Anderson J O, Dobson D C, Jack O K
Poult Sci. 1984 Feb;63(2):311-6. doi: 10.3382/ps.0630311.
Broiler chicks were fed diets differing in calcium (Ca) level, source, and particle size. The basal diet fed in most experiments contained .62% total phosphorus and .49% Ca from sources other than the Ca sources being compared. Performance was not affected by Ca source in diets with .9% Ca. In diets with 1.5% Ca, gain and bone ash were significantly lower with a powdered, USP grade calcium carbonate than with limestone particles passing through a 1,000-mu screen and retained by a 417-mu screen. Crushing these particles to allow them to pass through a 74-mu screen caused them to behave like the powdered calcium carbonate. Particles of this limestone had to at least pass through a 147-mu screen to cause a greater reduction in gain; the finest particles tested (passed a 74-mu screen) reduced performance most. When graded levels of fine and medium particles were fed, the higher levels reduced gain, and less of the fine particles was required to produce a given reduction. In a high Ca-low P diet, fine particles of the Ca source were more deleterious than medium. Apparently, chicks can shunt excess Ca in the form of medium particles (150 to 1,000 mu) through the digestive system better than they can the more reactive, fine particles.
给肉鸡雏鸡饲喂钙（Ca）水平、来源和粒度不同的日粮。大多数实验中饲喂的基础日粮含有0.62%的总磷和0.49%来自所比较钙源以外其他来源的钙。在钙含量为0.9%的日粮中，钙源对生产性能没有影响。在钙含量为1.5%的日粮中，与通过1000目筛网并保留在417目筛网的石灰石颗粒相比，USP级粉状碳酸钙组的增重和骨灰含量显著较低。将这些颗粒粉碎使其通过74目筛网后，其表现与粉状碳酸钙相似。这种石灰石颗粒至少要通过147目筛网才会导致增重有更大幅度的降低；测试的最细颗粒（通过74目筛网）对生产性能的降低作用最大。当饲喂分级水平的细颗粒和中等颗粒时，较高水平会降低增重，并且产生给定降幅所需的细颗粒更少。在高钙低磷日粮中，钙源的细颗粒比中等颗粒更有害。显然，雏鸡对中等颗粒（150至1000目）形式的过量钙通过消化系统的分流能力优于对更具反应性的细颗粒的分流能力。
