03/06/2026
This is one of many reasons why depth and capacity is important in sheep! These tubular types can’t be productive twinners in a forage based program.
Late Gestation in Sheep and Goats
Part 1: When Space Becomes the Problem
By Tim from Linessa Farms
Spend enough time around sheep and goats and you’ll hear a lot of simple advice about late pregnancy.
“Just feed more protein.”
“Give them more hay.”
“Add some grain the last couple weeks.”
The problem is that biology rarely works in simple one-line rules. Sheep and goats aren’t machines where one dial controls everything.
Late gestation is not about one nutrient.
It’s about how the entire system changes during the last weeks of pregnancy.
And one of the most important changes has nothing to do with feed ingredients.
It has to do with space.
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The Rumen Is Enormous
To understand what happens late in pregnancy, we first need to understand just how big the rumen really is.
In an adult sheep or goat, the rumen is massive.
In many animals it can hold roughly the volume of a five-gallon bucket of feed and fluid. In fact, the rumen alone can account for 60–70% of the entire digestive tract volume.
That large fermentation vat is what allows sheep and goats to live on forage. Inside the rumen, billions of microbes break down plant fiber and convert it into usable energy for the animal.
Under normal conditions, this system works extremely well.
But pregnancy changes the physical layout inside the abdomen.
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Two Organs Competing for the Same Space
As lambs or kids grow during the final weeks of pregnancy, the uterus expands rapidly.
In sheep and goats, roughly two-thirds of fetal growth occurs during the final four to six weeks of gestation.
That means the uterus is increasing in size very quickly during the same time period when the developing lambs or kids are demanding the most nutrients.
But the abdomen is a fixed space.
When the uterus expands, something else has to move.
And what gets pushed out of the way is the rumen.
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A Simple Way to Picture It
One way to visualize this is to imagine two balloons inside a box.
As one balloon grows larger, the other balloon has less room to expand.
The abdomen works in a similar way. As the uterus enlarges during late pregnancy, the rumen has less room to expand after a meal.
The rumen doesn’t disappear.
It simply has less space to work with.
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The System Starts to Tighten
As the uterus enlarges, it begins compressing the rumen.
This creates an important shift in the system:
The same animal that needs more nutrients is also losing some of her ability to consume large volumes of feed.
In other words:
• Nutrient demand is rising.
• Feed capacity is shrinking.
Late gestation is where those two curves begin to cross.
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Why “Just Feed More Hay” Doesn’t Always Work
A common piece of advice is to simply offer more hay during late pregnancy.
While forage remains extremely important, this advice misses a key biological reality.
As abdominal space becomes limited, the animal often cannot physically consume the same large volumes of bulky forage she could earlier in pregnancy.
This is especially true when animals are carrying twins or triplets.
It’s not that the animal suddenly refuses to eat.
It’s that the system is becoming physically constrained.
Understanding this mechanical pressure is one of the keys to understanding late gestation nutrition.
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Bigger Babies Are Not the Goal
Another misconception that sometimes appears in late-gestation discussions is the idea that larger birth weights should always be the goal.
Birth weight can certainly be useful data when tracking flock performance, but it should not be confused with future growth potential.
Just as in humans, a larger newborn does not necessarily mean the animal will become larger later in life.
The goal of late gestation feeding is not to create the biggest possible lambs or kids.
The goal is to maintain metabolic balance in the ewe or doe while supporting healthy fetal development.
Those are not always the same thing.
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Why Understanding the System Matters
Many sheep and goat producers do very well with simple feeding systems.
Pasture-based animals may raise healthy lambs every year.
Others feed round bales free-choice with few obvious problems.
But understanding how the system actually works allows producers to recognize when things begin to drift out of balance.
Late gestation is a period where several forces are all changing at the same time:
• fetal growth accelerates
• energy demand rises
• rumen capacity decreases
• abdominal pressure increases
When these changes line up poorly, metabolic problems can begin to appear.
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In the Next Article
Now that we understand the space problem, the next step is to look at the metabolic side of the equation.
Because once rumen intake begins to fall while fetal demand continues to rise, the ewe or doe must begin drawing energy from somewhere else.
And that’s where some of the most important late-gestation challenges begin.
