A new Iowa State University study has taken a closer look at how sucrose and lactose—two commonly used simple sugars—shape early nursery pig performance, feed intake, and diet preference immediately after weaning. Conducted at the ISU Swine Nutrition Farm, the research evaluated 420 newly weaned pigs across a 42-day nursery period.
The findings offer valuable guidance for nutritionists and producers looking to improve first-week stability, reduce removals, and address post-weaning feed intake challenges.
Why Simple Sugars Matter Post-Weaning
Weaning remains one of the most stressful periods in swine production. Reduced intake, weight loss, pathogen exposure, and digestive upset frequently challenge pigs in the first 7–10 days.
Simple sugars such as lactose and sucrose are used to:
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Increase diet palatability
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Provide easily digestible energy
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Support early feed intake and gut adaptation
However, sucrose is 10× sweeter than lactose and requires different digestive enzymes, making it a potentially powerful lactose substitute.
Study Design
The trial consisted of two components:
1. Growth Assay (300 pigs)
Three diets were fed:
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Control (CON)
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Lactose (LAC)
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Sucrose (SUC)
Pigs were monitored for:
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Feed intake
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Average daily gain (ADG)
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Gain-to-feed ratio (G:F)
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Removal/morbidity
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Fecal scores
2. Preference Test (120 pigs)
Pens contained all three diets simultaneously, with feeder positions rotated regularly to avoid location effects. Feed disappearance was monitored to determine preference.
Key Results
1. First-Week Feed Intake Improved with Sucrose
During the critical first 7 days:
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Pigs fed sucrose consumed the most feed (63.7 g/d)
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Lactose had a moderate increase (54.0 g/d)
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Control pigs ate the least (46.4 g/d)
This improvement did not carry through to later phases—but early intake is the hardest to drive, and sucrose clearly helped.
2. Sucrose Reduced Early Weight Loss
All pigs lost weight in Period 1, but sucrose-fed pigs lost significantly less:
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CON: –40 g/d
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LAC: –23 g/d
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SUC: –5 g/d (P < 0.01)
This suggests sucrose is more effective at blunting the “weaning dip.”
3. Removal Rates Cut in Half
Across the full nursery period:
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Control: 24% removals
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Lactose: 12%
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Sucrose: 12%
(P = 0.005)
The improvement likely reflects better early energy intake and more stable gut health.
4. Pigs Strongly Preferred Sucrose
In pens where pigs could choose among diets:
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Up to 76.9% of total feed consumed in Phase 2 was the sucrose diet.
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Preference for sucrose emerged from Day 1 and persisted.
This reinforces the role of sweeteners as behavioral drivers in newly weaned pigs.
5. No Differences in Overall Growth
Despite early advantages:
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ADG
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ADFI
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G:F
…were statistically similar across treatments by Day 42.
The sugars improved first-week adaptation and reduced removals, but final nursery weights were equivalent.
What This Means for Producers
This research confirms that while simple sugars do not change final nursery performance, they play a crucial role in early transition success.
Practical Implications:
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Sucrose is a highly effective palatant, driving early voluntary intake.
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Lower weight loss and reduced removals translate into better barn flow and reduced treatment needs.
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Lactose still provides value, but sucrose may offer a cost-effective alternative, especially when lactose prices spike.
For operations prioritizing weaning stability, barn throughput, and health outcomes, sucrose inclusion in Phase 1 diets appears to be a strong tool.
