Raising replacement heifers costs money. When done correctly, the payoff is an improvement in your herd’s productivity and longevity. Post-breeding management is  crucial, but often overlooked in a heifer development program.  

Post-breeding management begins with performing a pregnancy diagnosis to identify non-pregnant heifers. Identifying open heifers sooner rather than later allows you to make decisions to market them as heavy feeders or transition to feed on your own farm. Delaying this decision may result in marketing heifers that are discounted due to heavy weights and large frames before they are placed on feed. To learn more about pregnancy diagnosis methods and timing, read the UW-Madison Extension Livestock article “Determining Cattle Pregnancy Status”.

Recording breeding dates or having fetal aging estimated by a veterinarian can inform decision-making in retaining or marketing bred heifers. A compilation of season-long heifer pregnancy rate data by Moorey and Biase (2020) found a range of 64 to 95%, with an average of 85%, throughout the first breeding season. Looking closer, first-cycle conception rates are often between 60 and 70%. A study by Cushman et al. (2013) observed 7% of heifers conceiving during their third breeding cycle, despite being exposed during their first and second cycles. When the number of pregnant heifers exceeds the number of replacements needed, timing of conception (early or late in breeding season) can be added to the list of selection criteria. In this example, the 7% that conceived in the third cycle would be the first heifers to be scrutinized more closely for marketing.  

The advantages of selecting heifers that conceive early versus late include: 

• Weaning heavier calves 
• Greater fertility in their second breeding season 
• Having greater lifetime productivity 
• Tighter grouping to manage calving  

Replacement heifers should be grouped separately from the mature cow herd. Heifers should be fed to achieve approximately 85% of their mature weight at calving. In most cases, this results in a target average daily gain of between 0.8 and 1.2 pounds per day. Both underfeeding and overfeeding pregnant heifers should be avoided, as either extreme can lead to greater calving difficulty, with underfeeding also negatively affecting fetal programming and colostrum quality. Table 1 provides a general guide for target weights. However, factors such as breed, frame size, forage resources, replacement heifer value, and others influence the ideal target weight on each farm. 

Due to greater stress and nutritional demands first-calf heifers face following their first calving, feeding them to calve at a Body Condition Score (BCS) one point greater than the mature cow herd is advised. In most instances, the target BCS at calving is 6 for heifers and 5 for the mature cow herd. Consider the number of replacements you are raising and the uniformity of the group. Heifers may need to be re-grouped during this phase to avoid overfeeding or under-feeding certain individuals as they develop.

Author

 

Ryan Sterry

Regional Dairy Educator / Professor –  Ryan Sterry is a Regional Livestock Educator and Professor with the University of Wisconsin – Madison Division of Extension covering Chippewa, Dunn, and Eau Claire Counties. His educational programming and research focuses on beef and dairy genetics and reproduction and Beef x Dairy crossbreeding.

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