PDF(Pubmed)
Abstract：
The objective of this study was to determine the effects of dietary available phosphorus (P) levels and dietary phytase added into the very low-P diet on the performance, mineral balance, odor emission, and stress responses in growing pullets and laying hens during 13 to 32 wk of age. One hundred sixty-eight pullets (Hy-Line Brown) were randomly assigned into 1 of 4 dietary treatments with 7 replicates of 6 birds each. Experimental diets were formulated to contain 3 graded P levels at 0.25, 0.35, and 0.45% during 13 to 15 wk (phase 1), 0.25, 0.35, and 0.45% during 16 to 18 wk (phase 2), and 0.20, 0.30, and 0.40% during 19 to 32 wk (phase 3). In addition, dietary phytase (500 FTU/kg matrix values) was added into the very low-P diets (0.20% during 13-15 wk, 0.25% during 16-18 wk, and 0.20% during 19-32 wk) to meet the nutritional adequacy with standard P diets. In all phases, decreasing dietary P levels did not affect (P > 0.05) growth, laying performance, and egg qualities. Decreasing dietary P levels linearly increased the relative duodenal and oviduct weights (P < 0.05), and quadratically increased the relative ovary weight in pullets (P = 0.016). Dietary phytase lowered (P = 0.021) the relative duodenal weight compared with the very low-P diet. Tibia breaking strength and tibia Mg contents in pullets were linearly lowered (P < 0.05) as dietary P levels decreased. Dietary phytase tended to increase (P = 0.091) tibia breaking strength and significantly increased (P = 0.025) tibia Mg content compared with the very low-P diet. Dietary P levels and dietary phytase affected (P < 0.05) ileal crypt depth and ileal villus height: crypt depth ratio in pullets. Decreasing dietary P levels linearly decreased (P < 0.01) crude fat digestibility and P excretion in both pullets and laying hens. Dietary phytase reversed (P < 0.05) the very low-P diet-mediated decrease of crude fat digestibility in pullets and laying hens. Dietary P levels and dietary phytase affected (P < 0.05) odor emission including ammonia in pullets and total volatile fatty acids in laying hens. Finally, lowering dietary P levels increased (P < 0.01) yolk corticosterone concentrations and the increased corticosterone concentration by the very low-P diet was reversed by dietary phytase. Collectively, our study shows that decreasing dietary P levels induced nutritional and physiological responses in pullets and laying hens and these P-mediated negative effects were mitigated by dietary phytase.
摘要：
这项研究的目的是确定饲粮有效磷（P）水平和添加到极低P日粮中的植酸酶对性能的影响，矿物平衡，气味排放,以及在13至32周龄期间生长的小牛肉和产蛋鸡的应激反应。将168个小鸡（Hy-LineBrown）随机分配到4个饮食处理中的1个中，每个7个重复6只。在13至15周（第1阶段）期间，实验饮食被配制成含有3个分级P水平，分别为0.25、0.35和0.45％，在16至18周（第二阶段）期间为0.25、0.35和0.45％，在19至32周（第三阶段）期间，分别为0.20、0.30和0.40%。此外,饮食植酸酶（500FTU/kg基质值）被添加到极低P饮食中（13-15周期间为0.20％，在16-18周期间为0.25%，在19-32周期间为0.20％），以满足标准P饮食的营养充足性。在所有阶段,降低饲粮P水平不影响(P>0.05)生长，铺设性能,鸡蛋的品质降低饲粮P水平线性增加十二指肠和输卵管的相对重量（P<0.05），母鸡的相对卵巢重量呈二次增加(P=0.016)。与极低P饮食相比，饮食植酸酶降低了相对十二指肠重量（P=0.021）。随着饲粮P水平的降低，小鸡胫骨断裂强度和胫骨Mg含量呈线性降低（P<0.05）。与极低P饮食相比，日粮植酸酶倾向于增加（P=0.091）胫骨断裂强度，并显着增加（P=0.025）胫骨Mg含量。饲粮P水平和饲粮植酸酶影响（P<0.05）回肠隐窝深度和回肠绒毛高度：隐窝深度比。饲粮P水平的降低线性降低了肉鸡和蛋鸡的粗脂肪消化率和P排泄（P<0.01）。日粮植酸酶逆转了（P<0.05）极低P日粮介导的肉鸡和蛋鸡粗脂肪消化率降低。饲粮P水平和饲粮植酸酶影响（P<0.05）气味排放，包括小鸡中的氨和蛋鸡中的总挥发性脂肪酸。最后,降低日粮P水平会增加（P<0.01）卵黄皮质酮浓度，而极低P日粮增加的皮质酮浓度被日粮植酸酶逆转。总的来说，我们的研究表明，降低日粮磷水平可诱导小母鸡和蛋鸡的营养和生理反应，而这些磷介导的负面影响可通过日粮植酸酶得到缓解。
