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文章题目：Newly Hatched birds

重复年份 20150430 20130718 20100821 20070922

题材：动物

题型：暂无

文章大意：有一种通过敲击蛋壳加速蛋的孵化，并解释了同时孵化的原因。后面又比较

了各种鸟的喂食方式。

参考阅读：

The changes  in body  weight and composition  were examined  in broilers that  either had immediate access  to feed  and water  or had  not been  fed for 48  h posthatch.Chicks  without access to feed decreased in BW by 7.8%in the 48 h posthatch,which was equivalent to 5.3 kcal/45 g chick/d.However,during this period the small intestines increased in weight and protein content by 80%or more.The  decrease in yolk fat  and protein could account for  most of the changes  in body composition  in the  feed-deprived chick.In contrast,fed  chicks grew  by 5 g  and used  4.5 kcal/d for maintenance;during this period small intestines increased in weight by 110%.Intestinal absorption  of  exogenous  nutrients was  determined  from  hatch  through  4  d  posthatch by administration   of  a   bolus   of  labeled   glucose,methionine,or   oleic  acid,together   with   a nonabsorbed reference substance.Absorption of fatty acids was more than 80%at hatch and was higher  than that  of  glucose and  methionine,which  was low  especially  when  the bolus  was administered as a solution.Absorption of all components tested increased with age and was more than 80%on  Day  4.Duodenal in  situ uptake  determinations  in hatching  chicks indicated  that uptake  of  oleic acid  was  high  from  yolk  and  saline solutions  compared  with glucose and methionine,which exhibited low uptake from yolk but higher uptake from  saline solutions.These studies indicate that,although the  small intestine has the capacity to absorb carbohydrates and amino   acids   at   hatch,uptake   may   be    dependant   on   the   development   of   suitable conditions,including sufficient pancreatic and brush border enzymes  for digestion and adequate sodium for function of the glucose-sodium cotransporters.