Hi Gail,
Thank you for posting! For those who are new to this forum, Gail, or OG, is an incredible resource. I've emailed him with questions and photos and he's been so very helpful.
Those who have used the egg drench can attest to how well it works. If you'd prefer a marketed product and it's easier for you, then you should do what is best for you. The drench ingredients can be found locally just as Gail said. If you have chickens and an abundance of eggs it makes the drench pretty inexpensive.
We don't use a drench gun but rather top dress the feed and the lambs readily eat it. We start them with a small amount on their feed and gradually increase the amount.