THE EFFECTS OF VENTENSIVE ZINBREEDING (BROTHER x SISTER) onwxmous TRAITS m. . JAPANESE QUAIL (corunmx comex JAPONICA) Thesis for the Degree of Ph. D. mum-Hem STATE umvms’m’ :1me WILLIAM KULENKAMP 1970 ‘ i"‘1€bl§ This is to certify that the thesis entitled THE EFFECTS OF INTENSIVE INBREEDING (BROTHER X SISTER) ON VARIOUS TRAITS IN JAPANESE QUAIL (COTURNIX COTURNIX JAPONICA) presented by Alwin Willi am Kulenkamp has been accepted towards fulfillment of the requirements for Ph.D. degree in Poultgz Science 1% 74.4%.“, Major professor October 7, 1970 Date 0-169 IIxIx xx xx xxxxxxxxx‘x‘xx M1293 10737M TVlESI.J RETURNING MATERIALS: Place in book drop to LlBRARlES remove this ChECkOUt from your record. FINES wiII be charged if book is returned after the date stamped below. ABSTRACT THE EFFECTS OF INTENSIVE INBREEDING (BROTHER X SISTER) ON VARIOUS TRAITS IN JAPANESE QUAIL (COTURNIX COTURNIX JAPONICA) By Alwin William Kulenkamp The purpose of this study was to determine in Japanese quail the effects of consecutive brother x sister matings on egg production, egg weight, fertility, hatchability, three and seven-week livability and body weights at three and seven weeks of age. A goal was to establish inbred lines for future studies. The foundation stock from which the birds for this experiment originated was a population of Japanese quail maintained at Michigan State University as a closed flock for the past ten years. The immediate progenitors of the first generation of full sibs were a select group of aged individuals having been in production for about seven months with the less viable birds having been eliminated by natural selection. Con- trol matings were made from this stock and were carried along each generation with an effort to avoid any close inbreeding. A total of 974 full—sib matings and 285 control matings occurred over a period of five generations. Seventeen inbred lines with varying number of matings in the first generation were Started. In this experi- ment an inbred line is defined as including all birds for any given Alwin William Kulenkamp generation that were derived from an original parental pair. This does not mean that developing inbred lines in the classical sense of con- secutive brother x sister matings was followed, i.e. in most cases more than one mating per inbred line was made each generation thus forming many sublines within the original line. Six of these lines survived the five consecutive generations of full—sib matings. Lines were lost throughout the experiment from varying causes which were centered on declines in reproductive performance. Individual lines varied con- siderably as to the effects of inbreeding on the various traits studied. The group of inbred lines that survived for five generations had shown a better than average performance in the first generation for all traits, except livability, than had the lines that were lost. Weighted linear regression coefficients of the deviations of mean inbred pOpulation performance from the mean control performance were calculated on inbreeding level. Negative values were obtained for all traits except three-week body weight and egg weight. Tests for non- linearity were significant for all traits except three-week livability and egg weight. Data for egg weights were collected only in generations three through five. Of the traits measured, fertility, hatchability and average weekly egg production were affected most by inbreeding with the fifth generation means being lowered as compared to the control mean by about 40 percent. Three and seven week livabilities were re— duced by about 20 and 26 percent, respectively. Body and egg weights were reduced the least with values ranging from 4.8 percent for egg weight to 11.2 percent for seven—week female body weight. THE EFFECTS OF INTENSIVE INBREEDING (BROTHER X SISTER) ON VARIOUS TRAITS IN JAPANESE QUAIL (COTURNIX COTURNIX JAPONICA) By Alwin William Kulenkamp A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Poultry Science 1970 MUG»? To my wife and son 11 ACKNOWLEDGEMENTS There is one being to whom I owe special acknowledgement--"Thank God I'm done!" After all, God has aided me in many wonderful and mysterious ways. He gave me Dr. T. H. Coleman's ears and mind for listening, understanding and guidance throughout my course of study at this Univer- sity and a critical review of this manuscript. He gave me Dr. W. T. Magee's knowledge of computer programming and Dr. J. L. Gill's knowledge of statistics. He gave me Mrs. Lou Shockey's nimble fingers and scrutinizing eyes for her skillful typing and proofreading of the first draft and Mrs. Lucy Wells for her typing of the final draft of this thesis. . He gave me the willing help of Mr. Victor Thurlby who so ably marked the many thousands of eggs used in this study. He gave me understanding parents whose encouragement was very helpful throughout my work. He gave me the Poultry Science Department and Dr. H. C. Zindel for providing the funds and facilities required to complete this thesis. Above all, He gave me my wife, Caryn, for her love, encouragement, patience, understanding and all of her work which have made the comple- tion of this thesis tolerable and possible. Last, but not least, He gave me Our son to whom I owe a future of love, patience and understanding for being a good baby which aided his father's work considerably. iii TABLE OF CONTENTS Page LIST OF TABLES . . . . . . . . . . . . . . . . . . . v LIST OF FIGURES . . . . . . . . . . . . . . . . . . vii INTRODUCTION . . . . . . . . . . . . . . . . . . . . 1 REVIEW OF LITERATURE . . . . . . . . . . . . . . . . 3 Hatchability . . . . . . . . . . . . . . . 3 Egg Production . . . . . . . . . . . . . . . 7 Fertility O O O C O O O O O O O O 0 O O O O O 10 Body Weight or Growth . . . . . . . . . . . . 11 Egg Weight . . . . . . . . . . . . . . . . . 12 Mortality O O O O O O O O O O O O O O O O O O 12 Sexual Maturity . . . . . . . . . . . . . . . 13 General . . . . . . . . . . . . . . . . . . . 14 Other Species . . . . . . . . . . . . . . . . l4 OBJECTIVES C O O O O O O O O O O O O O O O O O O O O 17 EXPERIMENTAL PROCEDURE . . . . . . . . . . . . . . . 18 The Foundation Stock . . . . . . . . . . . . 18 Management Procedures . . . . . . . . . . . 19 Data Collection and Analysis . . . . . . 22 RESULTS AND DISCUSSION . . . . . . . . . . . . . . . 26 Control Line Performance . . . . . . . . . . 28 Inbred Lines Lost Prior to Fifth Generation . 3O Inbred Lines Surviving Five Generations of FUll-Sib Matings o o o o o o o o o o o o o 40 Overall Performance of the Inbred Population 49 GENERAL DISCUSSION 0 O O O O O O I O O O O C O O O O 57 SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . 63 LITERATIJRE CITED 0 O O O O I O O I O O O O O O O O O O O O O I 65 APPENDIX 0 O O O O O O O O C O O O O O I 69 iv Table 10. 11. 12. l3. 14. 15. 16. 17. 18. Coefficients of Regression of Performance on LIST OF TABLES Inbreeding Level Reported in Chickens . Summary of the Number of Matings Involved for the Control and Inbred Lines Summary of Performance for Summary Summary Summary Summary Summary Summary Summary Summary Summary Summary Summary Summary Summary of of of of of of of Performance Performance Performance Performance Performance Performance Performance Performance Performance Performance Performance Performance Performance for for for for for for for for for for for for for Summary of Performance for Weighted Linear Regression Control Line . Inbred Inbred Inbred Inbred Inbred Inbred Inbred Inbred Inbred Inbred Inbred Inbred Inbred Inbred Coefficients of Performance on Inbreeding Expressed as Deviations of Inbred' Population from Control Population Means V Line Line Line Line Line Line Line Line Line Line Line Line Line Line 53 . 7S . 20 . 7 43 . 73 . 4O . 95 . 17 . 22 . 24 . 7O . 72 . 89 Page 27 29 31 32 34 35 36 37 38 39 41 42 43 44 45 46 54 Table Page 19. Relative Change from Generation to Generation in Performance of Inbred Population as Compared to Control Population (Percent Change from Control) . . . . 55 20. Comparison of First Generation Performance of the Inbred Lines that Survived Five Generations of Full- Sib Matings with Those Lines that were Lost in Prior Generations . . . . . . . . . . . . . . . . . . . . 60 vi LIST OF FIGURES Figure Page 1. Deviations of Weighted Mean Values of Inbred Population from Control Values (Egg Production and Egg weight) 0 O O O O O O O O O O O O O O O O O O O 50 2. Deviations of Weighted Mean Values of Inbred Population from Control Values (Fertility and Hatchability) O O O O O O O O O O O O O O O O O O O 51 3. Deviations of Weighted Mean Values of Inbred Population from Control Values (3-Week Livability and 7-Week Livability) . . . . . . . . . . . 52 4. Deviations of Weighted Mean Values of Inbred Population from Control Values (3-Week Body Weight, 7—Week Body Weight—~Males and 7-Week Body Weight--Females) . . . . . . . . . . . . . 53 vii INTRODUCTION Inbreeding is generally defined as the mating of individuals more closely related to each other than the average relationship of the population. In dioecious animals the intensity can range from very slight to brother—sister or youngest parent and offspring matings which are the most intense forms possible. The consequences of inbreeding stem from the fact that the closer the relationship of two animals the more genes they tend to have in common; thus, any offspring resulting from a mating of these two individuals would be more homozygous than offspring from a random mating. Wright (1922) devised a measurement of this effect which is applicable to all systems of mating regardless of how irregular they might be. This measurement is the correlation between the uniting gametes which produce the offspring. It was designated by the letter ' "F" and is computed using the formula Fx = Z[(1/2)n+n +1 (1+FA)] (Wright, 1923). Fx is the inbreeding coefficient of the individual in question, while n and n' are the number of generations between a common ancestor and the sire and dam, respectively, whereas FA is the in- breeding coefficient of the common ancestor. The portion within the brackets is that part contributed by any given common ancestor to the coefficient of inbreeding of an individual. These parts are summed for all common ancestors of the individual. 1 2 The general effects of inbreeding observed in most animals are lowered reproductive fitness and decreased growth and vigor. Neverthe- less, inbreeding does have some useful aspects. Linebreeding, a mating system designed to keep relationship to a prized individual high, has the inevitable consequence of mild inbreeding. The development of in- bred lines of small laboratory mammals for the purpose of reducing the genetic variation among them is well known. The formation of several inbred lines and then selecting the better ones for crossing is done by some poultry breeders so as to take advantage of hybrid vigor. Japanese quail have been shown to be useful laboratory animals (Padgett and Ivy, 1959). Viable inbred lines of these birds could possibly be beneficial in this capacity as attested to by the use that has been made of inbred lines of rats and mice. Furthermore, Japanese quail are very suitable for avian genetic studies, primarily because of their unusually short reproductive cycle and, secondarily, because of their small body size which allows large numbers of individuals to be raised at a reasonably low cost of maintenance. The purpose of this study was to measure the effects of continuous brother-sister matings of Japanese quail and to establish inbred lines of this species. REVIEW OF LITERATURE Since the literature on inbreeding in chickens is rather exten— sive it will be discussed under the following headings: hatchability, egg production, fertility, body weight or growth, egg weight, mortality, sexual maturity and a general view for chickens. Literature pertaining to other species of domestic birds is presented in the remaining section. Hatchability Most of the early inbreeding work with chickens was done at a rather high intensity with regular systems of either full sib, one-half sib or parent-offspring mating types [Cole and Halpin (1922), Dunn (1923, 1928), Goodale (1927), Jull (1929a, 1929b and 1933), Dumon (1930), Dunkerly (1930), Hays (1934) and Knox (1946)]. The results of most of these researchers show that hatchability drops drastically with inbreeding, the largest decline occurring with the first generation of inbreeding followed by a slower rate of decline as inbreeding continued. The detrimental effects of inbreeding on hatchability apparently cannot be overcome by selection; however, Knox (1946) reported that he was able to maintain high hatchability through five successive generations of full-sib or equivalent matings. He attributed his success to selec- tion, in that the unselected inbreds showed a drop in performance whereas the selected inbreds remained at a constant high level. 3 4 Most of the more recent studies of inbreeding in the domestic fowl have not been restricted to a rigid form of mating system, e.g. only brother x sister matings, and have thus resulted in a much slower rise in the inbreeding coefficient than was the case in the earlier studies. This change in the mating systems occurred primarily because of the poor results of most of the earlier investigators who utilized a regular mating system. This, of course, results in a wide variation of level of inbreeding between individuals within an inbred line thus necessitating an average figure for the measure of the level of in- breeding for a particular line. Dumon (1930) was the first to report on inbreeding of the former type. Full-sib and parent-offspring matings were also conducted at the same time. In a not-too-detailed report he showed that close inbreeding was much more detrimental to hatchability and chick livability than was "removed" inbreeding. Sub- sequently, many researchers have reported the effects of inbreeding where irregular mating systems were employed. Waters (1932) reported that the results of seven generations of inbreeding showed that pros- pects of establishing several vigorous inbred lines were good. Few details were published in this report. Later papers, presumably dealing with the same.population of birds, showed that the lines de- scended primarily from a single male out of four original males mated to seven females (Waters and Lambert, 1936a and 1936b). These authors showed that over a period of nine years, six lines were developed with inbreeding coefficients ranging from 41 to 82 percent. Intense selec- tion for high hatchability apparently paid off even though a slow and gradual decline was noted; however, an average hatchability of greater 5 than 60 percent was obtained from the latest generation. The influence of inbreeding on hatchability was studied in fifteen inbred lines of Single Comb White Leghorns originating from nine different base popula- tions by Waters (1945b) over a period of six years. With few excep- tions, only parents with at least 70 percent hatchability were allowed to continue the lines. Average inbreeding coefficients at the end of the six-year period ranged from 25 to 59 percent. Overall hatchability dropped from more than 80 percent to a low point of 62 percent after three years and then rose to about 70 percent in the last year. The sharp drOp was attributed to four lethal genes that were discovered in the flocks; while the rise during the later years was thought to have resulted from the elimination of these from most of the lines. Waters (1945b) thought that unknown lethals probably still remained. Recently, regression of performance on level of inbreeding, usually intra-sire and/or intra-year, has been used to measure the effects of inbreeding [Wilson (1948a, 1948b), Shoffner (1948), Blow and Glazener (1953) and Morris (1962)]. Significant negative regressions were reported by three of these authors (Table 1). These must be looked at with caution in view of earlier observations that inbreeding effects on hatchability may not be linear [Goodale (1927), Jull (1929a, 1929b and 1933)]. Bernier gt 31. (1951) lends support to this reservation. Hatchability seems to be affected more by the coefficient of inbreeding of the embryo than the coefficient of inbreeding of the dam [Jull (1933), Shoffner (1948), Dfizgfines (1950) and Blow and Glazener (1953)]. The only conflicting evidence has been reported by Wilson .Hmmm wnfizmfl umufim onu mo H umnouoo Hausa had mo mafiaafiwon oau Eonm cofiuoswoua womzonlaos muuoaou anoH wow aofiuoovoum nuaos o umuam m.uo>w>u=m uuoaou uoaoumau mam 30am .owm mo when com ou coauoomoum uo>H>u=m muuomou umcmmozm .hmH mo bump phonon .wm.mm.aomao£moum vow nomafiza .ouon Bonn uaouomwav haucwofiMHame on on vouuoaon muaoaowmmooo aofimmopwom a» «asa.fiu Ammaav name HN.+ mm.+ Aommav woxmvuoz w huzmgomz me.x Ammmav .mm.mm.eomaonambm aw soo.H- aw wHo.- Nom.- Hum.x Ammaav bmcmumfio a scam No mmNH.: Aammav .mm.mm.uocoumau 2H «00.: No Noo.x «omm.x «omq.u Awemav Hegemonm and :m: mo uaowaom oH.+ NH.+ mH.+ mo.+ Imus“ wcwummmmo :m: NSHHQWHMO 3%: NO o~.+ ~N.- Ho.+ mH.x unmecmameaw awe :e: :onmouwou Hmfiuumm eN.+ oo.x eH.+ oH.x mcwuammmo :m: NN.+ fiH.I HH.+ OHol aw? :h: cofimmouwou oaaafim Aanma .qumav comafiz uH=v< xofiso evoked mumafioum .uB H.v0pm ANV ANV nosusm wwm wwm suaaauume sewafinmsuumm Awe sesambuoz .u3 mean .mcmxoano ma wouuomou Ho>mH wzfimomuncfi no mocmahomuom mo aowmmmuwmu mo mucoflofimwmou .H manme 7 (1948b) who showed, through simple and partial regressions of hatch- ability on inbreeding, that the dam had slightly more effect (Table 1). Egg Production Egg production was observed to be lower due to inbreeding as seen from some of the early work presented by Cole and Halpin (1922), Dunn (1923, 1928), Goodale (1927), Dunkerly (1930) and Jull (1933), in which such close inbreeding as full sib matings was practiced without any direct selection for this trait. Most of these authors indicated that sexual maturity was delayed and that this was part of the reason for the lower production in the inbred birds. Hays (1934) conducted an experiment in which a standard for selection was established for several characters which affect egg production. The effect of in- breeding was measured as the difference in the proportion of individuals which met the standard for each generation of inbreds and controls, respectively. The degree of inbreeding was either that of full or half-sib matings. It was found that inbreeding had a deleterious effect on most of the characters affecting egg production. Tebb (1957, 1958) and Morris (1962) studied the effects of in- breeding in populations selected for egg production where the inbreeding coefficient increased only because of limited flock size. These authors showed that even under these conditions losses in egg produc- tion characters can be substantial. An extensive investigation into the effects of inbreeding on egg production in the domestic fowl was made by Stephenson 35 a1. (1953). Twenty-three inbred and three con- trol lines involving 9,999 White Leghorn chickens within the period from 1932 to 1946 were studied. Apparently, no selection for egg 8 production was practiced. The coefficient of inbreeding ranged from 0 to 85 percent in these lines during the last year. Egg production rate was determined by dividing the number of eggs laid by the number of trapnest days up to a maximum of 364 days after the first egg was laid. This period was also arbitrarily divided into three subperiods each with its respective egg rate. A significant negative regression coefficient (Table l) was determined for egg production on inbreeding when the effects of lines, years, and year by line interaction were removed by the least squares method. No significant differences were found among the regression coefficients when they were calculated separately for each of the three arbitrary periods. This indicated that inbreeding affects egg production equally throughout the production period. Finally an analysis of variance showing significant mean squares for line, year and interaction effects strongly suggested that line and year differences were real and that different lines were affected uniquely by inbreeding with regard to egg production. Shoffner gt_§l, (1953) presented an equally extensive study of 16 inbred lines from which more than 25,000 chicks were hatched and approximately 9,000 pullets were housed and tested during the period from 1937 to 1950. Of the 16 lines used, ten were Single Comb White Leghorns, two were New Hampshires, one was White Plymouth Rocks, one was Barred Plymouth Rocks and two were of crossbred origin. Selection was a continuous process emphasizing egg production, mortality, and hatchability. The level of inbreeding varied from line to line with the average increase in the inbreeding coefficient ranging from a low of 3.1 percent to a high of 10.3 percent per generation. One-half of 9 the lines were lost or culled during the period. The average increase in the inbreeding coefficient of the lines that were lost was almost twice that of the surviving lines. Egg production was measured as the survivor production of those birds that lived until 500 days of age. Of all the traits measured, egg production was the only one that was consistently affected by inbreeding in that 15 out of the 16 lines showed a decrease from the level of the base population for this trait. In the 8 lines that were lost, a decrease of almost three times that of the 8 lines that remained was observed. Considering all inbred lines, the average change in egg production from the base population was -27.0 eggs, which represents a 17 percent loss. This loss in egg production occurred in spite of a relative average selection differ- ential, expressed as a percentage of the average performance, of 7.1 percent on sire's side and 18.9 percent on the dam's side. Even though egg production was generally lowered due to inbreeding, there were marked differences between lines as to the severity of the effect. This general observation was also noted by Dfizgfines (1950) who reported that two out of four inbred lines showed a significant decrease in egg production while the other two remained unchanged. More favorable results were reported by Waters and Lambert (1936a and 1936b). Although inbreeding caused a small decline in egg production, a reasonable level of production was maintained even when the average inbreeding coefficient exceeded 80 percent. Some indirect selection took place in that large family size was favored. Work of Knox (1946) and Yamada gt_al, (1958) also tended to show that high egg production and inbreeding are not incompatible. 10 Several authors have reported regression coefficients of the effects of inbreeding on egg production. These are listed in Table 1. These must be looked at with caution because inbreeding effects on egg production may not always be linear according to Stephenson gt_§1. (1953). Fertility The effects of inbreeding on fertility are quite variable as shown by the different results of various investigators. Dunkerly (1930) reported experiments using White Wyandotte, Rhode Island Red and White Leghorn breeds of chickens. Fertility was generally lower in the inbred birds than in the non-inbred birds. He used two systems of mating both of which were sire-daughter; however, in one case the daughter was a product of a brother-sister original mating while in the other case the daughter was not inbred, giving coefficients of inbreeding for the embryos of 37.5 and 25 percent, respectively. Fertility was, in most cases, lower for the matings in- volving the higher coefficient of inbreeding. Inbreeding effects on four distinct lines of White Leghorn chickens (high and low egg producers and high and low egg weight lines) pr0pagated by single male matings, showed a significant increase in infertility only in the high egg weight line whereas no significant difference was seen in the other three lines (Dflzgfines, 1950). Average coefficients of inbreeding of chicks hatched after three years of in- breeding ranged from .27 for the high egg weight line to .43 for the high egg production line. 11 In a study of inbreeding, outcrossing and crossbreeding, Bernier gt 31. (1951) reported that inbreeding appeared to affect fertility only when the mated birds were inbred, e.g., mating non—inbred relatives resulted in no decrease in fertility; however, when the related pair were inbred, fertility was lowered. Williams and McGibbon (1954) showed a two-day difference in average duration of fertility of males from two inbred lines when reciprocally mated with the females of these lines. Whenever any form of selection has been practiced for fertility no change due to inbreeding has been reported. Jull (1933), Waters and Lambert (1936a and 1936b), and Knox (1946) reported no change in fertility due to inbreeding even though the rate of inbreeding was in- tense. Wilson (1948a) reported positive regressions for fertility on inbreeding of either the dam or the offspring. Some selection, usually of the magnitude of less than one standard deviation, was done for fertility. The mating system used was quite irregular resulting in little change in the average coefficient of inbreeding from year to year. Body Weight or Growth Growth, as measured by how many times the chicks increased their hatching weights to three weeks of age, decreased in White Leghorn stock by the third generation of full sib mating. A value of 1.91 for the inbreds as compared to 2.36 for the controls was obtained (Dunn, 1923, 1928). Negative regressions of mature body weight on inbreeding were obtained by Shoffner (1948) and Blow and Glazener (1953); however, these regressions were small and nonsignificant. Glazener 35 31. (1951) 12 obtained a significant regression of -.1297 oz. for 12 week body weights of New Hampshire and Barred Plymouth Rock broilers (Table 1). Most workers were unable to show any significant change in mature body weights of chickens even with inbreeding as close as full sib with or without selection for the trait [Goodale (1927), Hays (1934, 1935), Waters and Lambert (1936b), and Knox (1946)]. Egg Weight There is general agreement among the published results of several investigators that inbreeding has little overall effect on egg size of a population [Dunn (1923), Waters and Lambert (1936a and 1936b), Waters (1945a), Shoffner (1948) and Blow and Glazener (1953)]. Hays (1934) actually found an increase in winter egg weight in inbred Rhode Island Red hens as compared with controls. When he mated inbred and non-inbred males with closed flock females a larger egg weight was obtained from the progeny of the inbred males (Hays, 1935). Dunn (1923) and Waters (1945a) reported that different lines tended to have either large or small egg size and it was concluded by Waters that the egg size of a line tended to remain at whatever size it was when inbreeding started. Mortality Viability of inbred birds was found to be generally reduced with inbreeding even though some selection accompanied each generation of matings [Dunn (1923, 1928), Hays (1934, 1935), Wilson (1948b) and Shoffner gt_al, (1953)]. MacLaury and Nordskog (1956) studied mortality data collected from 25 inbred lines over a period of 15 years and in- volving over 30,000 chicks. Inbreeding coefficients ranged from 0 to 13 83 percent. Significant positive regression values for brooder, range and layer mortality were obtained; the latter two were measured on females only (Table 1). The regressions were calculated three dif- ferent ways: simple regression, regression of values corrected for control flock mortality, and least squares method. No significant regressions of viability on inbreeding coefficient were obtained by Tebb (1958); however, the average inbreeding coefficient of the birds that died was slightly larger than that of birds that sur- vived. The inbreeding in this flock of birds was generally quite low with about a two percent increase per generation. Jull (1933), working with close inbreeding of White Leghorns, and Morris (1962), working with mild inbreeding of White Leghorns, presented data in which no appreciable effect of inbreeding on chick viability was noted. No direct selection for lower mortality was practiced by either of the authors. Sexual Maturity Most of the investigators reporting on this trait showed that sexual maturity, as measured by age at first egg, was usually increased with inbreeding [Dunn (1923, 1928), Jull (1933), Hays (1934, 1935), Shoffner (1948), Shoffner gt 31. (1953), Blow and Glazener (1953), and Glazener gt El- (1951)]. Waters and Lambert (1936b) reported a decrease in the number of days to attain sexual maturity when data from six lines were analyzed. In another paper the same year (Waters and Lambert 1936a) data were presented for three lines, presumably part of the six reported above, which showed no change in age at first egg. In yet another report by the senior author but from a different population 14 of birds, no change in age to sexual maturity as a result of inbreeding was found (Waters, 1945c). General Inbreeding of chickens has been shown to have a general delete- rious effect on most productive characters of economic importance. No one has been able to improve a line of chickens by inbreeding alone. There appears to be considerable variability between populations and lines within the populations as to the effects inbreeding has upon them. Inbreeding affects various characters differently in different lines; however, the general concensus seems to be that hatchability is the most uniformly affected with reductions in egg production, viability, and an increase in time to sexual maturity. Body and egg weights seem to be the least affected. Intensive selection appears to be necessary in order to establish useful, viable, inbred lines of chickens. Other Species Little work on inbreeding of domestic birds has been reported in species other than the chicken. Three abstracts of papers presented alt Poultry Science meetings have dealt with inbreeding of turkeys. Ihlss (1955) and Moreng and Thornton (1957) presented conflicting evi- dence. Buss reported fertility was the major factor affected whereas hfiareng and Thornton said hatchability and livability were affected the 1"lost, while fertility was slightly affected by inbreeding in these 'birds. Abplanalp and Woodard (1967) started two sets of 15 inbred illnes utilizing full sib matings. Their results parallel many 15 chicken experiments in that only three lines of the first set survived to a level of 50 percent inbreeding while 12 lines of the second set survived to the 37.5 percent level. Declines in hatchability, mortality and body weights were recorded. Egg size and age to first egg appeared unaffected. Only one significant study on inbreeding of the Japanese quail has been done. This work was published in 1966 by Sittmann gt_§l, Three male quail were imported from Taiwan and mated with 15 of their control females to start the base population. The offspring of these matings were then carried along four generations via mass matings after which pair matings were made. Lines starting with full sib matings from this base population were begun in the fifth generation and con- tinued to the ninth generation. Continuous full sib matings as well as crosses of inbred lines were done within this period of time. Also, a cyclical mating system with alternating generations of full sib matings and crosses between inbred lines was used. The results of the full sib matings were disasterous with complete reproductive failure by the third generation. For each ten percent increase in inbreeding of the progeny a Seven percent and 11 percent decline was observed in fertility and luatchability, respectively. Other production traits were affected to a lesser extent. Maternal inbreeding supposedly had an important effect on hatch- abiJity and viability of young birds; however, this was measured by mating unrelated, inbred individuals together and observing the progeny. 1“ this case both the sire and dam were inbred; therefore, any l6 conclusions on maternal inbreeding must be made assuming inbreeding of the sire had no effect. Effects of heterosis on hatchability, again attributed to be maternal in origin, was evident upon observing off- spring resulting from a four-way cross between inbred sib-lines. The only other inbreeding experiment on Japanese quail found in the literature was by Iton (1967). This work was done at the same university as that of Sittmann gt 31, (1966), presumably from the same population of quail. Few details are available and type of mating system used or level of inbreeding attained were not reported. Three inbred lines were reared for seven generations in three different environments: hot dry, cool dry, or hot humid. Inbreeding was re- ported to have caused depression in all traits studied. OBJECTIVES To establish highly inbred viable lines of Japanese quail. To study the effects of continuous successive brother x sister matings in Japanese quail (Coturnix coturnix japonica) on: a. b. Egg production Egg weight Fertility Hatchability 3-week livability 7-week livability 3-week body weights 7-week body weight - males 7-week body weight - females 17 EXPERIMENTAL PROCEDURE The Foundation Stock The Japanese quail used in producing inbred lines via brother— sister matings in this experiment originated from a population of birds that had been maintained by the Poultry Science Department of Michigan State University for at least ten years and an estimated minimum of 20 generations on a closed flock random mating basis. Small numbers in a few generations probably had produced a minimal amount of inbreeding in this base population. No reliable records are available on this population prior to the present study; however, some indication of per— formance can be obtained from 87 pairs of quail, part of which were the immediate progenitors of the first generation of full sibs used in this study. These birds were caged September 5, 1967. The esti- mated age of the birds at that time was eight to ten weeks of age. Records from three hatches beginning one week after caging show that reproductive performance of these birds was good with average fertility of 71.4 percent and average hatchability of 86.3 percent. The first hatch had a low fertility average of only 63 percent while the third hatch increased to 79 percent. Thus, the overall average of 71.4 percent is probably a low estimate of performance for fertility in these birds. Hen-housed egg production averaged a little over 51 per— cent for the 28—day period. 18 19 Offspring for the first generation full sib matings were not saved until the above birds had been in production for about seven months. Natural selection reduced the population by about 50 percent; thus, offspring for the inbreeding experiment were obtained only from the most viable parents. The first full sib matings were made July 7, 1968. Control matings were made from this stock and were carried along each generation. In order to avoid inbreeding in a small population of controls the matings were limited to only those individuals which had no more than four great-great grandparents in common. At least 20 percent of all matings made were controls with a low of 24 pairs mated in the first generation to a high of 80 pairs mated in the second generation. Management Procedures Housing A. Adult birds Two 9'8" x 15'4" windowless pens each containing 96 quail cages were utilized for the matings involved in this study. All of the cages in one of the rooms were 4" x 7" while the other room contained 36 5" x 8" cages and 60 6" x 8" cages. Air movement was regulated by a thermostatically controlled fan. Lighting was provided on a 24-hour basis by one 60 or 100 watt incandescent bulb from the ceiling in each pen. B. Chicks Brooding the quail chicks was accomplished by using a Petersime Brood Unit Battery Model 2 S D which was constructed specifically for quail. This unit consisted of six decks, 20 each with its own thermostatically controlled heating element. Each deck was divided into two 27" x 39" pens. The floors of the pens were constructed of 1/4" wire mesh so the quail chicks could stand without stepping through. Later, at about three to four weeks of age, this was re- placed with 1/2" size mesh floors. Room lights were con- trolled by a time clock on a regime of 15 1/2 hour light and 8 1/2 hour dark. A small light bulb was placed in the heating area of the pen for at least the first week, there- by inducing the chicks to move to this area when the room lights were turned off at night. Also, for the first week, paper towels were placed in this area with feed on them. Shallow trough feeders especially constructed for quail were placed in the unheated part of the pen. Jar waterers with either wire mesh or perforated plastic rings fitted into their bases to minimize drowning were used. Incubation and Egg Handling Eggs were gathered daily, marked, and placed small end down in regular chicken egg flats and stored up to one week in an egg holding room at the Michigan State University Poultry Science Research and Teaching Center. They were then brought to the incubation laboratory for sorting and setting. The eggs were sorted by cage number and set small end down in Jamesway 252 incubators. Wire mesh baskets were designed to fit in the cradles of the Jamesway tray. In this manner, one tray would hold about 420 eggs as compared to only 180 chicken eggs. When enough of these baskets were not available, egg flats cut to fit 21 the cradles were used. The temperature in the setter was held at 99.5° F with a relative humidity of about 60%. The eggs were turned automati- cally every two hours. Transfer into pedigree baskets was done on the 14th day of incubation at which time the eggs were placed in a hatcher where a temperature of 98.5° F and a relative humidity of 70% were maintained. Unlike the procedure used by Sittmann gt_§l, (1966), who stored their eggs up to two weeks prior to setting, the eggs in this experi- ment, with few exceptions, were held up to one week only. More inbred chicks were expected to be hatched from a given number of eggs with this procedure because Sittmann reported a much reduced hatchability of eggs, from inbred birds, which were stored one to two weeks as compared with eggs stored up to one week. No such reduction in hatchability was noted for eggs laid by Sittman's control birds. Previous experience at Michigan State University showed that hatchability was reduced in Japanese quail eggs which were stored one to two weeks as compared to storage up to one week. Bird Handling and Matings Dry chicks were removed from the hatcher and handed on the 17th day of incubation while the later hatching chicks were removed and banded on the 18th and 19th days. This was felt to be an improvement over Sittmann's procedure of not removing any chicks until the 19th day of incubation because chicks that hatched earliest were possibly the most viable of the lot. Letting them go without feed and water for three to four days probably reduced their chances of survival. All chicks from a given hatch were placed in one pen of the brooding unit 22 after they were removed from the hatcher. Feed and water were provided ad_libitum. The feed was a specially-formulated quail ration, the ingredients of which are listed in Appendix A. With the exception of two or three excessively large hatches, the chicks remained in the single pen until they were at least three weeks of age after which they were separated into two pens. Sexes were separated prior to six weeks of age. Full sibs and controls were mated and placed in cages at 7 1/2 weeks of age except for those from the first 13 hatches when this was done at 6 1/2 weeks of age. Matings were made within hatches whenever possible so that the age of the mated pair would be equal. Whenever mates were not available from a given hatch, the birds were held either on the floor or in other cages in anticipation of obtaining a mate who might be in a similar predicament in a future hatch. If a full sib died after being placed in a cage, it was replaced with another full sib if extras were available. Thus, emphasis was placed on making all possible matings of full sib pairs within the limitations of the facilities available; however, at all times the equal-aged pair was favored. No artificial selection was practiced at any time during the experiment. Control matings were made from each hatch. At least 20 percent of the matings were control matings. All surviving matings were maintained for a period of at least eight weeks; however, most matings were maintained for 13 weeks. Data Collection and Analysis Daily egg production records, from which soft-shelled and broken eggs were excluded, were kept for each mating. Within each generation, least square estimates and standard errors of the mean weekly egg L: El“: 23 production, corrected for age effects, were obtained for each inbred line and the controls. In this experiment an inbred line is defined as including all birds for any given generation that were derived from an original parental pair. This does not mean that developing inbred lines in the classical sense of brother x sister matings was followed, i.e. in most cases more than one mating per inbred line was made each generation thus forming many sublines within the original line. For any given week, records of all birds that were alive at the beginning of the week were used. This could be put into conventional terms as hen- housed production on a weekly basis. Data for the analysis were col- lected for a 13-week period corresponding to the eighth through let week of age. Egg weight was not recorded until the third generation after which time bi-weekly weights to the nearest hundredth gram were taken on the eggs produced in the week immediately preceding the weighing. All of the eggs from a given female for a seven-day period were weighed in a group from which an average egg weight was obtained. Least square estimates of mean egg weight and standard errors for each line within each generation were obtained using these values and correcting for the effect of age. Data from ages eight through 21 weeks were included in the analysis. Fertility was measured as the percent of the eggs set from any given mating that hatched plus all of the unhatched eggs which showed any degree of development as judged by macrosc0pically observing the interior contents of the eggs. The percentages were changed to twice the arcsin of their square roots prior to analysis (Winer, 1962). 24 Least square estimates and standard errors, corrected for age and hatch effects, were obtained for each line within each generation. Data were used only from matings in which the age of the sire and dam was equal and from a period from eight through 21 weeks of age. Hatchability was measured as the percent of the fertile eggs that hatched by the 19th day of incubation. These data were handled in the same manner as the data for fertility. Livability was calculated as the percent of the hatched birds in a given family and a given hatch that were alive at three and seven weeks of age. All birds accidentally killed and those which lost wing bands were excluded from analysis. Because of the number of birds in- volved it was decided that necropsies would be made only if unusually high mortality occurred in this study. Least square estimates of the mean livability and the standard errors were calculated, correcting for age of dam and hatch effects for each line within each generation. Data for the analysis were collected from an eight—week period cor- responding to the maternal ages of 8-16 weeks. Body weights at three and seven weeks of age were measured to the nearest gram for each bird. It was desirable to weigh birds during a period of rapid growth, therefor three weeks of age was chosen as a suitable time. Little or no effect of egg size and/or sex on body weights would be expected at this age. Seven week weights were taken because it was necessary for the birds to be handled at this time. Also it was the time when the birds were approaching sexual maturity. Family averages for each hatch were taken from the period of maternal ages of 8-16 weeks. These were used in calculating the least square means for 25 lines in each generation, correcting for age of dam and hatch effects. Seven-week weights were analyzed separately by sex. The least square analysis was accomplished through the use of the 3600 computer located on the Michigan State University campus. RESULTS AND DISCUSSION This study involved data from approximately 50,000 Japanese quail hatching eggs. All eggs were incubated and those which failed to hatch were broken to determine infertile and dead germs. From these eggs approximately 25,000 chicks were hatched. Most of these were wing banded and placed in pens to be raised for control and inbred matings. One control and 17 inbred lines were started with the first generation of matings. The number of full sib matings per inbred line ranged from one to 12 for the first generation (Table 2). The total number of full sib matings for the first generation (hereafter desig— nated (FSMl) was 79 while the number of control matings was 24. Fifty-one (64.6%) of the 79 FSM had offspring which survived to l the time of mating. From these, 283 second generation full sib matings (FSMZ) were made. Three lines failed to carry to the second generation. Eighty control matings were made in the second generation. Only 70 (about 25%) of the 283 FSM were able to produce offspring capable of 2 making third generation full sib matings (FSMB). Two more lines were lost at this point. In the third generation, there were 58 control matings and 214 FSM Only 45 (21%) of the 214 FSM were able to 3' 3 carry to the fourth generation producing offspring for 181 FSMA. One additional line was lost at this stage. Sixty-seven control matings were made in the fourth generation. Five lines were lost in the fourth 26 27 on No mm om «N mchuaa Nobbcou .02 m s N N N coaumumcou soN NN sN NN NN NN N NaNNemmNo NcNuzu Iona mwcauma 2mm mo .02 NNN an on Na No oN N mchsma nzme No .02 Nm 0 ON 0 NN NN o o NN N N o mchuaa mzmm NcNuse noun mwcfiuma qzmm mo .02 NNN N as N NN mm N N eN NN ms N mchbaa szmm No .oz ms N o N N N N N N ON 0 NN N mchbma szmm NcNosu Iona mwaauma mme wo .oz sNN a «N NN o NN oN N oN mN o as NN mNchma szN No .02 oN N N 0 ON N N o m s m NN N N NN mNaNuma Name NcNuse IoNn mmcauma Nme mo .02 NNN m oN NN as N NN N oN NN NN as N mN so mNaNuma szN No .02 Nm s m s NN N N N o N N N o N N N a mchuaa Name maNuae noun aweduua atmm mo .02 NN 9 ON 0 NN a N s N N N N N oN n N 0N achuaa Name No .02 Nance mm am mN NN NN oN mm as me os «N NN NN oN NN N nonasc ocNN .mocfia nausea can Houucoo ecu Now vo>Ho>aN auawuqa mo unease «nu uo muqaasm .N canny 28 generation; however, the percent of the matings going on to produce fifth generation full sib matings (FSMS) increased to 31.5 percent. Thus, six lines with a total of 217 FSM remained at the beginning of 5 the fifth generation. Although offspring were obtained from each of these six lines in the fifth generation, almost half of the total number of matings failed to produce any offspring. Fifty-six control matings were made in the fifth generation. Control Line Performance Table 3 contains the summary of performance data for the control birds used in this experiment. These data show that the overall per— formance of the controls was generally high. Furthermore, mean per- formance from generation to generation for most traits remained at a relatively constant level thus indicating that environmental effects on these traits did not change much throughout the five generations. Egg production showed a gradual but steady increase from genera- tion to generation even though no intentional selection was practiced. Possibly, natural selection played a role in that large families would tend to have a greater chance of having an offspring mated in the following generation than would small families. For no discernible reason, fertility dropped sharply in the third generation even though no such drop was seen in the other traits. Threedweek body weights showed about a 13 percent decline by the fifth generation; however, no such change occurred in the 7-week weights. One possible reason for the decline in three—week body weights was that the average size of the hatches increased as time went on, thereby causing more crowded growing conditions resulting in more competition 29 .no>~o>ca nouaaauu mo uonaaa onu cu uuowou .oz .auoouuo noun: nee Ban «0 own u0w nouuouuoo .moamaou uow uaaum cu unwwoa anon .33 n nan moans u0u nauuu ca unwwo3 anon .x: s .Amoxou noanaouv menu» cN munmuoa anon .x: m .>u«aana>wa usuuuoa .13 m nan .x: m come no nouqaauoo nuance uaaoAn .Anoo: mum: Nona» no: awn new ouau onu wo 0mm ecu :oNna ca mwc«uqa macov no>ao>cw mwcauua uo unnasc onu ou mquuu .oz .muoouuo noun: nod uNwa nouns ocu mo own uOu nouoouuoo zuwawponouan ucouuoa new auNNNuuou ucoouoa came MO @333 no nuance unmade .no>No>=« one; «o uonasc ou muouou .02 .co; we own uou nouoouuoo .uamum ca unwwoz man came «0 moumaauno muonvu umuoqm .no>~o>:N use: we uonaac ou ouomou .oz .omn mo .mx3 Hmlm aouw chnGquo nowuon .xa ma a u0w 3003 some «0 wcwndwwun one as 0>NNQ one: mo unease co nouns muuowmu emu u0m nouoouuoo coauosnoua wmo zaxoua some «0 moumaNumo ouasvu umaoNN .aucouan omega «0 chuamwuo ecu uom mum muamuu chcNmaou ecu uow mucoaousmaoz .nouoNH cum xonu noun: uonca coauauocow ecu uom mucoumn ozu an nooanoua ammo uOm cum zuwawamzoumn ncm zuuawuuow .ucmuo3 wwo .CONuoanouq wwu uow muauaouammuza Amoamaowv 3 N.N N.NNN 3 N.N N.NNN an N.N N.oNN an .N N.NNN 3 0..» EONN ASHE: NeoniaN NauNmae 3 N.N NEON an .1 N.NON N.N N.N N.NoN .Nm N.N 92: NN N.N oéoN manna: .33.sz Annamaow nan moamav on ON 9% mm N.N New N.N o.N 9% co .2 0.3 2 N.N N.Nn mans; Neoniam 2 ON New em to New N.N ON 93 8 no mg; 3 N.N 9.3 N.NNNNNSZN JEN ow N6 N.No on To N.N; N.N NS N.NN 8 io N.N... ON N5 N.N... NNNNNNQZN JEN Nm o.N 9.3 S no 0.2.. 3 N6 93 3 to N.Nm NN N.N N.No 13388:: Nm to N.No 8 ad 02. S To N.NN 3 N.o Q? N N.N NJ... «ENNNfioN Nm N.o 92 2 NS «.2 an N.o N.N: I I- I--- x- .i. 2... N23»: mum on N.o N: 3 as N; on N.o is 8 To N.N sN N6 9N $5388: mum .oz N.N 53: .oz N.N 53: .oz N.N 53: .02 .NJ. 5a: 62 N.N 8»: an nowunuoaoo an coauouocoo an coauuuocoo AN couuuuocoo HA coaunuocoo .ocua Houuaoo u0u oucqauOuuom uo huIIISm .n Qua-H 30 for feed and water; however, observation of the standard errors indi— cates that variation did not increase in these hatches as compared to that in earlier hatches. This may mean that if more competition did exist, all birds were affected about the same. Inbred Lines Lost Prior to Fifth Generation Inbred lines 2, 23, and 29 failed in the first generation of full-sib matings primarily because of poor livability and poor egg production. These lines were not included in the least squares analysis because of the small amount of information obtained from them. Lines 53 and 75 were lost in the second generation. In exam— ining Tables 4 and 5 it can be seen that performance of certain traits varied widely between these lines. In the first generation for line 75, with the exception of hatchability, most traits concerning reproduc- tion were not much different than for the controls. Although hatch- ability was lowered it still remained at a level sufficient to produce enough offspring which survived to make 22 FSMZ. The primary reason for the demise of line 75 was the very poor egg production of the 22 pair of FSMZ. This, coupled with poor fer- tility and hatchability, produced only two offspring that survived past three weeks of age and these were both males. In contrast, line 53 started out with poor reproduction in the first generation resulting in only enough offspring to make two FSMZ, one of which produced no eggs while the other was discarded accidentally two weeks after the mating was made. 31 .mouocuoow uom m oHan mome .oz .m.m cam: .02 .m.m new: .02 .m.m cmwz Hm GOHumuocow Hq :OHumuocow Hm oOHumuooou AmonaomV N N.N N.OON muanmz Neon .N3 N Amonav N N.N o.NN mbnmNms Neon .N3 N Amonaow nan mmHmav N s.s N.Ne muszms Neon .N3 N m o.m o.o0N mNuNNNNm>NN .N3 N s N.e o.OON mNbNNNnm>NN .N3 N m o.e N.NG «NuNNNnmnubmm m N.N N.Nn GNNNNNNNmN II In In In I: II musto3 mwm N m.o N.o s N.o N.N NaoNuuseoNa NNN .02 .m.m cams .oz .m.m ems: N GOHumuocou H coHumuoaow H H «.mm ocHH nouncH uom mommauomuom mo kumaasm .q mHHMB infill-NU! . u a 4 IL. .mQUOGUOOW HON m mHQWH 06m¥ 32 AmonBomV a o.N N.NoN NuaNNms Neon .N3 N AmmHva a o.N N.NN NbNNNms Neon .N3 N AmonEom nan mmHmav e N.N N.Ns NunNNms Neon .N3 N a N.N N.NN mNuNNNna>NN .N3 N e N.N N.NN NNNNNNNN>NN .N3 N e N.N N.N N N.N N.NN NNNNNNnmaoumm N N.N N.NN N N.N N.NN NNNNNNuNmN II II II II II II muSwHoB wwm HH m.o w.H m m.o o.q GOHuosnoum mwm N .oz .m.m fine: .02 .m.m cme .02 .m.m cam: .02 .m.m ammz .oz .m.m ado: m fiOHUmHmEMU HQ flOHuNHQCwO Hm fiOHumeGmU N GOHUQHQfiTO H GOHUQHflGGU H H H {.mn ocHH nouncH mo mocmauomumm mo NumEESm .m mHnmw 33 Body weights for the first generation were considerably less for these two lines than for birds of the control population at both three and seven weeks of age. Line 20 (Table 6) was the only remaining line that failed to produce any FSM4. Egg production in this line was fairly good through the second generation and then showed a moderate drop in the third generation. Fertility was low from the beginning. Hatchability was very high the first generation, then plummeted to 25 percent in the second generation with a further decrease in the third generation. The chicks that managed to hatch lived exceptionally well which probably was the prime reason the line survived three generations of full sib mating. Body weights in the first generation were all above the control values but dropped below these values in the third generation. This was especially noticeable in the seven-week female weights. Half of all lines lost in this experiment were lost in the fourth generation. Three of the lines (Lines 7, 43 and 73; Tables 7, 8, and 9) were lost because there was for each line only one FSM4 and in each case no eggs were secured from this single mating. Two other lines (Lines 40 and 95; Tables 10 and 11) produced offspring in the fourth generation but none lived beyond three weeks of age. The performance in the first generation of four of these five lines for egg production, three week livability and seven week livabil- ity was generally good and usually approached or exceeded the control values. Line 40 was lower than the control line for all three of these traits. Fertility and hatchability data were available for only four of these lines in the first generation. In two of the four lines 34 nmchuno ouoB kcowoum .uo>o30; mmHmNHmcm ecu kn nmuo>oo nOHuom .x3 w onu uom oHQMHHm>m mums mumn oz % .aOHumuoamw uxoc one on zuumo ou nOHuom uoumH m Scum ¥ .mmuoauoom uom m mHamH moms AmonEomV N N.ON N.NN NN N N.N N.NNN NuNNNms Neon .N3 N AmonSv N N.oN N.NON «N N o.e N.NON NuNNNms Neon .N3 N Aonmemm new monav N N.N N.Ne N« N N.N N.NN NuNNNms Neon .N3 N N N.oN o.o0N «N N N.N N.NN NNNNNNNN>NN .N3 N N N.N N.NN «N N N.N N.NN mNNNNNNN>NN .N3 N s N.N N.NN N N.N N.NN N N.N N.NN NNNNNNNNNUNNN N N.N N.Ns N N.N N.NN N N.N N.ON NNNNNNuumN N N.o o.oN xx xx xx xx xx xx NNNNNms NNN N s.o N.N N N.o N.N N N.o N.N NaONuuseoNa NNN .02 .N.N cam: .02 .N.N cam: .02 .N.N cam: .02 .N.N new: .02 .N.N saw: an COHumhwflwa HQ SOHHQHGCOO Hm GOHumHmGwU HN COHumHmeU HH ¢0Humumfiww «.om oaHH nouncH uow mommauomuom mo mumaasm .o oHnme 35 .mouonuoom uom m oHan mom k AmmHmammv N N.N N.NON NN N.N N.NNN N N.N N.NNN NNNNNoa Neon .N3 N Amonav N N.N N.NN NN N.N N.NN N N.N N.NN NNNNNms NNON .N3 N N N.N N.NN NN N.N N.NN N N.N N.NN NNNNNms Neon .N3 N NN o.s N.NN NN N.o N.NN N N.N N.NN NNNNNNNN>NN .N3 N NN N.N o.NN NN N.o N.ON N N.o o.NN NNNNNNNN>NN .N3 N NN N.N N.NN oN N.o N.NN N N.N N.NN NNNNNNNNNUNNN sN N.N N.NN NN N.o N.NN N N.N N.NN NNNNNNNNNN NN N.o N.oN xx xx xx xx xx xx NNNNNms NNN N N.N N.o NN N.o N.N NN N.N N.N oN «.0 N.N NaoNbosNoua NNN .02 .N.N ammz .oz .N.N cam: .02 .N.N can: .02 .N.N new: .02 .N.N new: no umuoao co umuoao Hm H u Hq H u H m soHumuoaoo N GOHumuocoo H H aOHumuoamo H N.N onHH nounnH uow monwauowuom mo mumaasm .N oHan x . I. II The 36 .mouocuoom uom m oHan mom « Amonammv N N.N N.NN N N.N N.NNN N N.N N.NNN NNNNNms NNoN .N3 N Amonav N N.N N.NN N N.N N.NN N N.N N.NN NNNNNmz Neon .N3 N AmmHmamm nan mmHmEv N N.N N.NN N N.N N.NN N N.N N.NN NNNNNNs Neon .N3 N N N.N N.NN N N.N N.NN N N.N N.NN NNNNNNNN>NN .N3 N N N.N N.NN N N.N N.NN N N.N N.NN NNNNNNNN>NN .N: N N N.N N.NN N N.N N.NN N N.N N.NN NNNNNNNNNUNNN N N.N N.NN N N.N N.NN N N.N N.NNN NNNNNNNNNN N N.N N.N xx xx x- xx xx xx NNNNNms NNN N N.N N.N NN N.N N.N NN N.N N.N N N.N N.N NaoNuuauoNN NNN .02 .N.N ammz .oz .N.N cam: .02 .N.N ammz .oz .N.N cam: .02 .N.N cam: Hm ¢0Humuoaoo He GOHumuocmw Hm GOHumuocou HN cOHumuoawu HH :OHumuoamw {.mq ocHH nounaH uom moawEHOMuom mo Numaasm .w oHan 37 .mouoauoom uom m oHan omm fl AmmHmammv N N.NN N.NNN NN N.N N.NNN NN N.N N.NNN NNNNNNB NNoN .N3 N AmmHmav N N.N N.NN NN N.N N.NN NN N.N N.NNN NNNNNNs NNoN .N3 N AmonSom nan monav N N.N N.NN NN N.N N.NN NN N.N N.NN NNNNNmz NNoN .N3 N N N.N N.NN NN N.N N.NN NN N.N N.NN NNNNNNNN>NN .N3 N N N.N N.NN NN N.N N.NN NN N.N N.NN NNNNNNNN>NN .N3 N NN N.N N.NN oN N.N N.NN NN N.N N.NN NNNNNNNNNQNNN NN N.N N.NN NN N.N N.NN ON N.N N.NN NNNNNNNNNN NN N.N N.N xx xx xx x- xx xx NNNNNNs NNN NN N.N N.N NN N.N N.N NN N.N N.N NaONNUNNouN NNN .02 .N.N cam: .02 .N.N cam: .02 .N.N cam: .02 .N.N new: .02 .N.N new: Hm aoHumuoaow H q COHuwuoaoU Hm GOHUNHMflUO N :OHumumaou H H aOHumumnou H «.mN oGHH nounaH uom mommauomuom mo huwaabm .m oHan 38 .Hmsvo awn nan ouHm mo own £NH3 mwaHuma oz ¥¥ .mouoauoom uom m oHan mom * Amonaomv N N.N N.NN N N.N N.NNN N N.N N.NNN NNNNNms NNoN .N3 N AmmHmEv N N.N N.NN N N.N N.NN N N.N N.NNN NNNNNms NNoN .N3 N Amonaom new monEv N N.N N.NN N N.N N.NN N N.N N.NN NNNNNma NNoN .N3 N N xx N.N N N.N N.NN N N.N N.NN N N.N N.NN NNNNNNNN>NN .N3 N N xx N.N N N.N N.NN N N.N N.NN N N.N N.NN NNNNNNNN>NN .N3 N N N.N N.N N N.N N.NN N N.N N.NN «« NNNNNNNNNUNNN N N.N N.N N N.N N.NN N N.N N.NN «« NNNNNNNNNN N N.N N.N N N.N N.N xx xx xx xx xx xx NNNNNms NNN N N.N N.N N N.N N.N NN N.N N.N N N.N N.N N:0NuuaNoua NNN .02 .N.N cam: .02 .N.N cam: .02 .N.N cam: .02 .N.N emu: .oz .N.N new: H m :OHuoumaoo HN GOHumuocmu Hm GOHumuoamo HN GOHUQHQfimU *.oc ozHH nounaH uow mommauomuom mo H GOHumumamu H aumaasm .QN QNQNN 39 .mouocuoom uom m mHnma mom N Awmfimawwv N N.N N.NNN N N.N N.NNN N N.N N.NNN NNNNNma NNoN .N3 N AmonBv N N.N N.NN N N.N N.NNN N N.N N.NNN NNNNNmz Neon .N3 N Amonaom new mmHmav N N.N N.NN N N.N N.NN N N.N N.NN NNNNNms NNoN .N3 N N N.N N.NN N N.N N.NN N N.N N.NN NNNNNNNN>NN .N3 N N N.N N.NN N N.N N.NN N N.N N.NN NNNNNNNN>NN .N3 N N N.N N.N N N.N N.NN N N.N N.NN N N.N N.NN NNNNNNNNNQNNN N N.N N.NN N N.N N.NN N N.N N.NN N N.N N.NN NNNNNNNNNN N N.N N.N N N.N N.N xx xx xx xx xx xx NNNNNms NNN N N.N N.N N N.N N.N N N.N N.N N N.N N.N NaoNuuseoua NNN .02 .N.N cam: .02 .N.N cam: .02 .N.N cam: .02 .N.N cam: .02 .N.N cam: Hm aoHuwuoaou HQ SOHumeGQU Hm GOHUMHQQMU N :oHumuocou H «.mm osHH nouncH mo mocmauowuoa mo mumaaam H aoHumuoaou H .2 £3 40 (Lines 7 and 43) fertility was above the control line value while in the other two lines it was below. Three of the four lines were lower in hatchability than was the control line. Body weights for the five lines were generally less than the control line values in the first generation. Subsequent generations showed an increased amount of variability among the traits both between and within the lines; however, by the third generation the performance in most traits was lower than in the first generation. Inbred Lines Surviving Five Generations of Full Sib Matings Six of the 17 original inbred lines survived through five con— secutive generations of full sib matings to attain an inbreeding co- efficient of 67 percent. The summaries of performance of these lines are contained in Tables 12 to 17. Weekly average egg production for these lines in the first generation was exceptionally good. It ranged from 4.8 to 6.0 eggs with each line exceeding the control line value; however, it should be noted that the hens producing eggs in the FSM1 were not inbred. Fertility in four of the six lines exceeded that in the control line; however, the other two lines had low fertility values. Hatchability was generally good for all lines in the first generation with values ranging from 77.8 to 95.5 percent. The control line value for this trait was 92.5 per- cent. Livability and body weights were more variable from line to line ltn.the first generation than were egg production, fertility and hatch— alaility. In all but one line first generation performance for three 41 .wouocuoom uom m oHan mom * AmonEomv N N.NN N.NNN N N.N N.NN NN N.N N.NN N N.N N.NNN N N.N N.NNN NNNNNma NNoN .N3 N Amonav N N.N N.NN N N.N N.NN NN N.N N.NN N N.N N.NN N N.N N.NN NNNNNNs NnoN .N3 N Amonaom new monav N N.N N.NN NN N.N N.NN NN N.N N.NN NN N.N N.NN N N.N N.NN NNNNNms NNoN .N3 N N N.N N.NN NN N.N N.NN NN N.N N.NN oN N.N N.NN N N.N N.NN NNNNNNNN>NN .N3 N N N.N N.NN NN N.N N.NN NN N.N N.NN oN N.N N.NN N N.N N.NN NNNNNNNN>NN .N3 N N N.N N.NN NN N.N N.NN NN N.N N.NN N N.N N.NN N N.N N.NN NNNNNNNNNONNN N N.N N.NN NN N.N N.NN NN N.N N.NN N N.N N.NN N N.N N.NNN NNNNNNNNNN N N.N N.N NN N.N N.N NN N.N N.N xx xx xx xx xx xx NNNNNms NNN N N.N N.N NN N.N N.N NN N.N N.N NN N.N N.N N N.N N.N NaoNuoaeoum NNN .02 .N.N emu: .oz .N.N ammz .oz .N.N new: .02 .N.N ammz .oz .N.N cam: m aOHumumaou H HN COHumuosmu Hm SOHumuwcow N GOHumuoaou H H aOHumuonow H .NH oaHH nouncH uom mommauomuom mo humaasm .NH MHAMH 42 .mouoauoom uow m oHan mom « AmmHmawmv H m.NH m.wm NH N.m m.NOH o H.m N.NOH HH o.N H.NOH w N.N H.mHH muanmB knon .33 N AmmHmav N m.m N.Nm HH N.H H.NOH HH o.m m.mo NH N.N N.Nm w N.N m.wm muanos NAnon .x3 N AmmHmaom new monEv m N.N N.NN mH N.H N.NN HH N.N N.NN wH o.H N.NN m o.N N.Nm muanms knon .33 m HH N.N m.mm mH N.o N.NN NH m.H N.Nw NN o.H o.wm a N.H N.Nm mNuHHHnm>HH .x3 N HH o.N m.mm mH 0.0 o.mw NH N.H m.mw NN N.o m.om m o.H N.Nm mmuHHHnm>HH .x3 m w N.H m.oN NH N.H N.NN NH H.H m.mm NN o.H N.Ho w N.H N.NN NzuHHHnmnoumm NH N.H m.wm NH N.H m.om mH o.H H.0N NN w.o N.om w N.H N.mm NNNHHHuuom mH N.o 0.0H oN m.o o.oH mH N.o N.N II II In In II II muanms wwm ON N.o N.N HN N.o H.N mN N.o m.m NN m.o N.N OH «.0 N.N NcoHuoanoum wwm .oz N.N cam: .oz N.N :82 .oz N.N 98: .oz .mN c8: .02 N.N new: Hm cOHumuocow HN coHumuocou Hm coHumuoaow HN aOHumuoaow HH coHuwumaoo «.NN mcHH nouncH uom mommauomuom mo Numaasm .NH mHan 43 .mmuoauoom How m mHan mmm « AmmHmammv NH N.N N.NHH a H.N N.OHH H o.N N.NoH N H.N o.ooH H N.N N.NNH muanms macs .x3 N AmmHmav oN N.N N.NN HH N.H N.HOH H N.N o.m0H N N.N N.NN H N.N H.NoH muanms Naon .x3 N AmmHmamm ccw mmHmav NN N.N N.NN NH N.H N.NN H N.N N.NN N H.N N.NN H N.N N.NN muanma Nuon .x3 N NN N.H N.NN NH N.o N.ow N N.m o.mm N N.H N.NN H N.N N.NN nNuHHHnm>HH .x3 N NN m.o N.NN NH N.o N.Hm N N.N N.NN N m.o N.NN H N.N N.mo mNuHHHpm>HH .H3 N HN H.H o.NN OH N.H N.Nm N N.N H.mN N N.N N.NN H N.N m.mm NNuHHHnmnoumm NN m.o H.Nm OH N.H N.ow N N.H H.m N N.H H.NN H H.N N.NN NNNHHHuumm NN H.o N.OH NH N.o N.N N N.o N.N .. n- u- u- u- .. mugmHms wwm No N.o N.N NH N.o o.N OH N.o H.N HH N.o H.N H m.o o.o NaoHuuavoua NNN .02 .m.m cams .oz .m.m cam: .02 .m.m cam: .02 .m.m cam: .02 .m.m cam: Hm :OHumumamw HQ COHumHmCOO H m GOHumefimo N QOHumumamu H H GOHumumamo H «.NN mcHH Nmuncfi How mommanomumm mo hHMEESm .NH mHQMH 44 .mmuoauoom How N mHan mmm « m COHumumcmu H HN GOHumuamo m coaumumcmw H «.oN mcHH NmunaH you mommahomumm no N fiOHUNHOd—ww H H GOHumHmamo H AmmHmammV N N.N N.NN NH H.N H.NOH N N.N 0.0HH N N.N N.NHH H H.N N.NOH muanm3 hvon .33 N AmmHva N N.N H.Nm NH N.H N.NN N H.N N.NN N N.N N.NN H N.N N.NN mustm3 hvon .33 N AmmHmem Nam mmHmav N N.N N.NN NH N.H N.NN N N.N N.NN m N.N N.Hm H N.N N.NN muanm3 NNON .33 m HH H.N N.NN NH N.N N.NN N N.H N.NN m N.H H.HN H N.N N.NN NNHHHHnm>HH .33 N HH N.H N.NN NH N.o N.NN N N.H N.NN N N.H N.NN H N.N H.NN NhuHHHnm>HH .33 m NH N.H H.Nm NH N.H N.NN N N.N N.NN N H.N N.NN H N.N N.HN NmuHHHpmnuumm NH H.H N.NN NN N.H N.NN N H.N N.NN N N.N N.NN H H.N c.00H NhuHHHuuwm NN H.o N.N NN N.o N.N N N.o m.m .. u- u- u- u- .. Nuanms mmm NN N.N N.N mm N.o N.N HH N.o N.N NH N.o N.N H N.N N.N NaOHuunvoua NNN .02 .N.N cmmz .oz .m.N 3mm: .02 .m.N sum: .02 .m.m cam: .oz .m.N cum: humEESN .NH mHan 45 .Hmsvm Emw Nam mHNm mo mwm zuH3 mwcwuma oz « yo .mmuoauoom How N mHan mmm « AmmHmammV N N.N N.NN HH N.N N.NOH N H.N N.HNH H N.N N.NNH H N.NH N.NNH NNNNHms NNoN .33 N AmMHmav N N.N N.NN NH N.H N.NN N N.N N.NoH H N.N N.NOH N N.N N.NN NNNNHms NNON .33 N AmmHmamm Nam mmHmEv N N.N N.NN NH N.H N.NN N N.N N.NN H N.N N.NN N N.N N.NN NNNNHms NNoN .33 N NH N.N N.HN NH N.N H.NN N H.N N.NN H H.N H.NN N N.N o.ooH NNNHHHNN>HH .33 N NH N.N N.NN NH N.N H.HN N N.H N.NN H N.N N.NN N N.N o.ooH NNNHHHNN>HH .33 N NH N.H N.NN HH N.H N.NN N N.N N.NN NN N N.N N.NN NNNHHHNNNUNNN NH N.H N.NN HH N.H N.NN N N.N N.NN «N N N.N N.NN NNNHHHNNNN HN N.N N.N NH N.N N.N N N.N H.HH .. u- n- u- u- .. NNNNHms NNN NN N.N N.N NH N.N H.N N N.N H.N H o.H N.N N N.N N.N NaoHuosNoNN NNN .02 .N.N cmmz .oz .N.N cam: .02 .N.N cam: .02 .m.N cam: .02 .3.N ammz Hm cowumumamu HN :oHuwumcmo HN coaumumamo N GOHumumcmo H N.NN chH NmuncH you moamauomumm mo H :OHumumamu H NumEESN .NH mHan 46 .mMuoauoom pom N mHan mmm N AmmHmammv NN N.N N.NoH NH N.N N.NoH N N.N N.NoH N N.N o.HHH N N.N N.NHH NNNNHN3 3N03 .33 N AmmHmEv NN N.N N.NN HH N.H N.NoH N N.N N.NN HH N.N N.NN N N.N N.NNH NNNNHN3 NNON .33 N AmmHmamm Nam mmHmav NN N.N N.NN NH N.N H.NN NH N.N N.NN NH N.H N.NN N H.N N.NN NNNNHN3 3N0N .33 N NN N.H N.NN NN N.N N.NN NH N.H N.NN NH N.N N.NN N N.H N.HN NNNHHNNN3HH .33 N NN N.N N.HN NN N.N N.NN NH H.H N.NN NH N.N N.NN N o.H N.HN NNNHHHNN3HH .33 N NN H.H N.NN NH N.H N.NN NH o.H N.HN NH N.N N.NN N N.H N.NN NNNHHHNNNUNNN NN N.N N.NN NH N.H H.NN HN N.N N.HN NH N.N N.NN N N.H N.NN NNNHHHNNNN NN H.N N.NH HN N.N N.N HN N.N N.N .. I- I- u- .. us NNNNHN3 NNN NN N.N N.N NN N.N N.N NN N.N N.N NN N.N N.N N N.N H.N N30H303No33 NNN .02 .N.N cam: .02 .N.N ammz .oz .N.N :Nmz .oz .m.N aNNz .oz .N.N cam: m coHumumamw H N COHumumcmu H N GOHumumamu H «.NN mcHH Nmuncw pom wucmapomumm mo Numaabm N GOHumumamu H H 30Humumamw H .NH oHan 47 and seven week livability, three week body weights and seven week male body weights measured less than in the control line. First generation inbred female body weights at seven weeks of age were greater than those of the control line females in two and less than the control line females in four of the six lines. In subsequent generations egg production for all of the six lines showed a decline. Although the decline was not consistent with each succeeding generation, all values for the six lines were consider— ably less in the fifth generation than in the first generation. Fertility in the two surviving lines which had shown low fer- tility in the first generation was greater in the fifth generation than in the first, and was equal to or greater than that for the other four lines where fertility was substantially lower in the fifth generation than in the first. Again the change was not consistent from generation to generation. Hatchability of the six lines was lower in the fifth generation than in the first. Two of the six lines showed a consistent decline with each succeeding generation while the other four lines showed fluctuations from generation to generation. In four of the six lines livability to three and seven weeks of age was lower in the fifth generation than in the first. Of the other two, one showed a substantial rise in livability in the second genera- tion as compared to the first and a still further increase in livability in the third generation with livability remaining at a high level through the fifth generation. The remaining line had higher livability for both 'the three and seven week categories in generations two, three and four 48 as compared to the first generation but then dropped again in the fifth generation to levels near those of the first generation. Average body weights showed considerable variation from genera- tion to generation. Of all body weight measurements, female body weight at seven weeks of age seemed to be most affected by inbreeding with at least a ten gram difference between the first generation and fifth generation values. Average egg weights, which were taken only from the third through the fifth generation, were generally less for the six inbred lines than for the control line. Little change from generation to generation was evident for three of the lines whereas two of the lines showed an in- crease in egg weight by the fifth generation while the remaining line showed a decrease of 1 1/2 grams from the third to the fourth generation and then remained at that level. Of all the six lines surviving the five generations of full sib matings, performance in the fifth generation for all the traits measured was highest in line 89. This line showed the least amount of change through the successive generations of inbreeding. This good performance is reflected by the large number of matings (38) that pro- duced offspring in the fifth generation (Table 17). Line 24 had the next highest number of matings (28) that produced offspring in the fifth generation; however, this represents only 45 percent of the total number of matings in the fifth generation for line 24 as compared to 70 percent for line 89. This reflects the poorer performance of line 24 for egg production, fertility and hatchability in this generation. 49 Overall Performance of the Inbred Population Average deviations from control line performance were computed for the inbred population by combining the results of all inbred lines on a weighted basis for each generation. The weighting factors were the number of matings or the number of families involved per inbred line depending upon which trait was being considered. The deviations were then plotted against the level of inbreeding at each generation. These are presented in Figures 1 to 4. Weighted linear regressions of per- formance on inbreeding level were computed for each trait following a procedure given by Steel and Torrie (1960). Tests for non—linearity were calculated for each trait. These results are listed in Table 18. Upon examination of Figures 1 to 4 it can be seen that perfor- mance as a whole for all the inbred lines was always less than the con- trol line performance between 25 and 67 percent levels of inbreeding. For all but two of the traits studied the regression coefficients were negative in sign (Table 18). Positive regression coefficients were obtained for 3—week body weight and egg weight. Significant tests for non-linearity were obtained for all traits except 3-week livability and egg weight. In examining Figure 3 it appears that the response to inbreeding of 7-week livability is also linear between 38 and 67 per- cent levels of inbreeding. In view of these findings, most of the regression coefficients in Table 18 cannot be used as adequate pre- dictors of performance for any given level of inbreeding. In order to determine which traits were affected most by in— breeding, changes relative to control line performance for each genera- tion were calculated. These are listed in Table 19. It can be seen 50 .mmsHm> Houucoo Souw GOHumHsmom NounaH mo mmsHm> Gama wouanm3 mo mdoaumfi>mn .H muame no: mo Hm>mH NaHNmmuncH no: mo HopmH NGHNmeNcH am on mm mm om mm mm T _ 3 H 3 H _ l smeig l (°sou) UOIJanOJd 883 Atxaan eBalaAv uanm3 NNm cOHuoswoum Nmm 51 .moDHm3 Houucoo aoum coHumHsmom Nounafi mo mode> name vmuanm3 mo maOHuwH>ma .N oustm omunfio mo NCNNmounaH mo Hm>mH omhnflo mo waHuomundH mo Hm>oH NN mm on NN mN NN mm on NN NN w H H \H H H. _ 3 . H .l 1 i ON. 1.0N- l oml I OMI 1a a 1 1 o - a u .4 L ONI 1 ON! 1 NH- L NH- L o 1.0 NNHHHNNNUNNN NNHHHNNNN nuaozaa 52 .mmaHm3 Houuaoo Soum coHumHsaom Nouncw wo mmnHm> Gama Nouanm3 mo maOHumH>mm NcHNomuNCH mo Hm>mH NnHNomup:N mo HmpoH .N ousmHm mm mm om mm mN no mm on mm mN H _ H _ _ _ H H H _ l Oql 1 ON! 1 Om! .d 1 Oml a 1 1 ON- N ..oNu u 3 1 OH! L OHI L o L o NNHHHNN3HH 3Nm3uN 3NHHHNNSH 3mm3uN nuaoxaa 53 NcHNmmuncH mo Hm>mH on NN H _ mmHmswm I uLNHm3 kvon 3mm3IN .mmsz3 Houuaoo 803m cowumHsmoa NouncH mo mmsHm> came NounNHw3 mo maOHumH>ma .N muswwm NaHNmmuncH mo Hm>mH NN NN mm on NN NN \fi. 11w .H H 1 H ON! ON! mH! MHI an NH- 3 NH- N ml ml 0 o mmHma I ufiNHm3 NNon 3mm3|N NGHNomuncH mo Hm>mH NN mm om NN NN H H 4‘ H H ucmeB hvon 3mm3IN SNEJB Table 18. Weighted linear regression coefficients of performance on inbreeding expressed as deviations of inbred population from control population means. Trait Regression Coefficient Fertility -.084 percent Hatchability -.262 percent 3 wk. body wt. +.O60 grams 7 wk. body wt. (male) -.122 grams 7 wk. body wt. (female) -.O62 grams 3 wk. livability -.264 percent 7 wk. livability -.262 percent Egg production -.023 eggs Egg wt. +.04O grams 1For all traits except egg production and egg weight regression coef— ficients were calculated from data obtained during the first five generations of full sib matings. through 2Linear. five. All the other traits resulted in significant tests for non- linearity. For egg production, data was from the first four generations and for egg weights from generations three 55 N.N: N.NN: N.NN: N.NHI N.HHI H.N: m.0HI H.NN: N.NN: m N.N! N.NN: H.NN: N.NHI N.NHI N.NI N.NI N.NN: N.NN: N H.HHI N.NNI N.NN: N.NHI N.NHI N.HHI N.NHI N.NN: H.NN: N N.NN: N.NHI N.NHI H.NHI N.NI N.NHI N.HN: H.NN: N N.NNI N.N: N.NI N.N: H.N: N.N: H.NHI N.NHI H .u3 GONuoawoua NNm .33 N .33 N mHmEom mHmE .33 N NuNHHnmnoumm NuHHHuumm cowumuocmo NNm 3H3mm3 .o>< .33 N .33 N .N3N NNHHHNN3HH .mu3 NNON mm GOHumHsmoa UQHNEH .AHouucoo Scum mwamao unmouoav COHumHsaoa Houuaoo ou Nmumaaoo mo mocmapomuoa :H coHumuocmN on :OHumumamN scum mwamso m>HumHmm .NH mHQMH 56 from this table that, in general, fertility, hatchability and egg pro- duction were affected to a greater extent by inbreeding than were body weights and egg weights. These findings are in general agreement with most of the published results on inbreeding effects in chickens. For most of the traits the biggest change occurred after the first genera- tion with performance remaining fairly stable thereafter. GENERAL DISCUSSION A common explanation for the degenerative effects of inbreeding is that most deleterious genes present in a population are recessive in character and, under random mating conditions, are usually "hidden" by the dominant genes. The resultant loss of heterozygosity with a con- comittant rise in the homozygous state uncovers these hidden recessives thereby reducing the performance of the population. Therefore, whether or not a particular pair of individuals chosen from a random mating population would have fewer deleterious recessives than another given pair is largely a consequence of chance. Of course, if the original pOpulation has a large number of deleterious genes to begin with, the chances of choosing a pair of individuals with only a few would be much lower than if the original population contained lesser numbers of the deleterious genes. In any case, since chance plays an important role in determining which parental pairs are superior, the larger the number of original parental pairs the better should be the chances of selecting some with a favorable genetic makeup. Also, if the original population had been under any form of selection, natural or otherwise, the number of deleterious recessives should be reduced, therefore any particular pair chosen from it should have greater chances of possessing a favor- able genetic make-up. 57 58 The present study was undertaken with the foregoing in mind. The original population of birds, as has already been pointed out in the experimental procedure section, was a more or less select popula- tion resulting from many generations of closed flock matings plus selection of the immediate parents on the basis of longevity along with the necessary reproductive performance needed to secure the off- spring for the first generation. The survival of inbred lines through five successive generations of full—sib matings in this experiment did not appear to depend upon large numbers of FSM1 since three of the six lines that survived the five consecutive generations of full—sib matings had only one mating the first generation (Table 2). Furthermore, in order to determine whether those lines having greater than the average number of FSM were more capable of surviving l the subsequent five generations of inbreeding than were those lines with less than the average number of FSM the following x2 test was 1, conducted: Above mean no. Below mean no. of FSM of FSM l l O E 0 E Total Lines surviving 2 2.47 4 3.53 6 Lines lost 5 4.53 6 6.47 ll Total 7 10 17 x2 = .0009 This non-significant test indicates that in this experiment large numbers of FSMl did not increase the survival chances of any given line 59 and that the genetic make-up of the original parental pair played an important role in whether or not a line survived through several con- secutive generations of full—sib matings. The observed variability among traits both within and between inbred lines in this experiment was not an unusual consequence of in- breeding. In chickens it was found by Shoffner (1948), Dfingnes (1950) and Stephenson e£_§l, (1953) that different lines responded differently to inbreeding. This again was probably due mostly to the variation in the original genetic composition of the base birds used. Also, part may have been due to what Lush (1948) attributes to unpredictability of results from inbreeding due to the tossing around of the gene fre- quencies irrespective of the size or variability of their effects. Data in Table 20 show that the group of inbred lines which sur- vived the five generations of full-sib matings performed better in the first generation for all traits, except livability, than did the group of inbred lines that were lost prior to the fifth generation. This suggests that selection in the first generation, especially for egg production and hatchability, should aid in removing those lines that may not survive in subsequent generations of inbreeding. A very striking observation was that mortality was considerably greater at both three and seven weeks of age in the surviving group of inbred lines than in the non-surviving group. This could mean that in those families with poor livability the birds that survived were those that were best able to cope with the effects of inbreeding. The overall performance of the inbred population was non-linear for all traits except two (Table 18 and Figures 1 to 4). Linear 60 .uamoumm NN mo NaHNomunaH mo uamHonmmoo cuH3 mam: >3 woodwoua oum3 NNNm man ..m.H .mNaNuma NHm HHSM aOHumuwcmN Naoomm scum aoHuosvoua Nmm N .mcms NmuaaHlaoc Na couscoum mum3 wwwm mnu ..m.H .mNaHumB uHmm nHm HHDM umuwm Eoum GOHuosvoum wwm N .mcHH NmNNaH comm How Nm>Ho>aH mmHHNawm Ho mNcHuma mo Hogans mnu Np Nounwwm3 mammE mcHH Houucoo Eoum mcmwa mcHH NouncH mnu mo mcoHumH>oN mwmum>m mzu mm NmHSNNmE mH moamauomumm H HN.H| NmNo.I NN.H| NN.NI NN.NI 0H.m| HN.NI NN.NHI HN.mHI umOH N mmcHH NounaH mocNH vaNGH NNNN.I NON.H+ HN.m| No.m| NN.N| NN.NI NN.NI oN.NI NN.NHI NdN>H>u=m coauosvoua wwo .33 N .33 N mHmeom mHma .33 N ANN ANV NH3NN3 .m3< HNN .33 N .33 N NNHHHNNNUNNN NNHHHNNNN NuHHNnm>NH N.NENV .mu3 Nvom H.NGOHumumamN HOHHQ CH uNOH mum3 uwsu mmcHH omonu nuH3 mNcHuma NNNIHHsm mo NGOHu Imumawm o>Hm Nm>H>u=m umnu mmcHH NouncH 03u wo moameuomumm aOHumuwcmw umuHm mo aomHumaaoo .ON oHan 61 declines in performance would be expected if the decline were due only to dominance effects [Lush (1948) and Kempthorne (1957)]. If there were no dominance or other genetic effects such as epistasis and no selec— tion, the mean performance of an inbred population should theoretically remain the same. The non—linear response observed for most traits in this experiment suggests that something more than dominance alone is involved. Kempthorne (1957) shows the relation of the mean of inbred pOpulations not only to be dependent upon the linear dominant effect but in addition curvilinearily related to the dominant interactions involved, e.g., dominant epistasis. This may in part explain why the curvilinear responses were observed in this experiment; however, in order for these theoretical considerations to hold, gene frequency must not change over the generations because the mean of a population is always dependent upon gene frequency [Lush (1948)]. Even though no intentional selection was practiced, natural selection played a very large role by eliminating, at varying times throughout the five genera- tions of inbreeding, a total of ll of the 17 original lines. This could very well have changed gene frequencies for the various traits in which case the population mean could have changed by this avenue as inbreeding progressed. The fact that egg weights increased with increased inbreeding levels over the period of inbreeding measured for this trait is note- worthy; however, without the information from the first two generations it cannot be known whether or not an initial drop actually occurred. It has already been pointed out in the literature review that in 62 chickens most investigators found little effect on egg weight due to inbreeding; however, two experiments conducted by Hays (1934; 1935) showed that in Rhode Island Red chickens egg weight was increased by inbreeding. SUMMARY AND CONCLUSIONS For the first time consecutive brother x sister matings in Japanese quail were made for five generations. Prior to this experiment no one had reported successfully passing three genera- tions of consecutive brother x sister matings. Six of 17 original lines remained viable at the end of five generations of brother x sister matings. Individual inbred lines of Japanese quail respond differently to consecutive generations of brother x sister matings. The group of inbred lines that survived five generations of full- sib matings as compared to those lines lost had on the average better performance in the first generation except for livability. This indicates selection in the first generation would aid in developing viable inbred lines. Performance for the inbred population as a whole was reduced with inbreeding. Linear regression coefficients calculated for weighted deviations from the control line performance on inbreeding were negative for all traits measured except 3-week body weight and egg weight. The regressions for all traits except 3dweek livability and egg weight showed a significant non-linear relationship with inbreeding level. 63 64 Of the traits measured, fertility, hatchability and weekly egg production were affected the most by inbreeding with livability being affected moderately and egg and body weights being affected the least. In the fifth generation, overall performance of the inbred popula— tion expressed as percent change from the control performance for the various traits was as follows: fertility, —36.7; hatchability, —43.l; weekly egg production, -39.2; three week livability, -19.9; seven week livability, -26.2; three week body weight, —10.9; seven week male body weight, -8.1; seven week female body weight, ~1l.2 and average egg weight, —4.8. 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Poultry Sci. 37:565-580. APPENDIX APPENDIX Quail Breeder Ration 25% Ingredient % of Ration Ground yellow corn Soybean meal, 49% protein Alfalfa meal, 17% protein Dried whey Meat and bone scraps, 50% protein Fish meal, 60% protein (menhaden) Ground limestone Dicalcium phosphate (24% Ca., 18.5% Phos.) Salt, iodized C O O 1 V1tamin trace-mineral premix Fat 40.90 37.00 5.00 2.50 2.50 2.50 5.00 1.50 0.50 0.60 2.00 lDawes Number 5004, Michigan State Turkey. 69 "I71111111111111I