Of the 372 chicks 35% showed smut. The P1 matings clean male X clean females gave 11.4% smutty progeny, clean male X smutty females gave 30.2% smutty progeny. The smutty male X clean females gave 45.2% while smutty male X smutty females gave 69.4% smutty progeny. Of the chicks that had black heads or necks 76% showed smut as adults, but there was no relationship found between shade or down and smut in adult undercolor. Chicks with black in wings gave 47.6% smutty adults, while only 19% of the non-black were smutty as adults.
From the results obtained in this experiment smut depends upon two independent pairs or autosomal genes. At one locus there is "E" gene for the extension or black throughout the feathers, or "e", recessive allele which gives no color. At the other locus is gene "Y", for red color in the under-cola; or its recessive allele "y" which gives no color.
Birds of genotypes Y/Y E/E, Y/Y E/e, Y/Y e/e, Y/y E/E, Y/y E/e, Y/y e/e, and y/y e/e give no smut. Those with genotypes y/y E/E and y/y E/e have smut. The amount of smut depends upon whether the gene "E" is in the E/E or E/e condition. Some chickens with genotype Y/y E/E may show smut since the epistatic condition is weakened when gene "Y" is in the heterozygous condition.
Theoretically, the most desirable genotype for producers of broilers and processors would be y/y e/e since the under-color would be white. However, this is not the color called for in the Standard. Nevertheless, breeders should select that type of bird that will satisfy his customers. Selecting birds homozygous for "e" would be a breeder's best insurance against having smut. This, however, is not easy to do. Selecting for lighter colors, both surface and undercolor, would be the best way since black helps to make the shade somewhat darker. Lighter colored birds are not as likely to have "E" at all.
It was noted in both field observation and actual experiment that those birds that had smut, laid fewer eggs during a seven month period. The P1 smutty females averaged 108.4 eggs; the P1 clean females averaged 130 eggs. The smutty females of the observed flock averaged 109 eggs; the clean females of the observed flock averaged 156 eggs.
On the basis of this experiment and the author's field observation it is concluded that:
1. Smut in this strain of New Hampshires is caused by the interaction or two genes, one a recessive allele of "Y", red under-color, and the other a dominant allele "E", the extension ot black throughout the feathers,
2. Although a higher percent of those chicks showing black in the wings have smut as adults, one can't be sure whether smut will show or not.
3. A high percent or those chicks having black on head or neck will have smut as adults (76%).
4. Hens of this strain that have no smut will usually lay more eggs than smutty hens during a given period.
5. It is necessary to check for smut much more often than usually done to accomplish any great improvement.
6. Progeny testing is the best procedure to follow in attempts to control smut. / M.S.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/106100 |
| Date | January 1955 |
| Creators | Williams, William Reid |
| Contributors | Poultry Husbandry |
| Publisher | Virginia Polytechnic Institute |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | 44 leaves, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 25850725 |
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