Classen H L, Scott T A
Poult Sci. 1982 Oct;61(10):2065-74. doi: 10.3382/ps.0612065.
The ability of pullets to selectively consume calcium to meet the requirements of the rearing and early laying period was studied in White Leghorns. In the first of two experiments, 456 pullets were fed either an .89% calcium rearing diet (control) or a .35% calcium diet in combination with a separate source of 38% calcium chick-sized grit (calcium self-selection) from 35 to 126 days of age. Twenty-four pullets from each of these rearing treatments were selected for the second experiment at 112 days of age and were housed in individual laying cages. Rearing treatments were continued until 176 days of age with mash and grit consumption recorded daily for each pullet. From 177 to 225 days of age these pullets were fed a 3.50% calcium diet containing either ground limestone or oyster shell as a calcium source or a .35% calcium diet fed in combination with a separate source of oyster shell. Pullet calcium intake reflected the requirements for growth during the rearing period, calcium storage in the medullary bone 19 days prior to lay, and egg shell formation during the laying period; average calcium intake for these periods was 1.18, 2.08, and greater than 3.50%, respectively. Pullets also demonstrated the ability to compensate for rearing deficiencies by increased calcium consumption when fed oyster shell on an ad lib basis. Calcium consumption was found to be significantly higher on days when an oviposition occurred than when no eggs were laid. Mash consumption during the early laying period also reflected the reproductive status of the hen with the highest consumption on days when both oviposition and ovulation occurred, intermediate consumption when either oviposition or ovulation occurred, and lowest consumption when neither oviposition nor ovulation was detected.
在白来航鸡中研究了小母鸡选择性摄取钙以满足育雏期和产蛋初期需求的能力。在两项实验的第一项中，456只小母鸡从35日龄到126日龄，要么喂食含钙量为0.89%的育雏日粮（对照组），要么喂食含钙量为0.35%的日粮并搭配单独的38%含钙量的雏鸡大小的砂砾（钙自我选择组）。在112日龄时，从这些育雏处理组中各挑选24只小母鸡用于第二项实验，并将它们饲养在单独的产蛋笼中。育雏处理持续到176日龄，每天记录每只小母鸡的粉料和砂砾消耗量。从177日龄到225日龄，给这些小母鸡喂食含钙量为3.50%的日粮，该日粮以石灰石粉或牡蛎壳作为钙源，或者喂食含钙量为0.35%的日粮并搭配单独的牡蛎壳源。小母鸡的钙摄入量反映了育雏期生长、产蛋前19天髓质骨中的钙储存以及产蛋期蛋壳形成的需求；这些时期的平均钙摄入量分别为1.18%、2.08%和大于3.50%。当自由采食牡蛎壳时，小母鸡还表现出通过增加钙摄入量来弥补育雏期不足的能力。发现产蛋日的钙消耗量显著高于不产蛋日。产蛋初期的粉料消耗量也反映了母鸡的生殖状态，在排卵和产蛋同时发生的日子里消耗量最高，在排卵或产蛋发生其一的日子里消耗量中等，在未检测到排卵和产蛋的日子里消耗量最低。
