R. Yossi Haglili said: If a ram, which is unfit (as an offering) in the beginning of its second year is kasher the entire second year, then a Pesach, which is kasher in the beginning (i.e., in the midst of its first year), how much more so is it kasher at the end!...
Rabbi Yosei Haglili Employed One of the Most Powerful Tools in
Mekhilta Tractate Pischa 4:2