Gordon King, Animal Science, University of Guelph, Canada
Dairy cows are commonly kept in mixed groups consisting of females in all lactational stages, often including dry cows. Management is usually improved if cows are segregated according to stage of production. This places all animals with similar requirements for feeding and observation together so attendants can focus attention on particular needs.
The recently calved cows should be segregated into a "Fresh Group" since they require the most care, with close attention paid to mammary and digestive function. Ideally, whenever conditions allow, the first-calf heifers should be kept separate from other cows in early lactation so they do not have to compete with older herdmates.
By 50 d postpartum, cows reach peak production and should have received a rectal examination to insure that the reproductive system recovered from the stress of their previous pregnancy. Normal females can then transfer to a second pen holding the "Breeding Group"which must be watched carefully for estrous signs so remating can occur. Placing these animals together increases the chance that more than one will be in or near estrus at the same time so mutual stimulation will produce longer and stronger behavioral signs. Also attention can be focused on this specific area and group rather than spread throughout the unit.
Many cows should be well into their next pregnancy by the time they are five or six months into their lactation . The status should be confirmed by rectal examination, or some other reliable method, and animal can then move on to the third unit housing the "Late Lactation Group". Cattle at this stage require little specialized attention since production has declined to the point were it creates little stress on the mammary or digestive systems, and checking for estrus is no longer necessary.
Finally, when lactation ceases, animals move to a "Dry Cow Group." Important considerations here are udder health, body condition and insuring individuals are moved into the calving area a few days before parturition is due.
Smaller herds may find sorting into only three groupings advantageous.
In contrast, very large herds could keep their first-calf heifers separated into Fresh, Breeding and Late groups throughout their first lactation so they do not have to compete with older cows.