The “hatch window” represents the 24–48-hour period in which hatching begins and ends for all eggs from the same batch. During this time, the chicks remain in the incubator until all the eggs hatch, after which they undergo routine treatments, including selection, vaccination, sexing, and sorting, before being transferred to the farm. In conventional commercial hatcheries, when chicks hatch, they have no food or water available until they are transported to the farms (delayed access). Long transports to their destination could exacerbate store depletion and dehydration through excessive thermoregulation and stress, which could affect body weight and chick mortality rates. European Union legislation stipulates that newly hatched chicks may be transported within the first 72 hours of life, including a maximum transport time of 24 hours, without food or water. This recommendation is because the metabolic reserves stored in the yolk sac may be sufficient for the chick during the first three days after hatching. However, chick mortality during the first week of life may reflect the stress of the transport process, as well as the fact that increased mortality is the most extreme consequence of delayed feeding.
This delay in feeding is one of several welfare risks associated with hatching in conventional hatcheries. Continuous exposure to darkness in the hatchery, high levels of noise and dust, and transport can all act as stressors that negatively affect chick welfare. Therefore, any negative consequences resulting from delayed nutrition on gut and muscle development and the immune system, as well as poor vaccination or reduced response to diseases, are considered animal welfare issues and should therefore be avoided.
In recent years, early nutrition strategies, before or after hatching, have been proposed and carried out as an alternative to overcome the drawbacks of late nutrition on chick health and performance.
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.
In-ovo feeding
The first in-ovo injection techniques date back to 1946, to check the effects of thiourea during and after hatching. Subsequently, the in-ovo technique was adopted for vaccination against Marek’s disease. The success achieved by in-ovo vaccination has established a paradigm shift in the poultry industry by adapting the technique to achieve greater benefits by changing the embryonic environment and improving the nutritional conditions of newborn chicks. In-ovo technology is used to deliver growth-promoting compounds and nutrients to the embryo, to improve the health and performance of the chick gastrointestinal tract, to determine sex, and to stimulate epigenetic changes to improve health and postnatal performance. In 2003, a method for introducing nutrient solutions into the amniotic fluid of bird embryos was patented. This in ovo feeding technique makes use of the knowledge that newborn birds naturally consume amniotic fluid before hatching. Consequently, adding a nutrient solution to the amniotic fluid provides essential nutrients to the gut of the embryo.
Various nutrients can be included in the in ovo feeding solution: carbohydrates as a glucose source; sodium and chlorine ions useful for the absorption of glucose and amino acids, minerals, and vitamins to support the development of the skeletal, immune, and digestive systems.
In ovo feeding is expected to bring numerous benefits to the poultry industry, including reduced post-hatch mortality, increased nutrient use efficiency of the feed, and at a younger age a better immune response against pathogens, a lower incidence of skeletal problems and greater muscle development.
Post-hatch feeding
Access to feed and water immediately after hatching is of paramount importance for the proper development of the immune and digestive systems of chicks. Today, there are feed management systems in the hatchery. In these systems, the hatching trays have openings into which the newly hatched chicks drop into a lower basket where they can find troughs with enough feed and water for the next 24-36 hours. This first feed provides the energy necessary for the basic maintenance of the chick, while the high-value nutrients in the yolk are used for the development of the immune system and vital organs.
Another innovative method to ensure nutrient intake from the first hours of life is the administration of hydrated gels that contain a wide variety of nutrients and additives. These gels, considered as complementary food, are sprayed on the chicks in the form of droplets directly in the incubators. These droplets are quickly consumed by pecking at each other. In this way, the chicks ingest all the nutrients contained in the gel drops without getting wet or cold.
Licuicel Complex is one of the most promising strategies for feeding chicks directly in the hatchery. This product can be administered together with gel and specialized dispensing machines since it contains an innovative formulation that includes several nutrients, vitamins, minerals, highly digestible amino acids, and prebiotics that promote the stimulation of gastrointestinal development and functioning, in addition to positively influencing growth and productive performance, thus favoring the well-being of the birds.
The company that created this formulation, CEALVET S.L.U., has carried out research on the benefits found when applying the gel immediately after hatching. Using bioacoustic feedback systems, a greater well-being was detected in chicks to which Licuicel Complex was administered, compared to a group of fasting chicks that simulated real conditions in the hatchery. In fact, chicks administered the gel show a significant reduction in stress in both bioacoustic and hematological parameters, suggesting that the administration of complementary feeds, such as Licuicel Complex, supports the chick until arrival at the farm, where they will grow and have free access to food and water.
Conclusions
We have seen how the lack of food in the first hours of life negatively affects the health and development of newborn chicks, consequently reducing their productive performance. The in-ovo feeding technique allows nutrients to be administered to the embryo by enriching the amniotic fluid that is consumed in the days prior to hatching, favoring the functional development of the intestine. The use of gels, such as Licuicel Complex, immediately after hatching, administered directly in the hatchery, provides essential nutrients for the survival and development of the chick during its first hours of life, avoiding long hours of fasting. Therefore, it is important that these innovative techniques are seen as an important aid in common practices, as they promote the health and well-being of chicks during the early stages of life, which are the most crucial for the correct development of the birds.
