Effects of chronic hypoxia and protein malnutrition on growth in the developing chick.
OBJECTIVE
The purpose of this study was to determine how chronic hypoxia and/or protein malnutrition in ovo affect growth in developing chicks.


METHODS
Chicken eggs were incubated under normoxic (21% oxygen; n = 30 eggs) or hypoxic (14% oxygen; n = 80 eggs) conditions. Hypoxia was imposed from day 0 (n = 38 eggs), day 10 (n = 22 eggs), or from day 0 to 10 (n = 20 eggs). Protein malnutrition alone (n = 20 eggs) or in combination with hypoxia (n = 24 eggs) was induced by removal of 10% of the estimated total albumin content of the egg. Embryos/chicks were killed and weighed at day 10, 15, or immediately after hatch; organs were removed and weighed.


RESULTS
Embryos to which hypoxia was imposed from day 0 weighed less than control embryos at day 10, which stayed the same until hatch (64.67% +/- 3.56% egg mass vs 69.36% +/- 3.90% [mean +/- SD]; P <.05). Malnourished chicks at day 15 and at hatch (63.42% +/- 4.28%; P <.05) weighed less than control chicks, as did malnourished plus hypoxia chicks (59.74% +/- 3.41%; P <.001). Malnourished plus hypoxia chicks weighed less than malnourished chicks alone (P <.05). Embryos that were hypoxic from day 0 to 10 weighed less than control embryos at day 15 (P <.05), but not at hatch. At hatch, neither hypoxia nor malnutrition decreased crown-rump length. Brain and heart weights were increased in both malnourished groups, but not chicks that were hypoxic from day 0.


CONCLUSIONS
Chick embryos exposed to malnutrition show asymmetric growth restriction with relative sparing of the brain and heart. Early growth restriction that was induced by hypoxia from the beginning of incubation is reversed by the restoration of normoxia at mid incubation.
Miller
Suzanne L
SL
Departments of Obstetrics and Gynaecology, University College London, UK.
Green
Lucy R
LR
Peebles
Donald M
DM
Hanson
Mark A
MA
Blanco
Carlos E
CE
D000818:Animals; D001835:Body Weight; D002642:Chick Embryo / Q000033:anatomy & histology / Q000502:physiology*; D002908:Chronic Disease; D005315:Fetal Diseases / Q000473:pathology / Q000503:physiopathology*; D005311:Fetal Hypoxia / Q000473:pathology / Q000503:physiopathology*; D009929:Organ Size; D011502:Protein-Energy Malnutrition / Q000473:pathology / Q000503:physiopathology*; D016019:Survival Analysis