进行了两个实验以确定Ca的影响,植酸酶,采样时间,和年龄对Ca和P的消化率(AID)及其转运蛋白表达的影响。在每个实验中使用Cobb500雄性小鸡(N=600),并将其分配给具有10(Exp1、8-11d)或5(Exp2、21-24d)鸟类/笼子和10(Exp1)或20(Exp2)代表/处理的笼子。处理是2×3阶乘排列,具有低(低)或标准(STD)Ca水平和3植酸酶(PHY)水平(0、300或3,000FYT/kg)。在8、12、24、48和72小时收集回肠消化物,和空肠组织在开始饲喂实验饮食后的12、48和72小时。在实验1中,Ca或植酸酶在8、12或24h对Ca的AID没有影响。植酸酶在所有时间点都增加了P的AID(P<0.05),大小受Ca的影响。在12小时,P(NaPi-IIb)和Ca(CaSR)转运蛋白的mRNA水平在不含植酸酶的低饮食中最高(Ca×PHY,P≤0.06)。在实验2中,STD日粮在8、24、48或72h时降低了Ca和P的AID(P<0.05)。植酸酶在8、12和24h时增加了Ca的AID(P<0.05)。并降低了Ca的AID(二次,STD饮食(48h)中的P<0.05)。在所有采样时间,P的AID(P<0.05)随植酸酶的增加而增加。在48小时,3,000FYT/kg降低(P<0.05)STD饮食中NaPi-IIb和Ca转运体ATP2B1的mRNA表达(Ca×PHY,P<0.05)。总之,为了避免肉鸡对钙和磷缺乏的适应,实验饮食的最佳时间对于年轻的肉鸡≤48小时,对于年龄较大的鸟类≤24小时,这是由于Ca和P转运蛋白的上调或下调对饮食Ca的反应,P,和植酸酶。
Two experiments were conducted to determine the impact of Ca, phytase, sampling time, and age on the digestibility (AID) of Ca and P and the expression of their transporters. Cobb 500 male chicks (N = 600) were used in each experiment and allocated to cages with 10 (Exp 1, 8-11 d) or 5 (Exp 2, 21-24 d) birds/cage and 10 (Exp 1) or 20 (Exp 2) reps/treatment. Treatments were a 2 × 3 factorial arrangement, with low (LOW) or standard (STD) Ca level and 3 phytase (PHY) levels (0, 300, or 3,000 FYT/kg). Ileal digesta were collected at 8, 12, 24, 48, and 72 h, and jejunum tissues at 12, 48, and 72 h after the start of feeding experimental diets. In Exp 1, there was no effect of Ca or phytase on the AID of Ca at 8, 12, or 24 h. Phytase increased the AID of P (P < 0.05) at all time points, and the magnitude was influenced by Ca. At 12 h, the mRNA level of P (NaPi-IIb) and Ca (CaSR) transporters was greatest in the LOW diets without phytase (Ca × PHY, P ≤ 0.06). In Exp 2, the STD diet decreased the AID of Ca and P (P < 0.05) at 8, 24, 48, or 72 h. Phytase increased the AID of Ca (P < 0.05) at 8, 12, and 24 h, and decreased the AID of Ca (quadratic, P < 0.05) in the STD diet (48 h). The AID of P (P < 0.05) increased with phytase at all sampling times. At 48 h, 3,000 FYT/kg decreased (P < 0.05) mRNA expression of NaPi-IIb and Ca transporter ATP2B1 in the STD diet (Ca × PHY, P < 0.05). In conclusion, to avoid adaptation of broilers to Ca and P deficiencies, the optimal time on experimental diets is ≤ 48 h for young broilers and ≤ 24 h in older birds due to up- or down-regulation of Ca and P transporters in response to dietary Ca, P, and phytase.