– Dr. Les Anderson, Beef Extension Specialist, University of Kentucky
Reducing the feed at calving causes problems!
I presented at a Master Cattlemen session recently and, after the meeting, got asked a common question about body condition and feeding cows at calving. His question was he had heard that he should reduce feed to his cows before calving to keep birthweights lower to reduce calving problems. He indicated that the BCS of his cows as they begin to calve was only 4. This is a frustrating question because it comes up often and nothing could be further from the truth.
Several researchers have addressed this issue over the last 20-30 years. Each of these experiments had cows that were fed to maintain weight, decrease weight, or increase weight right before calving began. The result of underfeeding cows before calving results in the exact problem the producer is trying to avoid. The research demonstrated that poor nutrition and low BCS precalving:
• Increased calving problems
• Decreased calf health (low colostrum consumption and poor-quality colostrum)
• Increased calf death loss
• Increased the number of days for females to resume estrous cycles.
One of the most extreme research trials on prebreeding nutrition in cows was conducted by Dr. Steve Loerch at The Ohio State University. At that time, the cost of hay was much higher than the cost of grain and Dr. Loerch was examining the impact of feeding corn as an alternative to hay for gestating and lactating cows. The cows used were large framed Charolais-cross cows and were either fed around 11 pounds of whole shelled corn, 2.5 pounds of a pelleted supplement, and 2 pounds of hay (dry matter basis) or offered hay and a salt and mineral mix free choice from November to April. Hay was predominantly first-cutting orchardgrass testing around 72% neutral detergent fiber (NDF) and 9.5% crude protein (CP). Cows fed free choice hay ate twice as much feed resulting in double the feed costs compared to limit feeding the corn-based diet.
In this study, cows consuming the corn-based diet had fewer calving problems than the cows consuming forage-based diets. Limit-feeding corn to meet the nutrient requirements of cows did not negatively impact calving performance, pregnancy rate, or calf weaning weight. I don’t bring this trial up to endorse feeding gestating cows corn-based diets but rather to reinforce that feeding cows prior to calving does not increase calving problems even if cows are fed corn-based diets.
This producer indicated that his cows were at a BCS of 4 prior to calving and this is going to create some issues for him. Rebreeding performance of cows is greatly influenced by BCS at calving. Cows that are thin (BCS < 5; visible ribs) at calving take longer to resume estrous cycles and therefore are delayed in their ability to rebreed. As precalving BCS decreases, the number of days from one calving to the next (calving interval) increases in beef cows. Females with a precalving BCS <5 tend to have production cycles greater than 1 year. For example, cows with a precalving BCS of 3 would be expected to have a calving interval of approximately 400+ days, while a cow with a precalving BCS of 6 would have a calving interval of approximately 360 days. Thin cows are anestrous for a longer period of time and are therefore more likely to be open at the end of the breeding season. They may also result in lighter calves to sell the next year because the calves from these thin cows will be born later in the calving season.
Let’s consider the impact of anestrus and calving date for a herd in BCS 4 that calves from March 1 until May 10. Bull turnout is May 20 and the length of anestrus for mature cows (BCS 4) is 90-120 days and for young cows is 120-150 days. A mature cow (BCS 4) that calves on March 1 will begin to cycle sometime in the month of June and will likely conceive later than desired. However, the thin mature cow that calves on April 20 won’t cycle until end of July/middle of August and her opportunity to conceive is minimal. Thin two-year olds nursing their first calf will likely begin cycles 4-5 months after calving and will have limited opportunities to conceive.
Reducing nutrients before calving is a huge mistake but this strategy has been circulating in the beef industry for decades. At first glance, it seems logical, but no research supports the notion of limit-feeding cows prior to calving and this dogma has cost the industry millions of dollars. So, beware of reducing feed to your cows at calving. It won’t impact calf size but will impact your cows ability to rebreed.