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Blood Pressure and Egg Formation1
FECUNDITY AND SEXUAL RECEPTIVITY
Zebra Finch (Peophila guttata) with special reference to pseudofemale behaviour and displacement activities. Behav. 6: 271-322. Parker, J. G., F. F. McKenzie and H. L. Kempster, 1940. Observations on the sexual behaviour of New Hampshire males. Poultry Sci. 19: 191-197. Skard, A. G., 1937. Studies in the psychology of needs. Acta Psychol. 2: 175-229. Upp, C. W., 1928. Preferential mating of fowls. Poultry Sci. 7: 225-232. Wilkins, R. H., 1915. Some factors influencing the fertility and hatching power of eggs of the domestic fowl. Unpubl. Thesis, Cornell Univ. Wood-Gush, D. G. M., 1954. The courtship of the Brown Leghorn cock. Brit. J. Anim. Behav. 2: 95-102. Wood-Gush, D. G. M., 1956. The agonistic and courtship behaviour of the Brown Leghorn cock. Brit. J. Anim. Behav. 4: 133-142. Wood-Gush, D. G. M., 1957. Aggression and sexual activity in the Brown Leghorn cock. Brit. J. Anim. Behav. 5: 1-6.
Blood Pressure and Egg Formation 1 H A R O L D S. W E I S S
Laboratory of Avian Physiology, Rutgers University, New Brunswick, New Jersey (Received for publication June 14. 1957)
T
HEORETICAL considerations suggest that blood pressure may influence the following characteristics of the egg. (1) Yolk weight. The membranous structure of the follicle indicates that filtration is involved in the transfer of material from the blood to the developing ovum (see review by Romanoff and Romanoff, Chap. 4). Since blood pressure can influence filtration rate (see reviews in Bard, pp. 37-39, 148 et seq.; Wiggers, p. 846), some relationship between blood
1 Paper of the Journal Series, New Jersey Agricultural Experiment Station, Rutgers, the State University of New Jersey, Department of PoultryScience, New Brunswick, New Jersey.
pressure and the quantity of material transferred is possible. (2) Albumen weight and score. Although the glandular structure of the oviduct (Romanoff and Romanoff, Chap. 4) points strongly to active cellular mechanisms controlling protein deposition, the transfer of the 88% of the albumen which is water (Romanoff and Romanoff, p. 316) may well be influenced by physical forces, i.e., filtration and blood pressure. (3) Egg weight. Changes in yolk and albumen weight should be reflected in whole egg weight. (4) Egg shape. Modification of muscular activity of the oviduct by neuromimetic drugs alters width/length index (Sturkie et ah, 1954). These same sympatho- and parasym-
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on May 5, 2015
small flocks of White Leghorns. Physiol. Zool. 18: 365-390. Guhl, A. M., and D. C. Warren, 1946. Number of offspring sired by cockerels related to social dominance in chickens. Poultry Sci. 25: 460-472. Heuser, G. F., 1916. A sjudy of the mating behaviour of the domestic fowl. Unpubl. Thesis, Cornell Univ. Hinde, R., 1954. The courtship and copulation of the Greenfinch (Chloris chloris). Behav. 7: 207-232. Lake, P. E., and D. G. M. Wood-Gush, 1956. Diurnal rhythms in semen yields and mating behaviour in the domestic cock. Nature, 178: 853. Lamoreux, W. F., 1940. The influence of intensity of egg production upon infertility in the domestic fowl. J. Agric. Res. 61: 191-205. Long, E., and G. F. Godfrey, 1952. The effect of dubbing, environmental temperature and social dominance on mating activity and fertility in the domestic fowl. Poultry Sci. 31:665-673. Morris, D., 1954. The reproductive behaviour of the
33
34
H. S. WEISS
PROCEDURE
All birds used were S. C. White Leghorn pullets, reared and maintained on the floor by conventional practices. Blood pressure was determined by sphygmomanometry (Weiss and Sturkie, 1951). Measurements made on the eggs included: (1) whole egg weight; (2) width/length index (Romanoff and Romanoff, p. 89); (3) shell thickness (Brant and Shrader, 1952); and (4) Van Wangen albumen score (Brant and Shrader, 1952). A few measurements of yolk and shell weight were included. In general, the average of at least two eggs per bird was used to establish individual values. Eggs were usually examined within 48 hours after lay. RESULTS
The first group of birds examined were from the second generation of a study of the heritability of blood pressure (Sturkie et al., 1956). The eggs came from approximately 35 birds each from the hyper- and hypotensive lines. Although selection of
TABLE 1.—Comparison of eggs from high and low blood pressure lines Pooled Low High standard pressure pressure error 36 34 • No. Birds 138** Systolic BP (mm.Hg) 185 71 74 Production (%) 3.8* 3.7 Body Weight (lbs.) 79 76 No. Eggs Analyzed 3.8 6.6 Blood Spots (%) Adjusted values3 Egg Wt. (oz./doz.) 23.9 23.6 Width/length Index 72.6 73.2 Shell Thickness 0.016 0.016 (inches) 2.5 2.5 Albumen Score
1.8 1 2
0.05 1
— —2 0.23 0.37 0.0002 0.09
* Significant at the 5% level of probability, analysis of variance. ** Significant at the 1% level of probability, analysis of variance. 1 Analysis of variance. 2 Chi Square analysis. 3 Covariance analysis.
these two lines was based primarily on blood pressure, and secondarily on productive characteristics, significant body weight differences had developed (Table 1). Since body weight is correlated with some egg measurements (Romanoff and Romanoff, p. 116), covariance analysis was used. As shown in Table 1, the egg measurements, adjusted for body weight, do not differ significantly between the hyper- and hypotensive lines. The fact that body weight differences had unexpectedly crept into the pressure lines suggested that some of the egg factors could have been biased too. Accordingly correlations were computed between blood pressure and egg weight and shape in an unselected flock. Partial correlation coefficient was used to eliminate the effect of body weight. For 63 birds whose systolic blood pressures ranged from 118 to 213, the r values were very small and completely non-significant (—0.08 and —0.02 for egg weight and width/length index, respectively). No differences were found in yolk and shell weights from a small but
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on May 5, 2015
pathomimetic drugs have well-known hyper- and hypotensive effects. If the mechanism controlling normal blood pressure in the chicken is through similar neuromuscular reflexes, then some relationship between blood pressure and egg shape may exist. (5) Blood spots. Blood spots are believed due to rupture of follicular vessels, and thus the stress imposed on the vessels by blood pressure could possibly influence their incidence (Nalbandov and Card, 1944). These possibilities were investigated by comparing eggs from pullets with different blood pressures. The normal wide range of blood pressure (Sturkie et al., 1953) was utilized, rather than any experimentally induced pressure changes, to avoid interaction between the tensive techniques themselves and egg formation.
BLOOD PRESSURE AND EGG FORMATION
selected sample of high and low pressure birds from this random group. DISCUSSION
Had blood pressure influenced yolk, albumen, or even shell deposition significantly, it should have been reflected in whole egg weight, as well as yolk and shell weight, or shell thickness directly. Also, any marked disproportion of water to solids in the albumen would likely have affected the albumen score. None of these measurements were altered, although the birds differed widely and significantly in pressure. However, these results do not permit a categorical elimination of filtration as a factor in egg formation, since the vascular force that influences filtration
directly is capillary hydrostatic pressure, not systemic arterial pressure. While arterial and capillary pressure are generally correlated, they are not necessarily so, and hemodynamic controls localized in the ovary and oviduct could operate to maintain a uniform capillary pressure (see Wiggers, p. 580, and Bard, pp. 37, 148 & 757 for discussions). Perhaps the complex venous drainage and spiral arteries of the follicle (Nalbandov and James, 1949) play such a role. SUMMARY
The eggs from White Leghorn pullets differing widely and significantly in systolic blood pressure, were compared as to weight, shell thickness, albumen score, width/length index, and incidence of blood spots. No statistically significant differences were found, suggesting that the normal range of pressure in the White Leghorn does not materially influence the commercially important characteristics of the freshly laid egg. ACKNOWLEDGMENT
The assistance of Dr. Robert K. Ringer, Dr. Donald Polin, Dr. Mary Sheahan, Mr. Walter Hunsaker and Mr. Eugene Borbely in the collection of these data is sincerely appreciated. REFERENCES Bard, P. A., 1956. Medical Physiology, 10th ed. The C. V. Mosby Co., St. Louis, Mo. Brant, A. W., and H. L. Shrader, 1952. How to measure egg I.Q. PA-202. Bureau of Animal Industry, U. S. Department of Agriculture. Burton, A. C , 1951. On the physical equilibrium of small blood vessels. Am. J. Physiol. 164:319-329. Kramar, J., 1953. Stress and capillary resistance (capillary fragility). Am. J. Physiol. 175: 69-74. Kramar, J., W. V. Meyers and C. M. Wilhelmj, Jr., 1955. Capillary stress response and species. Proc. Soc. Exper. Biol. Med. 89: 528-533. * Nalbandov, A. V., and L. E. Card. 1944. The problem of blood clots and meat spots in chicken eggs. Poultry Sci. 23: 170-180.
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on May 5, 2015
Since width/length index was not associated with pressure, it is unlikely that the mechanism controlling blood pressure is closely related to the neuromuscular forces that can affect egg shape (Sturkie et al., 1954). The incidence of blood spots was higher in the high pressure birds, but not significantly so, suggesting that high arterial pressure is not the primary cause of rupture of follicular vessels (Nalbandov and Card, 1944). However, the comparatively small numbers and the low overall incidence of blood spots in these birds limits elimination of blood pressure as a factor in blood spot formation. Normal capillaries in many species appear to be quite resistant to rupture, as shown by the high extracapillary suctions required to produce petechiae (Kramar et al., 1955), and by Burton's (1951) analysis of the factors permitting normal capillaries to withstand high pressures. Conceivably, in birds genetically susceptible to blood spots, or subjected to conditions which may reduce capillary resistance (Kramar, 1953), high blood pressure could be a contributory stress.
35
36
H. S. WEISS Am. J. Physiol. 174:405^07. Sturkie, P. D. ; H. S. Weiss and R. K. Ringer, 1954. Effects of injections of acetylcholine and ephedrine upon components of the hen's egg. Poultry Sci. 33: 18-24. Weiss, H. S., and P. D. Sturkie, 1951. An indirect method for measuring blood pressure in the fowl. Poultry Sci. 30: 587-592. Wiggers, C. J., 1949. Physiology in Health and Disease. 5th ed. Lea & Febiger, Philadelphia, Pennsylvania.
Measurement of the Thyroid Hormone Secretion Rate of Individual Fowls* t G. W. PIPES, B. N. PREMACHANDRA AND C. W. TURNER Department of Dairy Husbandry, University of Missouri, Columbia (Received for publication June 17, 1957)
S
INCE the rate of thyroid hormone; secretion is an important factor ini growth rate (Winchester and Davis, 1952)I and egg production (Winchester andl Scarborough, 1953), studies were undertaken to develop methods for determination of the thyroxine secretion rate in intact fowls. The earlier techniques of simultaneousi administration of thyroxine and thiouracil1 (Mixner et al., 1944) require sacrifice off the fowls and can be used only to measure; the average thyroid hormone secretionl rate of groups rather than of individual1 fowls. When I131 became available, Pipes et al. (1950) proposed that the thyroxine secretion rate could be determined in the intact rat by the injection of graded1 amounts of thyroxine up to the level1 which would inhibit thyrotropin secre* Contribution from the Missouri Agr. Exp. Sta. Journal Series No. 1761. Approved by the Director. , t Aided-in-part by a grant from the U.S. Atomic Energy Commission Contract No. AT(11-1)-301.
tion. This level would be shown by the effect upon the collection of I131 by the thyroid gland and the amount of proteinbound-P 31 in the blood. This plan of measuring thyroxine secretion has been explored by Pipes and Turner (1956) in cattle, by Henneman et al. (1952) in sheep and by Biellier and Turner (1957) in fowls. The method developed in this laboratory for the measurement of the thyroid hormone secretion rate of individual fowls by the use of I131 required serial blood sampling. In addition, due to lack of sufficiently sensitive detecting apparatus, the dosage of I131 sufficient to be detected in the blood approached the level that might damage the function of the thyroid glands (Biellier and Turner, 1957). With more sensitive detecting apparatus available, the possibility of measuring thyroid hormone secretion rate in individual birds by means of an in vivo method was explored. In this method, the two above difficulties would be eliminated.
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on May 5, 2015
Nalbandov, A. V., and M. F. James, 1949. The blood-vascular system of the chicken ovary. Am. J. Anat. 85: 347-378. Romanoff, A. L., and A. L. Romanoff, 1949. The Avian Egg. John Wiley & Sons, Inc., New York, N . Y. Sturkie, P. D., R. K. Ringer and H. S. Weiss, 1956. Inheritance of blood pressure and its relationship to mortality in chickens. Fed. Proc. 15: 182. Sturkie, P. D., H. S. Weiss and R. K. Ringer, 1953. Effects of age on blood pressure in the chicken.
Zebra Finch (Peophila guttata) with special reference to pseudofemale behaviour and displacement activities. Behav. 6: 271-322. Parker, J. G., F. F. McKenzie and H. L. Kempster, 1940. Observations on the sexual behaviour of New Hampshire males. Poultry Sci. 19: 191-197. Skard, A. G., 1937. Studies in the psychology of needs. Acta Psychol. 2: 175-229. Upp, C. W., 1928. Preferential mating of fowls. Poultry Sci. 7: 225-232. Wilkins, R. H., 1915. Some factors influencing the fertility and hatching power of eggs of the domestic fowl. Unpubl. Thesis, Cornell Univ. Wood-Gush, D. G. M., 1954. The courtship of the Brown Leghorn cock. Brit. J. Anim. Behav. 2: 95-102. Wood-Gush, D. G. M., 1956. The agonistic and courtship behaviour of the Brown Leghorn cock. Brit. J. Anim. Behav. 4: 133-142. Wood-Gush, D. G. M., 1957. Aggression and sexual activity in the Brown Leghorn cock. Brit. J. Anim. Behav. 5: 1-6.
Blood Pressure and Egg Formation 1 H A R O L D S. W E I S S
Laboratory of Avian Physiology, Rutgers University, New Brunswick, New Jersey (Received for publication June 14. 1957)
T
HEORETICAL considerations suggest that blood pressure may influence the following characteristics of the egg. (1) Yolk weight. The membranous structure of the follicle indicates that filtration is involved in the transfer of material from the blood to the developing ovum (see review by Romanoff and Romanoff, Chap. 4). Since blood pressure can influence filtration rate (see reviews in Bard, pp. 37-39, 148 et seq.; Wiggers, p. 846), some relationship between blood
1 Paper of the Journal Series, New Jersey Agricultural Experiment Station, Rutgers, the State University of New Jersey, Department of PoultryScience, New Brunswick, New Jersey.
pressure and the quantity of material transferred is possible. (2) Albumen weight and score. Although the glandular structure of the oviduct (Romanoff and Romanoff, Chap. 4) points strongly to active cellular mechanisms controlling protein deposition, the transfer of the 88% of the albumen which is water (Romanoff and Romanoff, p. 316) may well be influenced by physical forces, i.e., filtration and blood pressure. (3) Egg weight. Changes in yolk and albumen weight should be reflected in whole egg weight. (4) Egg shape. Modification of muscular activity of the oviduct by neuromimetic drugs alters width/length index (Sturkie et ah, 1954). These same sympatho- and parasym-
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on May 5, 2015
small flocks of White Leghorns. Physiol. Zool. 18: 365-390. Guhl, A. M., and D. C. Warren, 1946. Number of offspring sired by cockerels related to social dominance in chickens. Poultry Sci. 25: 460-472. Heuser, G. F., 1916. A sjudy of the mating behaviour of the domestic fowl. Unpubl. Thesis, Cornell Univ. Hinde, R., 1954. The courtship and copulation of the Greenfinch (Chloris chloris). Behav. 7: 207-232. Lake, P. E., and D. G. M. Wood-Gush, 1956. Diurnal rhythms in semen yields and mating behaviour in the domestic cock. Nature, 178: 853. Lamoreux, W. F., 1940. The influence of intensity of egg production upon infertility in the domestic fowl. J. Agric. Res. 61: 191-205. Long, E., and G. F. Godfrey, 1952. The effect of dubbing, environmental temperature and social dominance on mating activity and fertility in the domestic fowl. Poultry Sci. 31:665-673. Morris, D., 1954. The reproductive behaviour of the
33
34
H. S. WEISS
PROCEDURE
All birds used were S. C. White Leghorn pullets, reared and maintained on the floor by conventional practices. Blood pressure was determined by sphygmomanometry (Weiss and Sturkie, 1951). Measurements made on the eggs included: (1) whole egg weight; (2) width/length index (Romanoff and Romanoff, p. 89); (3) shell thickness (Brant and Shrader, 1952); and (4) Van Wangen albumen score (Brant and Shrader, 1952). A few measurements of yolk and shell weight were included. In general, the average of at least two eggs per bird was used to establish individual values. Eggs were usually examined within 48 hours after lay. RESULTS
The first group of birds examined were from the second generation of a study of the heritability of blood pressure (Sturkie et al., 1956). The eggs came from approximately 35 birds each from the hyper- and hypotensive lines. Although selection of
TABLE 1.—Comparison of eggs from high and low blood pressure lines Pooled Low High standard pressure pressure error 36 34 • No. Birds 138** Systolic BP (mm.Hg) 185 71 74 Production (%) 3.8* 3.7 Body Weight (lbs.) 79 76 No. Eggs Analyzed 3.8 6.6 Blood Spots (%) Adjusted values3 Egg Wt. (oz./doz.) 23.9 23.6 Width/length Index 72.6 73.2 Shell Thickness 0.016 0.016 (inches) 2.5 2.5 Albumen Score
1.8 1 2
0.05 1
— —2 0.23 0.37 0.0002 0.09
* Significant at the 5% level of probability, analysis of variance. ** Significant at the 1% level of probability, analysis of variance. 1 Analysis of variance. 2 Chi Square analysis. 3 Covariance analysis.
these two lines was based primarily on blood pressure, and secondarily on productive characteristics, significant body weight differences had developed (Table 1). Since body weight is correlated with some egg measurements (Romanoff and Romanoff, p. 116), covariance analysis was used. As shown in Table 1, the egg measurements, adjusted for body weight, do not differ significantly between the hyper- and hypotensive lines. The fact that body weight differences had unexpectedly crept into the pressure lines suggested that some of the egg factors could have been biased too. Accordingly correlations were computed between blood pressure and egg weight and shape in an unselected flock. Partial correlation coefficient was used to eliminate the effect of body weight. For 63 birds whose systolic blood pressures ranged from 118 to 213, the r values were very small and completely non-significant (—0.08 and —0.02 for egg weight and width/length index, respectively). No differences were found in yolk and shell weights from a small but
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on May 5, 2015
pathomimetic drugs have well-known hyper- and hypotensive effects. If the mechanism controlling normal blood pressure in the chicken is through similar neuromuscular reflexes, then some relationship between blood pressure and egg shape may exist. (5) Blood spots. Blood spots are believed due to rupture of follicular vessels, and thus the stress imposed on the vessels by blood pressure could possibly influence their incidence (Nalbandov and Card, 1944). These possibilities were investigated by comparing eggs from pullets with different blood pressures. The normal wide range of blood pressure (Sturkie et al., 1953) was utilized, rather than any experimentally induced pressure changes, to avoid interaction between the tensive techniques themselves and egg formation.
BLOOD PRESSURE AND EGG FORMATION
selected sample of high and low pressure birds from this random group. DISCUSSION
Had blood pressure influenced yolk, albumen, or even shell deposition significantly, it should have been reflected in whole egg weight, as well as yolk and shell weight, or shell thickness directly. Also, any marked disproportion of water to solids in the albumen would likely have affected the albumen score. None of these measurements were altered, although the birds differed widely and significantly in pressure. However, these results do not permit a categorical elimination of filtration as a factor in egg formation, since the vascular force that influences filtration
directly is capillary hydrostatic pressure, not systemic arterial pressure. While arterial and capillary pressure are generally correlated, they are not necessarily so, and hemodynamic controls localized in the ovary and oviduct could operate to maintain a uniform capillary pressure (see Wiggers, p. 580, and Bard, pp. 37, 148 & 757 for discussions). Perhaps the complex venous drainage and spiral arteries of the follicle (Nalbandov and James, 1949) play such a role. SUMMARY
The eggs from White Leghorn pullets differing widely and significantly in systolic blood pressure, were compared as to weight, shell thickness, albumen score, width/length index, and incidence of blood spots. No statistically significant differences were found, suggesting that the normal range of pressure in the White Leghorn does not materially influence the commercially important characteristics of the freshly laid egg. ACKNOWLEDGMENT
The assistance of Dr. Robert K. Ringer, Dr. Donald Polin, Dr. Mary Sheahan, Mr. Walter Hunsaker and Mr. Eugene Borbely in the collection of these data is sincerely appreciated. REFERENCES Bard, P. A., 1956. Medical Physiology, 10th ed. The C. V. Mosby Co., St. Louis, Mo. Brant, A. W., and H. L. Shrader, 1952. How to measure egg I.Q. PA-202. Bureau of Animal Industry, U. S. Department of Agriculture. Burton, A. C , 1951. On the physical equilibrium of small blood vessels. Am. J. Physiol. 164:319-329. Kramar, J., 1953. Stress and capillary resistance (capillary fragility). Am. J. Physiol. 175: 69-74. Kramar, J., W. V. Meyers and C. M. Wilhelmj, Jr., 1955. Capillary stress response and species. Proc. Soc. Exper. Biol. Med. 89: 528-533. * Nalbandov, A. V., and L. E. Card. 1944. The problem of blood clots and meat spots in chicken eggs. Poultry Sci. 23: 170-180.
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on May 5, 2015
Since width/length index was not associated with pressure, it is unlikely that the mechanism controlling blood pressure is closely related to the neuromuscular forces that can affect egg shape (Sturkie et al., 1954). The incidence of blood spots was higher in the high pressure birds, but not significantly so, suggesting that high arterial pressure is not the primary cause of rupture of follicular vessels (Nalbandov and Card, 1944). However, the comparatively small numbers and the low overall incidence of blood spots in these birds limits elimination of blood pressure as a factor in blood spot formation. Normal capillaries in many species appear to be quite resistant to rupture, as shown by the high extracapillary suctions required to produce petechiae (Kramar et al., 1955), and by Burton's (1951) analysis of the factors permitting normal capillaries to withstand high pressures. Conceivably, in birds genetically susceptible to blood spots, or subjected to conditions which may reduce capillary resistance (Kramar, 1953), high blood pressure could be a contributory stress.
35
36
H. S. WEISS Am. J. Physiol. 174:405^07. Sturkie, P. D. ; H. S. Weiss and R. K. Ringer, 1954. Effects of injections of acetylcholine and ephedrine upon components of the hen's egg. Poultry Sci. 33: 18-24. Weiss, H. S., and P. D. Sturkie, 1951. An indirect method for measuring blood pressure in the fowl. Poultry Sci. 30: 587-592. Wiggers, C. J., 1949. Physiology in Health and Disease. 5th ed. Lea & Febiger, Philadelphia, Pennsylvania.
Measurement of the Thyroid Hormone Secretion Rate of Individual Fowls* t G. W. PIPES, B. N. PREMACHANDRA AND C. W. TURNER Department of Dairy Husbandry, University of Missouri, Columbia (Received for publication June 17, 1957)
S
INCE the rate of thyroid hormone; secretion is an important factor ini growth rate (Winchester and Davis, 1952)I and egg production (Winchester andl Scarborough, 1953), studies were undertaken to develop methods for determination of the thyroxine secretion rate in intact fowls. The earlier techniques of simultaneousi administration of thyroxine and thiouracil1 (Mixner et al., 1944) require sacrifice off the fowls and can be used only to measure; the average thyroid hormone secretionl rate of groups rather than of individual1 fowls. When I131 became available, Pipes et al. (1950) proposed that the thyroxine secretion rate could be determined in the intact rat by the injection of graded1 amounts of thyroxine up to the level1 which would inhibit thyrotropin secre* Contribution from the Missouri Agr. Exp. Sta. Journal Series No. 1761. Approved by the Director. , t Aided-in-part by a grant from the U.S. Atomic Energy Commission Contract No. AT(11-1)-301.
tion. This level would be shown by the effect upon the collection of I131 by the thyroid gland and the amount of proteinbound-P 31 in the blood. This plan of measuring thyroxine secretion has been explored by Pipes and Turner (1956) in cattle, by Henneman et al. (1952) in sheep and by Biellier and Turner (1957) in fowls. The method developed in this laboratory for the measurement of the thyroid hormone secretion rate of individual fowls by the use of I131 required serial blood sampling. In addition, due to lack of sufficiently sensitive detecting apparatus, the dosage of I131 sufficient to be detected in the blood approached the level that might damage the function of the thyroid glands (Biellier and Turner, 1957). With more sensitive detecting apparatus available, the possibility of measuring thyroid hormone secretion rate in individual birds by means of an in vivo method was explored. In this method, the two above difficulties would be eliminated.
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on May 5, 2015
Nalbandov, A. V., and M. F. James, 1949. The blood-vascular system of the chicken ovary. Am. J. Anat. 85: 347-378. Romanoff, A. L., and A. L. Romanoff, 1949. The Avian Egg. John Wiley & Sons, Inc., New York, N . Y. Sturkie, P. D., R. K. Ringer and H. S. Weiss, 1956. Inheritance of blood pressure and its relationship to mortality in chickens. Fed. Proc. 15: 182. Sturkie, P. D., H. S. Weiss and R. K. Ringer, 1953. Effects of age on blood pressure in the chicken.