If you’re raising sheep, understanding the gestation period of sheep is vital to your success. The time a ewe spends pregnant directly impacts lamb survival rates and, ultimately, the productivity of your flock.
So, how long are sheep pregnant? On average, a ewe’s pregnancy lasts about 21 weeks. But many factors can influence that timeline.
In this article, we’ll explore the different factors that can affect the gestation period of sheep, including the hormonal influences at play, the specific nutritional needs of a pregnant ewe, common diseases to watch out for, and essential preparations you’ll need to make when lambing season arrives.
How long are sheep pregnant?
The gestation period is the length of time between when a sheep conceives and when she gives birth (or “lambs”). Knowing this period is really important for sheep farmers.
So, how long is it? Sheep are usually pregnant for 142 to 152 days. Most of the time, it’s around 147 days.
However, there are several things that can change the length of a sheep’s pregnancy. These include:
- The breed of sheep
- What the sheep eats
- The sheep’s age
- How many lambs she’s carrying
- The temperature of the environment
- The sheep’s genetics
What affects how long sheep are pregnant?
While the average gestation period for sheep is around 147 days, a number of factors can make the time shorter or longer.
Breed
Some breeds of sheep are known to gestate for slightly shorter or longer periods, probably because of genetic selection over time.
Nutrition
Good nutrition is essential for a healthy pregnancy, and it can affect how long the gestation period is. Ewes that are malnourished may gestate for a slightly longer time.
Age and parity
Younger ewes sometimes gestate for slightly longer than mature ewes, and older ewes can have variations, too. Ewes carrying multiple lambs tend to have shorter pregnancies and often give birth a few days early.
Environmental factors
Temperature and seasonal changes can play a role. Extreme temperatures can stress the animals and affect their pregnancies. Melatonin, a hormone related to the light/dark cycle, also has an effect.
Hormonal changes during sheep pregnancy
Several hormones play essential roles throughout a ewe’s pregnancy:
- Estrogen levels increase toward the end of pregnancy. Estrogen readies the ewe’s body for labor by triggering contractions in the uterus.
- Progesterone maintains the lining of the uterus and prevents the ewe from going into labor too early.
- Cortisol levels go up right before lambing. Cortisol helps the lamb’s organs mature so it can survive outside the womb.
- Relaxin loosens the ligaments in the ewe’s pelvis, which makes it easier for her to give birth.
Nutritional Needs of Pregnant Ewes
Nutrition is key to a healthy pregnancy and healthy lambs. What a ewe eats during gestation has a big effect on her health and the development of her lambs, particularly in the later months. Good nutrition helps prevent metabolic problems and ensures the lambs are born at a healthy weight.
Trimester-by-Trimester Nutritional Needs
- First Trimester: Focus on keeping the ewe in good condition. The lambs don’t grow much during the first few months.
- Second Trimester: The lambs start to grow more, so the ewe needs more nutrients. You might need to give her extra food, depending on how good the pasture is.
- Third Trimester: The lambs grow a lot during the last trimester, so the ewe needs a lot more nutrients. If it’s spring, fresh grass can be a great source of nutrients. But you might still need to give her extra feed to make sure she’s getting enough.
Key Nutrients
- Protein: Important for the lambs’ growth and for the ewe to produce colostrum (the first milk).
- Energy: Helps the ewe’s body function and supports the lambs’ development.
- Minerals and Vitamins: Essential for strong bones, a healthy immune system, and overall health.
Practical Feeding Tips
- Check the ewe’s body condition regularly.
- Make sure she has access to good-quality pasture, silage, hay, or straw.
- Give her extra feed based on how many lambs she’s carrying and how good the pasture is.
- Always provide clean, fresh water.
Common Diseases During Sheep Pregnancy
Just like any pregnant mammal, ewes are susceptible to certain diseases and conditions during gestation.
Ovine Pregnancy Toxemia (Twin Lamb Disease)
Ovine pregnancy toxemia, also known as twin lamb disease, is common in lowland flocks when ewes are carrying twins or triplets. It’s caused by inadequate energy intake, which leads to fat mobilization and ketone production.
Symptoms of pregnancy toxemia include lethargy, loss of appetite, and neurological signs.
Prevention focuses on ensuring adequate energy intake, especially late in the pregnancy. Regularly monitor the ewe’s body condition score (BCS). Scanning pregnant ewes early in gestation can help you assess their nutritional needs based on the number of lambs they’re carrying.
Hypocalcemia (Milk Fever)
Hypocalcemia, or milk fever, typically occurs in the last six weeks of gestation and the first month of lactation. It’s caused by low blood calcium levels due to the high calcium demands of the developing lambs and the ewe’s milk production.
Symptoms include muscle tremors, weakness, and recumbency (inability to stand).
Preventive strategies include providing a balanced mineral supplement with adequate calcium and phosphorus. Avoid sudden changes in the ewe’s diet.
Other Potential Health Issues
Other diseases can affect pregnant ewes, including abortion diseases like enzootic abortion of ewes. Vaccination is an important tool for disease prevention.
Getting Ready for Lambing Season
If you’re raising sheep, lambing season is a crucial time. There are a few things you can do to help ensure a healthy start for both ewes and lambs:
- Vaccinate. Talk to your vet about pre-lambing vaccinations, particularly in the last month of gestation, to reduce disease risks.
- Create a clean space. Provide a lambing area that is clean, dry, and has good ventilation.
- Keep a close watch. Monitor your ewes for any signs of disease or the beginning of labor.
- Gather supplies. Have colostrum replacer, iodine for navel dipping, and lambing ropes on hand.
Key Takeaways
A successful sheep pregnancy depends on knowing the gestation length, providing proper nutrition, and preventing diseases. Understanding these factors will help you manage your flock effectively.
Throughout the gestation period, close monitoring of each ewe’s body condition score (BCS) and overall health is crucial for a successful lambing season. Keep a close watch for signs of pregnancy problems and seek veterinary assistance promptly.
By taking proactive steps, such as providing appropriate nutrition and managing the flock’s health, you can ensure healthy lambs and a more productive and profitable sheep operation.