Which Is Correct?

[Maggoty]

1) The biggest problem with PRA and breeding is that the onset of the disease is late and usually develops after offspring are produced; so controlling the disease is quite difficult.

or

2) The biggest problem with PRA and breeding is that the onset of the disease is late and usually develops after offspring are produced, so controlling the disease is quite difficult.

do I use a ; or a , - or are both acceptable :-)

Thanks guys

[boxtops]

I would say this

~~ after offspring are produced. Controlling the disease is therefore quite difficult.

[woofgang]

By me both are acceptable, I would tend towards the comma.

[Baldric]

" , " imho.

[Maggoty]

Thanks guys - comma it is ;-)