Some Effects of Thyroid and Gonadotrophic Preparations in the Fowl

Abstract

WITsCHI [1935] has shown that certain pituitary and allied preparations can induce maturation and even full activity in the resting gonads of sparrows and finches. But while hormonal control appears to be involved in the non-breeding season, as it is in the cestrous cycle of mammals and the brooding cycle of birds, there is general agreement that the initiation and termination of the quiescent period are also related to certain external stimuli such as light variations. The researches of Bissonnette and Benoit indicate that these external agents require the intermediation of the anterior pituitary in order to exert their effect [reviewed by Marshall, 1936; Van Dyke, 1939, p. 58].As a rule, the annual autumnal cessation of egg production in the fowl coincides with the onset of the moulting period, and it might be assumed that the two processes are mutually incompatible, or too expensive physiologically to be carried on together. These views are supported by evidence from an inbred line, maintained at this Institute, in which a number of females have occurred which laid for two consecutive years without a break; such birds either did not moult, or replaced only a small percentage of their feathers while laying at a reduced rate.Nevertheless, the length of the infecund period varies greatly in individuals, and often far exceeds the time required for the completion of feather replacement. In a group of 58 hens, drawn from hatches in three successive years, the length of the gap at the end of the first laying year was 84-8 days, with a standard deviation of 34-56 days. The gap also lengthens with age: for the same 58 birds the mean difference between the dates of renewal of production in the second and third years is 2029 days (S.E., 3.89), and between the second and fourth years 29-74 days (S.E., 4 03). Greenwood et al. [1940] showed that although individual birds appeared to have a genetically determined date on which production ended, second-year birds tended to cease laying slightly earlier than pullets. In the same communication it was also pointed out that the range of dates on which birds cease to 175

Ovarian Response of Hens and Pullets to Injections of Ambinon

“…The thyrotropic potency of the material used might have been a contributing factor to the cause of the follicular degeneration but in no case did the injections result in the birds beginning a molt as reported by Walker (1925) and Greenwood and Blyth (1942). Dubowik (1930) reported that egg production was increased by injecting laying hens with the anterior lobe of pituitary glands obtained from other birds but the injections of whole glands inhibited production.…”

“…Two year old hens which were injected by Noether at Rutgers University Libraries/Technical Services on April 10, 2015 http://ps.oxfordjournals.org/ Downloaded from (1928,1930) stopped laying the day following one injection of the extract he prepared and production was not resumed for two to three weeks, but no effects were produced by any of the five commercial preparations which also were injected. Likewise, it has been shown by the work of Bates, Lahr, and Riddle (1935), Fraps and Riley (1942), and Greenwood and Blyth (1942) that injections of pregnantmare serum causes a cessation of egg production in the fowl.…”