ABSTRACT Sturkie's Avian Physiology is a highly regarded textbook for the study of comparative poultry physiology. Less well known, however, is the contribution of Paul D. Sturkie (1909–2002) as a pioneer in the experimental physiology of avian species. His seminal research on the cardiovascular and hemodynamic controls of chickens and egg-laying hens had a notable impact on the poultry industry and breeding practices of farmers. The purpose of this article is to highlight the contributions and practical insights of Paul D. Sturkie to the field of poultry science. INTRODUCTION Paul David Sturkie (1909–2002) was an avian physiologist best known as the editor of the textbook Avian Physiology. The first edition of this textbook was published in 1954. The four editions (1954, 1965, 1976, and 1986) of Avian Physiology edited by Paul Sturkie, and the subsequent two editions (2000 and 2014) of Sturkie's Avian Physiology, are still regarded as the best comparative physiology reference for poultry science researchers and educators. Much of the lasting appeal of this textbook can be ascribed to the meticulous description of physiology principles given by Paul Sturkie and his chapter contributors. Dr. Sturkie had the ability to layer physiological concepts and weave them together with experimental data gathered in poultry species. In addition to writing multiple editions of this textbook, Paul Sturkie was an extremely productive bench-top researcher for over 40 years. In all, he authored or co-authored approximately 170 peer-reviewed publications. Paul D. Sturkie was born in Proctor, Texas, and received his bachelor's degree in 1933 and master's degree in 1936 from Texas A & M University. He received his Ph.D. in 1939 from Cornell University. Dr. Sturkie was on the faculty at Auburn University before his appointment as an Associate Professor at Rutgers University in 1944. He spent the remainder of his academic career at Rutgers and was appointed Professor in 1950. Dr. Sturkie retired as Emeritus Professor in 1977. RESEARCH The first peer-reviewed article authored by Paul Sturkie appeared in Poultry Science in 1937. This study investigated the inheritance pattern of shank color in chickens (Sturkie et al., 1937). Several of the early investigations of Dr. Sturkie focused on determining the penetrance of inherited traits in fowl (Sturkie et al., 1937; Sturkie, 1941,1942b,1943a). The experiments from his dissertation work at Cornell University examined the physiological basis for the congenital baldness in several breeds of chicken. The type of congenital baldness under investigation was characterized by the formation of blebs, fluid-filled vesicles, that emerged over the cerebral hemisphere and eyes of developing embryos at 10 to 11 d of development (Sturkie, 1941). The blebs would resolve by 15 to 16 d of development; however, they would leave an area devoid of feather follicles for the lifespan of the bird (Sturkie, 1941). The experiments conducted by Dr. Sturkie indicated that the blebs were not caused by ectopic cerebrospinal fluid or extravasated blood. Additionally, he discovered that the baldness was caused by the separation of the dermal layers during development (Sturkie, 1941). As a junior faculty member at Auburn University, Dr. Sturkie realized the practical importance of accurate record keeping for egg-laying hens to the poultry field. He published a manuscript in 1942 detailing a method using formatted sturdy cards for measuring the egg record of individual hens (Sturkie, 1942a). While this Poultry Science publication might not have been the most frequently cited by his scientific colleagues, Dr. Sturkie provided a methodology for the average poultry farmer who needed a sensible and inexpensive way to determine the most effective egg production scheme (Sturkie, 1942a). One of the first physiological experiments published by Dr. Sturkie examined the function of the avian spleen. It had been reported that the avian spleen functions similarly to the mammalian spleen as a hemoglobin reserve that could be mobilized following a hypoxic event (Harmon et al., 1932). However, there are anatomical differences between the spleens of birds and mammals. As such, Dr. Sturkie performed the first experiments that examined the hemoglobin response of the avian spleen in response to a brief episode of asphyxia. The results indicated that the hemoglobin concentrations in the central circulation were unchanged in hens before and after the episode of asphyxia. In addition, splenectomized hens had the same hemoglobin response as spleen-intact birds (Sturkie, 1943b). The results from his physiological experiments supported the anatomical observation that the avian spleen does not have the capacity to expel erythrocytes to raise blood hemoglobin levels during a hypoxic challenge (Sturkie, 1943b). After joining the Rutgers faculty, Dr. Sturkie began his extensive research on the cardiovascular function of avian species. His first paper on cardiac function used electrocardiograms (ECG) to determine how the position of the chicken heart changed the recorded electrical potentials (Sturkie, 1948). His experimental findings revealed that rotating the heart on the anteroposterior axis altered the waveform, but the change in electrical activity was not proportional to the degree of rotation and the relationship between heart position and electrical activity in the chicken was similar to the relationship reported in mammalian species (Sturkie, 1948). He also recorded the ECG in 72 White Leghorn hens (5 to 6 months of age) at regular intervals over the course of a year (Sturkie, 1949). Dr. Sturkie could not find a strong association between ECG waveform abnormalities and a common disease or increased mortality. However, he did establish a standard electrocardiogram methodology for studying cardiac function in poultry, an important technique that led to other discoveries benefiting the poultry industry (Sturkie, 1949). One major finding was that, unlike in mammals, there is no Q wave in the ECG of healthy chickens (Sturkie, 1949). In a subsequent study, Dr. Sturkie examined the effects of a potassium-free diet on the ECG waveforms and the influence of certain medications on potassium-deficient abnormalities in heart function (Sturkie, 1950). Diethylaminoethanol (DAE) was the only medication that reliably normalized the potassium-deficient altered ECG waveforms, whereas procaine and atropine sulfate were equally effective, but both were less effective than DAE (Sturkie, 1950). Further studies by Dr. Sturkie confirmed that the most common ECG abnormality related to a potassium deficiency was a second-degree atrioventricular block (Sturkie, 1952). Investigations were also performed to determine the effects of thiamine and vitamin E deficiency on ECG waveforms of chicks and chickens (Sturkie, 1954; Sturkie et al., 1954). The ability to measure blood pressure alterations of birds was a critical methodology for the study of the cardiovascular system in avian species. Indeed, Drs. Sturkie and Harold S. Weiss developed and validated a method for indirectly measuring blood pressure in conscious non-anesthetized avian species (Weiss and Sturkie, 1951). This plethysmographic method used limb volume changes obtained with a small cuff to reliably measure systolic blood pressure (Weiss and Sturkie, 1951). The use of this noninvasive method allowed Dr. Sturkie and colleagues to measure the blood pressure in the same bird longitudinally to determine age- or treatment-related changes in blood pressure, see Figure 1. Early observations by Dr. Sturkie and colleagues revealed that there were sex- and age-related differences in blood pressure in chickens. In adult White Leghorn chickens, they found that male chickens had a 15 to 25% higher systolic blood pressure compared with females (Sturkie et al., 1953). They also found that there was an age-related increase in blood pressure and that male chickens reached blood pressure plateau levels at a younger age than female chickens. The rise in blood pressure from 1 year of age to 3 to 4 years was 14% in males versus 24% in females (Sturkie et al., 1953). Additional studies demonstrated that the sex-dependent divergence in blood pressure starts at 8 wk of age in chickens (Weiss et al., 1957). Sturkie and colleagues conducted similar blood pressure experiments in Pekin ducks and White King pigeons to determine whether sex- and age-dependent blood pressure alterations were evident in other avian species (Ringer et al., 1955). Interestingly, they did not find any sex-related or age-related differences in arterial blood pressure measured in ducks and pigeons (Ringer et al., 1955). Other experiments by Sturkie and colleagues, however, demonstrated that plasma norepinephrine and epinephrine are found in a higher ratio in ducks (2.60) than chickens (0.14), pigeons (0.39), and turkeys (0.47) (Sturkie et al., 1970). The observation of a difference in the neuroendocrine control of blood pressure of chickens compared to the other avian species tested, suggested that the domestication process and selective breeding for production in chickens could account for the blood pressure alterations (Ringer et al., 1955). Figure 1. View largeDownload slide Paul D. Sturkie measuring cardiovascular parameters circa 1951. Photo courtesy of the Special Collections and University Archives, Rutgers University Libraries. Figure 1. View largeDownload slide Paul D. Sturkie measuring cardiovascular parameters circa 1951. Photo courtesy of the Special Collections and University Archives, Rutgers University Libraries. Dr. Sturkie's observations of variations in blood pressure and his early work examining inherited traits (Sturkie et al., 1937; Sturkie, 1941; Sturkie, 1942b; Sturkie, 1943a) led him to investigate the relationship of blood pressure on mortality in chickens (Sturkie et al., 1956). These experiments were performed by Sturkie and colleagues by measuring blood pressure in a large population of White Leghorns and crossbred hens (7 to 10 months of age) (Sturkie et al., 1956). Hens were stratified based on mean blood pressures into high (30% of the population), median (40% of the population), and low (30% of the population) groups (Sturkie et al., 1956). They found a significant difference in mortality rate based on the grouping of the birds. The low blood pressure group (i.e., hypotensive birds) had a higher mortality rate than the median and high blood pressure groups. No apparent cardiac pathologies were noted in the chickens at necropsy. Based on breeding practices in the 1950s, mortality losses were 15 to 50%; therefore, the findings that low blood pressure birds had a greater mortality was practical information that could be used by the poultry industry (Sturkie, 1956). Subsequent studies in 7 generations of selective breeding revealed the heritability of the hypotensive trait to 45 and 33% for male and female chickens, respectively (Sturkie, 1970). A summary of the study and an overview of Dr. Sturkie's research appeared in the poultry farmer's periodical, Everybody's Poultry Magazine, in 1956 (Sturkie, 1956). Further work revealed that the selectively bred hypotensive female chickens had higher cardiac output, even when normalized to body weight, compared with selectively bred hypertensive birds (Sturkie et al., 1962). There were no differences in heart rate between the hypotensive and hypertensive birds, which suggests that the higher cardiac output in hypotensive birds was attributed to increased stroke volume (Sturkie et al., 1962). To further determine the basis of the increased mortality rate in hypotensive female chickens, Dr. Sturkie investigated the birds’ response to physical stressors. Specifically, Dr. Sturkie and Kurt Textor exposed selectively bred hypotensive and hypertensive male and female chickens to temperature variations and forced exercise to exhaustion (Sturkie and Textor, 1961). Overall, males were able to perform better than females, but hypotensive birds had a significantly lower survival time in response to hypothermia and reduced time to exhaustion following forced exercise (Sturkie and Textor, 1961). The results were interpreted to suggest that hypotensive female chickens have a selective disadvantage for coping with stressors compared with hypertensive female chickens, which could contribute to the relatively higher mortality rates observed in those birds. Several experiments by Paul Sturkie sought to investigate the environmental influences on the physiological variation in the cardiovascular system of chickens. One set of experiments examined the effects of hypothermia on cardiovascular and hemodynamic parameters in chickens (Whittow et al., 1965). For this, adult White Leghorn hens were immersed in a cold-water bath that reduced their body temperature from 40.9 ± 0.2°C to 27 ± 0.9°C after 80 min. Similar to mammals, birds initially increased their cardiac output followed by a compensatory reduction in total peripheral resistance to produce a reduced cardiac output by the end of the 80 min cold-water immersion (Whittow et al., 1965). To understand the long-term cardiovascular adaptations to ambient temperature differences, Drs. Sturkie and James Vogel used a within-subjects study design to measure the seasonal variations in chickens (Vogel and Sturkie, 1963). In both male and female chickens, there was a decrease in cardiac output (i.e., reduced stroke volume, no change in heart rate) and an increase in blood pressure (i.e., increase in total peripheral resistance) from winter (February) to summer (August) (Vogel and Sturkie, 1963). To control for influencing factors, hens were not different in their egg production during the winter and summer measurements, and artificial light was provided to normalize the light/dark cycle across the seasons. The decrease in cardiac output in response to higher ambient temperature is notable because humans and other mammals increase cardiac output to facilitate heat loss through cutaneous mechanisms, whereas avian species rely on heat loss through the respiratory system (Vogel and Sturkie, 1963). AWARDS AND ACCOLADES Paul Sturkie was recognized with various prestigious awards throughout his career, such as the Poultry Science Award in 1947, the Borden Award in 1956, and the Golden Egg Award for Service to the New Jersey Poultry Industry in 1989. In addition, Dr. Sturkie received numerous speaking invitations from several different countries. One notable invitation was to speak at the 13th World's Poultry Congress in 1966, which was held in Kiev, Ukraine. This was a rare invitation for an American scientist in 1966. At the time, Ukraine was a member of the Union of Soviet Socialist Republics (USSR), and the conference occurred during the height of the Cold War with increasing American involvement in the Vietnam War. The trip made an impression on the Texas-born Paul Sturkie. The account of the trip was given as a talk to Rutgers University and was entitled “Travels Through Russia” and was chronicled in the Rutgers Report on World Affairs in 1968 (Sturkie, 1968). Dr. Sturkie's trip, on which he was accompanied by his wife, was financially supported by the Russian government and travel arrangements were made by the government-controlled tourist bureau. As Dr. Sturkie recalled, there was a series of “mishaps and bungling” by the Russian government-controlled travel bureau. When Dr. Sturkie finally arrived at the World Poultry Congress, there were a few talks by Russian officials, but the general program was cancelled. It took several days to get the travel arrangements back to the United States and this was only finally expedited because Dr. Sturkie's wife told one of the travel bureau officials: “If you don’t do something, my husband gets angry, and he is liable to have a heart attack” (Sturkie, 1968). In the end, Dr. Sturkie's trip mostly consisted of seeing the tourist sites in Moscow, Leningrad, and Kiev, and visiting poultry farms in the Ukraine countryside. In his reflections on the trip, Dr. Sturkie remarked how much he enjoyed the Russian people and their culture during his trip, but felt the USSR’s government, with all its available resources and centralized power, did not provide a standard of living that benefited the USSR’s people (Sturkie, 1968). CONCLUSION Paul D. Sturkie's longstanding contribution to the advancement of poultry sciences is twofold. First, as an educator he edited the first single-volume comparative avian physiology textbook, which has remained a widely read and referenced book since the first edition published over 60 years ago. Second, as a highly productive researcher, his innovative approaches to understanding the integrative capacity of the cardiovascular system of avian species was unparalleled. What is exceedingly evident in his peer-reviewed publications and personal communications is Dr. Sturkie's passion for scientific inquiry and his enduring dedication to providing practical solutions for avian physiology and the poultry industry. ACKNOWLEDGMENTS The Department of Animal Sciences would like to thank Victor Failmezger (Paul Sturkie's stepson) for his generous donation of Paul Sturkie's personal writings, research papers, and other materials. The authors would like to thank Special Collections and University Archives, Rutgers University Libraries for archival materials and Katherine Manger for her editorial assistance in preparing this manuscript. NTB is supported by the National Institutes of Health R01AT008933 and U.S. Department of Agriculture -National Institute for Food and Agriculture NJ06180. REFERENCES Harmon I. W., Ogden E., Cook S. F.. 1932. The reservoir function of the spleen in fowls. Am. J. Physiol. 100: 99– 101. Ringer R. K., Weiss H. S., Sturkie P. 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Poultry Science – Oxford University Press
Published: Mar 23, 2018
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