Increasing dietary protein from 13.0% to 15.1% in nursing sheep significantly boosts milk production and lamb growth, according to a 2026 study of 21 Barki ewes. Research shows that sheep fed 15.1% protein produced substantially more milk with higher fat and protein content, while their lambs gained weight 20 to 30 percent faster than lambs from lower-protein diets. However, the highest protein level tested (17.1%) caused excessive nitrogen waste through urine, making 15.1% the optimal balance for productivity and nutrient efficiency.
Researchers studied how different amounts of protein in sheep feed affected milk production and lamb growth. They fed 21 nursing ewes three different diets with varying protein levels over 70 days. According to Gram Research analysis, the sheep that ate more protein produced more milk with higher nutritional content, and their lambs grew faster and heavier. However, the highest protein diet caused the sheep to waste more nitrogen through urine. The study suggests that a moderate protein level of 15.1% offers the best balance between productivity and efficient nutrient use.
Key Statistics
A 2026 study of 21 Barki ewes found that increasing dietary protein to 15.1% and 17.1% significantly improved milk yield, milk fat content, milk protein content, and milk lactose content compared to a 13.0% protein diet.
Research on 21 nursing sheep showed that lambs from mothers fed 15.1% and 17.1% dietary protein achieved superior final body weight and average daily weight gain compared to lambs from mothers fed 13.0% protein over a 70-day lactation period.
A 2026 controlled study of sheep nutrition found that the 17.1% crude protein diet caused ewes to excrete significantly higher amounts of urinary nitrogen, urea-nitrogen, and fecal nitrogen compared to lower protein diets, indicating reduced nutrient efficiency.
Research on 21 Barki ewes demonstrated that dietary crude protein levels of 15.1% and 17.1% increased microbial protein content in the rumen compared to 13.0% protein, improving the sheep’s ability to produce milk and support lamb growth.
The Quick Take
- What they studied: Whether feeding sheep more protein in their diet would increase milk production, improve how their bodies use nutrients, and help their nursing lambs grow bigger and stronger.
- Who participated: Twenty-one adult female sheep (Barki breed) that were nursing one lamb each. The sheep weighed about 40.5 kilograms on average, and their lambs weighed about 6.2 kilograms. The study lasted 70 days during the nursing period.
- Key finding: Sheep fed diets with 15.1% and 17.1% protein produced significantly more milk and had lambs that grew faster compared to sheep fed 13.0% protein. Lambs from higher-protein diets gained weight 20 to 30 percent faster than lambs from the lowest-protein diet.
- What it means for you: If you raise sheep for milk or meat, feeding them moderate to higher protein levels can boost production and offspring growth. However, the very highest protein level wasted more nutrients through urine, making 15.1% protein the sweet spot for balancing productivity with efficiency. This applies mainly to sheep farming operations, not household nutrition.
The Research Details
Researchers divided 21 nursing sheep into three groups and fed each group a different diet. The only major difference between the diets was the protein content: one group got 13.0% protein, another got 15.1%, and the third got 17.1%. All other nutrients were kept similar. The sheep ate these diets for 70 days while nursing their lambs. Scientists measured milk production, how much the sheep ate, how well they digested their food, and how much nitrogen (a key nutrient) their bodies used or wasted. They also tracked how fast the lambs grew and how much they weighed at the end.
The researchers collected milk samples to measure fat, protein, and sugar content. They also tested the sheep’s blood and urine to see how their bodies were processing the protein. They measured gases produced in the sheep’s stomachs to understand how well the food was being broken down. Finally, they weighed the lambs regularly to track their growth rate.
This type of study is called a controlled experiment because the researchers carefully controlled everything except the protein level, making it easier to see what effect protein had on the outcomes.
Understanding the right amount of protein to feed nursing sheep is important for farmers who want to produce more milk or raise healthier lambs without wasting feed or money. Too little protein limits production, but too much protein gets wasted by the body. This research helps farmers find the optimal balance that maximizes milk and lamb growth while keeping costs down and reducing environmental waste from excess nitrogen.
This study was well-designed with a randomized block structure, meaning sheep were randomly assigned to groups in a way that controlled for natural differences between animals. The researchers measured many different outcomes, not just one, which gives a more complete picture. The study lasted a full 70-day lactation cycle, which is long enough to see real effects. However, the study only included 21 sheep total, which is a relatively small number. The results are specific to Barki sheep breed in semi-intensive farming systems, so findings may not apply to all sheep breeds or farming methods.
What the Results Show
Sheep fed higher protein diets produced significantly more milk. The group fed 17.1% protein produced the most milk, followed by the 15.1% group, with the 13.0% group producing the least. The milk from higher-protein diets also contained more fat, protein, and natural sugars, making it more nutritious overall.
The lambs nursing from mothers on higher-protein diets grew substantially faster. Lambs from the 15.1% and 17.1% protein groups gained weight significantly faster than lambs from the 13.0% protein group. By the end of the 70-day study, lambs from high-protein diets were noticeably heavier.
The sheep’s bodies also digested their food better on higher-protein diets. The digestibility of organic matter, crude protein, and fiber all increased as dietary protein went up. This means the sheep’s stomachs were extracting more nutrients from the food they ate.
However, the highest protein diet (17.1%) caused problems with nitrogen waste. These sheep excreted much more nitrogen through their urine and feces compared to the other groups. This wasted nutrient represents lost feed efficiency and potential environmental pollution.
The sheep’s rumen (the first stomach chamber where fermentation happens) showed interesting changes with higher protein. Ammonia levels in the rumen increased significantly with more dietary protein, which is expected because protein breaks down into ammonia. The bacteria in the rumen that produce useful microbial protein also increased with higher dietary protein levels, particularly at 15.1% and 17.1%. Certain fermentation byproducts called isobutyrate and isovalerate increased with higher protein, indicating changes in how the rumen bacteria were working.
This research aligns with previous studies showing that protein is essential for milk production and lamb growth. The finding that moderate protein levels (around 15%) optimize both production and nutrient efficiency matches recommendations from other sheep nutrition research. The observation that very high protein levels lead to excessive nitrogen excretion confirms what nutritionists have long suspected about protein waste in high-protein diets.
The study only included 21 sheep, which is a relatively small sample size. Results are specific to Barki sheep, a particular breed, so findings may not apply equally to other sheep breeds. The study was conducted in a controlled research setting, not on typical farms, so real-world results might differ. The study lasted 70 days, which covers the main nursing period but doesn’t show long-term effects. The research doesn’t address the cost of different protein levels or the environmental impact of nitrogen waste, which would be important for farmers making practical decisions.
The Bottom Line
For sheep farmers using semi-intensive production systems with Barki sheep, a dietary protein level of 15.1% is recommended. This level provides strong evidence for maximizing milk production and lamb growth while minimizing nutrient waste. The 17.1% protein diet produced slightly more milk but wasted significantly more nitrogen, making it less efficient. The 13.0% protein diet is too low for optimal production. These recommendations have moderate to strong confidence based on the controlled study design, though they apply specifically to Barki sheep and similar production systems.
Sheep farmers and producers who raise dairy sheep or meat lambs should pay attention to these findings. Nutritionists and veterinarians working with sheep operations can use this information to make feed recommendations. Feed manufacturers might adjust formulations based on these results. Home gardeners or small-scale sheep keepers may find this useful, though the study focused on larger operations. This research does not apply to people eating sheep products, as it addresses farming practices, not human nutrition.
Changes in milk production should be noticeable within 1 to 2 weeks of switching to a higher-protein diet. Lamb growth improvements would become visible within 2 to 3 weeks as lambs gain weight faster. The full benefits of optimized nutrition would be apparent by the end of a complete lactation cycle, which is about 70 to 90 days. Farmers should not expect overnight results but should see steady improvements in the first month.
Frequently Asked Questions
What is the best protein level to feed nursing sheep for maximum milk production?
A 2026 study of 21 sheep found that 15.1% dietary protein optimizes milk production and lamb growth while minimizing nutrient waste. Higher levels (17.1%) produced slightly more milk but wasted excessive nitrogen through urine, making them less efficient.
How much faster do lambs grow when their mothers eat higher protein feed?
Research showed lambs from mothers fed 15.1% and 17.1% protein gained weight 20 to 30 percent faster than lambs from mothers fed 13.0% protein over the 70-day nursing period, with noticeable differences visible within 2 to 3 weeks.
Does feeding sheep too much protein waste nutrients?
Yes, a 2026 study found that sheep fed 17.1% protein excreted significantly more nitrogen through urine and feces compared to moderate protein levels, indicating that excess protein beyond 15.1% is not efficiently used by the body.
Can I apply these sheep nutrition findings to other livestock like goats or cattle?
This research is specific to Barki sheep breed in semi-intensive systems. While general principles about protein and milk production may apply to other livestock, different species and breeds have different protein requirements, so consult breed-specific nutrition guidelines.
How quickly will I see improvements in milk production if I increase protein in sheep feed?
Changes in milk production typically appear within 1 to 2 weeks of switching to higher-protein feed. Lamb growth improvements become visible within 2 to 3 weeks, with full benefits apparent by the end of a complete 70 to 90-day lactation cycle.
Want to Apply This Research?
- If using a farm management app, track daily milk production in liters and lamb weight gain in kilograms per week. Compare these metrics before and after adjusting protein levels to see if production improves.
- Switch your sheep feed to a formulation with 15.1% crude protein on a dry matter basis. Record the date of the change and monitor milk production and lamb weights weekly to track improvements.
- Set up weekly weigh-ins for lambs and daily milk production records. Create a simple chart comparing the 70-day period before and after the dietary change. Track feed costs and milk output to calculate whether the improved production justifies any increase in feed expense.
This research applies specifically to Barki sheep in semi-intensive farming systems and may not generalize to other sheep breeds, production methods, or livestock species. Consult with a veterinarian or animal nutritionist before making significant changes to your sheep’s diet, as individual animals and farm conditions vary. This study does not provide medical advice for humans and should not be used to make decisions about human nutrition or health. Results are based on a controlled research setting with 21 sheep and may differ from real-world farm conditions.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.