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Proper feeding management of gestation sows is crucial to the success of breeding, breed-to-wean and farrow-to-finish operations. You may not be responsible for formulating diets, but if you’re responsible for the sows’ daily care you play an important role in ensuring a successful feeding program.

Monitoring feed costs and economics is always important, but it’s especially critical with today’s volatile prices. Typically, feed accounts for two-thirds to three-fourths of the total cost of producing a market hog. Each sow will consume about 1 ton of feed, 60 percent or more of which is eaten during gestation. So, overfeeding sows can become costly quickly. However, it’s important that sows receive enough feed to ensure adequate nutrient intake required for their maintenance and growth, for mammary development and the developing litter’s growth.  Feeding correct  levels of a properly formulated gestation diet will ensure that those nutrient needs are met.

The most important reason to provide the right amount of feed to each sow during gestation is that it has a direct influence on the sow’s performance during farrowing, lactation and the following reproductive period. 

Sows that are over-conditioned entering the farrowing barn will have increased farrowing difficulty, lower lactation feed intake (resulting in potentially poorer milk production), will crush more piglets and are more susceptible to heat stress. These sows will be in poor condition when they leave farrowing, will be difficult to rebreed after weaning and have higher embryonic mortality. 

Thin sows often eat well during lactation but can be difficult to breed after weaning. Once the sow is bred, lower conception rates and smaller litter sizes are common. In severe cases, “downer-sow syndrome” can occur due to increased catabolism of the sow’s own calcium and phosphorus stores to support milk production, resulting in bone breakage.

Proper management to increase the number of sows entering the farrowing crate in ideal condition, which is 17 mm to 21 mm backfat, involves checking sow body weight and body condition early in gestation and adjusting feeding levels accordingly. It’s common to identify extremely thin or fat sows and adjust feed intake for them, but do you take into account the sow’s body weight? About 60 percent to 75 percent of the sow’s energy needs are used to maintain body tissue, which is directly correlated to body weight.  A scale best determines sow weight, but it may not be practical on the farm to weigh every sow, so an acceptable alternative is to use a special tape measurement to estimate the sow’s body weight.

Body condition can be evaluated by using a scoring system of 1 to 5, with 1 being extremely thin, 3 ideal and 5 overly obese. Research has shown that considerable variation occurs with body-condition scoring and actual fatness levels, so it is much more consistent and accurate to measure body condition using a backfat scanner.

Work with a nutritionist to develop a gestation-sow feeding chart as shown in the table. Consider the diet’s energy density, the breeding herd’s genetics and housing environment.  As you can see, using such a chart lets you quickly and easily determine the appropriate feeding level for a sow using its body weight and condition data. These actions should increase sows entering the farrowing crate in excellent condition, which can reduce management issues and increase herd reproductive performance.

Mark Whitney is the Extension swine team leader at the University of Minnesota.

Options to Determine Daily Feed Allowance

Here are daily feed-allowance levels for gestating sows using sow body weight and condition data. To determine the sow’s weight use either the flank-to-flank tape measurement or an actual scale, then use the scanned backfat level to reflect its body condition. You should start feeding the selected diet regimen once you get the backfat scan, continuing on through the 101st day of gestation.