epi.ltd {epiR} | R Documentation |
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 (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. |
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 and Mark Stevenson (IVABS, Massey University, Palmerston North New Zealand).
Kirkpatrick M, Lofsvold D, Bulmer M (1990). Analysis of the inheritance, selection and evolution of growth trajectories. Genetics 124: 979 - 993.
## Generate 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 <- as.data.frame(cbind(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")