The link between nutrition and reproduction has become more evident and supported through research in recent years. Through controlled research trials and on-farm experiences, we’ve known for some time that cows not eating well or eating an unbalanced diet won’t get pregnant as fast as those provided a sound ration.

We’re continuing to learn more about how nutrition impacts reproduction and which specific nutrients are important in improving reproductive function.

The most crucial period of lactation to manage nutrition is immediately after freshening. There are many factors at play as cows recover from calving. Regardless of stress at calving, cows spend a substantial amount of time in negative energy balance during the first few weeks of lactation. They are unable to consume more energy than is lost through daily maintenance and milk production. The longer cows spend in negative energy balance, the more time lost before first ovulation and, ultimately, conception.

By feeding the proper ration to fresh cows, they can spend fewer days in negative energy balance, speed up days to first ovulation and ensure being bred back on time. A University of Florida study found that earlier cycling cows produced more milk, consumed more energy and experienced the shortest negative energy balance.

According to independent nutritionist Dr. Amos Zook of Nampa, Idaho, the easiest way to avoid these reproductive downfalls is to minimize the rapid weight loss that often happens in the fresh cow pen. He recommends supplementing fresh cows with rumen-protected calcium salts of long-chain fatty acids to keep energy levels high while still maintaining high dry matter intake (DMI). Because these fats bypass the rumen and are absorbed in the small intestine, rumen microbes are protected from degradation, maintaining a healthy rumen environment.

Only found in the ration
The ration also can provide the important feed ingredients cows can’t produce naturally, such as essential fatty acids (EFAs). Two EFAs, Omega-3 and Omega-6, have been shown to boost reproductive performance, especially in high-producing cows. Omega-3 and Omega-6 EFAs leave the cow’s body through milk, so very low levels are available to be absorbed and used for other purposes; higher levels are necessary to support important processes, such as reproduction and immune function.

While several feed sources, such as cottonseed and soybean hulls, provide EFAs, these sources are often absorbed in the rumen, making them almost useless for reproductive function. As with energy sources, we can solve this problem by feeding bypass fats containing an adequate balance of both Omega-3 and Omega-6 EFAs. When fed at recommended levels, these can deliver the necessary nutrition to the small intestine where it can be utilized without being broken down.

A study completed at the University of Arizona showed how important Omega-3 and Omega-6 EFAs can be in the ration. Cows in the study were supplemented with a calcium salt bypass fat ingredient containing Omega-3 and Omega-6 EFAs. Results of the study showed that supplemented cows experienced:

• 25 percent fewer uterine health disorders

• 81 percent more ovulations by 30 DIM

• 38 percent more estrous cycles in the first 60 DIM

• Up to 22 percent more pregnancies

• Fewer post-calving disorders, displaced abomasums (DA), milk fevers and abortions

Producers have seen how effective Omega-3 and Omega-6 EFAs can be as well. Sarah Head of New Hope View Farms LLC of Homer, New York, has seen improvements in her 850-cow herd since she started feeding EFAs nine months ago to close-up cows from 30 days prior to freshening through calving. Over these nine months the farm has maintained a pregnancy rate of 22 percent while seeing major improvements in milk production, even through summer heat.

“What I’ve really liked about feeding Omega-3 and Omega-6 EFAs is that we’ve been able to maintain our pregnancy rates while seeing an increase in milk production,” Head says. “It was very effective in the summer, too. During the summer we usually see a drop in pregnancy rates, but this past summer our pregnancy rates stayed consistent.”

Head, who worked as a full-time nutritionist before starting the dairy operation, first started using Omega-3 and Omega-6 EFAs in her client’s herds, where she noted herds were having good results increasing reproductive performance by feeding Omega-3 and Omega-6 EFAs. Seeing these results helped her to add the feed ingredient to her own herd’s ration.

Other ration highlights
Beyond EFAs, a balanced ration is key to maintaining body condition to speed up the time to first ovulation. Focusing on achieving balance in five major groups can help you prepare for reproductive success.

Energy. Maintaining energy balance can be difficult in early lactation. In many cases, cows reach peak milk before they reach positive energy balance. This makes it very important to get cows to eat as much energy-rich feed as soon as possible after calving.

Keep in mind the challenge of increasing DMI; energy density and feed quality must be higher to ensure energy and other nutrient needs are met even if the cow isn’t eating to her full potential.

Protein. Researchers often argue about the impact of protein levels on reproduction. Zook believes protein is an area that should be looked at closely to make sure cows have the right amount of degradable and undegradable protein. He also notes that producers should provide high levels of carbohydrates that cows can use as their main energy source. If these carbs are not available, cows will break down protein, which results in lower available protein for other important functions, such as reproduction.

Macrominerals. Balancing the dietary cation/anion difference (DCAD) both before and after calving can have a direct impact on how soon cows are ready for breeding. Before calving, DCAD should be between -8 and -12 meq per 100 grams of ration dry matter to avoid costly metabolic disorders that can impact cow health and reproduction. Once cows calve, a positive DCAD between +35 and +45 has been shown to improve intake and performance.

Again, it’s all about intake. By improving intake, cows will spend less time in negative energy balance, so more energy can be used for milk production and reproductive function, rather than daily maintenance requirements.

Vitamins. It’s important to make sure all essential vitamins are fed at adequate levels for growth and maintenance. If these levels are not met, normal processes, including ovulation, may be stunted. Zook notes that he sees fewer reproductive problems in herds focused on providing essential vitamins.

Fiber. Proper ration fiber levels lead to optimal rumen health. Without adequate rumen health, overall herd health will suffer, leading to reduced reproductive efficiency. To promote optimal DMI and rumen health, make sure effective fiber levels are provided in the ration.

Management matters, too
Zook notes that nutrition is only one piece of the reproduction puzzle and many other factors on the dairy influence reproductive success every day. Especially in larger herds, he emphasizes the importance of heat detection, calling it the biggest challenge for producers in their quest to improve reproductive performance by improving pregnancy rates, conception rates and services per conception. As with many other management factors, good record keeping will help identify gaps in reproductive performance and lead to effective solutions.

Nutrition is one of the solutions to overcoming reproductive challenges, and new opportunities are being identified to positively affect reproductive function in your herd. We know that by feeding the right ingredients and managing your feeding program to optimize intake, improved reproductive success can be achieved. PD

References omitted but are available upon request at editor@progressivedairy.com

Elliot Block
ARM & HAMMER
Animal Nutrition
elliot.block@
churchdwight.com