (NA if lactation incomplete), herd test milk yield (litres), herd test fat (percent), and herd test protein (percent).

std

std = "305" returns 305-day milk volume, fat, and protein yield. std = "270" returns 270-day milk volume, fat, and protein yield.

Author

Nicolas Lopez-Villalobos (IVABS, Massey University, Palmerston North New Zealand) and Mark Stevenson (Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Australia).

Details

Lactation to date yields will only be calculated if there are four or more herd test events.

References

Kirkpatrick M, Lofsvold D, Bulmer M (1990). Analysis of the inheritance, selection and evolution of growth trajectories. Genetics 124: 979 - 993.

Examples

## EXAMPLE 1:
## Generate some herd test data:
ckey <- rep(1, times = 12)
pkey <- 1:12
lact <- rep(1:2, each = 6)
dim <- c(25,68,105,145,200,240,30,65,90,130,190,220) 
llen <- c(280,280,280,280,280,280,NA,NA,NA,NA,NA,NA)
vol <- c(18,30,25,22,18,12,20,32,27,24,20,14)
fat <- c(4.8,4.3,4.5,4.7,4.8,4.9,4.8,4.3,4.5,4.7,4.8,4.9)/100
pro <- c(3.7,3.5,3.6,3.7,3.8,3.9,3.7,3.5,3.6,3.7,3.8,3.9)/100
dat.df01 <- data.frame(ckey, pkey, lact, dim, llen, vol, fat, pro)

## Lactation to date and 305-day milk, fat, and protein yield:
epi.ltd(dat.df01, std = "305")

## Lactation to date and 270-day milk, fat, and protein yield:
epi.ltd(dat.df01, std = "270")