Lamb milk and colostrum is easily frozen and retains its nutritional value for up to one year if stored in a chest freezer or hree months in a refrigerator freezer. The best way to freeze the milk is in small amounts.  To do this, put it in ice trays until frozen and then store the cubes in freezer storage bags. The small cubes will allow you to thaw what you need.  Freeze the milk as quickly after milking as possible to maintain quality.  Try to avoid freezer burn so milk flavor will not be affected.  Thaw the milk in a warm water bath (about 85-90 degrees fahrenheit).  It is recommended to not use the microwave.
Research performed by the University of Wisconsin has shown frozen sheep milk can also be successfully used to make cheese.