fatten up

give a person or animal plenty to eat，causing him or it to gain weight长肥；养壮

The pigs are being fattened up for market．这些猪正在被催肥待售。

She is fattening up the ducks．她正在把鸭子养肥。

I'm trying to fatten him up as fast as I can．我在努力尽快把他养得壮实些。