The effects of transport of 18-day old hatching eggs on physiology and behaviour of slow growing broiler chicken

Abstract

Incubation and hatching commonly takes places at hatcheries, separate from the grow-out facilities where broiler chicks are raised. This means that chicks are sorted and transported immediately after hatch, during which time they typically do not have access to feed and water, and are subjected to transport stress. Recently, innovative housing systems are being developed in which fertilised eggs are transported on embryonic day 18 (E18) from the hatchery to the grow-out facility, where they hatch on day 21. In chicken, the hypothalamic–pituitary–adrenal (HPA)-axis becomes functional around embryonic day 14–16. It is therefore conceivable that transport of eggs at E18 may lead to a stress response in the chick embryo. Exposure to prenatal stress may affect the coping capacity of the individual and negatively impact its further development. We investigated whether prolonged transport on E18 has effects on the development of a slow growing broiler chicken strain (Hubbard JA257). E18 eggs were transported for either 41 min (short transport, ST) or 219 min (long transport, LT). Transportation significantly increased embryonic heart rate after ST. This increase continued during an intermediate measure at 120 min. The increased embryonic HR then remained high at measurement immediately following LT. We did not find effects of prolonged transport on behavioural parameters measured in the juvenile chicken in the tonic immobility and open field test. Concentrations of feather corticosterone as well as faecal corticosterone metabolites did not differ on postnatal day 36. We showed that transport leads to an autonomic stress response in chicken embryos at E18, but that this elevation had no further effects on other indicators of prenatal stress. Nevertheless, our results emphasise that transport of incubated eggs should be as refined as possible to minimise the exposure to stress.