Incubation

About: Incubation is a research topic. Over the lifetime, 5748 publications have been published within this topic receiving 126541 citations.

Incubation period of Creutzfeldt-Jakob disease in human growth hormone recipients in France.

Abstract: Objective: To estimate the statistical distribution of the incubation period of Creutzfeldt–Jakob disease (CJD) in human growth hormone (hGH) recipients in France. Background: Published papers suggest that the median incubation period of hGH-related CJD is approximately 15 years, but there are as yet no statistical data that support this assertion. Methods: Of the 1,361 hGH recipients who were included in this study, 55 had developed CJD at the time of the study. Individual data on hGH treatment history were available. Different mathematical models were used to estimate the statistical distribution of the incubation period. One main feature of the models was to take into account the occurrence of future CJD cases. Results: Models showed that the mean incubation period was 9 to 10 years, and the 95th percentile of the distribution was 15 to 16 years. Data and models indicated that the incubation period was significantly shorter in homozygotes at codon 129 of the prion protein gene than in heterozygotes. Conclusions: The short mean incubation period of CJD in French hGH recipients may be due to high infectivity in hormone lots. Estimates of the 95th percentile indicate that the number of hGH-related CJD cases may continue to increase in the coming years.

Embryonic developmental plasticity of the chick: Increased CO2 during early stages of incubation changes the developmental trajectories during prenatal and postnatal growth

Abstract: This study investigated the effect of non-ventilation of the incubator during the first 10 days of incubation on carbon dioxide (CO2) concentrations in the incubator and its effects on the embryonic and post-hatch development of the chicken (Gallus gallus). Two different incubation conditions were created, one incubator was kept at standard conditions, with adequate ventilation (V) and a second incubator was non-ventilated (NV) during the first ten days of incubation, allowing the CO2 to rise. After the first 10 days, both incubations were continued under standard conditions. The experiment was repeated twice with different ages of the breeders (45 and 60 wks) which resulted in different CO2 levels at ED10 (1.5 and 1%). The CO2 concentration in the V incubators remained below 0.1% in these first 10 days. The eggs of the NV incubation showed higher pCO2 levels in the air cell from ED10 until ED14 compared to the eggs of the V group. The NV embryos had significantly higher absolute and relative (to egg weight) body weights from ED10 until ED18, pointing to an accelerated embryonic growth. At internal pipping, the NV chick embryos had higher plasma corticosterone and T3 levels and higher pCO2 in the air cell. Chicks incubated under NV conditions hatched 10 h earlier in the first and 15 h earlier in the second experiment and the spread of hatch was narrower. During the post-hatch period, the NV chickens had a higher body weight compared to the V chickens. From these results, it is clear that higher levels of CO2 during the first ten days of incubation have persistent (epigenetic) effects during the incubation and early post-hatch period.

Storage of the Eggs of the Fowl (Gallus domesticus) before Incubation: A Review

Abstract: The literature relating to storage of hatching eggs prior to incubation is reviewed under 5 headings:— 1. Storage time—prolonged storage leads to reduced hatchability and also produces a longer inc...

The constancy of incubation

Abstract: N an earlier paper (1957) I briefly surveyed the bewildering variety of incubation patterns which birds exhibit and attempted to correlate their incubation habits with their coloration, the form of their nests, their environment, and other factors that seemed to be pertinent. From this survey, it appeared that many modifications in the incubation pattern, especially those involving the participation of the sexes, are non-adaptive, in the sense that they are not more conducive to the reproductive efficiency of a particular species than some alternative pattern might be. The best than can be said in their favor, in the light of our present understanding, is that they are not deleterious. Even within a single incubation pattern, such as those classified in the above-mentioned paper, the student of the incubation habits of birds discovers bewildering diversity, caused principally by the varying lengths of the birds' continuous sessions on the eggs. Some birds sit for hours or even days at a stretch, others rarely cover their eggs uninterruptedly for as long as half an hour in the daytime. In some species of which only a single parent incubates, its absences are far shorter than its sessions, so that a high constancy of incubation is achieved; in others, the absences are of about the same length as the sessions with which they alternate, so that the eggs are covered only about half of the day. What causes these differences? Can we correlate them with differences in the birds themselves or in their environments-with factors such as size, diet, weather, type of nest, and the like? As, over the years, I have given attention to the incubation habits of a great variety of birds and have tried to explain what I found, these questions have occurred to me again and again. The present paper is a preliminary attempt to answer them.

Gas Exchange of the Avian Egg Time, Structure, and Function

Abstract: Data are presented for oxygen consumption water loss during incubation water vapor conductance of the shell and pore number of avian eggs and the way in which these values relate not only to egg mass but also to incubation time It is proposed that all these functions are proportional to the product of egg mass and rate of development where the latter is defined as the inverse of incubation time These interrelationships account at the end of incubation for similar O2 and CO2 tensions in the air space of eggs utilization of calories (05 kcal g−1) and water loss (15 g g−1)