Very low-protein (VLP) diets negatively impact calcium (Ca) metabolism and absorption. The objective of this study was to investigate the effect of supplemental branched-chain amino acids (BCAA) and limiting amino acids (LAA) on Ca digestibility, absorption and reabsorption in pigs fed with VLP diets. Forty-eight piglets were assigned to six treatments: positive control (PC), negative control (NC), and NC containing LAA 25%, LAA 50%, LAA + BCAA 25% (LB25) and LAA + BCAA 50% (LB50) more than recommendations. Relative to PC or NC, LB25 and LB50 had higher digestibility of Ca and plasma Ca and phosphorus (P), but lower plasma vitamin D3. LB50 tended to increase vitamin D receptor transcript and protein in the gut, but decreased mRNA or protein abundance of parathyroid hormone 1 receptor (PTH1R), calbindin 1 (CALB1), cytochrome P450 family 27 subfamily B member 1 and occludin in small intestine. LB50 increased the transcript of cytochrome P450 family 24 subfamily A member 1 and PTH1R but decreased the transcript of transient receptor potential cation channel subfamily V member 5, CALB1 and solute carrier family 17 member 4 in kidney. Overall, BCAA increased Ca digestibility through regulating the transcellular and paracellular Ca absorption in the gut and reabsorption in kidney during protein restriction.

中文翻译：

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膳食支链氨基酸调节蛋白质限制猪的钙吸收和重吸收动态

极低蛋白 (VLP) 饮食会对钙 (Ca) 代谢和吸收产生负面影响。本研究的目的是研究补充支链氨基酸 (BCAA) 和限制性氨基酸 (LAA) 对饲喂 VLP 日粮的猪的钙消化率、吸收和再吸收的影响。将 48 头仔猪分配到六个处理组：阳性对照 (PC)、阴性对照 (NC) 和含有 LAA 25%、LAA 50%、LAA + BCAA 25% (LB25) 和 LAA + BCAA 50% (LB50) 的 NC超过建议。相对于 PC 或 NC，LB25 和 LB50 对 Ca 和血浆 Ca 和磷 (P) 的消化率较高，但血浆维生素 D3 较低。LB50 倾向于增加肠道中的维生素 D 受体转录物和蛋白质，但降低甲状旁腺激素 1 受体 (PTH1R)、钙结合蛋白 1 (CALB1) 的 mRNA 或蛋白质丰度，细胞色素 P450 家族 27 亚家族 B 成员 1 和小肠中的 occludin。LB50 增加了细胞色素 P450 家族 24 亚家族 A 成员 1 和 PTH1R 的转录，但降低了肾脏中瞬时受体电位阳离子通道亚家族 V 成员 5、CALB1 和溶质载体家族 17 成员 4 的转录。总体而言，BCAA 通过在蛋白质限制期间调节肠道中跨细胞和细胞旁的钙吸收以及肾脏中的重吸收来增加钙的消化率。