Development of an Assay to Determine the Amount of Ca-Fatty Acid Soaps in Feces

BACKGROUND

The quantification of fecal Ca-fatty acid soaps is important to understand how fatty acids behave in the gastrointestinal tract.

OBJECTIVE

As current methods to extract Ca-fatty acid soaps from feces give low recoveries an accurate assay to determine the amount of fatty acid soaps in feces was developed.

METHOD

Ca-fatty acid soaps are determined indirectly after non-soap fatty acid compounds have been extracted from the feces. Synthetic Ca-fatty acid soaps of different chain lengths (C12-C18) and degree of saturation (C18:0-C18:2) were incubated with several solvents to find the solvents that least-solubilize the Ca-fatty acid soaps. A three-step extraction was devised using extractions with hexane, hexane-isopropanol and water either at room temperature or at 60°C, 37°C, or 80°C, respectively. Feces were spiked with free fatty acids, Ca-fatty acid soaps, Na-fatty acid salts, and phospholipids.

RESULTS

All of the free fatty acids and phospholipids and almost all of the Na-fatty acid salts were removed and 98% of Ca-lauric acid soap, 99% of Ca-stearic acid soap, and 93% of oleic acid soap were recovered.

CONCLUSIONS

The method is suitable for determining fatty acids in the form of Ca-fatty acid soaps in feces.

HIGHLIGHTS

New method to determine fecal Ca-fatty acid soaps. Consistent and high recovery of fatty acid-soaps.

Effects of increasing dietary levels of full-fat canola on performance, nutrient retention, and bone mineralization

Day-old male broiler chickens were fed diets containing 0, 5, 10, 15, or 20% raw, ground, full-fat canola for a period of three weeks. Increasing the dietary proportion of full-fat canola significantly reduced feed intake (P less than .05) and weight gain (P less than .01), without altering feed:gain ratio. Diet had no significant effect on protein retention although there was a significant decrease in fat retention with an increase in dietary levels of full-fat canola (P less than .01). This was accompanied by a significant decrease in metabolizable energy (P less than .01). Increasing the proportion of dietary full-fat canola significantly reduced the concentration of soap in the digesta (P less than .05) and excreta (P less than .01). There was no significant effect of the dietary treatments on calcium or phosphorus retention. There was also no effect of the dietary full-fat canola on bone ash, bone calcium, or phosphorus content.