Studies of the Pirouette Mutation

Studies of the Pirouette Mutation

RESEARCH NOTES Studies of the Pirouette Mutation. 2. A Detrimental Phenotypic Interaction with Naked Neck 1 J. J. BITGOOD,2 E. P. EUTSLER,2 and M. P. ...

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RESEARCH NOTES Studies of the Pirouette Mutation. 2. A Detrimental Phenotypic Interaction with Naked Neck 1 J. J. BITGOOD,2 E. P. EUTSLER,2 and M. P. WALLACE3 Departments of Poultry Science and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin 53706 (Received for publication December 9, 1985)

INTRODUCTION

MATERIALS AND METHODS

The pirouette mutation (pir) (McGibbon, 1974) is a neurological mutation with minimal effect on the viability of affected individuals. The nervous tremor associated with the disorder throughout the life of the bird is readily apparent at hatch time. Using artificial insemination, the line is relatively easy to maintain (personal observations). Bitgood et al. (1987) have shown that affected chicks will hatch as well as their normal sibs. A mating was conducted to determine if any linkage association existed between pir and naked neck (Na) (Bitgood et al., 1986). This began as a class project in the Poultry Breeding course taught at University of Wisconsin. Students conducting the project noticed that at hatch time some of the naked neck pirouette chicks showed lacerations on the area of the neck that was not covered by down. These lacerations were apparently caused by the uncontrolled movement of the chick's head and neck causing the neck to rub against the edges of the shell during hatching. Two additional hatches were conducted to estimate the frequency and severity of this "automutilation" condition.

A male carrying the Na gene was mated to several pirlpir females in cages using artificial insemination. The F, chicks created were genetically Na, Pir+/na+, pir, the two mutant traits being in repulsion. These F, chicks were reared and intercrossed in a floor pen using a single male mating. Chicks were hatched and phenotypes recorded at hatch time. Both Na and pir are easily identified in the newly hatched chick. Two hatches were conducted by the students, who noted neck lacerations in some of the Na/-, pirlpir chicks. Two additional hatches were obtained to determine frequency and severity of the lacerations.

'Supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison. 2 Department of Poultry Science. department of Wildlife Ecology. Current address: Greater Los Angeles Zoo Association, 5333 Zoo Drive, Los Angeles, CA 90027. 166

RESULTS AND DISCUSSION

Ninety-eight chicks hatched in the last two hatches, of which 13 were Na/-, pirlpir. Ten of these had no apparent marks on the bare skin of the neck. One had a single scratch approximately 1 cm in length, and a second had several scratches ranging from 1 to 3 cm in length. A third chick was more severly affected, being scratched entirely around the neck in a band approximately 1 cm wide. In the two earlier hatches conducted by the students, the frequency of injury was not recorded, but several chicks were bleeding from the cuts. A large number of matings involving the pir locus have been conducted at University of Wisconsin. In addition to the tests reported here and by Bitgood et al. (1986), annual propagation matings have produced a number of pirouette

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ABSTRACT During a study to determine if any genetic linkage existed between the chicken mutations pirouette and naked neck, it was found that when both traits are expressed simultaneously in an individual, an "automutilation" condition can be created in some cases. The tremulous head movements of naked neck-pirouette chicks cause scraping of the skin on the neck against the egg shell during hatching, resulting in lacerations of the neck in varying degrees. Because of this potential for injury, it is suggested that matings between carriers of tremulous neurological disorders and carriers of mutations that result in lack of down cover be avoided whenever possible. (Key words: pirouette, naked neck, neurological, bare skin, hatch injury) 1987 Poultry Science 66:166-167

RESEARCH NOTE

study be avoided whenever possible. Other linked markers, if available, should be used instead to prevent unnecessary suffering on the part of the tested animals. REFERENCES Abbott, U. K., and V. S. Asmundson, 1957. Scaleless, an inherited ectodermal defect in the domestic fowl. J. Hered. 48:63-70. Bitgood, J. J., E. P. Eutsler, and M. P. Wallace, 1987. Studies of the pirouette mutation. 1. Lack of linkage association with marked regions of chromosomes 1 and 2. Poultry Sci. 66:(in press). Crawford, R. D., H. Patterson, and R. S. Gowe, 1982. Ottawa naked, a mutation causing abnormal feathering and toe fusion in the domestic fowl. Poultry Sci. 61:1441. (Abstr.) Hutt, F. B., and P. D. Sturkie, 1938. Genetics of the fowl. IX. Naked, a new sex-linked mutation. J. Hered. 29:371-379. McGibbon, W. H., 1974. Pirouette: a behavioral mutation in the domestic fowl. J. Hered. 65:124-126. Smyth, J. R., Jr., M. M. Jerszyk, and N. Montgomery, 1985. Congenital quiver, an inherited neurological defect in the chicken. J. Hered. 76:263-266.

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chicks. No other cases of injury to any chicks have been noted (personal observations). This indicates that in addition to providing insulation and camouflage, the down cover also functions to protect the skin of young birds. This would be particularly important in those precocial species that rear their young in areas containing heavy cover that could cause damage to bare skin. There are a number of neurological mutations in the chicken that create tremulous head movements in newly hatched chicks (See Smyth et al., 1985). There are also several mutations that result in a lack of down cover on newly hatched chicks. These include sex-linked naked (Hutt and Sturkie, 1938), scaleless (Abbott and Asmundson, 1957), and Ottawa naked (Crawford et al., 1982). Any combination of a neurological mutant with a downless mutant could possibly recreate the same "automutilation" condition reported in this study. In light of this, it is recommended that matings similar to the one in this

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