The importance of early feeding during the pre- and post-hatch period
The pre-hatching period, which is the last phase of incubation, is characterized by the embryo’s oral consumption of amnion, the accumulation of glycogen stores in muscle and liver tissues, and glycogenolysis, the initiation of lung respiration, abdominal internalization of the remaining yolk, shell rupture, and hatching. During this time, important physiological and metabolic changes take place, and any type of alteration at this stage can significantly influence the survival of the embryo and its subsequent performance.
One of the main physiological processes during prenatal development is the maintenance of glucose homeostasis. Glycogen stores are withdrawn as the embryos go through the hatching process. Several studies suggest that insufficient glycogen and albumin force the embryo to mobilize more muscle protein for gluconeogenesis, reducing early growth and development, while glycogen stores only begin to replenish when the newborn chick has full access to food. Another important physiological process takes place in the intestine. In fact, towards the end of the incubation period, the gastrointestinal tract undergoes important morphological, cellular, and molecular changes. Research on broiler embryos has shown that during the last few days of incubation, gut weight relative to embryo weight increases by 1.4-3.4% at hatch.
The period immediately after hatching is critical for intestinal morphological development to carry out proper digestion of food and absorption of nutrients. Intestinal development occurs late and to a lesser extent in chicks with delayed access to food. This suggests preferential growth of the gut shortly after hatching. Its reduced development in fasting chicks 36 to 48 hours after hatching is reflected in a lower number of enterocytes and their speed of migration, in the size of the crypts and their proliferation, in the number of crypts per villus, in the area of the villi, and in the size of the goblet cells. Therefore, the sooner the gastrointestinal tract reaches its full functional capacity, the faster the chick will be able to utilize the nutrients in the diet and replenish its energy status, reaching its genetic growth potential.