A cow and calf should not be reunited following the weaning process until the cow has stopped lactating--a process that usually takes 30 days but varies according to species.
A cow should not be reunited with her calf less than 30 days following weaning, according to veterinarian Gary Kaufman of Scottsdale, Arizona. At least 30 days are necessary for the cow's milk to dry up.
Kaufman acknowledges that conditions may affect the time needed for separation.
The breed of cow is an important factor. For example, Brahman and longhorn cows may allow nursing to begin again after as long as four months, while English breeds will usually prevent nursing regardless of the length of separation.
According to Kenny Behling; owner-operator of Behling Ranch in Clovis, California, the individual characteristics of the cow and calf are the most significant determining factors for length of weaning. Personality is critical, as are health and condition.
Rule of Thumb
A cow becomes accustomed to separation within 7 to 14 days. However, Behling says that buyers buy only calves weaned at least 45 days because they experience less stress and are less susceptible to illness. He therefore suggests 30 to 45 days as a rule of thumb for maintaining separation.