According to Gram Research analysis, lambs born to pregnant sheep fed poor-quality feed during mid-pregnancy showed a 2026 study experienced significantly higher rates of dangerous low body temperature in their first week of life and grew 15-20% slower after four weeks of age, even though they were born at normal size. This demonstrates that maintaining consistent good nutrition throughout pregnancy—not just at the end—is critical for lamb health and development.
A 2026 study found that pregnant sheep fed low-quality feed during winter months gave birth to lambs that struggled with body temperature control and grew more slowly than lambs from well-fed mothers. Even though the pregnant sheep received better nutrition in the final weeks before birth, the damage from earlier poor nutrition couldn’t be fully reversed. The lambs were born at normal size but developed problems keeping warm and showed uneven growth patterns. This research shows that maintaining good nutrition throughout pregnancy—not just at the end—is crucial for healthy lamb development.
Key Statistics
A 2026 research article of 66 lambs found that lambs born to ewes fed poor-quality diet during mid-gestation showed significantly increased incidence of hypothermia (rectal temperatures below 38°C) in their first week of life despite having normal blood glucose levels.
In a 2026 study of 66 lambs, those born to poorly-fed ewes weighed significantly less starting at four weeks of age through weaning at 70 days, demonstrating that moderate nutritional challenges during pregnancy impair offspring growth.
A 2026 controlled study found that lambs from nutrient-restricted ewes exhibited asymmetric growth patterns with increased body length-to-weight ratios and disproportionate head and abdominal measurements compared to control lambs, indicating altered developmental programming.
Research published in 2026 showed that late-gestation nutritional supplementation could not fully reverse the negative effects of earlier poor nutrition on lamb thermoregulation and growth, highlighting the importance of consistent nutrition throughout pregnancy.
The Quick Take
- What they studied: Whether pregnant sheep fed poor-quality winter feed followed by better feed in late pregnancy would have healthy lambs compared to sheep fed good nutrition the entire time.
- Who participated: 66 lambs total (33 from each group) born to Rambouillet × Merino sheep. One group of pregnant ewes ate poor-quality feed for about 3 months, then switched to good feed. The other group ate good feed throughout pregnancy.
- Key finding: Lambs from poorly-fed mothers were more likely to develop dangerously low body temperatures in their first week of life and grew slower after four weeks old, even though they were born at normal size.
- What it means for you: If you raise sheep, maintaining consistent good nutrition for pregnant ewes throughout pregnancy—not just at the end—helps ensure healthier, stronger lambs. This is especially important during winter when forage quality drops.
The Research Details
Researchers divided pregnant sheep into two groups. One group ate a poor-quality diet (similar to winter pasture) from day 30 to day 125 of pregnancy, then switched to high-quality feed for the rest of pregnancy. The other group ate high-quality feed the entire time. Scientists tracked the mother sheep’s weight and body condition every week, and after the lambs were born, they measured the lambs’ body temperature, weight, and body measurements daily for the first week, then weekly until weaning at 70 days old.
This approach allowed researchers to see what happens when pregnant animals experience a long period of poor nutrition followed by improved nutrition—a realistic scenario for sheep farmers dealing with winter feed shortages. By comparing lambs born to both groups, they could determine whether late-pregnancy nutrition improvements could make up for earlier nutritional problems.
The study was carefully controlled, with researchers randomly assigning ewes to each diet group and keeping detailed records of all measurements. This type of controlled experiment is considered strong evidence because it reduces the chance that other factors (like genetics or environmental differences) affected the results.
Most previous research looked at severe, short-term starvation during pregnancy. This study is important because it examines moderate, long-term poor nutrition—which is what actually happens to grazing sheep during winter. Understanding this realistic scenario helps farmers make better decisions about when and how much to supplement pregnant sheep.
This is a controlled experimental study with a reasonable sample size (66 lambs), careful measurement of multiple outcomes, and clear documentation of methods. The researchers tracked animals from pregnancy through weaning, providing a complete picture. However, the study used only one breed type and was conducted in a controlled barn setting, so results may not apply to all sheep breeds or outdoor grazing situations. The study was published in a peer-reviewed scientific journal, meaning other experts reviewed the work before publication.
What the Results Show
Lambs born to poorly-fed mothers showed a striking problem: they were more likely to develop hypothermia (dangerously low body temperature below 38°C) during their first week of life. This happened even though blood tests showed these lambs had normal blood sugar levels, suggesting the problem wasn’t simple starvation but rather a deeper issue with how their bodies regulated temperature.
Starting at four weeks of age and continuing until weaning at 70 days, lambs from poorly-fed mothers weighed significantly less than lambs from well-fed mothers. Interestingly, the lambs were born at the same size as control lambs, meaning the growth problems developed after birth.
The most unusual finding was that poorly-fed lambs showed ‘asymmetric growth’—meaning different parts of their bodies grew at different rates compared to control lambs. Their bodies were proportionally longer relative to their weight, and their head and belly measurements didn’t match their body weight the way they should. This suggests the poor nutrition during pregnancy affected how their bodies developed in ways that persisted even after nutrition improved.
Mother sheep on the poor-quality diet lost weight and body condition during the treatment period (weeks 6-17 of pregnancy), even though they were later given better nutrition. This weight loss happened well before the typical time when farmers supplement pregnant sheep, suggesting that winter forage quality problems develop earlier than commonly expected. The poor-quality diet ewes never fully recovered their body condition even after switching to better feed.
Previous research has shown that severe, short-term starvation during pregnancy damages lamb development. This study extends that knowledge by showing that moderate, sustained poor nutrition—even when followed by improved nutrition—also causes lasting harm. The finding that late-pregnancy supplementation couldn’t fully reverse earlier nutritional damage is important and somewhat surprising, suggesting that timing of nutrition throughout pregnancy matters more than previously understood.
The study used only one sheep breed type (Rambouillet × Merino), so results may not apply to all sheep breeds. All lambs were born indoors in a controlled barn environment, which differs from typical outdoor lambing. The study didn’t examine whether these lambs would have long-term health problems beyond weaning. Additionally, the study simulated winter forage quality but didn’t test actual pasture conditions, which can vary considerably.
The Bottom Line
Sheep farmers should maintain consistent, adequate nutrition for pregnant ewes throughout the entire pregnancy, not just in the final weeks. This is particularly important during winter when forage quality naturally declines. Farmers should monitor ewe weight and body condition starting in mid-pregnancy and provide supplemental feed if needed. Monitor newborn lambs closely for signs of low body temperature during the first week of life, especially if mothers experienced poor nutrition during pregnancy. (Confidence level: High—based on controlled experimental evidence)
Sheep farmers and ranchers, particularly those using extensive grazing systems where winter forage quality is poor. Veterinarians working with sheep operations. Agricultural extension educators advising on sheep nutrition. This research is less relevant to farmers using intensive feeding systems with consistent feed quality year-round.
Problems appeared immediately after birth (hypothermia in the first week) and continued through the first 70 days of life (slower growth starting at week 4). Farmers should expect to see benefits from improved ewe nutrition within the first few weeks after lambs are born, with improved growth rates visible by 4-6 weeks of age.
Frequently Asked Questions
Can poor nutrition during early pregnancy harm lambs even if the mother gets better feed later?
Yes. A 2026 study found that lambs from ewes fed poor-quality feed in mid-pregnancy developed hypothermia and grew slower after birth, even though mothers received better nutrition in late pregnancy. Late supplementation couldn’t fully reverse the damage.
What are the signs that a newborn lamb has low body temperature from poor maternal nutrition?
Hypothermia (body temperature below 38°C) in the first week of life is a key sign. Affected lambs may appear weak, uncoordinated, or reluctant to nurse. Interestingly, blood sugar levels may be normal, so the problem involves temperature regulation, not just energy availability.
When should sheep farmers start supplementing pregnant ewes during winter?
A 2026 study showed that ewes on poor-quality winter feed lost weight and body condition starting around week 6 of pregnancy, earlier than traditionally expected. Farmers should monitor ewe condition from mid-pregnancy onward and supplement if weight or body condition drops.
How much slower do lambs grow if their mothers had poor nutrition during pregnancy?
In the 2026 study, lambs from poorly-fed mothers weighed significantly less starting at four weeks of age through weaning at 70 days. Growth differences became apparent after the first month of life, suggesting early nutrition problems have delayed effects on growth.
Does it matter which part of pregnancy a ewe experiences poor nutrition?
Yes. This 2026 study specifically examined mid-to-late pregnancy poor nutrition and found lasting effects on lamb health. The timing and duration of poor nutrition during pregnancy both appear to influence how severely offspring are affected.
Want to Apply This Research?
- Track pregnant ewe weight and body condition score weekly from day 30 of pregnancy through lambing. Record newborn lamb rectal temperature daily for the first 7 days of life. Monitor lamb weight weekly from birth through weaning at 70 days.
- Set calendar reminders to weigh and score pregnant ewes weekly during winter months. Create alerts if ewe weight drops more than expected or body condition score falls below target. Log newborn lamb temperatures and weights in the app to identify problems early.
- Compare current year’s ewe weight and body condition trends to previous years using the app’s historical data. Track lamb growth curves and flag lambs growing slower than expected. Use the app to correlate ewe nutrition levels with lamb health outcomes to optimize supplementation timing and amounts.
This research describes findings from a controlled animal study and should not be interpreted as medical advice for humans. Sheep farmers should consult with veterinarians and animal nutritionists before making changes to feeding programs. Individual results may vary based on breed, environment, and management practices. This summary is for educational purposes and does not replace professional veterinary or nutritional guidance.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.