1981 Volume 18 Issue 5 Pages 290-300
Embryos died in the late stage of hatch in 20 hatchability tests carried out as a 5-year project in collaboration of 7 prefectural experiment stations, Nagoya University, and National Institute of Animal Industry were examined teratologically, and classified into 28 types of deformity. Statistical analysis of the incidence of each type of deformity revealed that neither the difference in the diets fed to the hens nor the difference in other experimental conditions such as the strain and generation of the hens could explain the variation of the incidence.
Accordingly, all the data were pooled with those of 192 lots of almost identical experiments to estimate the population mean, standard deviation of the data after angular or square root transformation, and 99% fiducial upper limit of the mean. Among 78, 311 fertile eggs tested in 752 lots, 1, 216 embryos were deformed. The deformity of the beak, including the short beak, was the most popular, being 578 cases in total, followed by the poor development and the umbilical hernia. The deformity in the brain and the eye was also popular, being 297 cases in total.
Equation 1 was found fit to describe the relationship between hatchability (y%) and mortality of embryo at early stage (x1%) and percent of deformed embryo (x2%).
y=94.36-1.0519x1-1.5586x2……(1)
The percent x2 can be estimated from y and x1, both of which are commonly determined in ordinary hatcheries as a routine work.
It was recommended to test hatchability in the experiment monitoring the presence of unknown or unexpected teratogenicity in a feed ingredient. Most of deformed chicks cannot break the egg shell by themselves, and died in the shell. Therefore, hatchability is a good criterion for teratogenicity without special knowledge and technique on teratology, anatomy and histology. Fiducial limits and Equation 1 are useful guides in hatchability tests.
