Replacing barley silage with hybrid rye silage in dairy cow diets reduces milk production and milk protein content, according to a 2026 study of 12 Holstein cows published in the Journal of Dairy Science. Cows fed increasing amounts of hybrid rye silage ate less food and produced less milk, though their digestive systems became more efficient at breaking down plant fiber and starch. The research suggests hybrid rye silage may not be suitable as a complete replacement for barley if maximizing milk production is the goal.
Researchers tested whether hybrid rye silage, a type of plant feed, could replace barley silage in dairy cow diets. Twelve Holstein cows were fed different amounts of hybrid rye silage over four 28-day periods. According to Gram Research analysis, replacing barley with hybrid rye silage decreased how much cows ate and how much milk they produced, though it did improve how well cows digested certain nutrients. The study suggests that while hybrid rye silage has some digestive benefits, it may not be the best choice for maximizing milk production on dairy farms.
Key Statistics
A 2026 study of 12 lactating Holstein dairy cows found that replacing barley silage with hybrid rye silage linearly decreased milk yield and milk protein concentration as the dietary inclusion of hybrid rye silage increased.
According to research reviewed by Gram, hybrid rye silage replacement improved total-tract digestibility of neutral detergent fiber and starch in dairy cows, though this benefit did not offset the negative effects on milk production.
The 2026 Journal of Dairy Science study showed that ruminal ammonia-nitrogen concentration increased linearly as dietary hybrid rye silage inclusion increased, indicating altered protein metabolism in the cow’s digestive system.
Research found that cows fed the highest level of hybrid rye silage (46.4% of diet) experienced the greatest decreases in dry matter intake, milk yield, and milk protein concentration compared to cows fed only barley silage.
The Quick Take
- What they studied: Whether feeding cows a plant called hybrid rye silage instead of barley silage would affect how much they eat, how much milk they produce, and how well their digestive systems work.
- Who participated: Twelve lactating Holstein dairy cows (the most common dairy breed), including four first-time mothers and eight experienced mothers. The cows weighed about 670 kilograms on average and were producing milk at the time of the study.
- Key finding: Replacing barley silage with hybrid rye silage caused cows to eat less food and produce less milk. However, the cows’ digestive systems became better at breaking down fiber and starch from the hybrid rye.
- What it means for you: If you buy dairy products, this research suggests that farms using hybrid rye silage might produce less milk per cow. However, the improved digestion could mean healthier cows in some ways. Farmers need to weigh whether the digestive benefits are worth the lower milk production.
The Research Details
Researchers used a controlled experimental design called a Latin square, which means each cow received all four different diets over time in a rotating pattern. This design helps researchers compare diets fairly because each cow serves as its own control. The study lasted 28 days for each diet, with 18 days for the cows to adjust to the new feed and 10 days for collecting data and samples.
The four diets tested were: a control diet with only barley silage, and three diets where barley was replaced with increasing amounts of hybrid rye silage (15.3%, 31.1%, and 46.4% of the total diet). Four of the cows had special tubes placed in their stomachs so researchers could directly sample the digestive fluids and measure fermentation, which is the chemical process that breaks down food in a cow’s stomach.
Researchers measured multiple outcomes including how much food the cows ate, milk production and quality, stomach acid levels, nutrient digestion, and nitrogen (a key nutrient) use in the cows’ bodies.
Understanding how different feed sources affect cow digestion and milk production is crucial for dairy farmers trying to maximize profits while maintaining animal health. This research matters because hybrid rye silage is a potential alternative feed that might be cheaper or more sustainable than barley, but only if it doesn’t harm production too much. The detailed measurements of stomach fermentation and nutrient flow help explain why milk production changed.
This study was published in the Journal of Dairy Science, a well-respected scientific journal. The research used a rigorous experimental design with controlled conditions and multiple measurement methods. However, the study included only 12 cows, which is a relatively small number, so results may not apply to all dairy farms or all cow breeds. The study lasted only 28 days per diet, so long-term effects are unknown. The findings are specific to Holstein cows and may not apply to other dairy breeds.
What the Results Show
When cows ate increasing amounts of hybrid rye silage instead of barley silage, they consumed less total feed. This lower feed intake led directly to reduced milk production. Specifically, milk yield decreased in a linear pattern, meaning the more hybrid rye silage was added, the more milk production dropped. The amount of milk fat and lactose (milk sugar) stayed relatively stable, but milk protein concentration decreased as hybrid rye silage increased.
Inside the cow’s stomach, the fermentation process changed in specific ways. The concentration of acetate, a key fermentation product, decreased as hybrid rye silage increased. However, other important fermentation products like propionate remained stable. The ratio of acetate to propionate, which affects cow health and milk composition, was not affected by the diet change.
Nitrogen, an essential nutrient for milk protein production, showed interesting patterns. Ammonia-nitrogen in the stomach increased as hybrid rye silage increased, suggesting the cows’ digestive systems were processing protein differently. The amount of nitrogen the cows excreted in urine tended to decrease, while nitrogen in feces decreased significantly.
The study found that cows’ digestive systems actually became more efficient at breaking down certain nutrients when fed hybrid rye silage. Specifically, the total-tract digestibility of neutral detergent fiber (NDF), which is plant fiber, increased linearly with more hybrid rye silage. Starch digestibility also improved. However, the overall digestibility of dry matter, crude protein, and fat were not affected by the diet changes. The amount of starch that reached the cow’s small intestine decreased significantly as hybrid rye silage increased, suggesting less starch was available for absorption.
This study adds to existing research showing that different forage sources affect dairy cow performance differently. Previous research has shown that forage quality and type significantly influence milk production and composition. This research is consistent with the general principle that feeds lower in energy density tend to reduce milk production. The finding that hybrid rye silage improves fiber digestibility aligns with research on rye as a forage crop, though the negative impact on milk production was more pronounced than some researchers might have expected.
The study included only 12 cows, which is a small sample size that may not represent all dairy farms or conditions. The research lasted only 28 days per diet, so researchers could not determine if cows would adapt over longer periods and potentially recover some milk production. The study used only Holstein cows, so results may not apply to other dairy breeds. The study was conducted in a controlled research setting, which may not reflect real farm conditions. Researchers did not measure feed costs or overall farm profitability, so the economic implications are unclear. The study did not examine potential long-term health benefits or problems that might result from the dietary changes.
The Bottom Line
Based on this research, dairy farmers should be cautious about completely replacing barley silage with hybrid rye silage if their primary goal is maximizing milk production. The evidence shows a clear negative effect on milk yield and protein content. However, if farmers are interested in improving fiber digestion or reducing feed costs, a partial replacement (using hybrid rye silage for only 15 to 30 percent of the forage) might be worth testing on their own farms. Farmers should conduct their own trials before making large-scale changes. Confidence in these recommendations is moderate, as the study was small and short-term.
Dairy farmers and farm managers should pay attention to this research, especially those considering alternative forages to reduce costs. Feed suppliers and agricultural advisors should understand these findings when recommending feed changes. Consumers interested in how dairy products are made may find this relevant. Researchers studying sustainable agriculture and alternative crops should consider these results. People who are not involved in dairy farming or agriculture do not need to change their behavior based on this research.
If a dairy farm switched to hybrid rye silage, the negative effects on milk production would likely appear within days to weeks, as cows typically adjust to new feeds within 2 to 3 weeks. Any potential long-term adaptations or benefits would take several months to become apparent, but this study did not measure effects beyond 28 days. Farmers should expect reduced milk production immediately if they make this switch, not gradual improvement over time.
Frequently Asked Questions
Does hybrid rye silage reduce milk production in dairy cows?
Yes, a 2026 study of 12 Holstein cows found that replacing barley silage with hybrid rye silage linearly decreased milk yield and milk protein concentration. The more hybrid rye silage used, the greater the reduction in milk production.
What are the benefits of feeding hybrid rye silage to dairy cows?
The study found that hybrid rye silage improved how efficiently cows’ digestive systems broke down plant fiber and starch. Total-tract digestibility of neutral detergent fiber and starch increased with higher hybrid rye silage inclusion levels.
Can dairy farmers partially replace barley silage with hybrid rye silage?
Partial replacement may be an option, though the study showed negative effects even at lower inclusion levels. Farmers interested in testing partial replacement should monitor milk production closely and compare results to their baseline production before making large-scale changes.
How quickly would milk production decrease if I switched to hybrid rye silage?
Cows typically adjust to new feeds within 2 to 3 weeks, so dairy farmers should expect to see decreased milk production within days to weeks of switching. This study measured effects over 28 days, so longer-term adaptations are unknown.
Would hybrid rye silage work better for some dairy breeds than others?
This study tested only Holstein cows, the most common dairy breed. Results may not apply to other dairy breeds like Jerseys or Guernseys. Farmers with other breeds should conduct their own trials before making feed changes.
Want to Apply This Research?
- Track daily milk production volume and milk protein percentage for each cow or group of cows. Record the type and amount of silage fed each day. Compare milk production before and after any feed changes to quantify the actual impact on your farm.
- If using a dairy farm management app, input the specific forage sources and proportions in your feed rations. Set alerts to monitor milk production metrics weekly. Use the app to calculate the financial impact of any milk production changes against potential feed cost savings from using hybrid rye silage.
- Establish a baseline of milk production and composition for at least two weeks before making any feed changes. After introducing hybrid rye silage, monitor milk production daily for at least four weeks to see the full effect. Track milk protein concentration specifically, as this study showed it decreased with hybrid rye silage. Compare your farm’s results to the research findings to determine if your cows respond similarly.
This research describes effects of hybrid rye silage on dairy cows in a controlled research setting with a small number of animals over a short time period. Results may not apply to all farms, breeds, or management systems. Dairy farmers considering changes to their feed programs should consult with a veterinarian or animal nutritionist before making significant dietary changes. This article is for informational purposes only and should not replace professional agricultural or veterinary advice. Individual farm results may vary based on many factors including cow genetics, farm management practices, and local feed availability.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.