INFLUENCE OF DIETARY VOLATILE FATTY ACID MIXTURES ON PERFORMANCE AND ON FAT COMPOSITION OF GROWING PIGS

Abstract

Two experiments were conducted to evaluate the acceptability, calculated digestible energy, influence on performance, and effect on fatty acid composition of backfat when a mixture of volatile fatty acids (VFA) or of a sodium salt of these fatty acids (Na VFA) was fed to pigs. The weight percent of the VFA mixture was 40 acetic, 40 propionic and 20 butyric acid. Adding 2 to 8% VFA or Na VFA to the diet, without adjustment for digestible energy or total protein, did not influence feed intake or rate of gain. Dietary levels of 10 or 12% VFA or Na VFA depressed daily gain. When 4% VFA or Na VFA was fed from an initial weight of 12 kg, feed intake was not altered in comparison with that of pigs fed a control diet. Rate of gain averaged 0.64 kg per day for pigs fed either VFA or Na VFA, compared with 0.60 kg for control pigs. The digestible energy values of the VFA and Na VFA, based on calculated energy conversion from 38 to 75 kg liveweight, were higher than the gross energy values of the compounds determined by oxygen bomb calorimetry, presumably because of a synergistic action of VFA with other energy sources in the diet. Carcass backfat thickness, area of loin and lean in the ham face were not significantly altered by feeding VFA or Na VFA. When pigs received up to 12% VFA or Na VFA, weight percent oleic acid in the outer backfat was increased (P < 0.05) from 49.9% in the control pigs to between 52.7 and 53.3 percent. There was no influence on backfat composition when 4% VFA or Na VFA was fed continuously.