Like just about everything else in a cow’s life, her ability to get pregnant after calving depends largely on how well she transitions after that calving.
"Reproduction doesn’t begin at the end of the voluntary waiting period—that is, 70 days in milk—but back in the transition period," says Carlos Risco, a veterinarian and reproduction specialist with the University of Florida. Cows that have difficulty calving, retained placentas, uterine infections, ketosis, displaced abomasums or mastitis will have more difficulty conceiving.
One of the primary causes of these and later ills for dairy cows is a drop in dry-matter intake just prior to and just after calving. "A drop in dry-matter intake at calving results in non-esterified fatty acids [NEFAs] rising dramatically, indicative of subclinical ketosis. This, in turn, suppresses the immune system and leads to these problems," Risco says. "Cows with mastitis, even subclinical mastitis, during the voluntary waiting period are less likely to conceive, for example. And if they do conceive, they are more likely to abort."
The key to it all is dry-matter intake around the time of calving. Obviously, transition cows need well-balanced rations and 30" of bunk space so they can access feed.
Also limit pen moves before and after calving. "When you move cows, they will eat less. If they have subclinical ketosis, eating less can tip them to becoming clinical and predispose them to displaced abomasums," Risco says.
Canadian research shows that regrouped cows spend 15 minutes less time eating during the first hour of regrouping. As they battle for social position in the new group, they are displaced from bunks twice as often by dominant cows. And they spend three hours less lying down and ruminating, all of which affect digestion.
Fresh cows need close monitoring for at least 12 days after calving. "Probably the best health parameter is milk production," Risco says. "If you can monitor daily milk production, do it."
Healthy fresh cows will increase milk production 10% per day during the first 14 days after calving and should reach 100 lb. per day three weeks after calving. Healthy heifers will increase milk 8% per day during the first 18 days and should reach 70 lb. per day by three weeks.
You should also routinely monitor fresh cows for attitude, rectal temperature (greater than 103°F), uterine discharge, mastitis and ketone bodies in urine. University of Florida protocols call for examining cows at four, seven and 12 days after calving. (Cows that drop in milk 10% anytime during the first two weeks should undergo a complete physical exam.)
"Be careful if you are relying on rectal temperature alone," Risco says. "If you do, you’ll miss more than 50% of cows with metritis."
Routinely check fresh cows seven to 21 days in milk for subclinical ketosis. If two of 12 cows have beta-hydroxybutyrate levels greater than 14 mg/dl, 30% of fresh cows are likely at risk for subclinical ketosis.
Finally, ensure that your calving crew is well schooled in assisting cows at calving. Make sure they know the right time to intervene and how to deliver a calf. Periodic retraining is necessary not only to refresh memories but to reinforce the importance of proper techniques.