Poision

Are Leylandi cuttings poisionous to cattle?

Yew is certainly poisionous.

But yew is not leylandii. Yew contains some specific chemicals called taxines.

Just below is a link to a book about poisonous plants. The book has a section about yews. You can look in fhe index, and there doesn't seem to be any reference to Leylandii (through that doesn't mean Leylandii is safe to eat)...

http://www.amazon.co.uk/Handbook-Poisonous-Injurious-Plants-Goldfrank/dp/0387312684/ref=sr_1_3?ie=UTF8&qid=1354791459&sr=8-3#reader_0387312684

do not feed your cattle leylandi or anything like that,yew is very deadly and I could go on.feed them what they normally eat.I known so many horses that have been fed what people think is alright and they die .

Why are we talking about yew?  Leylandi is absolutely nothing to do with yew! 

However, Leylandi can be a skin irritant and there are some reports of it causing abortion in cattle if a lot is eaten.  IME most cattle would not eat much of a growing Leylandi, but if someone put prunings in their fodder they might well eat enough to cause problems. Some cattle just do not have much of a self-preservation instinct!