Animal genetics / Frederick B. Hutt.

  • Hutt, Frederick Bruce, 1897-1991.
Date:
[1964]
Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Animal genetics / Frederick B. Hutt. Source: Wellcome Collection.

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    SIMPLE MENDELIAN INHERITANCE 23 of them would sire six black calves in a row is ( V2 )®, or 1 in 64. We might, therefore, be fairly certain that the particular bull being tested is BB, but to make assurance doubly sure, we might reserve decision until four more calves have been added to the test. If no reds have appeared among the ten calves, the probability that the bull is Bb is reduced to V1024, and most of us would say that odds of 1,023 : 1 against his carrying b are enough. Few breeders of domestic animals can make test-crosses as easily as the poultryman. Breeders of Wyandottes want birds with typical rose combs (Fig. 2-3), but for years they have been plagued by the single-combed chicks hatched from purebred (rose-combed) Wyan¬ dotte parents. The problem has persisted because heterozygous rose-combed birds (Rr) are indistinguishable from homozygotes (RR) except by a breeding test. Single comb (rr) behaves as a simple recessive to rose. FIG. 2—3. White Wyondotte male (left) and Single Comb White Leghorn (right) showing the rose and single combs, respectively, that are essential char¬ acteristics of these breeds. To find sires that will throw no single combs, prospective breed¬ ing cockerels should each be tested (separately) before the regular breeding season by a mating with half a dozen, or more single- combed hens. A dozen chicks, if all are rose-combed, will give as¬ surance that their sire is RR. By allowing ten days to establish fer-