Protective Antibodies 
A lamb that is born normally and suckled by its mother automatically receives protective antibodies at the start of its life. Antibodies are protective substances that assist the new-born lamb to combat infections and diseases. Lambs normally receive antibodies from their ewes in the colostrum or first milk. 
The antibodies received protect the lamb until it starts to manufacture its own. Colostrum differs from normal milk in that it is thicker, yellow in colour and rich in antibodies, vitamin A and protein. Its value and importance cannot be stressed too strongly. 
Lambs that have received colostrum during the first or second day of life are always easier to rear than lambs that never received colostrum. This matter of colostrum and antibodies is the most important factor in the successful rearing of orphan lambs.

Overfeeding 
It is important not to overfeed a lamb. To do so is not a kindness; it is the reverse and it is better to underfeed than to overfeed. During the first week of life, a newborn lamb should be fed every three hours; thereafter, every six hours. 
While this is the ideal feeding routine, it is time-consuming and bothersome to carry out for the whole 24 hours of the day. It is a matter for each person to organise, depending upon his or her day
The principle of lamb feeding is to give little and often at regular intervals. It is well known that the young of any species thrives best on the milk of its kind. However, cow milk is similar in composition to that of the ewe and is suitable for use, unchanged, for raising lambs. 
It is essential that the milk is fresh and warmed to body heat. Sterility bottle-fed lambs are more susceptible to infection than at foot lambs – and it is essential that the milk and utensils are sterilised by boiling. 
The bottle and the teat should be rinsed after feeding and always sterilised by boiling before use. It is important that orphan lambs being reared are housed in a warm shelter out of wind and rain, as they appear to be more susceptible to temperature changes. 

Complications 
The complications most likely to occur are enteritis or diarrhoea and pneumonia. Enteritis, which more commonly occurs, is usually the result of overfeeding, feeding milk at the incorrect temperature, contaminated milk or feeding from contaminated utensils. The incidence of enteritis can be reduced to a minimum by closely following the recommendations in this article. Using limewater and vitamin are additional means of preventing diarrhoea.
- roysfarm.com