Getting more pigs out of your sows requires management beyond the breeding barn. Lee Johnston, University of Minnesota nutritionist, says there are 10 nutritional keys to feeding sows and gilts to maximize litter size.

1. Johnston recommends feeding development diets once gilts reach 100 pounds. This diet should contain a breeding-herd premix, and the calcium/phosphorous should be increased by 0.1 percent over grower diets.

He suggests restricting feed in the gilt pool. Limit feed once gilts reach 240 pounds. “Flush” gilts beginning 14 days before anticipated breeding. This should lead to a 150 percent to 200 percent increase in energy intake, says Johnston.

2. Next, adjust diets to enhance embryo survival. “Flushing after breeding can drop embryo survival,” he notes. “Stop flushing gilts within 24 hours after mating.” This may be difficult to implement in pen-housing systems. 

Increased feed intake also can hurt embryo survival. In the first days after breeding, high feed intake leads to a high liver metabolism. That causes progesterone (the pregnancy hormone) to clear the sow’s blood quickly, thereby reducing embryo survival.

3. Encourage mammary development through diet. In the gilt stage, don’t over feed energy. Lower energy levels (5.75 mega-calories) result in better mammary development than high levels of 10.5 mega-calories.

Lysine intake also is important. Milk yield tends to increase with increased lysine intake, says Johnston.

4. Control gestation weight gain. As the pounds of feed increase, the percentage of sows completing four parities decreases (see table).

5. Encourage high feed intake throughout lactation. “Negative energy and nutrient balance can be detrimental to sow performance,” says Johnston. “A sow’s body stores of nutrients buffer management and nutritional mistakes.”

6. Wean sows in good body condition. Poor body condition delays return to estrus and can reduce the size of the next litter. Minimizing fat and protein tissue loss is key.

Heavier sows and those with more fat depth tend to have shorter weaning-to-estrus intervals and have more pigs born alive in their next litter.

7. Control Environmental Stresses. “Heat stress is the main problem, but cold also can be challenging,” says Johnson. “The rule is for every 1 degree above 65°F, feed intake drops 0.2 pounds per day.”

Some management practices to control stressors include:

  • Drip or evaporative cooling.
  • Wet feeding.
  • Increase feeding frequency. Feed intake tends to increase with more frequent feedings.
  • Feed in the early morning and evenings, when temperatures are cooler to promote intake.
  • Review feeder design.
  • Check water flow rate (at least 1 liter per minute).
  • Prioritize herd health. Use good biosecurity, cleanliness and sanitation methods.
  • Minimize how much the sow is moved in the first 30 days after breeding.
  • Clean the feeders.

8. Increase daily nutrient intake. You can do this by increasing feed intake and/or increasing the diet’s nutrient density. Increasing feed intake is preferred, because increasing nutrient density can cause problems in balancing energy levels, says Johnson.

Adding fat to sow diets has caused mixed results. Feed intake and interval-to-estrus have had a negative response, while energy intake, lactation weight change and litter weaning weight tend to improve.

9. New feed additives may increase productivity. Chromium tripicolinate can increase litter size when fed at 200 ppb chromium for more than six months. It also may reduce sow death loss, and sows may rebreed quicker, says Johnston. However, he cautions against paying too much for unproven additives.

10. Feed fiber. Increased litter size, lactation-feed intake, animal well-being and health are benefits of adding fiber to sow diets. But feeding fiber is not all positive, there are challenges. It will increase manure handling, requirement, costs and feed handling, as well as depress energy utilization, says Johnston. All fiber sources had positive effects on litter size, with the exception of distiller’s grain, according to a study on feeding fiber to sows.

Nutritional changes alone won’t produce more pigs per litter, good management and farrowing skills remain key. But some or all of these tips may get you to that next level of productivity.