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Nutrition and Rebreeding

A cow can only rebreed on time if her body has the resources to restart her cycle. Nutrition is the biggest lever a producer controls.

The rebreeding clock

The estrous cycle averages about 21 days, and gestation runs roughly nine months, about 283 days. A cow that wants to deliver a calf every year has a narrow window after calving to heal and return to cycling. Every day she spends not cycling cuts into the margin.

A cow that calves late this year usually calves later next year, and the calves from late-bred cows are often lighter at weaning. Timing compounds over the years.

This is why many producers treat the breeding season as a fixed window and judge each cow by whether she calved early and raised a calf, not just whether she eventually got pregnant.

Body condition drives return to heat

Cows in poor condition are slower to resume cycling, and the effect is strongest in first-calf heifers and thin cows. Condition scoring on the 1 to 9 scale before breeding tells you which group is at risk while there is still time to act.

Your extension specialist can give you target scores for your herd. Use them as goals rather than a rule, and record scores each year so you can track trends.

Cows that are thin at calving and then lose more weight while nursing are the ones most likely to miss the window, so look at the whole year of feed, not only the weeks around breeding.

Energy and protein before and during breeding

Cows that are losing weight at breeding are in trouble. Energy is usually the first limiting nutrient, and protein shortages often show up with poor-quality dry forage. A forage test and a ration review give you facts instead of guesses.

If a group needs more, ask whether to improve forage, supplement, or wean calves earlier. Changes should be gradual, and supplements and feed additives should follow label directions.

Feeding a thin cow harder after breeding starts is late. Feed changes made before the season begins give the cow time to gain condition and start cycling, while changes made halfway through the season mostly show up as a bill.

Minerals and trace nutrients

Minerals affect fertility, and shortages differ by region. Do not rely on a bag that worked for a neighbor. Ask a nutritionist or extension agent what your forage and water supply, and design the program around that.

Check that cattle are actually eating the mineral. Poorly placed feeders, weather damage and competition all reduce intake.

Mineral needs also change with the season and with forage growth stage, so review the program at least once a year with someone who knows your area, and write down which product you used and when.

Other things that look like nutrition problems

Not every open cow is a feed problem. Bull fertility, disease, stress, heat and handling can all reduce pregnancy rates. Have your veterinarian involved in pregnancy checks and herd health planning, and have bulls evaluated before breeding.

Calves that nurse hard keep their mothers under nutritional pressure. When forage is short or cows are thin, earlier weaning of calves may help the cow recover, and some producers also separate calves from cows for a short time before breeding. These are management options to discuss with your advisers, since the right choice depends on calf age and your market. Whatever you choose, plan it ahead and write down the results, so you can see what it did for pregnancy rates and calf weights.

Keep records on each cow: calving date, condition scores, pregnancy status and any treatments. Patterns across years point to either the cow or the feeding program, and they show which cows are worth keeping.

What to ask and common mistakes

Ask your advisers what condition targets fit your herd, how forage quality changes through the year and which groups need separate feeding. Common mistakes include waiting until pregnancy check to find thin cows, feeding for the average cow, ignoring minerals and blaming the bull before checking the feed. Any treated animal must be held through withdrawal times.

Heifers and young cows deserve their own plan

First-calf heifers must meet their own growth needs, feed a calf and rebreed, which is a tall order. They are the group most often late to rebreed.

Keep them separate where possible, feed them to their needs and check condition more often. Your advisers can help you decide when a young cow has caught up enough to join the main herd.

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• Least-Cost Winter Feeding
• Custom Grazing Agreements