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By Damon Smith and Brette Poliakiwski, Graduate Research Assistants, Physiology of Reproduction, Department of Animal Science, Texas A&M University, and Ky Pohler, Ph.D., Assistant Professor, Department of Animal Science, Texas A&M University Improving Reproductive Success

W hen trying to improve reproductive results on the ranch, there are essentially two pathways to consider – improving cow reproductive performance or

improving bull reproductive perfor- mance. Instead of separating these pathways, let’s focus on both as we cannot truly get acceptable reproductive results without both excelling. This article is going to

be formatted in a pyramid fashion. The base of this pyramid signifies management strategies that should be implemented on all cattle operations to improve reproductive perfor- mance. The lower sections of the pyramid are important to establish on your operation prior to using strategies higher up on the pyramid to be successful at capturing benefits of these upper-level, more intensive management strategies. As we progress to higher levels on the pyramid, each tends to require more resources (labor, money and equipment), but all of these should be considered an investment that can provide a positive return. It all starts with good record keeping. One phrase to keep in mind is that “you can’t manage what you don’t measure.” Lucky for us, we have an excess of tools in our toolbox that can measure many different parameters to enhance success and ease of management. At the bottom of the cow pyramid, we start with a preg- nancy diagnosis. Pregnancy diagnosis can be done by many methods, the most common being rectal palpation, rectal ultrasonography and blood tests. All have pros and cons, but what is most important is to find what method works best for your operation. For instance, it may be easier and cheaper to perform a chute-side blood pregnancy diagnosis if there isn’t a veterinarian anywhere close to your operation. If the preg- nancy test for her is non-pregnant, she then falls into one of the “Four O’s” – open, oddball, ornery or old – all reasons to cull a female. Open females are costing money consuming feed and resources while not producing a calf in return. The sooner a pregnancy diagnosis is performed, the sooner the open animals can be identified and culled. Taking your reproduc- tive success one level higher on the pyramid is incorporating

in heavier weaning weights as well as gives the cow more time to undergo uterine involution before the next breeding cycle. This is considered a more intensive strategy because there’s a chance that more females will be open and need to be culled compared to a longer breeding season. Culling unproductive females is a good management decision because this strategy also has long-term benefits of improving the fertility of the entire herd. Removing females that cannot optimally recover from calving in a timely matter, and therefore cannot establish pregnancy within the short- ened breeding season, will allow producers to select females that are more likely to get bred quicker, thus having a short- ened postpartum interval. This will allow for only the most superior genetics, regarding fertility, to remain in the herd. Next, we move one level up our pyramid to estrous synchronization. This is higher up because it requires more planning, cow workings and labor. Estrous synchronization can be as simple as giving a single injection of prostaglandin (Lutalyse, Estrumate, Synchsure, etc.) and turning bulls out, or watching heat for five to seven days after and inseminat- ing the female based on her showing signs of estrus. More intensive synchronization protocols last two to five weeks and include many handling events. Which one works the best? The most typical animal agriculture answer ever applies here: It depends! Opera- tions with facilities that can efficiently process cattle over many handling events are better equipped to consider the more intensive artificial insemination protocols. Operations not equipped to handle animals frequently would be better

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a shorter breeding season. This means reducing the bull’s time with females to around 60 to 80 days, allowing three to four breeding cycles per female. If the females are cycling at the beginning, they have three or four chances to get pregnant during this breeding season. By shortening the breeding season, we are increasing the number of calves that are born early in the season, which results

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