SPECIAL REPORT: Amino acids fuel intestinal health in the transition dairy cow
Getting dietary protein and amino acids just right is critical for helping cows through the challenging transition period.
By Kristin Bakker
The transition period – about three weeks before through three weeks after calving – is a time full of challenges in a dairy cow’s life. The metabolic adaptations involved in calving and starting lactation increase the cow’s risk for disease and metabolic issues such as displaced abomasum, ketosis, lameness and mastitis, Dr. Phil Cardoso, professor of animal sciences at the University of Illinois, Urbana-Champaign, told the 2025 Kemin Intestinal Health Symposium in October.
Once cows face disease or other health challenges, their risk of being culled from the herd greatly increases, according to Cardoso, who gave his presentation on “Amino Acids and Intestinal Health in Dairy Cattle: Beyond Protein Supply.” Keeping cows healthy, productive and reproducing is crucial for the longevity of an industry that has gone from 70,000 dairy farms to around 21,000 in the last 25 years.
Cardoso said after the cow calves, farm managers have a common goal: “They want a cow that is not sick, they want a cow that is going to produce a lot of milk and they want a cow that is going to get pregnant.” This means dairy producers must put special emphasis on nutrition during this time.
One management challenge is sorting. Cows are picky and will sort through their feed, taking only what they want and potentially missing out on nutrients. Cardoso underscored the importance of effective feed delivery and implementing a controlled-energy diet to ensure proper nutrition. Providing pre-chopped straw will prevent cows from sorting the ration so they get all the nutrients intended.
Protein nutritionThe prepartum cow’s protein intake is important. Cardoso referenced research on dairy reproduction that showed when cows were consuming too much protein, the concentration of nitrogen in their milk was too high, and the cows had a lower chance of becoming pregnant on first breeding, which was also associated with lower milk production. Elevated nitrogen interferes with the cow’s metabolism, he explained. When cows in a separate trial ate a lot of protein, the nitrogen in their blood increased and their uterine pH decreased. Prior data show that conception rates drop if uterine pH drops. “Clearly, feeding too much protein will impact the cow’s ability to reproduce,” said Cardoso; it’s “not a good idea.”
When formulating diets, the equation starts with crude protein, which breaks down into components like rumen degradable protein, undegradable protein, microbial protein and amino acids to provide metabolizable protein. If the protein source is lower quality and the diet contains a lot of crude protein, the rumen microbes can’t handle all the nitrogen coming in. This will affect not only the uterus but the liver too, as it works to convert the ammonia into urea. The balance of degradable protein in the diet needs to be right – “not too much, not too little,” Cardoso said. The bacteria in the rumen, the microbiome, needs energy “to grow and be able to degrade some of that protein and become microbial protein.”
Another experiment looked at what happens in the gastrointestinal tract when cows are given too much energy in the form of a high-starch diet, which in the U.S. comes mainly from corn. An examination showed disruption of the GI tissue, especially the enterocytes that line the villi in the ileum, so nutrient absorption depends on not feeding too much energy.
In addition, when tissue of the intestinal layer known as the Peyer’s Patch is disrupted, “we may be impacting not only absorption of nutrients but also the ability of that cow to produce antibodies, for example, and build a response against antigens” such as pathogens, Cardoso said.
Methionine and lysineThe dairy cow diet typically falls short on lysine and methionine, according to Cardoso. These can now be provided in a rumen-protected form so cows get all the amino acids they need, and many studies show the benefits.
For example, feeding cows rumen-protected methionine resulted in better functionality of the GI tract. It has been shown to increase the protein in milk as well as milk yield. Further, cows receiving methionine were better able to “engulf” and kill bacteria, improving their immune response. When cows lack the right nutrients, they build an inflammatory response for too long, or not at all, and struggle to get pregnant, he said.
Cows receiving rumen-protected methionine versus a control group also scored better on the Liver Functionality Index. A high LFI score “is suggestive of a smooth transition for the cow,” according to Cardoso. Cows with a high-functioning liver also give more milk and have a higher concentration of methionine in the blood, meaning they “don’t need to deplete as much muscle” during the transition period to generate amino acids.
Rumen-protected lysine has myriad benefits as well – for the cow and the calf. Cardoso said it was important to determine the best time to feed lysine: before calving, after calving or all the time.
Studies found that feeding cows rumen-protected lysine prepartum actually improved the uterine environment post-calving, and the cows tended to eat more after calving. While it didn’t change milk yield, it did alter the milk composition, increasing the protein, fat and casein.
Epigenetic effects were seen in the calves of dams that received rumen-protected lysine. These calves tended to eat more protein, and even when they transitioned out of milk replacer to solid feed, they gained more weight, had fewer days of medicated feed and had better-functioning neutrophils as well, “so there is a huge impact on those calves,” Cardoso said.
Cows that did not receive rumen-protected lysine before and after calving, on the other hand, had high levels of haptoglobin, an acute-phase protein. “When they're classified as high in haptoglobin, they have more chances to be sick, they have less milk, more chances to get [displaced abomasum] and also worse repro performance,” he added.
Cardoso said the take-home message is that the dairy industry now knows several associated effects of feeding methionine and lysine – but there is more to dig into, such as how protected lysine impacts the alveoli, or whether higher concentrations of methionine can benefit during heat stress. “I think there is still a lot of potential that we can use from the cow genetics perspective that we are not doing, and perhaps that should be a sign,” he concluded.
Watch the full presentation from Dr. Cardoso and access all content from the 2025 Kemin Intestinal Health Symposium at kemin.com/symposium.
