The effects of citric acid on phytate-phosphorus utilization in young chicks and pigs

• Published in: Journal of animal science Vol. 78; no. 3; pp. 682 - 689
• Main Authors: Boling, S. D, Webel, D. M, Mavromichalis, I, Parsons, C. M, Baker, D. H
• Format: Journal Article
• Language: English
• Published: Savoy, IL Am Soc Animal Sci 01.03.2000; American Society of Animal Science; Oxford University Press
• Subjects: 6-Phytase - metabolism; Acids; Animal Feed; Animal productions; Animals; Biological and medical sciences; Biological Availability; Chickens - metabolism; Citric Acid - pharmacology; Dietary Supplements; Digestion - drug effects; Female; Fundamental and applied biological sciences. Psychology; Glycine max; Hogs; Male; Phosphorus; Phosphorus, Dietary - pharmacokinetics; Phytic Acid - pharmacokinetics; Poultry; Swine - metabolism; Terrestrial animal productions; Vertebrates; Weight Gain; Zea mays; Performance evaluation; Animal feeding; 6-Phytase; Phosphoric monoester hydrolases; Esterases; Food additive; Phytic acid; Weight gain; Dose activity relation; Antinutrient factor; Ash content; Aves; Ungulata; Farming animal; Enzyme; Bioavailability; Experimental study; Young animal; Citric acid; Pig; Vertebrata; Mammalia; Hydrolases; Rearing; Phosphorus compound; Chicken; Artiodactyla; Bone
• ISSN: 0021-8812; 1525-3163; 0021-8812
• DOI: 10.2527/2000.783682x

Several bioassays were conducted with young chicks and pigs fed phosphorus (P)-deficient corn-soybean meal diets. With diets for chicks containing .62% Ca and .42% P (.10% available P), graded doses of a citric acid + sodium citrate (1:1, wt:wt) mixture (0, 1, 2, 4, or 6% of diet) resulted in linear (P < .01) increases in both weight gain and tibia ash. Relative to chicks fed no citric acid, tibia ash (%) and weight gain (g/d) were increased by 43 and 22%, respectively, in chicks fed 6% citric acid. Additional chick trials showed that 6% citric acid alone or sodium citrate alone was as efficacious as the citric acid + sodium citrate mixture and that 1,450 U/kg of phytase produced a positive response in bone ash and weight gain in chicks fed a diet containing 6% citrate. Varying the Ca:available P ratio with and without citrate supplementation indicated that citric acid primarily affected phytate-P utilization, not Ca, in chicks. Moreover, chicks did not respond to citrate supplementation when fed a P-deficient (.13% available P), phytate-free casein-dextrose diet. Young pigs averaging 10 to 11 kg also were used to evaluate citric acid efficacy in two experiments. A P-deficient corn-soybean meal basal diet was used to construct five treatment diets that contained 1) no additive, 2) 3% citric acid, 3) 6% citric acid, 4) 1,450 U/kg phytase, and 5) 6% citric acid + 1,450 U/kg phytase. Phytase supplementation increased (P < .01) weight gain, gain:feed, and metatarsal ash, whereas citric acid addition increased only gain:feed (P < .05) and metatarsal ash (P < .08). A subsequent 22-d pig experiment was conducted to evaluate the effect of lower levels of citric acid (0, 1, 2, or 3%) or 1,450 U/kg phytase addition to a P-deficient corn-soybean meal diet. Phytase supplementation improved (P < .01) all criteria measured. Weight gain and gain:feed data suggested a response to citric acid addition, but this was not supported by fibula ash results (P > .10). The positive responses to phytase were much greater than those to citric acid in both pig experiments. Thus, dietary citric acid effectively improved phytate P utilization in chicks but had a much smaller effect in pigs.