Highland Cattle. Weight estimate

We have just purchased a 2 hectare block at Mangatangi and have inherited 3 Highland calves that are about 9 months old.
I suspect they haven't been dosed for a while.
The largest is 1.0m at the shoulder.
How do I estimate their approximate weight so I can measure out the correct dose of "pour on"
I wanted to weigh them, but the boss won't let them into the bathroom.
Thanks
Murray

You do not take the animals to the bathroom - you take the bathroom to the animals. To use bathroom scales, you put them inside a plastic bag with just the digital reader showing. Then grab the animal just behind the front legs, lift it up and you (and it) stand on the scales. Take the reading, put the animal back, then weigh yourself. Take total weight, subtract your weight, and that it the animals weight. Easy as .... until the animal gets too big so the scales won't read total weight.
For cattle, you can buy tape measures which are calibrated to read their chest measurement and convert that to weight. Otherwise, get an ordinary dressmakers tape, put the animals in the race in the yards, suspend the tape over it's shoulders so that the end dangles just behind the front legs, grab the end (without getting your arm caught between legs and posts), and measure the girth . Post back that measurement in Our Place, and hopefully someone might be able to convert it for you.
But, but, but ..... why do you think they need drenching? If they have firm poo then they likely don't need drenching, unless they are rubbing themselves continuously. If they are rubbing themselves then look for lice when they are in the race. They will need some Sel-por selenium though, which is given according to weight.

Murray & Sh'ann;423515 wrote: ...How do I estimate their approximate weight so I can measure out the correct dose of "pour on"?...

You don't estimate and approximate with pour-on or you might as well pour the stuff into a hole in the ground. Underdosing with pour-on will advance worm drench resistance very quickly.

LongRidge;423532 wrote: ...To use bathroom scales, you put them inside a plastic bag with just the digital reader showing. Then grab the animal just behind the front legs, lift it up ...

Nine month old cattle? Just a little unrealistic, I think.

As LR also says, get a weight band, or better still, ask your vet if they have platform scales to hire/lend. They have a couple of load bars and the platform sits over them in your race (you do have a race and yards, I hope?) and then you'll know for sure how much to give them.