While egg yolks are rich in lipids, chicks consume mainly carbohydrates after hatching. This ability to switch between using nutrients provided by the mother in the egg and those the chick must acquire from the environment is important for the normal growth and metabolism of the birds after hatching. Delayed access to foods after hatching can therefore have long term effects on the animals. Transport of animals from hatcheries to farms commonly results in delays to food access by up to 48 hours. During this time, newly hatched chicks must rely on the residual yolk sac for nutrients.
Researchers examined which genes were altered by delayed food intake in newly hatched broiler chicks to determine why these delays can result in long-term health issues. Their findings were published recently in the American Journal of Physiology -Regulatory, Integrative and Comparative Physiology.
The research team found chicks that did not have access to foods within the first 48 hours after hatching weighed less one week after hatching than chicks that had access to food within 3 hours of hatching. Moreover, food-deprived chicks had delays in switching from genes responsible for lipid to those responsible for carbohydrate metabolism. The findings also showed that food-deprived chicks must rely not only on the residual yolk sac for energy but also on stored amino acids and proteins in their muscles.
JA Payne, M Proszkowiec-Weglarz, LE Ellestad. Delayed access to feed alters expression of genes associated with carbohydrate and amino acid utilization in newly hatched broiler chicks. American Journal of Physiology – Regulatory, Integrative and Comparative Physiology. 317(6):R864-R878, 2019 https://www.physiology.org/doi/abs/10.1152/ajpregu.00117.2019