data <- matrix(scan(),ncol=2,byrow=TRUE)
           3.52               1
           3.36               1
           3.57               1
           4.19               1
           3.88               1
           3.76               1
           3.94               1
           3.47               2
           3.73               2
           3.38               2
           3.87               2
           3.69               2
           3.51               2
           3.35               2
           3.64               2
           3.54               3
           3.52               3
           3.61               3
           3.76               3
           3.65               3
           3.51               3
           3.74               4
           3.83               4
           3.87               4
           4.08               4
           4.31               4
           3.98               4
           3.86               4
           3.71               4

data

OEx3.1 <- data.frame(data)
colnames(OEx3.1) <- c("LiverWt","Diet")

OEx3.1$Diet <- as.factor(OEx3.1$Diet)

rm(data)

library(lsmeans)

levels(OEx3.1$Diet)

OEx3.1.lm <- lm(LiverWt ~ Diet, data = OEx3.1)

anova(OEx3.1.lm)

OEx3.1.lsm <- lsmeans(OEx3.1.lm, "Diet")
OEx3.1.lsm

Contrasts = list(First3vsLast = c(1, 1, 1, -3))

contrast(OEx3.1.lsm, Contrasts, adjust = "none")