Dietary free fatty acids complex with amylose creating another form of resistant starch: Gastrointestinal formation with fowl and swine

Fat added to poultry and swine feeds often contains abundant free fatty acids (FFA) that can impair digestible energy (DE). Placement of the fatty acid (FA) hydrocarbon chain in the helix core reformed from amylose creates a complex of both nutrients. Resulting modifications create a new structure termed the V-helix that becomes resistant to α-amylase. Granules in grain naturally contain minimal amounts of these complexes with more being generated during food manufacturing when moisture and heat release amylose in the presence of FFA. A paucity of FFA usually exists in complete feeds without sources of poor-quality fat. Animal fats and by-product meals from rendering are prominent in their saturated FFA content which favorably complex within the helix. V-helix-FA complexes may arise during their concurrent encounter of FFA together with amylose during feed manufacture, particularly pelleting. FFA in the gastrointestinal tract (GIT) are speculated to further form complexes when present together with amylose. Although amylose may be dissolved in the gastric and small intestinal milieu, FFA separately coalesce into hydrophobic fat droplets along with other dietary lipids. Formation of complexes is likely restricted until FFA are released into the aqueous phase during fat digestion. Although α-amylase may be prominent, V-helix-FA complexes being resistant to enzymic attack pass into the large intestine. Subsequent microbial catabolism of V-helices may generate volatile fatty acids that are absorbed by the mucosa; however, an inability to use FFA once released leads to their excretion and basis for decreased DE. Immature microbial populations with young animals usually lack the capacity to fully catabolize the V-helix, further extending the loss in DE.

Unhydrolyzed vegetable sucrose polyester in broiler diets

Duplicate 42-d broiler studies were conducted in pens with litter on the floor, beginning with 1-d-old chicks obtained from a commercial hatchery. Seven replicate pens, each starting with 12 male and 12 female chicks, received each dietary treatment in a randomized-block design. Dietary treatments comprised 0, 0.5, 1.0, 1.5, 2.0, or 2.5% unhydrolyzed vegetable sucrose polyester (UVSP) added to the starting and finishing diets at the expense of filler. In both studies, up to 2.5% UVSP did not have a significant negative effect on body weights, daily feed intake, feed conversion, or litter moisture. In Experiment 2, average body weights were significantly greater than control for groups that received 0.5, 2.0, or 2.5% UVSP. However, the degree of shank yellowness as measured with a Minolta Chroma-meter was consistently and significantly reduced by 0.5% or more UVSP. Although xanthophyll levels were intentionally lowered somewhat to improve sensitivity (7.9 and 9.6 mg/kg for starter and finished feeds, respectively), it is obvious that the utilization of xanthophyll was reduced somewhat by UVSP. Additional pigment titration trials could provide valuable information about the levels required to overcome this effect.