1Animal Sciences Department,Université Laval,2425 rue de l'Agriculture,Québec, QC,Canada G1V 0A6.
2URA,INRA,37380,Nouzilly,France.
Animal. 2018 Aug;12(8):1555-1563. doi: 10.1017/S1751731117003093. Epub 2017 Dec 4.
The ability of birds to modify dietary phosphorus utilisation when fed with low-phosphorus and calcium (Ca) diets was studied using different sequences of dietary phosphorus and Ca restriction (depletion) and recovery (repletion) during the grower and the finisher phases. A total of 3600 Ross 708 broilers were randomly divided into 10 replicate pens per treatment (60 per pen, six pens per block). Chicks were fed a common starter diet from days 0 to 10, then a grower control diet (C: 0.90% Ca, 0.39% non-phytate phosphorus, nPP), mid-level diet (M: 0.71% Ca, 0.35% nPP) or low Ca and nPP diet (L: 0.60% Ca, 0.30% nPP) from days 11 to 21, followed by a finisher diet C, M or L containing, respectively, 0.85%, 0.57% or 0.48% Ca and 0.35%, 0.29% or 0.24% nPP from days 22 to 37. Six treatment sequences were tested: CC, MM, LL, ML, LC and LM. Bone mineral content by dual-energy X-ray, tibia ash, toe ash weight and tibia breaking strength were measured on days 21 and 37. No significant effect was observed on growth performance throughout the experiment. Diet L reduced bone mineral content, breaking strength, tibia and toe ash by 9%, 13%, 11% and 10%, respectively, on day 21 (compared with diet C, for linear effect, P<0.05). On day 37, bone mineral content, breaking strength, tibia and toe ash remained lower compared with control values (CC v. MM v. LL, P<0.05 for linear and quadratic effects). Mineral depletion duration (ML v. LL) did not affect bone mineral status. Replenishing with the C diet during the finisher phase (LC) restored bone mineral content, tibia ash and toe ash weight better than the M diet did, but not to control levels (CC v. LC v. LM, for linear effect, P<0.05). These results confirm that dietary Ca and nPP may be reduced in the grower phase without affecting final growth performance or breaking strength as long as the finisher diet contains sufficient Ca and nPP. The practical applications of this strategy require further study in order to optimise the depletion and repletion steps.
当用低磷和钙（Ca）日粮喂养时，鸟类在生长期和育肥期改变日粮磷利用的能力通过不同的磷和 Ca 限制（耗竭）和恢复（补充）的日粮顺序来研究。总共 3600 只罗斯 708 肉鸡被随机分为 10 个处理重复（每处理 60 只，每块 6 个重复）。小鸡从第 0 天到第 10 天喂普通起始日粮，然后从第 11 天到第 21 天喂生长期对照日粮（C：0.90% Ca，0.39%非植酸磷，nPP）、中水平日粮（M：0.71% Ca，0.35% nPP）或低 Ca 和 nPP 日粮（L：0.60% Ca，0.30% nPP），然后从第 22 天到第 37 天分别喂含有 0.85%、0.57%或 0.48% Ca 和 0.35%、0.29%或 0.24% nPP 的育肥期 C、M 或 L 日粮。测试了 6 种处理顺序：CC、MM、LL、ML、LC 和 LM。第 21 天和第 37 天测定双能 X 射线骨矿物质含量、胫骨灰分、趾灰分重量和胫骨断裂强度。整个试验期间，生长性能无显著影响。日粮 L 使骨矿物质含量、断裂强度、胫骨和趾灰分分别降低 9%、13%、11%和 10%，第 21 天（与 C 日粮相比，线性效应，P<0.05）。第 37 天，与对照值相比，骨矿物质含量、断裂强度、胫骨和趾灰分仍较低（CC 比 MM 比 LL，线性和二次效应，P<0.05）。矿物耗竭持续时间（ML 比 LL）对骨矿物质状态无影响。在育肥期用 C 日粮补充（LC）比 M 日粮更好地恢复了骨矿物质含量、胫骨灰分和趾灰分重量，但未恢复到对照水平（CC 比 LC 比 LM，线性效应，P<0.05）。这些结果证实，只要育肥期日粮含有足够的 Ca 和 nPP，生长期就可以降低 Ca 和 nPP 的含量，而不会影响最终的生长性能或断裂强度。为了优化耗竭和补充步骤，需要进一步研究该策略的实际应用。
