Department of Animal Science, University of Manitoba, Winnipeg, Manitoba, Canada.
Poult Sci. 2012 Jan;91(1):121-8. doi: 10.3382/ps.2011-01711.
Different aspects of folic acid (FA) transport in the intestine of the laying hen have been characterized. Less is known about the adaptive response of this process to a dietary challenge. To this end, a study was conducted to evaluate the effect of increased dietary FA supplementation on the rate of intestinal FA transport and the expression of the intestinal folate transporter genes, the proton-coupled folate transporters (PCFT) and the reduced folate carrier (RFC), in the laying hen. Twenty-four Shaver White hens at 34 wk of age were randomly assigned to receive 1 of 3 dietary treatments: 1) basal diet with no supplemental folate (n = 8), 2) basal diet + 10 mg/kg of crystalline FA (n = 8), and 3) basal diet + 100 mg/kg of crystalline FA (n = 8). A completely randomized design with 3 dietary treatments was used. Production performance was not affected by FA supplementation; however, egg and plasma folate concentrations increased (P < 0.001), whereas plasma homocysteine concentrations decreased (P < 0.011) in birds fed 10 or 100 mg of FA/kg of diet, relative to controls. Mucosal to serosal uptake of FA in the duodenum was decreased (P < 0.002), but the mRNA levels of the duodenal PCFT and RFC genes were not affected when birds were fed 10 or 100 mg of FA/kg of diet. In the jejunum, the mucosal to serosal uptake of FA, as well as the mRNA levels of the PCFT and RFC genes, were not influenced by increased FA supplementation. Overall, increased dietary levels of FA resulted in decreased transport of FA in the duodenum but not in the jejunum of laying hens. This decrease was not associated with decreased mRNA expression of the duodenal PCFT and RFC genes. Therefore, a posttranscriptional or translational adaptation of the intestinal folate transporters may be involved in the much lower transport of FA in the duodenum of laying hens during increased dietary supplementation of FA.
叶酸（FA）在产蛋母鸡肠道中的转运的不同方面已经得到了描述。而对于这一过程对膳食挑战的适应性反应，人们的了解则较少。为此，本研究旨在评估增加日粮 FA 补充对肠道 FA 转运速率以及产蛋母鸡肠道叶酸转运体基因（质子偶联叶酸转运蛋白（PCFT）和还原叶酸载体（RFC））表达的影响。34 周龄的 24 只 Shavers 白母鸡被随机分配到 3 种日粮处理组中的 1 种：1）基础日粮，不添加叶酸（n = 8）；2）基础日粮+10mg/kg 晶体 FA（n = 8）；3）基础日粮+100mg/kg 晶体 FA（n = 8）。采用完全随机设计，有 3 种日粮处理组。FA 补充并未影响生产性能；然而，与对照组相比，日粮添加 10 或 100mg/kg 日粮 FA 会增加蛋和血浆叶酸浓度（P < 0.001），降低血浆同型半胱氨酸浓度（P < 0.011）。十二指肠黏膜至浆膜 FA 摄取减少（P < 0.002），但当母鸡饲喂 10 或 100mg/kg 日粮 FA 时，十二指肠 PCFT 和 RFC 基因的 mRNA 水平不受影响。在空肠中，增加 FA 补充并未影响 FA 的黏膜至浆膜摄取以及 PCFT 和 RFC 基因的 mRNA 水平。总之，增加日粮 FA 水平会导致产蛋母鸡十二指肠 FA 转运减少，但不影响空肠。这种减少与十二指肠 PCFT 和 RFC 基因的 mRNA 表达减少无关。因此，肠道叶酸转运体可能发生了转录后或翻译后适应，这可能与产蛋母鸡在增加日粮 FA 补充时十二指肠 FA 转运减少有关。
