Variation in plumage response of brown leghorn capons to oestrone I-intramnuscular injection

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Abstract
I. A study of the variation in the response of breast feathers to a standard dose of estrone. 4 tests, covering the period of 1 yr., were carried out with about 60 capons. No significant variation due to body weight, or to season of the year, could be demonstrated, but birds became more responsive to the treatment with age. Differential responses in the individual, related to the position of the feather in the feather tract, were disclosed. An examination of the whole range and trend of variability encountered showed that it was necessary to postulate that both genetic and physiological factors were involved in its production; the nature of the latter influence could not be determined and the hypothesis, seeking to correlate feather growth rate with threshold of response to the hormone, was found insufficient to accommodate all the modifications obtained.[long dash]II. Subcut. inj. of less than 1/20 of the magnitude used in the previous expt. produced a local effect in a restricted area of the feather tract. The patterning induced waned progressively from the site of injection and many of the feathers were asymmetrically marked, the greater effect being on the side nearer the point where the estrone was introduced.