Boling S D, Webel D M, Mavromichalis I, Parsons C M, Baker D H
Department of Animal Sciences, University of Illinois, Urbana 61801, USA.
J Anim Sci. 2000 Mar;78(3):682-9. 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.
对饲喂低磷玉米-豆粕日粮的幼雏和仔猪进行了多项生物测定。在含钙0.62%和磷0.42%（有效磷0.10%）的雏鸡日粮中，添加不同剂量的柠檬酸+柠檬酸钠（1:1，重量比）混合物（占日粮的0%、1%、2%、4%或6%），雏鸡的体重增加和胫骨灰分均呈线性增加（P<0.01）。与未添加柠檬酸的雏鸡相比，添加6%柠檬酸的雏鸡胫骨灰分（%）和体重增加（克/天）分别提高了43%和22%。另外的雏鸡试验表明，单独添加6%柠檬酸或柠檬酸钠的效果与柠檬酸+柠檬酸钠混合物相同，在饲喂含6%柠檬酸盐日粮的雏鸡中，添加1450 U/kg植酸酶对骨灰分和体重增加有积极影响。在添加和不添加柠檬酸盐的情况下改变钙与有效磷的比例表明，柠檬酸主要影响雏鸡植酸磷的利用率，而非钙的利用率。此外，当雏鸡饲喂低磷（有效磷0.13%）、无植酸的酪蛋白-葡萄糖日粮时，添加柠檬酸盐无效果。平均体重10至11千克的幼猪也用于两项试验中评估柠檬酸的功效。采用低磷玉米-豆粕基础日粮配制了五种处理日粮，分别为：1）不添加任何添加剂；2）添加3%柠檬酸；3）添加6%柠檬酸；）添加1450 U/kg植酸酶；5）添加6%柠檬酸+1450 U/kg植酸酶。添加植酸酶可提高（P<0.01）体重增加、增重/饲料比和跖骨灰分，而添加柠檬酸仅提高了增重/饲料比（P<0.）和跖骨灰分（P<0.08）。随后进行了一项为期22天的仔猪试验，以评估在低磷玉米-豆粕日粮中添加低水平柠檬酸（0%、1%、2%或3%）或1450 U/kg植酸酶的效果。添加植酸酶改善了（P<0.01）所有测定指标。体重增加和增重/饲料比数据表明添加柠檬酸有效果，但腓骨灰分结果不支持这一点（P>0.10）。在两项仔猪试验中，植酸酶的积极作用均远大于柠檬酸。因此，日粮柠檬酸可有效提高雏鸡植酸磷的利用率，但对仔猪的作用较小。
