the effects of calcium phosphorus levels on egg shell quality were experimented in white leghorn type shaver-288 laying hen 147-300 days of age for three years.
对147—300日龄白来航型星杂288产蛋母鸡用三年时间进行了钙磷水平对蛋壳质量影响的试验。
author, based on actual production in the case with reasons for the decline of the laying hen to label the following main aspects.