texto <- 'Animal    Time    Consumo
5   1   2.53396
5   2   2.32906
5   3   2.94379
5   4   3.36162
6   1   2.89082
6   2   2.53898
6   3   2.97881
6   4   3.03876
7   1   2.81885
7   2   2.73889
7   3   2.67891
7   4   2.87885'

Consumo <- read.table(text = texto, header = TRUE)
Consumo$Animal <- factor(Consumo$Animal)

Consumo$especial <- ifelse(Consumo$Animal == '7', 'especial', 'normal')

library(ggplot2)
gg1 <- ggplot(data = Consumo, aes(x = Time, y = Consumo, colours=Animal)) +
  geom_line(aes(color = especial))
gg1

gg2 <- gg1 +
  scale_color_manual(values = c(especial = 'red', normal = 'grey')) +
  guides(colour = 'none')
gg2

gg2 + xlab("Time, d") +
  ylab("Forecast daily feed intake,kg") +
  theme_bw() +
  labs(title = "C: Current model") +
  theme(plot.title = element_text(face = "bold", size = 18, hjust = 0),
        axis.title = element_text(size = 18),
        axis.text = element_text(size = 14))