Section 14 — Animal Genetics and Breeding 



of LH (Armour), however the mean heritability 

 was 0.24. 



Overall response to a combination injection 

 of LH and FSH (Armour) was significantly 

 greater than that obtained when either was ad- 

 ministered singly. An additive effect was noted 

 within some families while in others the response 

 was similar to that obtained when either was 

 administered alone. 



When NIH-FSH and NIH-LH were injected, 

 differences among sire families were not signi- 

 ficant for the FSH but were for the LH. 

 Mean heritabilities were 0.03 for FSH and 0.80 

 for LH. 



Significant differences were observed among 

 sire families for two sources of PMS. The rank 

 correlation of the familial response to each 

 source was 0.80. 



This experiment demonstrated genetic in- 

 fluences on the response of target organs to 

 gonadotropins. Genetic control of assay ani- 

 mals facilitated excellent precision in bioassays 

 of gonadotropins. 



1. To be published in full in The Virginia Journal 

 of Science 15. 



14.29. Genetic Variation in Chick Bioassays for 

 Gonadotropins. II. Histological and Histochem- 

 ical Responses.^ 1 ) H. S. Siegel and P. B. 

 Siegel (Blacksburg, U.S.A.). 



Histological and histochemical observations 

 were made on testes of newly hatched progeny 

 of White Rock sires after subcutaneous ad- 

 ministration of purified gonadotropins. Hema- 

 toxylin-eosin for structural details, methyl 

 green-pyronin for nucleic acid differentiation 

 and sudan black for lipids were employed. 



Non-significant differences were observed in 

 the response of seminiferous tubules among 

 progeny of 5 sires in a dosage range of 5 to 40 

 Ug/chick of FSH (Armour). However, significant 

 differences were found when the range was 

 extended to 625 ug. Similarly, significant sire 

 effects were observed with NIH-FSH levels rang- 

 ing from 5 to 125|ig. Differences in tubule res- 

 ponse among families were not significant when 

 NIH-LH was used at doses of 1 to 25 ug. 

 Rankings of families for tubule diameter res- 

 ponses were not necessarily the same as those 

 ranked for testes weight response. 



Significant linear increases in tubule dia- 

 meters were found in a range of 5 to 125 |ag per 

 chick of Armour FSH. When sire differences 

 were considered, precision (A) for these assays 



were 0.35 and 0.11, respectively. A significant 

 quadratic response between the 125 and 625 pg 

 levels indicated that this was above effective 

 assay limits for this method. Precisions with 

 NIH-FSH and LH were 0.23 and 0.25, respec- 

 tively. 



No noticeable differences were noted in lipid 

 depletion among families. At 25 ug/chick of 

 LH, lipoid depletion and increased nuclear 

 activity were observed. This appeared as an all 

 or nothing response and could not be effectively 

 quantitated. Although FSH significantly in- 

 creased tubule diameters, neither increases in 

 mitotic figures nor nuclear activity were observed. 



1. To be published in full in The Virginia Jour- 

 nal of Science 15. 



14.30. The Effect of Microdose Irradiation of Hen's 

 Eggs upon Hatchability and Other Characters 

 of Chickens. H.F. Kushner, I. G. Kostin, 



L. A. Zubareva, L. I. Shershunova, N. I. 

 Kuznetzov, and M. G. Salganick (USSR). 



1. The eggs of Russian White and New- 

 Hampshire hens were used to study the effect 

 of microdoses of y-rays on economic and repro- 

 ductive characters of hens. 



2. The eggs over the incubation period were 

 irradiated continuously or intermittently in dif- 

 ferent trials with uranium and thorium salts. 



3. If the eggs during the incubation period 

 were irradiated intermittently with total doses of 

 0.003-2.9 r the embryonic mortality was decre- 

 ased and owing to it the average hatchability 

 was 3.5 per cent higher than in control. 



4. The results of irradiation depended upon 

 the initial quality of the eggs: the lower the 

 hatching properties of the control eggs, the higher 

 was the degree of hatching improvement of 

 irradiated eggs. 



The effect of irradiation on New-Hampshire's 

 eggs was superior to that on Russian White's 

 eggs. 



A high negative correlation between hatch- 

 ability of control eggs and the difference in hatch- 

 ability between the experimental eggs and con- 

 trols was established (r = —0.585 ± 0.0695). 



5. The effect of intermittent irradiation of 

 0.003 — 0.021 mr doses was equally good. 



6. Morphological and physiological studies 

 on embryos under the intermittent irradiation 

 showed that the hen's embryos were more sen- 

 sitive to irradiation at their earlier stages of 

 development. Treated embryos developed more 

 rapidly than controls. 



260 



