- Email: [email protected]
Variant Forms of Accidental Rumplessness in Chickens and their Influences on the Growth and Egg Production Performances1
568
J. K. B L E T N E R , N . E. C H A L H O U B AND 0 . E.
1948. Investigations upon vegetable protein sources for poultry rations. Proc. Eighth World's Poultry Congress 1: 181-187. Schneider, B. H., 1947. Feeds of the World. West Virginia University, Agricultural Experiment
GOIT
Station, Morgantown, W.Va. Young, R. J., H. M. Edwards, Jr. and M. B. Giles, 1958. Studies on zinc in poultry nutrition 2. Zinc requirement and deficiency symptoms of chicks. Poultry Sci. 37: 1100-1107.
K E N N E T H T.
S.
YAO2
Department of Poultry Husbandry, University of Nebraska, Lincoln, Nebraska (Received for publication May 31, 1961)
T
H E existence of rumpless chickens has been known for centuries. Such birds were described, at the turn of the century, as a separate breed of the domestic fowl b y a number of investigators. However, Davenport (1906) pointed out t h a t rumplessness in chickens was a hereditary character, and might be found in any race of the domestic fowl. D u n n (1925) made known the two types of rumplessness in chickens—hereditary and accidental. Nevertheless, the rumpless b a n t a m is still a miniature variety of the fanciers' birds in the United States and abroad, and appears in many poultry exhibits. Hereditary rumplessness in chickens has been extensively studied by Landauer and D u n n (1925), Landauer (1928, 1945b) and D u n n and Landauer (1934, 1936). 1
Published with the approval of the Director as Paper No. 1111, Journal Series, Nebraska Agricultural Experiment Station. Project No. 424, in cooperation with the North Central States Regional Poultry Breeding Project U.S.D.A. 2 Present address—Institute for Cell Biology, University of Nebraska, Lincoln, Nebraska. The assistance of A. Yeshewalul and H. S. Tolman, graduate students, in preparing chicken bone specimens is hereby acknowledged.
There are three types of hereditary rumplessness: dominant, intermediate, and recessive. The dominant rumplessness, Rp, is described as being a lack of the fleshy portion of rump, all the tail feathers, and the uropygial gland; and, anatomically, lack of all caudal vertebrae as well as the pygostyle. The rumplessness of this type is called complete rumplessness and is dominant to the normal condition. Accidental rumplessness has the same description as the dominant, except t h a t the accidentally rumpless chicken lacks the last two synsacro-caudal vertebrae, while the chicken with dominant rumplessness has one or two vertebrae missing from the center of the five synsacro-caudals. The accidentally rumpless chickens do not transmit the rumpless condition to their offspring. The intermediate rumplessness is extremely variable from almost normal to the almost completely rumpless condition. The number of tail feathers varies from 1 to 8 in contrast to 14 in the normal. I n a few cases a rudimentary uropygial gland is present but usually this gland is absent. Two synsacro-caudals are missing as in the dominant rumplessness. Some of the
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
Variant Forms of Accidental Rumplessness in Chickens and Their Influences on the Growth and Egg Production Performances1
569
RUMPLESSNESS IN CHICKENS
Phenocopies of t h e rumpless mutations were induced b y Landauer (1945a), Landauer and Bliss (1946), and Landauer and Lang (1946), with insulin and other chemicals. The chemically treated eggs produced as many as 41.6 percent rumpless embryos, while t h e control eggs produced only 1.3 percent. With sudden changes of temperature during the early part of the incubation period, Danforth (1932) successfully obtained rumpless chicks. Landauer a n d Baumann (1943) produced a rumpless condition b y me-
chanical shaking of eggs prior to incubation. An average of 6.9 percent of these treated eggs produced rumpless embryos, while only 1.3 percent were obtained from the untreated eggs. T h e description of the induced rumplessness was the same as t h e accidental ones. However, a few cases of caudal scoliosis were observed in t h e embryos produced from the eggs treated with mechanical shaking. During 1958 in t h e University breeding flock, more than 80 chickens were found to have various degrees of rumplessness. The abnormality occurred sporadically in nearly all breeding groups on t h e farm (Table 1) including two breeds, three Leghorn strains, two Leghorn inbred lines, and several crossbred groups. N o rumpless chickens had been included in breeding pens at the University farm; and none on t h e farms from which hatching eggs were shipped to t h e University farm. The rumplessness was considered to be accidental. When these chickens were artificially bred inter se and produced more than 300 offspring, none of the offspring were rumpless. The size of the University flock in 1958 was around 4,000 chickens. The number of such abnormal birds was unusual. T h e rumplessness regarded to be accidental in these chickens was different from t h a t described b y previous investigators. These TABLE 1.—Sources of the chickens having abnormal tail conditions Tail condition
M R
chickens "™SP" Droopy Nebraska purebred Leghorns Regional Cornell Control Leghorns Regional Cornell Randombred Leghorns (imported eggs) Purebred California Grays Commercial Leghorns (imported eggs) Leghorn inbreds Leghorn incrosses Breed crosses (Grays XLeghorns) Top crosses Three-way crosses Total
2 1
1 0
1 1
4 1
2 0
2 1
2 5 8 9 9 6
2 2 5 5 5 3
0 i H . 4 4 3
47
25
22
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
caudal vertebrae are present b u t fused together in a more or less irregular fashion. A small bony protuberance representing the last two vertebrae of t h e pygostyle is present and fused with the caudal vertebrae. The presence of modifying genes suppressive to the abnormal condition in the heterozygous chickens is t h e factor causing the varying degrees of rumplessness. The recessive rumplessness, rp2, closely resembles the dominant rumplessness and its modifications. T h e appearance of the chickens of this type ranges from the completely rumpless to nearly normal. T h e uropygial gland is lacking or rudimentary. Tail feathers are lacking or reduced in number. The free caudal vertebrae and the pygostyle are entirely absent or fused into a bony knob. The fused or rudimentary caudal vertebrae m a y have lateral compression and marked lordosis. T h e vertebral column m a y have synsacral kypho-scoliosis of varying degrees, and the compensatory thoracic or synsacrothoracic scoliosis. Deformed pelvic bones asymmetric levels of acetabula, and supernumerary ribs may be present. Among the progeny of the rumpless birds mated inter se, only 33 to 38 percent were rumpless. A series of modifying genes was responsible for the low " p e n e t r a n c e " a n d " expressibili t y " of this mutation.
570
K. T. S.
rumpless chickens were pedigreed and recorded for their growth and egg production performances, which were comparable to those of their sibs. The description of the structural irregularities and a report of their influences on the growth and egg production performances of these abnormal birds should be of interest to poultry breeders and producers as well. Such a report is the purpose of this paper.
The mortality of the rumpless or droopy-tailed chickens was very high. Only 47 female birds having these abnormalities were secured, and their skeletal specimens were obtained. Although two rumpless roosters were used in the matings, no skeletal specimen was obtained from the males. The origins and the tail conditions of these birds are listed in Table 1. The appearance of the abnormal birds ranged from completely rumpless to having a normal but droopy tail. Of these birds, 16 had no tail feathers, two had one, and one had 16, while the remainder had 5 to 13. The uropygial gland was absent in 22 birds, and rudimentary, small or normal for all others. No relationship between the number of tail feathers and the size of uropygial gland was found. The appearances of one completely rumpless bird and one bird with the intermediate type are shown in Figures 1 and 2. The bone specimens of these birds were observed along with those of the normal birds. According to Chamberlain (1943), the vertebral column of a normal bird consists of 14 cervical, 7 thoracic, 14 lumbo-sacral, and 4 to 8 coccygeal or caudal vertebrae. The last 3 caudal vertebrae are fused into a single piece called urostilus or pygostyle. Du Toit (1913) reported t h a t in synsacrum there were 1 synsacro-thoracic, 4 synsacro-thoraco-
lumbar, 4 synsacro-lumbar, 2 synsacrosacral, and 5 synsacro-caudal vertebrae. In addition, there were 5 free caudal vertebrae and one pygostyle. Bradley (1950) reported that the second to the fifth thoracic vertebrae were fused together, while the first and the sixth thoracic vertebrae were free. The seventh thoracic vertabra was fused with the first lumbar vertebra in the synsacrum. In this study, the number of vertebrae of the normal birds was recorded, and it was found that in different regions there were varying numbers of vertebrae: synsacro-thoraco-lumbar region, 3 to 4; synsacro-lumbar, 3 to 5; synsacro-sacral, 2; synsacro-caudal, 4 to 5; and free caudal region, 5 to 6 vertebrae. There was difficulty in separating synsacro-sacral from synsacro-caudal vertebrae. Therefore, in this study the vertebrae in synsacro-sacral and synsacro-caudal sections were considered as in one region, and named synsacro-sacro-caudal vertebrae, 6 to 7 in the normal bird (Fig. 3-D). Table 2 shows the number of vertebrae in the synsacro-sacro-caudal region, free caudal region, and pygostyle, the length of these regions, and other abnormalities of the chickens. Bird number 44 was a normal White Leghorn, while the others were rumpless or droopy-tailed. I n the synsacro-sacro-caudal region the number of vertebrae varied from 3 to 8, and the length from 8 to 40 mm. Twentyfour abnormal birds had the normal number of 6 to 7 vertebrae, but in one-half of these birds this region was compressed or shortened. Seven birds had 8 vertebrae with a normal length. The other 10 had 3 to 5 vertebrae, and the length of this region was greatly reduced. The missing vertebrae were mostly at the posterior end. In the free caudal region, 24 birds had no caudal vertebrae, 11 had a reduced number of 1 to 4. Sixteen birds had no
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
STRUCTURAL IRREGULARITIES
YAO
571
RUMPLESSNESS IN CHICKENS TABLE 2.—Number of vertebrae in and length of synsacro-sacrocaudal region, free caudal region, and pygostyle, and other abnormalities of the rumpless chickens Synsacro-sacrocaudal region Bird No.
Free caudal region
Pygostyle Other abnormalities
No. of vert.
Length (mm.)
No. of vert.
Length (mm.)
No. of vert.
Length (mm. )
1 2 3 4
5 7 3 7
22 25 10 33
0 0 0 2
0 0 0 9
0 0 0 1
0 0 0 10
5 6 7 8
5 7 6 6
22 33 26 31
2 3 0 4
15 13 0 19
1 0 1 1
15 0 10 13
9 10 11 12
8 7 7 8
32 32 37 32
4 0 4 5
17 0 20 10
0 1 1 1
0 12 22 12
13 14 15 16
7 7 3 8
37 32 12 30
0 0 0 0
0 0 0 0
0 1 0 1
0 4 0 10
17 18 19 20
6 3 5 7
24 12 25 15
0 0 1 0
0 0 7 0
1 0 1 0
2 0 15 0
21 24 25 26
5 4 3 6
15 14 8 18
0 0 0 0
0 0 0 0
1 0 0 1
3 0 0 3
27 28 29 30
5 6 6 6
14 25 28 19
0 4 0 0
0 17 0 0
0 1 1 1
0 28 5 6
31 32 33 34
8 6 6 7
35 38 20 22
5 6 0 0
23 28 0 0
1 1 0 0
21 13 0 0
35 36 37 38
8 7 6 7
29 32 25 32
0 0 0 5
0 0 0 13
1 1 1 0
3 7 11 0
Thor. & lumb. scol., twisted pelv.
39 40 41 42
8 7 7 6
29 24 40 34
3 5 5 2
14 13 28 7
1 0 1 1
12 0 25 5
Sacr. kyph. Sacr. scol., 8 prs. of ribs. 8 prs of ribs, internal layer. Thor. scol., sacr. kyph., twisted pelvis.
43 44
8 6
30 33
2 5
8 24
1 1
16 24
Sacr. scol., 8 prs. of ribs. Normal White Leghorn chicken.
2, 6th thor. vert. Thor. scol.
Thor. scol. Thor. scol., caud. kyph., twisted pelvis. Sacr. scol. & lat. fiat. vert. Twisted pelvis. Thor. scol., caud. kyph. Caud. kyph., extra rib at 1st lumbar vert.
Sacr. kyph. & lat. flat, vert., 16 tail feath. 2, 6th thor. vert. 2, 6th thor. vert. Thor. & sacr. scol., sacr. & caud. kyph. Sacr. kyph. & lat. flat. vert. Thor. scol., 8 pairs of ribs.
Sacr. kyph. & lat. flat, vert., 8 prs of ribs. Sacr. kyph. & lat. flat. vert. 2, 6th thor. vert. Caud. scol., twisted pelvis. Caud. kyph., 8 prs. of ribs. 8 prs of ribs.
Caud. kyph.
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
Sacr. & caud. lat. flat. vert.
572
K. T. S.
pygostyle and 9 had rudimentary ones. Three birds had no free caudal vertebrae, but each had a sizeable pygostyle. Some of the rudimentary pygostyles were knobshaped.
YAO
Twelve birds had kyphosis or lordosis, 12 had scoliosis, 6 had their sacral or caudal vertebrae laterally flattened, while the other 6 each had a twisted or deformed pelvis. Eighteen birds had no other ab-
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
PLATE 1. Explanation of Figures FIG. 1. A completely rumpless White Leghorn hen (bird No. 20). FIG. 2. A California Gray hen with intermediate rumplessness (bird No. 42). FIG. 3. A skeletal specimen from a normal White Leghorn hen: A. Thoracic vertebrae; B. Synsacrothoraco-lumbar vertebrae; C. Synsacro-lumbar vertebrae; D. Synsacro-sacro-caudal vertebrae; E. Free caudal vertebrae; F. Pygostyle. FIG. 4. A specimen from a completely rumpless chicken (bird No. 13), showing the similarity to that of the hereditary dominant rumplessness described by previous investigators. FIG. 5. A specimen from a completely rumpless chicken (bird No. 3), showing the similarity to that of the accidental rumplessness described by previous investigators. FIG. 6. A specimen from a completely rumpless chicken (bird No. 7), showing the absence of the free caudal vertebrae, the presence of a pygostyle and the thoracic scoliosis.
RUMPLESSNESS IN CHICKENS
the fused caudal vertebrae and pygostyle, the caudal kyphosis, and an extra rib at the first lumbar vertebra. Figure 10 (No. 28) shows the sacral kyphosis and the laterally flattened sacral vertebrae. Figure 11 (No. 32) shows the caudal kypholordosis. EARLY GROWTH AND EGG PRODUCTION PERFORMANCES
Since the abnormal birds were from different breeding groups, the early growth and egg production performances of these birds were not directly comparable with each other. However, most of them had full or half sisters in the flock, while the others had chickens of the same groups, such as those from the imported hatching eggs. Comparisons between the abnormal birds and their sisters or groupmates might give the indications concerning the influence of various kinds of abnormality on the early growth and egg production performances of the birds.The 10-week body weight is regarded in this study as the early growth rate of the birds. The birds were divided into 8 main groups according to the structural irregularities. The average 10-week body weight, mature body weight, and egg production rate of each group, and the differences between these birds and their normal sisters or group-mates for each character are listed in Table 3. The performances of each abnormal bird were compared with the average performances of her 1 to 8 normal sisters or group-mates. The abnormal birds and their normal sisters or group-mates were kept together at the brooding and rearing stages, but the abnormal ones were in cages after they started laying eggs. Their normal sisters or group-mates were housed in litter floor pens. Egg production of the abnormal birds was recorded from February 1 to May 1, while that of their sis-
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
normalities than a rumpless or droopytailed condition. Bird No. 41 was an internal layer having a droopy tail with a synsacro-sacro-caudal region and a free caudal region longer than the normal. She had 4 hard-shelled eggs in her body cavity and one hard-shelled egg in her uterus when she was dissected. The obstacle was found to be a long and z-shaped vagina. Of eight abnormal birds, each had two free sixth thoracic vertebrae. Six of them each had 8 pairs of ribs, while the two others (No. 17 and No. 18) each had 7 pairs due to the fact that the transverse processes of the seventh thoracic vertebra bore no ribs. The bone specimen of one bird which had two free sixth thoracic vertebrae and eight pairs of ribs is shown in Figure 12, The specimen of another abnormal bird (No. 12) which had an extra rib attached on the left transverse process of the first lumbar vertebra is shown in Figure 9. The representative bone specimens of the completely rumpless chickens are shown in Figures 4 and 5 (No. 13 and No. 3). These two specimens resemble those of the dominant and accidental rumplessness, respectively, described by Landauer and Dunn (1925). The specimen shown in Figure 12 (No. 40) resembles some of the intermediate and recessive types of hereditary rumplessness described by Landauer (1928, 1945). Figure 6 (No. 7) shows the specimen with the free caudal vertebrae missing but having a pygostyle. Figure 6 also shows the thoracic scoliosis. Figure 7 (No. 35) shows the thoracic and lumbar scoliosis, the absence of the free caudal vertebrae and the presence of a rudimentary pygostyle. Figure 8 (No. 16) shows the sacral kyphosis and the laterally flattened vertebrae, the absence of the caudal vertebrae but having a pygostyle. Figure 9 (No. 12) shows
573
574
K. T. S. YAO
t e r s or g r o u p - m a t e s w a s f r o m J a n u a r y 1 t o
w e r e c o m p a r e d . M a t u r e b o d y w e i g h t of
J u n e 1. E g g p r o d u c t i o n r a t e s of t h e a b n o r m a l b i r d s in cages a n d t h o s e of t h e i r n o r m a l s i s t e r s or g r o u p - m a t e s o n floor
the abnormal birds was obtained at the t i m e of sacrifice, w h i l e t h a t of t h e n o r m a l b i r d s w a s o b t a i n e d in A p r i l .
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
PLATE 2. Explanation of Figures FIG. 7. A specimen from a completely rumpless chicken (bird No. 35), showing the absence of the free caudal vertebrae, the presence of a rudimentary pygostyle, the thoracic scoliosis, and the twisted pelvis. FIG. 8. A specimen from a completely rumpless chicken (bird No. 16), showing the absence of the free caudal vertebrae, the presence of a pygostyle, the sacral kyphosis, and the laterally flattened sacral vertebrae. FIG. 9. A specimen from a chicken (bird No. 12) with intermediate rumplessness, showing the fused caudal vertebrae, the caudal kyphosis, and an extra rib at the left transverse process of the first lumbar vertebrae. FIG. 10. A specimen from a chicken (bird No. 28) with intermediate rumplessness, showing the sacral kyphosis and the extremely laterally flattened sacral and caudal vertebrae. FIG. 11. A specimen from a chicken (bird No. 32) with intermediate rumplessness, showing the caudal kyphosis and lordosis. FIG. 12. A specimen from a chicken (bird No. 40) with intermediate rumplessness, showing the fused caudal vertebrae, the absence of the pygostyle, and the presence of the supernumerary ribs (eight pairs): a. the free first thoracic vertebra and the first pair of ribs; b. the second to the fifth thoracic vertebrae which are fused together, and the second to the fifth pairs of ribs; c. the free sixth thoracic vertebra and the sixth pair of ribs; d. the second piece of the free sixth thoracic vertebrae and the second pair of the sixth ribs; e. the seventh thoracic vertebra fused with the first lumbar vertebra, and the seventh pair of ribs.
575
RUMPLESSNESS IN CHICKENS
TABLE 3.—Ten-week body weight, mature body weight, and egg production rate of the rumpless chickens and the differences from those of their normal sisters or group-mates 10-week body wt. (gm.) Structural irregularity
Mature body wt. (lbs.)
DifferRumpence less from bird normals
Rumpless , •j
DifEer ence
Egg production rate
(%) -
f
1. Complete rumplessness 1. 3-5 sacro-caudal vert. (8) a. With pygostyle (1) b. Without pygostyle (7) 2. 6-8 sacro-caudal vert. (16) a. With pygostyle (11) b. Without pygostyle (5)
736
-54
3.8
irom normals -0.5
— 765
-30
3.7
730 722
59 69
2. Intermediate rumplessness (16) 1. 3-5 sacro-caudal vert. (2) a. 1-3 caudal vert. (2) b. 4-6 caudal vert. (0) 2. 6-8 sacro-caudal vert. (14) a. 1-3 caudal vert. (5) b. 4-6 caudal vert. (9) 3. With pygostyle (12) 4. Without pygostyle (4)
709
Rumpless ,• ,
Differ ence
-
f
72
from normals + 17
-0.4
74
+20
3.8 3.8
-0.6 -0.5
72 69
+21
20
3.8
-0.6
60
+ 10
750 —
24
3.9
-0.6
51
- 5
709 700 750 621
13 22 3 79
3.5 4.0 3.9 3.4
-1.0 -0.4 -0.5 -0.8
62 62 61 59
+17 + 12 + 9 + 12
3. Rumplessness only (17)
736
35
3.8
-0.5
72
+ 16
4. Rumplessness with kyphosis (12)
708
69
4.1
-0.4
68
+ 15
5. Rumplessness with scoliosis (12)
739
•17
3.7
-0.6
57
+ 11
49
3.8
-0.4
68
+8
•49
3.8
-0.4
68
+23
8. Rumplessness with kyphosis and scoliosis •80 (4) 764 The number in the parentheses is the number of chickens.
4.1
-0.4
58
+ 13
/
blrd
blrd
6. Rumplessness with laterally flattened vert. (6) 7. Rumplessness with twisted pelvis (6)
706
+2
706
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
average egg production rate (+17 percent) over the normal birds than did the droopy-tailed chickens (+10 percent). Among the completely rumpless chickens, the birds which had 6 to 8 sacrocaudal vertebrae without pygostyle suffered most for the early growth rate (10-week body weight, —69 gm.), and had the least increase in egg production performance ( + 2 percent) over their normal sisters. Among the droopy-tailed chickens, the birds that had no pygostyle suffered seriously for the early growth rate ( — 79 gm.) and mature body weight ( — 0.8 lbs.).
The results show that the abnormal birds had a lower rate of early growth, and a lighter mature body weight than their normal sisters or group-mates. However, egg production rates of the abnormal birds were higher than those of the normal birds, except for the group which had droopy tail and 3 to 5 sacro-caudal vertebrae. This group of birds had an egg production rate 5 percent less than their normal sisters or group-mates. Completely rumpless birds suffered a greater detrimental effect on the early growth rate (10-week body weight) but had a higher
576
K. T. S.
The results showed that pygostyle played an important role for the early growth rate and also had more influence on mature body weight and egg production rate than the absence of other vertebrae. Kyphosis severely impaired the early growth rate, and caused more damage on the early growth rate when combined with scoliosis. However, the rumpless conditions and other abnormalities did not have a reverse effect on the egg production rate. DISCUSSION
Accidental rumplessness in the domestic fowl has not been thoroughly studied due to the fact that the accidental or nongenetic type of rumplessness occurs sporadically and infrequently in normal flocks. Previous investigators described the accidental rumplessness as identical to the complete rumplessness in appearance,
but, anatomically, missing two vertebrae at the posterior end instead of at the center of the five synsacro-caudals. However, Danforth (1932) observed a considerable range of variation in the specimens of the rumpless embryos induced by sudden changes of temperature at the early stage of incubation. Landauer and Baumann (1943) reported that the rumplessness induced by mechanical shaking of eggs prior to incubation was the same as the accidental ones, but a few cases of caudal scoliosis were observed. Landauer (1945a) found partial tail skeletons in some of the insulin induced rumpless embryos. Various degrees of rumpless conditions and skeletal irregularities observed in the three genetic types of rumplessness by previous investigators appeared in the materials in this study, which were considered to have the accidental or nongenetic type of rumplessness. The abnormal chickens were from a number of breeding groups and offspring of normal breeders. When these rumpless chickens were mated inter se, they did not produce rumpless offspring. The failure of the turning device during incubation in 1958 might be the factor causing the rumplessness. With the turning device functioning properly in 1959, the offspring of the rumpless chickens did not have this kind of abnormality. Thus, the rumplessness obtained in 1958 was accidental. These abnormalities could be considered to be analogous to the three types of hereditary rumplessness, but whether these irregularities had some kind of connection with the rumpless genes cannot be determined. However, it is reasonable to assume that adverse environment, such as the failure of the turning device might have lowered the modification force conducive to normal development, and lead the hidden hereditary mutant genes of all three types, as well as the accidental type, to
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
The birds having 6 to 8 sacro-caudal and 1 to 3 free caudal vertebrae suffered most for mature body weight (—1.0 lb.), but had the highest egg production performance with a 17 percent egg production rate over the normal birds. More than half of the rumpless chickens had concurrently another kind of structural abnormality. Based on these structural abnormalities, the birds were divided into six groups, as 3 to 8 in Table 3. The performances of the birds in the six groups showed that those with kyphosis as well as scoliosis suffered most for the early growth rate (— 80 gm.). Those which had only scoliosis suffered least for the early growth rate (—17 gm.) but most for mature body weight ( — 0.6 lbs.). The birds with a deformed or twisted pelvis had the highest egg production performance of 23 percent over the normal ones. The mature body weight differences between abnormal and normal birds were not correlated with the mature body weight of the abnormal birds.
YAO
RUMPLESSNESS IN CHICKENS
I n recessive rumpless stock, Landauer (1945b) reported t h a t the occurrence of supernumerary ribs in the birds with abnormal caudal vertebrae was found more often than in the normal birds, and still more often in the birds having scoliosis. The extra ribs may occur bilaterally, or on one side only; may be completely formed, or rudimentary. No sign of sternal parts of the extra ribs has ever been seen. The number of thoracic vertebrae of the rumpless birds was not mentioned. I n this study two conditions of supernumerary ribs were observed. Some rumpless birds had an extra free sixth thoracic vertebra (Fig. 12), and hence had eight pairs of ribs. Another condition was t h a t extra ribs emerged from the transverse processes of the first lumbar vertebra of the thoracolumbar synsacrum (Fig. 9). T h e supernumerary rib condition of the first t y p e was observed in six birds, and the extra ribs were completely and bilaterally formed. The second type of supernumerary rib was observed in one bird, and the extra rib was completely formed on one side only. All the extra ribs had sternal parts and connected to the sternum. Another variation in thoracic vertebrae which has not been previously reported
was the presence of an extra free sixth thoracic vertebra, and the lack of the seventh pair of ribs on the seventh thoracic vertebra, which was normally fused with the first lumbar vertebra in the synsacrum. Therefore, the bird had the normal number of seven ribs. Two birds with this condition were observed. The relationship between these three diversities and the rumpless conditions of the birds cannot be determined. D u n n and Landauer (1936) found t h a t the fertility of the rumpless chickens was greatly reduced, corresponding to the manifestation of the character with the lowest fertility reached by the completely rumpless chickens. I n this study artificial insemination was used. Although no effort was made to secure fertility records for these birds, the fertility of the eggs obtained from the rumpless birds were as satisfactory as t h a t of the eggs from the normal birds. The low fertility reported by D u n n and Landauer was probably caused by the mechanical incompatibility of the birds in natural matings rather than physiological incapability. Egg production rate showed a contrast to the early growth rate and mature body weight when the rumpless birds were compared to their normal sisters or groupmates. Rumplessness imposed a detrimental effect on the early growth rate and mature body weight, b u t not on the reproductive characters such as egg production rate. I n other words, the early growth rate and mature body weight were physical characters which responded to the rumpless condition differently t h a n did the reproductive characters. Most of the rumpless chickens had a better egg production rate t h a n their sisters or groupmates. The defective rumpless conditions might have given the chickens an impetus to produce more eggs. The relationships between the defective physical conditions, such as rumplessness, and the increase of
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
develop into these irregularities. The offspring of the rumpless chickens were under a normal incubation environment, and the modifying genes could have resumed the force conducive to promoting normal development of the vertebrae in the tail region of these chickens. If this was true, a further assumption could be suggested t h a t the accidental type of rumplessness might be also of genie origin but having a much lower "penetrance" and "expressibility" t h a n the recessive rumplessness. Only under certain environmental conditions, when the modifying genes were not in function, might the transmission of this character be expressed and studied.
577
578
K. T. S.
reproductive rate would be an interesting subject to explore in the improvement of egg production in chickens. SUMMARY
REFERENCES Bradley, 0. C , 19S0. The structure of the Fowl. 3rd ed. Oliver and Boyd, London.
Chamberlain, F. W., 1943. Atlas of Avian Anatomy. Hallenbeck Printing Co., Lansing, Michigan. Danforth, C. H., 1932. Artificial and hereditary suppression of sacral vertebrae in the fowl. Proc. Soc. Exptl. Biol. Med., 30:143-145. Davenport, C. B., 1906. Inheritance in poultry. Carnegie Institution of Washington, No. 52, Washington, D. C. Dunn, L. C , 1925. Inheritance of rumplessness in domestic fowl. J. Heredity, 16: 127-134. Dunn, L. C , and W. Landauer, 1934. The genetics of the rumpless fowl with evidence of a case of changing dominance. J. Genet. 29: 217-243. Dunn, L. C , and W. Landauer, 1936. Further data on genetic modification of rumplessness in the fowl. J. Genet. 33: 401-405. Du Toit, P. J., 1913. Untersuchungen uber das Synsacrum und den Schwanz von Gallus domesticus nebst Beobachtungen uber Schwanzlosigkeit bei Kaulhuhnern. Jena. Z. Naturw. 49: 149-312. Landauer, W., 1928. The morphology of intermediate rumplessness in the fowl. J. Hered. 19: 453467. Landauer, W., 1945a. Rumplessness of chicken embryos produced by the injection of insulin and other chemicals. J. Exptl. Zool., 98: 65-77. Landauer, W., 1945b. Recessive rumplessness of fowl with kypho-scoliosis and supernumerary ribs. Genet. 30: 403-428. Landauer, W., and L. Baumann, 1943. Rumplessness of chicken embryos produced by mechanical shaking of eggs prior to incubation. J. Exptl. Zool., 93:51-74. Landauer, W., and C. I. Bliss, 1946. Insulin induced rumplessness of chickens. III. The relationship of dosage and of developmental stage of injection to response. J. Exptl. Zool. 102: 1-22. Landauer, W., and L. C. Dunn, 1925. Two types of rumplessness in domestic fowls. J. Hered. 16: 152-160. Landauer, W., and E. H. Lang, 1946. Insulin-induced rumplessness of chickens. II. Experiments with inactivated and reactivated insulin. J. Exptl. Zool. 101:41-50.
NEWS AND NOTES ARIZONA NOTES Dr. A. A. Kurnick, Head of the Department of Poultry Science, University of Arizona, resigned, effective November IS, 1962, to accept a position with Ray Ewing Co., Division of Hoffman La Roche, Pasadena, California.
WISCONSIN NOTES J. B. Hayes, who retired as Extension Poultryman, University of Wisconsin, on July 1, after 48 years of service, has been appointed Public Relations Director, Vita Plus Corporation, Madison, Wisconsin.
(Continued on page 594)
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
In 1958 more than 80 chickens in the University breeding flock were found having various degrees of rumplessness. The birds were of a number of breeding groups and offspring of normal chickens. No rumpless bird was found in the offspring of these rumpless chickens. The rumplessness was considered to be accidental. Bone specimens of 43 female rumpless birds were studied. It was found that some of the bone specimens showed irregularities similar to the three types of hereditary rumplessness—complete, intermediate, and recessive, as well as the accidental type described by previous investigators. Two types of supernumerary ribs, and the specimens with two free sixth thoracic vertebrae not previously reported were observed. Ten-week body weight, mature body weight, and egg production rate of the rumpless birds were compared with those of their full sisters or group-mates. The results showed that rumplessness had a detrimental effect on the early growth rate (10-week body weight) and mature body weight, but seemed to have some favorable influence on egg production rate.
YAO
J. K. B L E T N E R , N . E. C H A L H O U B AND 0 . E.
1948. Investigations upon vegetable protein sources for poultry rations. Proc. Eighth World's Poultry Congress 1: 181-187. Schneider, B. H., 1947. Feeds of the World. West Virginia University, Agricultural Experiment
GOIT
Station, Morgantown, W.Va. Young, R. J., H. M. Edwards, Jr. and M. B. Giles, 1958. Studies on zinc in poultry nutrition 2. Zinc requirement and deficiency symptoms of chicks. Poultry Sci. 37: 1100-1107.
K E N N E T H T.
S.
YAO2
Department of Poultry Husbandry, University of Nebraska, Lincoln, Nebraska (Received for publication May 31, 1961)
T
H E existence of rumpless chickens has been known for centuries. Such birds were described, at the turn of the century, as a separate breed of the domestic fowl b y a number of investigators. However, Davenport (1906) pointed out t h a t rumplessness in chickens was a hereditary character, and might be found in any race of the domestic fowl. D u n n (1925) made known the two types of rumplessness in chickens—hereditary and accidental. Nevertheless, the rumpless b a n t a m is still a miniature variety of the fanciers' birds in the United States and abroad, and appears in many poultry exhibits. Hereditary rumplessness in chickens has been extensively studied by Landauer and D u n n (1925), Landauer (1928, 1945b) and D u n n and Landauer (1934, 1936). 1
Published with the approval of the Director as Paper No. 1111, Journal Series, Nebraska Agricultural Experiment Station. Project No. 424, in cooperation with the North Central States Regional Poultry Breeding Project U.S.D.A. 2 Present address—Institute for Cell Biology, University of Nebraska, Lincoln, Nebraska. The assistance of A. Yeshewalul and H. S. Tolman, graduate students, in preparing chicken bone specimens is hereby acknowledged.
There are three types of hereditary rumplessness: dominant, intermediate, and recessive. The dominant rumplessness, Rp, is described as being a lack of the fleshy portion of rump, all the tail feathers, and the uropygial gland; and, anatomically, lack of all caudal vertebrae as well as the pygostyle. The rumplessness of this type is called complete rumplessness and is dominant to the normal condition. Accidental rumplessness has the same description as the dominant, except t h a t the accidentally rumpless chicken lacks the last two synsacro-caudal vertebrae, while the chicken with dominant rumplessness has one or two vertebrae missing from the center of the five synsacro-caudals. The accidentally rumpless chickens do not transmit the rumpless condition to their offspring. The intermediate rumplessness is extremely variable from almost normal to the almost completely rumpless condition. The number of tail feathers varies from 1 to 8 in contrast to 14 in the normal. I n a few cases a rudimentary uropygial gland is present but usually this gland is absent. Two synsacro-caudals are missing as in the dominant rumplessness. Some of the
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
Variant Forms of Accidental Rumplessness in Chickens and Their Influences on the Growth and Egg Production Performances1
569
RUMPLESSNESS IN CHICKENS
Phenocopies of t h e rumpless mutations were induced b y Landauer (1945a), Landauer and Bliss (1946), and Landauer and Lang (1946), with insulin and other chemicals. The chemically treated eggs produced as many as 41.6 percent rumpless embryos, while t h e control eggs produced only 1.3 percent. With sudden changes of temperature during the early part of the incubation period, Danforth (1932) successfully obtained rumpless chicks. Landauer a n d Baumann (1943) produced a rumpless condition b y me-
chanical shaking of eggs prior to incubation. An average of 6.9 percent of these treated eggs produced rumpless embryos, while only 1.3 percent were obtained from the untreated eggs. T h e description of the induced rumplessness was the same as t h e accidental ones. However, a few cases of caudal scoliosis were observed in t h e embryos produced from the eggs treated with mechanical shaking. During 1958 in t h e University breeding flock, more than 80 chickens were found to have various degrees of rumplessness. The abnormality occurred sporadically in nearly all breeding groups on t h e farm (Table 1) including two breeds, three Leghorn strains, two Leghorn inbred lines, and several crossbred groups. N o rumpless chickens had been included in breeding pens at the University farm; and none on t h e farms from which hatching eggs were shipped to t h e University farm. The rumplessness was considered to be accidental. When these chickens were artificially bred inter se and produced more than 300 offspring, none of the offspring were rumpless. The size of the University flock in 1958 was around 4,000 chickens. The number of such abnormal birds was unusual. T h e rumplessness regarded to be accidental in these chickens was different from t h a t described b y previous investigators. These TABLE 1.—Sources of the chickens having abnormal tail conditions Tail condition
M R
chickens "™SP" Droopy Nebraska purebred Leghorns Regional Cornell Control Leghorns Regional Cornell Randombred Leghorns (imported eggs) Purebred California Grays Commercial Leghorns (imported eggs) Leghorn inbreds Leghorn incrosses Breed crosses (Grays XLeghorns) Top crosses Three-way crosses Total
2 1
1 0
1 1
4 1
2 0
2 1
2 5 8 9 9 6
2 2 5 5 5 3
0 i H . 4 4 3
47
25
22
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
caudal vertebrae are present b u t fused together in a more or less irregular fashion. A small bony protuberance representing the last two vertebrae of t h e pygostyle is present and fused with the caudal vertebrae. The presence of modifying genes suppressive to the abnormal condition in the heterozygous chickens is t h e factor causing the varying degrees of rumplessness. The recessive rumplessness, rp2, closely resembles the dominant rumplessness and its modifications. T h e appearance of the chickens of this type ranges from the completely rumpless to nearly normal. T h e uropygial gland is lacking or rudimentary. Tail feathers are lacking or reduced in number. The free caudal vertebrae and the pygostyle are entirely absent or fused into a bony knob. The fused or rudimentary caudal vertebrae m a y have lateral compression and marked lordosis. T h e vertebral column m a y have synsacral kypho-scoliosis of varying degrees, and the compensatory thoracic or synsacrothoracic scoliosis. Deformed pelvic bones asymmetric levels of acetabula, and supernumerary ribs may be present. Among the progeny of the rumpless birds mated inter se, only 33 to 38 percent were rumpless. A series of modifying genes was responsible for the low " p e n e t r a n c e " a n d " expressibili t y " of this mutation.
570
K. T. S.
rumpless chickens were pedigreed and recorded for their growth and egg production performances, which were comparable to those of their sibs. The description of the structural irregularities and a report of their influences on the growth and egg production performances of these abnormal birds should be of interest to poultry breeders and producers as well. Such a report is the purpose of this paper.
The mortality of the rumpless or droopy-tailed chickens was very high. Only 47 female birds having these abnormalities were secured, and their skeletal specimens were obtained. Although two rumpless roosters were used in the matings, no skeletal specimen was obtained from the males. The origins and the tail conditions of these birds are listed in Table 1. The appearance of the abnormal birds ranged from completely rumpless to having a normal but droopy tail. Of these birds, 16 had no tail feathers, two had one, and one had 16, while the remainder had 5 to 13. The uropygial gland was absent in 22 birds, and rudimentary, small or normal for all others. No relationship between the number of tail feathers and the size of uropygial gland was found. The appearances of one completely rumpless bird and one bird with the intermediate type are shown in Figures 1 and 2. The bone specimens of these birds were observed along with those of the normal birds. According to Chamberlain (1943), the vertebral column of a normal bird consists of 14 cervical, 7 thoracic, 14 lumbo-sacral, and 4 to 8 coccygeal or caudal vertebrae. The last 3 caudal vertebrae are fused into a single piece called urostilus or pygostyle. Du Toit (1913) reported t h a t in synsacrum there were 1 synsacro-thoracic, 4 synsacro-thoraco-
lumbar, 4 synsacro-lumbar, 2 synsacrosacral, and 5 synsacro-caudal vertebrae. In addition, there were 5 free caudal vertebrae and one pygostyle. Bradley (1950) reported that the second to the fifth thoracic vertebrae were fused together, while the first and the sixth thoracic vertebrae were free. The seventh thoracic vertabra was fused with the first lumbar vertebra in the synsacrum. In this study, the number of vertebrae of the normal birds was recorded, and it was found that in different regions there were varying numbers of vertebrae: synsacro-thoraco-lumbar region, 3 to 4; synsacro-lumbar, 3 to 5; synsacro-sacral, 2; synsacro-caudal, 4 to 5; and free caudal region, 5 to 6 vertebrae. There was difficulty in separating synsacro-sacral from synsacro-caudal vertebrae. Therefore, in this study the vertebrae in synsacro-sacral and synsacro-caudal sections were considered as in one region, and named synsacro-sacro-caudal vertebrae, 6 to 7 in the normal bird (Fig. 3-D). Table 2 shows the number of vertebrae in the synsacro-sacro-caudal region, free caudal region, and pygostyle, the length of these regions, and other abnormalities of the chickens. Bird number 44 was a normal White Leghorn, while the others were rumpless or droopy-tailed. I n the synsacro-sacro-caudal region the number of vertebrae varied from 3 to 8, and the length from 8 to 40 mm. Twentyfour abnormal birds had the normal number of 6 to 7 vertebrae, but in one-half of these birds this region was compressed or shortened. Seven birds had 8 vertebrae with a normal length. The other 10 had 3 to 5 vertebrae, and the length of this region was greatly reduced. The missing vertebrae were mostly at the posterior end. In the free caudal region, 24 birds had no caudal vertebrae, 11 had a reduced number of 1 to 4. Sixteen birds had no
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
STRUCTURAL IRREGULARITIES
YAO
571
RUMPLESSNESS IN CHICKENS TABLE 2.—Number of vertebrae in and length of synsacro-sacrocaudal region, free caudal region, and pygostyle, and other abnormalities of the rumpless chickens Synsacro-sacrocaudal region Bird No.
Free caudal region
Pygostyle Other abnormalities
No. of vert.
Length (mm.)
No. of vert.
Length (mm.)
No. of vert.
Length (mm. )
1 2 3 4
5 7 3 7
22 25 10 33
0 0 0 2
0 0 0 9
0 0 0 1
0 0 0 10
5 6 7 8
5 7 6 6
22 33 26 31
2 3 0 4
15 13 0 19
1 0 1 1
15 0 10 13
9 10 11 12
8 7 7 8
32 32 37 32
4 0 4 5
17 0 20 10
0 1 1 1
0 12 22 12
13 14 15 16
7 7 3 8
37 32 12 30
0 0 0 0
0 0 0 0
0 1 0 1
0 4 0 10
17 18 19 20
6 3 5 7
24 12 25 15
0 0 1 0
0 0 7 0
1 0 1 0
2 0 15 0
21 24 25 26
5 4 3 6
15 14 8 18
0 0 0 0
0 0 0 0
1 0 0 1
3 0 0 3
27 28 29 30
5 6 6 6
14 25 28 19
0 4 0 0
0 17 0 0
0 1 1 1
0 28 5 6
31 32 33 34
8 6 6 7
35 38 20 22
5 6 0 0
23 28 0 0
1 1 0 0
21 13 0 0
35 36 37 38
8 7 6 7
29 32 25 32
0 0 0 5
0 0 0 13
1 1 1 0
3 7 11 0
Thor. & lumb. scol., twisted pelv.
39 40 41 42
8 7 7 6
29 24 40 34
3 5 5 2
14 13 28 7
1 0 1 1
12 0 25 5
Sacr. kyph. Sacr. scol., 8 prs. of ribs. 8 prs of ribs, internal layer. Thor. scol., sacr. kyph., twisted pelvis.
43 44
8 6
30 33
2 5
8 24
1 1
16 24
Sacr. scol., 8 prs. of ribs. Normal White Leghorn chicken.
2, 6th thor. vert. Thor. scol.
Thor. scol. Thor. scol., caud. kyph., twisted pelvis. Sacr. scol. & lat. fiat. vert. Twisted pelvis. Thor. scol., caud. kyph. Caud. kyph., extra rib at 1st lumbar vert.
Sacr. kyph. & lat. flat, vert., 16 tail feath. 2, 6th thor. vert. 2, 6th thor. vert. Thor. & sacr. scol., sacr. & caud. kyph. Sacr. kyph. & lat. flat. vert. Thor. scol., 8 pairs of ribs.
Sacr. kyph. & lat. flat, vert., 8 prs of ribs. Sacr. kyph. & lat. flat. vert. 2, 6th thor. vert. Caud. scol., twisted pelvis. Caud. kyph., 8 prs. of ribs. 8 prs of ribs.
Caud. kyph.
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
Sacr. & caud. lat. flat. vert.
572
K. T. S.
pygostyle and 9 had rudimentary ones. Three birds had no free caudal vertebrae, but each had a sizeable pygostyle. Some of the rudimentary pygostyles were knobshaped.
YAO
Twelve birds had kyphosis or lordosis, 12 had scoliosis, 6 had their sacral or caudal vertebrae laterally flattened, while the other 6 each had a twisted or deformed pelvis. Eighteen birds had no other ab-
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
PLATE 1. Explanation of Figures FIG. 1. A completely rumpless White Leghorn hen (bird No. 20). FIG. 2. A California Gray hen with intermediate rumplessness (bird No. 42). FIG. 3. A skeletal specimen from a normal White Leghorn hen: A. Thoracic vertebrae; B. Synsacrothoraco-lumbar vertebrae; C. Synsacro-lumbar vertebrae; D. Synsacro-sacro-caudal vertebrae; E. Free caudal vertebrae; F. Pygostyle. FIG. 4. A specimen from a completely rumpless chicken (bird No. 13), showing the similarity to that of the hereditary dominant rumplessness described by previous investigators. FIG. 5. A specimen from a completely rumpless chicken (bird No. 3), showing the similarity to that of the accidental rumplessness described by previous investigators. FIG. 6. A specimen from a completely rumpless chicken (bird No. 7), showing the absence of the free caudal vertebrae, the presence of a pygostyle and the thoracic scoliosis.
RUMPLESSNESS IN CHICKENS
the fused caudal vertebrae and pygostyle, the caudal kyphosis, and an extra rib at the first lumbar vertebra. Figure 10 (No. 28) shows the sacral kyphosis and the laterally flattened sacral vertebrae. Figure 11 (No. 32) shows the caudal kypholordosis. EARLY GROWTH AND EGG PRODUCTION PERFORMANCES
Since the abnormal birds were from different breeding groups, the early growth and egg production performances of these birds were not directly comparable with each other. However, most of them had full or half sisters in the flock, while the others had chickens of the same groups, such as those from the imported hatching eggs. Comparisons between the abnormal birds and their sisters or groupmates might give the indications concerning the influence of various kinds of abnormality on the early growth and egg production performances of the birds.The 10-week body weight is regarded in this study as the early growth rate of the birds. The birds were divided into 8 main groups according to the structural irregularities. The average 10-week body weight, mature body weight, and egg production rate of each group, and the differences between these birds and their normal sisters or group-mates for each character are listed in Table 3. The performances of each abnormal bird were compared with the average performances of her 1 to 8 normal sisters or group-mates. The abnormal birds and their normal sisters or group-mates were kept together at the brooding and rearing stages, but the abnormal ones were in cages after they started laying eggs. Their normal sisters or group-mates were housed in litter floor pens. Egg production of the abnormal birds was recorded from February 1 to May 1, while that of their sis-
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
normalities than a rumpless or droopytailed condition. Bird No. 41 was an internal layer having a droopy tail with a synsacro-sacro-caudal region and a free caudal region longer than the normal. She had 4 hard-shelled eggs in her body cavity and one hard-shelled egg in her uterus when she was dissected. The obstacle was found to be a long and z-shaped vagina. Of eight abnormal birds, each had two free sixth thoracic vertebrae. Six of them each had 8 pairs of ribs, while the two others (No. 17 and No. 18) each had 7 pairs due to the fact that the transverse processes of the seventh thoracic vertebra bore no ribs. The bone specimen of one bird which had two free sixth thoracic vertebrae and eight pairs of ribs is shown in Figure 12, The specimen of another abnormal bird (No. 12) which had an extra rib attached on the left transverse process of the first lumbar vertebra is shown in Figure 9. The representative bone specimens of the completely rumpless chickens are shown in Figures 4 and 5 (No. 13 and No. 3). These two specimens resemble those of the dominant and accidental rumplessness, respectively, described by Landauer and Dunn (1925). The specimen shown in Figure 12 (No. 40) resembles some of the intermediate and recessive types of hereditary rumplessness described by Landauer (1928, 1945). Figure 6 (No. 7) shows the specimen with the free caudal vertebrae missing but having a pygostyle. Figure 6 also shows the thoracic scoliosis. Figure 7 (No. 35) shows the thoracic and lumbar scoliosis, the absence of the free caudal vertebrae and the presence of a rudimentary pygostyle. Figure 8 (No. 16) shows the sacral kyphosis and the laterally flattened vertebrae, the absence of the caudal vertebrae but having a pygostyle. Figure 9 (No. 12) shows
573
574
K. T. S. YAO
t e r s or g r o u p - m a t e s w a s f r o m J a n u a r y 1 t o
w e r e c o m p a r e d . M a t u r e b o d y w e i g h t of
J u n e 1. E g g p r o d u c t i o n r a t e s of t h e a b n o r m a l b i r d s in cages a n d t h o s e of t h e i r n o r m a l s i s t e r s or g r o u p - m a t e s o n floor
the abnormal birds was obtained at the t i m e of sacrifice, w h i l e t h a t of t h e n o r m a l b i r d s w a s o b t a i n e d in A p r i l .
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
PLATE 2. Explanation of Figures FIG. 7. A specimen from a completely rumpless chicken (bird No. 35), showing the absence of the free caudal vertebrae, the presence of a rudimentary pygostyle, the thoracic scoliosis, and the twisted pelvis. FIG. 8. A specimen from a completely rumpless chicken (bird No. 16), showing the absence of the free caudal vertebrae, the presence of a pygostyle, the sacral kyphosis, and the laterally flattened sacral vertebrae. FIG. 9. A specimen from a chicken (bird No. 12) with intermediate rumplessness, showing the fused caudal vertebrae, the caudal kyphosis, and an extra rib at the left transverse process of the first lumbar vertebrae. FIG. 10. A specimen from a chicken (bird No. 28) with intermediate rumplessness, showing the sacral kyphosis and the extremely laterally flattened sacral and caudal vertebrae. FIG. 11. A specimen from a chicken (bird No. 32) with intermediate rumplessness, showing the caudal kyphosis and lordosis. FIG. 12. A specimen from a chicken (bird No. 40) with intermediate rumplessness, showing the fused caudal vertebrae, the absence of the pygostyle, and the presence of the supernumerary ribs (eight pairs): a. the free first thoracic vertebra and the first pair of ribs; b. the second to the fifth thoracic vertebrae which are fused together, and the second to the fifth pairs of ribs; c. the free sixth thoracic vertebra and the sixth pair of ribs; d. the second piece of the free sixth thoracic vertebrae and the second pair of the sixth ribs; e. the seventh thoracic vertebra fused with the first lumbar vertebra, and the seventh pair of ribs.
575
RUMPLESSNESS IN CHICKENS
TABLE 3.—Ten-week body weight, mature body weight, and egg production rate of the rumpless chickens and the differences from those of their normal sisters or group-mates 10-week body wt. (gm.) Structural irregularity
Mature body wt. (lbs.)
DifferRumpence less from bird normals
Rumpless , •j
DifEer ence
Egg production rate
(%) -
f
1. Complete rumplessness 1. 3-5 sacro-caudal vert. (8) a. With pygostyle (1) b. Without pygostyle (7) 2. 6-8 sacro-caudal vert. (16) a. With pygostyle (11) b. Without pygostyle (5)
736
-54
3.8
irom normals -0.5
— 765
-30
3.7
730 722
59 69
2. Intermediate rumplessness (16) 1. 3-5 sacro-caudal vert. (2) a. 1-3 caudal vert. (2) b. 4-6 caudal vert. (0) 2. 6-8 sacro-caudal vert. (14) a. 1-3 caudal vert. (5) b. 4-6 caudal vert. (9) 3. With pygostyle (12) 4. Without pygostyle (4)
709
Rumpless ,• ,
Differ ence
-
f
72
from normals + 17
-0.4
74
+20
3.8 3.8
-0.6 -0.5
72 69
+21
20
3.8
-0.6
60
+ 10
750 —
24
3.9
-0.6
51
- 5
709 700 750 621
13 22 3 79
3.5 4.0 3.9 3.4
-1.0 -0.4 -0.5 -0.8
62 62 61 59
+17 + 12 + 9 + 12
3. Rumplessness only (17)
736
35
3.8
-0.5
72
+ 16
4. Rumplessness with kyphosis (12)
708
69
4.1
-0.4
68
+ 15
5. Rumplessness with scoliosis (12)
739
•17
3.7
-0.6
57
+ 11
49
3.8
-0.4
68
+8
•49
3.8
-0.4
68
+23
8. Rumplessness with kyphosis and scoliosis •80 (4) 764 The number in the parentheses is the number of chickens.
4.1
-0.4
58
+ 13
/
blrd
blrd
6. Rumplessness with laterally flattened vert. (6) 7. Rumplessness with twisted pelvis (6)
706
+2
706
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
average egg production rate (+17 percent) over the normal birds than did the droopy-tailed chickens (+10 percent). Among the completely rumpless chickens, the birds which had 6 to 8 sacrocaudal vertebrae without pygostyle suffered most for the early growth rate (10-week body weight, —69 gm.), and had the least increase in egg production performance ( + 2 percent) over their normal sisters. Among the droopy-tailed chickens, the birds that had no pygostyle suffered seriously for the early growth rate ( — 79 gm.) and mature body weight ( — 0.8 lbs.).
The results show that the abnormal birds had a lower rate of early growth, and a lighter mature body weight than their normal sisters or group-mates. However, egg production rates of the abnormal birds were higher than those of the normal birds, except for the group which had droopy tail and 3 to 5 sacro-caudal vertebrae. This group of birds had an egg production rate 5 percent less than their normal sisters or group-mates. Completely rumpless birds suffered a greater detrimental effect on the early growth rate (10-week body weight) but had a higher
576
K. T. S.
The results showed that pygostyle played an important role for the early growth rate and also had more influence on mature body weight and egg production rate than the absence of other vertebrae. Kyphosis severely impaired the early growth rate, and caused more damage on the early growth rate when combined with scoliosis. However, the rumpless conditions and other abnormalities did not have a reverse effect on the egg production rate. DISCUSSION
Accidental rumplessness in the domestic fowl has not been thoroughly studied due to the fact that the accidental or nongenetic type of rumplessness occurs sporadically and infrequently in normal flocks. Previous investigators described the accidental rumplessness as identical to the complete rumplessness in appearance,
but, anatomically, missing two vertebrae at the posterior end instead of at the center of the five synsacro-caudals. However, Danforth (1932) observed a considerable range of variation in the specimens of the rumpless embryos induced by sudden changes of temperature at the early stage of incubation. Landauer and Baumann (1943) reported that the rumplessness induced by mechanical shaking of eggs prior to incubation was the same as the accidental ones, but a few cases of caudal scoliosis were observed. Landauer (1945a) found partial tail skeletons in some of the insulin induced rumpless embryos. Various degrees of rumpless conditions and skeletal irregularities observed in the three genetic types of rumplessness by previous investigators appeared in the materials in this study, which were considered to have the accidental or nongenetic type of rumplessness. The abnormal chickens were from a number of breeding groups and offspring of normal breeders. When these rumpless chickens were mated inter se, they did not produce rumpless offspring. The failure of the turning device during incubation in 1958 might be the factor causing the rumplessness. With the turning device functioning properly in 1959, the offspring of the rumpless chickens did not have this kind of abnormality. Thus, the rumplessness obtained in 1958 was accidental. These abnormalities could be considered to be analogous to the three types of hereditary rumplessness, but whether these irregularities had some kind of connection with the rumpless genes cannot be determined. However, it is reasonable to assume that adverse environment, such as the failure of the turning device might have lowered the modification force conducive to normal development, and lead the hidden hereditary mutant genes of all three types, as well as the accidental type, to
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
The birds having 6 to 8 sacro-caudal and 1 to 3 free caudal vertebrae suffered most for mature body weight (—1.0 lb.), but had the highest egg production performance with a 17 percent egg production rate over the normal birds. More than half of the rumpless chickens had concurrently another kind of structural abnormality. Based on these structural abnormalities, the birds were divided into six groups, as 3 to 8 in Table 3. The performances of the birds in the six groups showed that those with kyphosis as well as scoliosis suffered most for the early growth rate (— 80 gm.). Those which had only scoliosis suffered least for the early growth rate (—17 gm.) but most for mature body weight ( — 0.6 lbs.). The birds with a deformed or twisted pelvis had the highest egg production performance of 23 percent over the normal ones. The mature body weight differences between abnormal and normal birds were not correlated with the mature body weight of the abnormal birds.
YAO
RUMPLESSNESS IN CHICKENS
I n recessive rumpless stock, Landauer (1945b) reported t h a t the occurrence of supernumerary ribs in the birds with abnormal caudal vertebrae was found more often than in the normal birds, and still more often in the birds having scoliosis. The extra ribs may occur bilaterally, or on one side only; may be completely formed, or rudimentary. No sign of sternal parts of the extra ribs has ever been seen. The number of thoracic vertebrae of the rumpless birds was not mentioned. I n this study two conditions of supernumerary ribs were observed. Some rumpless birds had an extra free sixth thoracic vertebra (Fig. 12), and hence had eight pairs of ribs. Another condition was t h a t extra ribs emerged from the transverse processes of the first lumbar vertebra of the thoracolumbar synsacrum (Fig. 9). T h e supernumerary rib condition of the first t y p e was observed in six birds, and the extra ribs were completely and bilaterally formed. The second type of supernumerary rib was observed in one bird, and the extra rib was completely formed on one side only. All the extra ribs had sternal parts and connected to the sternum. Another variation in thoracic vertebrae which has not been previously reported
was the presence of an extra free sixth thoracic vertebra, and the lack of the seventh pair of ribs on the seventh thoracic vertebra, which was normally fused with the first lumbar vertebra in the synsacrum. Therefore, the bird had the normal number of seven ribs. Two birds with this condition were observed. The relationship between these three diversities and the rumpless conditions of the birds cannot be determined. D u n n and Landauer (1936) found t h a t the fertility of the rumpless chickens was greatly reduced, corresponding to the manifestation of the character with the lowest fertility reached by the completely rumpless chickens. I n this study artificial insemination was used. Although no effort was made to secure fertility records for these birds, the fertility of the eggs obtained from the rumpless birds were as satisfactory as t h a t of the eggs from the normal birds. The low fertility reported by D u n n and Landauer was probably caused by the mechanical incompatibility of the birds in natural matings rather than physiological incapability. Egg production rate showed a contrast to the early growth rate and mature body weight when the rumpless birds were compared to their normal sisters or groupmates. Rumplessness imposed a detrimental effect on the early growth rate and mature body weight, b u t not on the reproductive characters such as egg production rate. I n other words, the early growth rate and mature body weight were physical characters which responded to the rumpless condition differently t h a n did the reproductive characters. Most of the rumpless chickens had a better egg production rate t h a n their sisters or groupmates. The defective rumpless conditions might have given the chickens an impetus to produce more eggs. The relationships between the defective physical conditions, such as rumplessness, and the increase of
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
develop into these irregularities. The offspring of the rumpless chickens were under a normal incubation environment, and the modifying genes could have resumed the force conducive to promoting normal development of the vertebrae in the tail region of these chickens. If this was true, a further assumption could be suggested t h a t the accidental type of rumplessness might be also of genie origin but having a much lower "penetrance" and "expressibility" t h a n the recessive rumplessness. Only under certain environmental conditions, when the modifying genes were not in function, might the transmission of this character be expressed and studied.
577
578
K. T. S.
reproductive rate would be an interesting subject to explore in the improvement of egg production in chickens. SUMMARY
REFERENCES Bradley, 0. C , 19S0. The structure of the Fowl. 3rd ed. Oliver and Boyd, London.
Chamberlain, F. W., 1943. Atlas of Avian Anatomy. Hallenbeck Printing Co., Lansing, Michigan. Danforth, C. H., 1932. Artificial and hereditary suppression of sacral vertebrae in the fowl. Proc. Soc. Exptl. Biol. Med., 30:143-145. Davenport, C. B., 1906. Inheritance in poultry. Carnegie Institution of Washington, No. 52, Washington, D. C. Dunn, L. C , 1925. Inheritance of rumplessness in domestic fowl. J. Heredity, 16: 127-134. Dunn, L. C , and W. Landauer, 1934. The genetics of the rumpless fowl with evidence of a case of changing dominance. J. Genet. 29: 217-243. Dunn, L. C , and W. Landauer, 1936. Further data on genetic modification of rumplessness in the fowl. J. Genet. 33: 401-405. Du Toit, P. J., 1913. Untersuchungen uber das Synsacrum und den Schwanz von Gallus domesticus nebst Beobachtungen uber Schwanzlosigkeit bei Kaulhuhnern. Jena. Z. Naturw. 49: 149-312. Landauer, W., 1928. The morphology of intermediate rumplessness in the fowl. J. Hered. 19: 453467. Landauer, W., 1945a. Rumplessness of chicken embryos produced by the injection of insulin and other chemicals. J. Exptl. Zool., 98: 65-77. Landauer, W., 1945b. Recessive rumplessness of fowl with kypho-scoliosis and supernumerary ribs. Genet. 30: 403-428. Landauer, W., and L. Baumann, 1943. Rumplessness of chicken embryos produced by mechanical shaking of eggs prior to incubation. J. Exptl. Zool., 93:51-74. Landauer, W., and C. I. Bliss, 1946. Insulin induced rumplessness of chickens. III. The relationship of dosage and of developmental stage of injection to response. J. Exptl. Zool. 102: 1-22. Landauer, W., and L. C. Dunn, 1925. Two types of rumplessness in domestic fowls. J. Hered. 16: 152-160. Landauer, W., and E. H. Lang, 1946. Insulin-induced rumplessness of chickens. II. Experiments with inactivated and reactivated insulin. J. Exptl. Zool. 101:41-50.
NEWS AND NOTES ARIZONA NOTES Dr. A. A. Kurnick, Head of the Department of Poultry Science, University of Arizona, resigned, effective November IS, 1962, to accept a position with Ray Ewing Co., Division of Hoffman La Roche, Pasadena, California.
WISCONSIN NOTES J. B. Hayes, who retired as Extension Poultryman, University of Wisconsin, on July 1, after 48 years of service, has been appointed Public Relations Director, Vita Plus Corporation, Madison, Wisconsin.
(Continued on page 594)
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
In 1958 more than 80 chickens in the University breeding flock were found having various degrees of rumplessness. The birds were of a number of breeding groups and offspring of normal chickens. No rumpless bird was found in the offspring of these rumpless chickens. The rumplessness was considered to be accidental. Bone specimens of 43 female rumpless birds were studied. It was found that some of the bone specimens showed irregularities similar to the three types of hereditary rumplessness—complete, intermediate, and recessive, as well as the accidental type described by previous investigators. Two types of supernumerary ribs, and the specimens with two free sixth thoracic vertebrae not previously reported were observed. Ten-week body weight, mature body weight, and egg production rate of the rumpless birds were compared with those of their full sisters or group-mates. The results showed that rumplessness had a detrimental effect on the early growth rate (10-week body weight) and mature body weight, but seemed to have some favorable influence on egg production rate.
YAO