Lactation to date and standard lactation milk yields
Calculate lactation to date and standard lactation (that is, 305 or 270 day) milk yields.
epi.ltd(dat, std = "305")
dat |
an eight column data frame listing (in order) cow identifier, herd test identifier, lactation number, herd test days in milk, lactation length ( |
std |
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Lactation to date yields will only be calculated if there are four or more herd test events.
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).
Nicolas Lopez-Villalobos (IVABS, Massey University, Palmerston North New Zealand) and Mark Stevenson (Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Australia).
Kirkpatrick M, Lofsvold D, Bulmer M (1990). Analysis of the inheritance, selection and evolution of growth trajectories. Genetics 124: 979 - 993.
## 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 <- data.frame(ckey, pkey, lact, dim, llen, vol, fat, pro) ## Lactation to date and 305-day milk, fat, and protein yield: epi.ltd(dat, std = "305") ## Lactation to date and 270-day milk, fat, and protein yield: epi.ltd(dat, std = "270")
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