Fertilized Unincubated Egg Infertile Egg Chicken Embryo Development From Fertilized Egg: Day 2 Day 3 Day 5 ay s Day 9 Day 10 ay 11 Day 14 D3y16 Day 17 D3y18 Dau 19 Day 20 Day 21
胚胎发育过程
重要发育阶段 First day 16 hours-first sign of resemblance to a chick embryo 18 hours-appearance of alimentary tract 20 hours-appearance of vertebral column 21 hours-beginning of nervous system 22 hours-beginning of head 24 hours-beginning of eye Second day 25 hours-beginning of heart 35 hours-beginning of ear 42 hours-heart beats
重要发育阶段 First day First day First day First day 16 hours - first sign of resemblance to a chick embryo 18 hours - appearance of alimentary tract 20 hours - appearance of vertebral column 21 hours - beginning of nervous system 22 hours - beginning of head 24 hours - beginning of eye Second day Second day Second day Second day 25 hours - beginning of heart 35 hours - beginning of ear 42 hours - heart beats
Eighth day-beginning of feathers Tenth day-beginning of hardening of beak Thirteenth day-appearance of scales and claws Fourteenth day-embryo gets into position suitable for breaking shell Sixteenth day-scales,claws and beak becoming firm and horny Seventeenth day-beak turns toward air cell Nineteenth day-yolk sac begins to enter body cavity Twentleth day-yolk sac completely drawn into body cavity;embryo occupies practically all the space within the egg except the air cell Twenty-first day-hatching of chick
Eighth day Eighth day Eighth day Eighth day - beginning of feathers Tenth day Tenth day Tenth day Tenth day - beginning of hardening of beak Thirteenth day Thirteenth day Thirteenth day Thirteenth day - appearance of scales and claws Fourteenth day Fourteenth day Fourteenth day Fourteenth day - embryo gets into position suitable for breaking shell Sixteenth day Sixteenth day Sixteenth day Sixteenth day - scales, claws and beak becoming firm and horny Seventeenth day Seventeenth day Seventeenth day Seventeenth day - beak turns toward air cell Nineteenth day Nineteenth day Nineteenth day Nineteenth day - yolk sac begins to enter body cavity Twentieth day Twentieth day Twentieth day Twentieth day - yolk sac completely drawn into body cavity; embryo occupies practically all the space within the egg except the air cell Twenty-first day Twenty-first day Twenty-first day Twenty-first day - hatching of chick
(三)胚胎发育过程中的物质代理 ▣水 整个孵化过程中损失的水分约占蛋重的 15%一18% ·能量 能量来自于蛋白质、炭水化合物、脂肪 发育早期利用炭水化合物，后期利用蛋白 质、脂肪
（三）胚胎发育过程中的物质代理 � 水 整个孵化过程中损失的水分 约占蛋重的 15％－18％ � 能量 能量来自于蛋白质、炭水化合物、脂肪 发育早期利用炭水化合物，后期利用蛋白 质、脂肪
(三)胚胎发育过程中的物质代理 ·蛋白质 蛋白质是形成胚胎组织器官的主要营养物 质，蛋白质逐渐减少 ·矿物质 钙主要来自于蛋壳，从孵化第十二天开始 增加 ·维生素 维生素不足是残、弱雏的主要原因
（三）胚胎发育过程中的物质代理 • 蛋白质 蛋白质是形成胚胎组织器官的主要营养物 质，蛋白质逐渐减少 • 矿物质 钙主要来自于蛋壳，从孵化第十二天开始 增加 • 维生素 维生素不足是残、弱雏的主要原因