Producer Question from 2015
Q: How can I get late calving cows to breed earlier so they calve earlier in the calving season next year? (May 1, 2015)
A: There are a number of things that producers can do that will encourage cows to return to estrus more quickly after calving and thus be more likely to conceive and calve earlier in the next calving season.
- Body condition score at calving and plane of nutrition.
Cows that are nursing a calf have the highest nutrient requirements of the year approximately 45 days after calving. These high nutrient demands are also when we want the cow to begin cycling again. Mature cows that are in a body condition score of 5 or higher at the time of calving and are maintaining or gaining weight will be more likely to return to estrus sooner than cows that are in a body condition score of 4 or less. Cows that are losing weight between calving and breeding are less likely to return to estrus and conceive.
- Temporary removal of calves.
Removing calves from cows for 48 hours or weaning calves has been shown to trigger cows that are in a body condition score 4 or 5 but are in anestrus to start cycling. For more information on this practice please see the article Short Term Calf Removal May Help. Completely weaning calves is a more drastic practice but can be very effective. For more information on early weaning calves see the article Early Weaning Calves Sometimes Makes Sense (PDF 1.18MB).
- Use of a progesterone controlled internal drug releasing device (CIDR) for 7 days.
Research has shown that once a cow is 20 days after calving, the use of a progesterone CIDR can initiate cycling earlier than may occur naturally. By initiating estrus earlier, cows are more likely to conceive earlier in the breeding season. This initial estrus induced through the use of a CIDR is fertile and cows can be bred either by artificial insemination or through the use of natural service. Many producers associate the use of a CIDR device with estrus synchrony for the purpose of artificial insemination. However, a CIDR device may also be used effectively with natural service. Cow-calf producers who utilize natural service may benefit from identifying non-cycling cows that are at least 20 days post calving and utilizing a 7-day CIDR protocol to initiate estrus that coincides with the start of the breeding season. For more information on the use of estrus synchronization utilizing a CIDR with natural service, please see the UNL Extension Circular EC283 Synchronizing Estrus in Beef Cattle.
- Bull exposure to cows after calving.
This practice has, in some circumstances been shown to decrease the time interval that it takes for a cow to return to estrus when compared to herd mates that were not exposed to a bull. The use of a bull that has had an epididymectomy can be used to induce estrus, but keep cows from conceiving until the start of the breeding season.
- Nutritional "flushing" of cows with high levels of energy from calving through breeding.
Nutritional "flushing" may have limited benefit in reducing the time that it takes for cows to return to estrus. However, adequate nutrition to maintain or improve body condition right prior to and through the breeding season has been shown to be beneficial for conception rates.
A cow must conceive by approximately 85 days after calving to maintain a yearly calving interval.
Calves born in the first 30 days of the calving season have many advantages over their contemporaries who are born later. Early-born calves weigh more at weaning and replacement heifers born early in the calving season are more likely to conceive early in the breeding season as a yearling.
Research has shown in a fixed-breeding season, two-year-old heifers that calve early in the calving season are more productive throughout their lives than herd mates calving later.
In a fixed-breeding season, cows that calve late in the calving season are less likely to become pregnant in the subsequent breeding season than early-calving cows. Cows calving early will have more opportunity to have multiple estrus cycles during the breeding season and therefore be more likely to conceive. The economic loss associated with later-born calves and the higher tendency of late-calving cows to not conceive in a fixed-breeding season highlights the potential benefits of inducing estrus earlier than may naturally occur for later-calving cows.
Aaron Berger, Extension Educator
Panhandle Research & Extension Center
University of Nebraska