The emergence from the shell delineates the end of a period of incubation with extremes between 480 to 510 hours after the chicken lays the egg. Precocial birds hatch with a yolk sac attached containing residual albumen and yolk. These reserves are very important in the first hours after hatching while the birds adapt to the independent feeding with resources originating from the external environment. Apparently, the post-hatched bird does not have important restrictions to utilize nutrients obtained externally. One possible exception is the reduced ability for fat emulsification due to lower availability o bile salts. However, placing the birds as soon as they hatch accelerates adaptation to the independent life that leads to improved performance. Delaying bird placement in the house reduces the overall potential for protein deposition, especially in the breast muscle. Traditional broiler feeding programs use one feed from hatching to 3 weeks. There is an increasing interest for a diet elaborated to compensates for the uniqueness of the first days of birds lives. Differences in nutrient requirements between the post-hatching chick and more mature birds seem to be obvious. However, the information available on this subject is scarce which makes the proposed commercial pre-starter diets be very conflicting.
chicks; nutrition, post-hacthing