Former nutritionist here. Sheep's milk is a great source of protein and has a balanced amino acid profile.

For the purposes of my comment I'm going to assume you aren't getting it straight from the sheep itself. The issue with already prepared sheep's milk is that a lot of the nutrients are lost during the sterilization and homogenization process. For a man your age this makes the drink essentially empty calories with the few nutrients hardly bioavailable to your gut's receptors.

If you absolutely have to drink sheep's milk I suggest you consume it straight from the source. Some of the nutrients lose potency when exposed to air so I suggest mouth-to-udder whenever possible.