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Suboptimal feed intake during lactation is associated with reduced litter weight gain and increased sow weight loss. This weight loss may lead to a prolonged weaning-to-estrus interval and decreased embryo survival in subsequent parities. Feed intake is a particular concern in primiparous sows, which consume 15% less feed than multiparous sows.
The consequences of low feed intake and excess body weight loss during lactation have received considerable attention. However, little research has focused on the mechanisms that regulate feed intake in the lactating sow. Furthermore, the progress being made in increasing litter size will continue to increase milk production and nutrient demands during lactation.
Numerous researchers have found that adding relatively large amounts of fat to the diet of lactating sows (e.g., 10% of the diet) results in increased energy intake, increased milk fat and energy, and increased litter weight gain. At these levels of fat addition, energy intake is increased by approximately .8% for every 1% addition of fat to the diet. However, adding fat seems to have little effect on reducing lactation weight loss.
Our research sought to identify possible physiological mechanisms whereby energy intake is increased when tallow (fat) is added to the diets of lactating sows.