We weaned early this past year and weaned everything over 110kg. I believe you can go lower but a lot more risk is involved. But also can involve the welfare of the cow. It is worth talking to your local LLS vet as ours has been doing a great job and I can highly recommend the LLS vet based out of Central West NSW and Coonamble.
We yard weaned for 2 weeks and as we didn't have a lot of paddock feed we continued to supplement feed them after weaning. After the 2 weeks we used confined lots/yards to save them from wasting energy walking and instead put it into growing. You cannot maintenance feed weaners or calves, especially if you are planning on keeping/breeding the heifers. You will be feeding for growth and it is important to have good nutritional information.
Basics of our set up was:
- Clean water,
- Ad lib high quality hay (I planned ahead and stocked oaten and barley hay for this reason) also helps to have decent hay feeders to reduce waste and injury. Weaners will find a way to climb into the weirdest positions!!
- High protein feed. ours was around that 18% protein mark. we didn't muck around with mixing our own grain ration as we would have had to buy all the grain and additives so we went with a pellet specifically designed for the age and weight of our weaners. I worked out the cost would slightly higher for the pellets but I also considered hours sourcing, mixing and handling a grain ration. We also had no loses and no health problems on this brand of pellet. Investigate what you are purchasing and request a feed test if one hasn't already been done, even do feed tests for bought grain so you know exactly what you are feeding.
- Feeding and troughs: we started them on hay for the first day and inducted them onto the pellets in troughing with enough head space to fit each weaner at the same time. I think the DPI drought handbook lists it at 30cm for weaners...you may have to work out what suits you best. Once inducted (building slowly on the amount of feed over 7-10days and we also feed morning and night to reduce risk)
- We moved from the troughs to self feeders at full ration as we found this worked best for us. We used advantage feeders and were able adjust the feed to the correct weight. this was very helpful as we held them in the lot past weaning and were able to keep them in forward and growing condition.
This is just my experience/opinion as a farmer/grazier and I highly recommend having a large animal nutritionist in your contact list and utilising your local LLS or local vet. There are also some really great free information days on early weaning, depending on where you are located in NSW. Good luck.