My 38 year old brother yelled at my 8 month old...

So my family (my husband, 8 year old, 8 month old and myself) are staying at my parents house to help take care of their animals while they're on vacation (horses, chickens, cats, dog). My brother lives with them but isn't willing to help out so my parents have my family come to take care of them. I've had issues with my brother in the past. He's about 12 years older than I am and has a history of saying mean things to my oldest daughter and wasn't very nice when I was a kid. I've addressed this with him in the past and he started to get better... until today. He reached a new low. My 8 month old was up for a few minutes babbling in her crib (her room is next to my brothers and I'm downstairs with the baby monitor). I went to the bathroom and she started crying. My brother then proceeds to yell at her repeatedly yelling "SHUT UP!" She wasn't making noise for very long. It was about 8 am so it wasn't the ass crack of dawn or anything. My brother has an odd schedule and doesn't go to sleep until morning and sleeps into the evening. Apparently he had just gone to bed when she woke up. I'm just looking for some advice on how to approach my brother. I feel like I need to say something.