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Effects of Infectious Bronchitis in Baby Chicks
EMBRYOS AND LOW TEMPERATURE
Arch. Anat. u. Physiol, p. 319-328. Quoted from Taylor et al., 1933. Lamson, G. H., Jr., 1918. The effects of subnormal temperature upon the chick embryo in incubation. J. Amer. Assoc. Instr. and Invest, in Poultry Husb. 4: 35-36. Moreng, R. E., and R. L. Bryant, 1954. Effects of sub-freezing temperature exposures on the chicken embryo. 1. Survival and subsequent growth up to time of hatch. Poultry Sci. 33: 855-863.
757
Moreng, R. E., and R. L. Bryant, 1955. The tolerance of the chicken embryo to periods of low temperature exposure. Poultry Sci. 34: 1342-1348. Payne, L. F., 1919. Distribution of mortality during the period of incubation. J. Amer. Assoc. Instr. and Invest, in Poultry Husb. 6: 9-12. Taylor, L. W., C. A. Gunns and B. D. Moses, 1933. The effect of current interruption in electrical incubation. Rept. of Calif. Ag. Expt. Sta. No. 550.
D.
I.
BROADFOOT
Ey-Line Poultry Farms, Owatonna, Minnesota B.
S.
POMEROY
University of Minnesota, St. Paul, Minnesota AND
W. M. SMITH, JR.
Hy-Line Poultry Farms, Des Moines, Iowa (Received for publication January 9, 1956),
TNFECTIOUS bronchitis commonly •*• causes a drastic and usually sudden decrease in egg production. Mortality is slight, seldom amounting to more than 5% of the laying flock. The most damaging effect is the failure to return, after several weeks pause, to what is considered a profitable rate of lay. In addition, abnormality of egg shape, shell strength, and texture, and of poor interior quality, further reduce the profitability of a recovered flock. In parent flocks, hatchability is considerably reduced. These conditions following the occurrence of the disease in a mature flock make infectious bronchitis one of the most costly diseases of the poultry industry. During the past four years the authors have had occasion to observe field cases in which flocks, having recovered from infectious bronchitis at a very early age (3 days to 3 weeks), failed ever to reach a satisfactory rate of lay. Thirty-five such farm flocks so affected varied from 35% to 63% production individually, with 45%
production typical of most cases. Culling by ordinary criteria failed to show any appreciable percentage of physical culls, and generally all birds in each flock showed depigmentation, capacity, handling qualities and temperament of a normal productive flock. Trapnesting of a divided flock (Broadfoot, Pomeroy and Smith, 1954) consisting of one-half hybrid and one-half cross-bred birds showed 43% of the hybrids and 10.5% of the cross-breds to be non-layers, or false layers, similar to those described by Cole and Hutt (1952). These non-layers nested with variable regularity, similar to what one might expect in high-producing birds, but produced no eggs (Table 1). The hybrids and cross-bred birds had exhibited severe respiratory symptoms at 3 and 7 days of age respectively. The outbreak was later determined as infectious bronchitis by serum neutralization tests. Autopsy of 26 of these so-called nonlayers showed apparently normal ovaries,
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on May 4, 2015
Effects of Infectious Bronchitis in Baby Chicks
758
D. I. BROADFOOT, B. S. POMEROY AND W. M. SMITH, JR. TABLE 1.—A summary of the fourteen-day trapnesting Hybrid pen No.
Birds in pen Non-layers Normal layers (8-16 eggs) Low intensity layers (4-7 eggs) Occasional layers (1-3 eggs) Birds t h a t did not lay or go to the nest
Died
Total number of eggs for 14 da. Total production in percentage for 14 days Age infected
123 53 41 V 11 8 3 554
Cross-bred pen
%
No.
J.
43.0 33.3 5.7 8.9
143 IS 51 19 7
— 10.5 35.6 13.3 4.9
47 4 698
32.9 2.8 —
6.5 2.4
— 32.2 3 days
34.9 7 days
EXPERIMENT 1. SUSCEPTIBLE CHICKS EXPOSED TO A FIELD STRAIN OF INFECTIOUS BRONCHITIS VIRUS
Seven hundred and fifty White Leghorn pullet chicks were hatched on March 28, 1953, from two infectious bronchitis susceptible parent flocks. The chicks were wing-banded at hatching time in six groups of 125 each, with all birds in each group having the same wing-band number. On the day of hatching, one group wing-band number (1), was delivered to the farm of a cooperator, and exposed through the eye to a strain of infectious bronchitis (Steele),
A 15.5% protein intake was maintained while on range, and a 17% protein ration was supplied after housing. This was ac-
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on May 4, 2015
with empty follicles as a proof of ovulation. Yolk fluid and concretions in the body cavity also bore out the theory that ovulation was taking place directly into the body cavity, rather than into the infundibulum. Examination of the oviduct itself found it considerably less than normal in length, and in many cases non-patent, as Cole and Hutt (1952) had found in certain nonlayers. These abnormalities of production in field cases, found consistently over a period of four years, and over a very wide area, prompted the authors to attempt to reproduce the syndrome experimentally, in an effort to determine the age beyond which damage to the flock would not warrant its disposal.
isolated the previous year from flocks in the same county. The virus used was undiluted allantoic fluid of 3rd egg passage of the I. B. strain (Steele). All other groups were held in batteries in Owatonna, Minnesota, until the time for exposure to the virus. The exposures were made at 1, 4, 8, 11, 15 and 18 days of age, of groups with wing-band numbers 1, 2, 3, 4, 5, and 7 respectively. No other vaccination was administered to this flock during its lifetime. During the first 48 hours, in all cases, steel cut corn was fed, after which a good 20% protein commercial starter was fed. Temperature in the battery and in the brooder house was maintained at 90° for the first week and an abundance of feeder and watering space was supplied. Respiratory symptoms were first observed on the fifth day, after exposure of the first group. These symptoms, typical of infectious bronchitis, then appeared in each of the remaining groups about 36 hours after their exposure. Serum-neutralization tests for LB. made at 13 weeks of age gave a serum neutralization index of 1,000 or greater. Hemagglutination inhibition tests for Newcastle disease were negative. Twenty-six chicks died from all causes during the first 3 weeks, twenty of which were attributed to infectious bronchitis. This loss of chicks was not proportionate to age at time of exposure. One hundred and twenty-five birds were lost in their tenth week, by smothering during a rainstorm. No disease was evident in the flock until maturity; a few birds showed respiratory symptoms of gapping and, on autopsy, plugs were found in bronchi and lower trachea; about 25 birds were lost from this cause. Predatory animals accounted for the remainder of the loss.
759
INFECTIOUS BRONCHITIS IN CHICKS
I
flge
-J
6*
at
II
--
•—
Time, of Exposure.,
Pays
FIG. 1. Relationship of age of exposure to infectious bronchitis virus and non-layers at maturity.
every day, others in "clutches" that were characteristic of mediocre or poor layers. Some birds typically entered the nest 2 or 3 times a day, in a futile effort to lay. Of 52 non-layers autopsied, 33 were found to have non-patent oviducts. The incidence of this condition, within each group of non-layers, decreased, generally speaking, with increased age at time of exposure to the infective agent. The incidence of all non-layers also tended to decrease with increased age at time of exposure (Figure 1). Measurements of the infundibulum, magnum, isthmus, uterus, and vagina of the 52 non-layers autopsied were made. The non-layers with non-patent oviducts were
TABLE 2.—Results of trapnesting and autopsy of chickens exposed to 13. at an early age Wing-band number No. wing-banded Age at time of exposure to virus Died from infectious bronchitis Trapped birds in group No. non-layers Non-layers % of group No. birds with incomplete oviducts % of non-layers with incomplete oviducts % of group with incomplete oviducts % of non-layers with complete oviducts
4 125
2 125
3 125
4 days
8 days
11 days
15 days
18 days
2 59 9
6 61 9
26.6
15.3
14.8
1 51 3 5.9 0
3 54 5 9.3 2
00.0 00.0
40.0
8
6
2 56 5 8.9 2
71.4 18.9
88.9 13.6
66.7
40.0
7.6
1.7
9.8 5.0
7.1 1.8
15
5 125
7 125
1 25 day 7 79 21
5.9
5.6 3.7
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complished by the use of a 26% protein commercial supplement on range and during the first two months after housing. At this time the ration was changed to a commercial 20% protein mash with corn and oats hand fed. Observations. The first egg was laid at S months of age, from which time production slowly increased to a peak of 70% at seven months. After this time, production leveled off at 64%, about which level it remained until the flock reached 9 months of age. As it is customary that this strain of layer reach an 80% to 90% rate of lay at from seven to eight months of age, it became apparent to the authors that a certain amount of damage to the reproductive system might have been incurred at the time of exposure to the virus. On December 29, all individuals still carrying wing-bands were leg-banded with a colored band on one leg and a numbered band on the other. For example, group 1, wing-band 1, all carried red leg bands, but were distinguished individually by their numbered bands of 1 to 79. On January 2, trapnesting was begun and continued for 7 days. After a pause of one week, trapping was carried on for another 4 days. Results are shown in Table 2. The activity of a number of the flock in visiting the nest without producing an egg was again observed, as described in previous reports. Some frequented the nest
760
D. I. BROADFOOT, B. S. POMEROY AND W. M. SMITH, JR.
TABLE 3.—Measurements of the various segments of the oviducts from non-layers Group'" d i b X m cm. 5.1 4.1 7.4 6.7 6.1 7.9 6.2 9.0
M
<«num cm.
10.3 10.2 12.6 13.3 31.8 15.4 15.6 33.0
Isthmus
cm. 9.0 8.0
10.6 13.8 15.8 9.4
11.1 10
Uterus
cm. 2.6 3.7 3.7 4.5 5.2 3.7 3.9
10-12
Va
«ina
cm.
2.5 4.0 3.4 3.5 4.9 3.0 4.3 12
* Romanoff and Romanoff, 1949.
EXPERIMENT 2. SUSCEPTIBLE CHICKS EXPOSED TO I.B. INTRANASAL VACCINE
Because of the possibility of carriers among the recovered birds and danger of spread of infectious bronchitis to a nonexposed control group, no control group was used on the same farm. However, a similar experiment, using an attenuated virus (commercial LB. vaccine, Salsbury), was conducted on a nearby farm. This flock, consisting of 8 groups, similarly exposed at 3 and 4 day intervals, were from the same parent flocks as those used in the first flock. This flock attained a peak production of 94% at iy2 months of age. Trapping of this flock showed no significant difference in rate of lay for each group, and only one non-layer was detected. Serum neutralization tests showed immunity to infectious bronchitis, and exposure to a virulent strain of LB. virus at 11 months resulted in some mild respiratory symptoms, but no decrease in rate of lay. In addition, another flock of the same parentage were within 2,000 feet of the experimental flock on a neighboring farm. This flock reached a production peak of 85%, and maintained an 80% rate of lay for 4 months. These birds were not trapnested, as the rate of lay was considered normal. DISCUSSION
It is not the purpose of this paper to establish the manner in which infectious bronchitis at an early age produces the described syndrome and lesions. The experiment does, however, confirm the observations by the writers that infectious bronchitis was the agent responsible in the
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on May 4, 2015
found to have considerably shortened oviducts (Table 3) with varying amounts of yolk material in the body cavity. Nineteen non-layers with patent oviducts had generally less yolk material among the intestines than non-layers with non-patent oviducts, with entire oviducts shorter and showing less glandular development than normal. In all but one bird, the ovaries were active, with 4 to 9 ova greater than 1.5 cm. in diameter. A few birds also had a large number of ova from .75 to 1.25 cm. in diameter, suggesting over-stimulation possibly by the reabsorption of yolk material from the body cavity. Patent oviducts found in non-layers were shorter than normal and did not show the normal, non-glandular, translucent ring which demarks the border between the magnum and isthmus. This lack of sharp demarcation between segments made accurate measurement of the various segments difficult. In the non-patent oviducts, the caudal portion of the isthmus and the cephalic portion of the uterus were absent, their outline occasionally visible on the membrane of the mesasalpinx. In most of these, the sac-like remnant of the magnum was glandular, but the uterine wall was non-glandular, translucent, and cystic, containing a clear fluid with what appeared to be floating concretions of mucin fibers resembling the chalazae of a normal egg. The magnum contained no fluid. In seven non-layers the right oviduct had become
cystic, one having reached the length of 17.5 cm. and a width of 5 cm. This had occurred in the only bird whose ovary showed resorbing yolks and inactivity at time of autopsy. Typical non-patent oviducts are shown in Figures 2, 3, and 4.
761
INFECTIOUS BRONCHITIS IN CHICKS
2
Fie. 3
FIG.
4
Figures 2, 3, and 4 show the cystic, non-patent condition of the oviduct found in non-layers. Note the active condition of the ovary and the sac like occlusions of the oviduct. In Figure 2, no trace of the anterior portion could be detected. Figure 3 shows a similar condition but with more development of the magnum. Figure 4 shows a portion of the magnum fairly well developed, non-patent anteriorly and joining the caudal portion of the oviduct only by the mesasalpinx, against which the outline of an infantile portion of the oviduct was faintly visible.
many field cases reported previously. These observations include those made on flocks of hybrid, standard-bred, and cross-bred birds, as well as crosses of inbred birds. The authors do not discount the possibility of a similar, or identical condition occurring to a considerably lesser degree in an unexposed population, nor the possibility that sire differences may have a decided bearing on such an occurrence. It would also be logical to expect that sire differences could have a considerable effect on the extent to which the infective agent would damage a flock, as not all birds are damaged. It is postulated, however, that the appearance of the syndrome and lesions in the experimental flock was entirely brought about by the exposure of the virulent I.B. virus as birds of identical breeding in another flock trapnested were unaffected by exposure to an attenuated commercial I. B. vaccine virus. A third flock of full sisters which served as controls and
were not trapnested, attained such high production that trapping was considered impractical. The presence of varying amounts of yolk material in the body cavities of all nonlayers, suggests to the authors the malfunctioning of the anterior oviduct, resulting in the failure of the infundibulum to engulf the yolk. This theory is also put forth by Cole and Hutt, 1952. This inability seemed evident whether or not the oviduct was patent. Alternately the infundibulum might have engulfed the yolk normally and later disgorged it by antiperistalsis with the same result. The embedding of yolk concretion showing concentric layers into the fat of the abdominal wall and mesentery, would suggest that at least some ova were dropped without the rupturing of the yolk membrane. Heavy layers of oily abdominal fat may have been caused by resorbing yolk material. The urge to nest is apparently not
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on May 4, 2015
FIG.
762
D. I. BROADFOOT, B. S. POMEROY AND W. M. SMITH, JR.
POULTRY SCIENCE INDEX A subject matter index of volumes 1 to 20 inclusive, is available from C. B. Ryan, SecretaryTreasurer, Poultry Science Association, Texas A. and M. College System, College Station, Texas, at $1.00 per copy.
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on May 4, 2015
brought on entirely by the presence of a ably greater in chicks exposed at 1 and 4 shelled egg in the lower oviduct, as those days than in chicks exposed at 15 and 18 individuals in which such a condition was days. These permanent abnormalities may impossible showed normal nesting habits. take the form of (1) a non-patent oviduct; Warren and Scott (1935) found increased (2) a patent oviduct of less than normal motility of the lower oviduct at ovulation, length, having no demarcation between the which would lead to the belief that the ab- magnum and isthmus, and of less than normal birds visited the nest at time of normal diameter and glandular developovulation. ment; or (3) cysts in the wall of the oviRecent observations with experimental duct or supporting ligament. The incidence groups of chicks from bronchitis immune of abnormality of the oviduct decreased, and non-immune sources indicate that pas- generally, with increasing age at exposure. sive immunity may protect the young Live non-layers, regardless of the type of chicks from the development of abnormal abnormality, were almost impossible of oviducts when exposed to a virulent field differentiation from normal layers. Apstrain of LB. parent good health, bright combs, depigmentation, handling qualities and capacity SUMMARY AND CONCLUSIONS did not distinguish non-layers from normal Groups of chicks of the same parentage layers. and age were exposed to a field isolated The activity of the ovary was apparently strain (Steele) of infectious bronchitis not decreased, but may have been stimuvirus, at ages ranging from 1 to 18 days, lated, in some cases, to produce an excesat 3 and 4 day intervals. This was done in sive number of immature ova. an effort to reproduce the syndrome of A commercial attenuated infectious bronnon-patent oviducts found in flocks of chitis vaccine was found to have almost no layers where field cases of infectious bron- tendency to produce similar abnormalities. chitis had appeared during the first few REFERENCES days of life. The same, or similar, autopsy findings Broadfoot, D. I., B. S. Pomeroy and W. M. Smith, Jr., 19S4. Effects of infectious bronchitis were noted on examining non-layers in this on egg production. J. Amer. Vet. Med. Assoc. study as were detected by the writers in 124: 128-130. previous field cases. Careful examination Cole, R. K., and F. B. Hutt, 19S2. Normal ovulaof 52 non-layers from the six age groups tion in non-laying hens. Poultry Sci. 3 3 : 481492. led to the conclusion that exposure of susceptible baby chicks during the first 18 Romanoff, A. L., and A. J. Romanoff, 1949. The Avian Egg, John Wiley and Sons, Inc., New days of life to the virulent field strain York, N.Y. (Steele) of infectious bronchitis virus can Warren, D. D.. and H. M. Scott, 193S. The time cause permanent abnormalities of the eggfactor in egg formation. Poultry Sci. 14: producing organs. This effect was consider19S-207.
Arch. Anat. u. Physiol, p. 319-328. Quoted from Taylor et al., 1933. Lamson, G. H., Jr., 1918. The effects of subnormal temperature upon the chick embryo in incubation. J. Amer. Assoc. Instr. and Invest, in Poultry Husb. 4: 35-36. Moreng, R. E., and R. L. Bryant, 1954. Effects of sub-freezing temperature exposures on the chicken embryo. 1. Survival and subsequent growth up to time of hatch. Poultry Sci. 33: 855-863.
757
Moreng, R. E., and R. L. Bryant, 1955. The tolerance of the chicken embryo to periods of low temperature exposure. Poultry Sci. 34: 1342-1348. Payne, L. F., 1919. Distribution of mortality during the period of incubation. J. Amer. Assoc. Instr. and Invest, in Poultry Husb. 6: 9-12. Taylor, L. W., C. A. Gunns and B. D. Moses, 1933. The effect of current interruption in electrical incubation. Rept. of Calif. Ag. Expt. Sta. No. 550.
D.
I.
BROADFOOT
Ey-Line Poultry Farms, Owatonna, Minnesota B.
S.
POMEROY
University of Minnesota, St. Paul, Minnesota AND
W. M. SMITH, JR.
Hy-Line Poultry Farms, Des Moines, Iowa (Received for publication January 9, 1956),
TNFECTIOUS bronchitis commonly •*• causes a drastic and usually sudden decrease in egg production. Mortality is slight, seldom amounting to more than 5% of the laying flock. The most damaging effect is the failure to return, after several weeks pause, to what is considered a profitable rate of lay. In addition, abnormality of egg shape, shell strength, and texture, and of poor interior quality, further reduce the profitability of a recovered flock. In parent flocks, hatchability is considerably reduced. These conditions following the occurrence of the disease in a mature flock make infectious bronchitis one of the most costly diseases of the poultry industry. During the past four years the authors have had occasion to observe field cases in which flocks, having recovered from infectious bronchitis at a very early age (3 days to 3 weeks), failed ever to reach a satisfactory rate of lay. Thirty-five such farm flocks so affected varied from 35% to 63% production individually, with 45%
production typical of most cases. Culling by ordinary criteria failed to show any appreciable percentage of physical culls, and generally all birds in each flock showed depigmentation, capacity, handling qualities and temperament of a normal productive flock. Trapnesting of a divided flock (Broadfoot, Pomeroy and Smith, 1954) consisting of one-half hybrid and one-half cross-bred birds showed 43% of the hybrids and 10.5% of the cross-breds to be non-layers, or false layers, similar to those described by Cole and Hutt (1952). These non-layers nested with variable regularity, similar to what one might expect in high-producing birds, but produced no eggs (Table 1). The hybrids and cross-bred birds had exhibited severe respiratory symptoms at 3 and 7 days of age respectively. The outbreak was later determined as infectious bronchitis by serum neutralization tests. Autopsy of 26 of these so-called nonlayers showed apparently normal ovaries,
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on May 4, 2015
Effects of Infectious Bronchitis in Baby Chicks
758
D. I. BROADFOOT, B. S. POMEROY AND W. M. SMITH, JR. TABLE 1.—A summary of the fourteen-day trapnesting Hybrid pen No.
Birds in pen Non-layers Normal layers (8-16 eggs) Low intensity layers (4-7 eggs) Occasional layers (1-3 eggs) Birds t h a t did not lay or go to the nest
Died
Total number of eggs for 14 da. Total production in percentage for 14 days Age infected
123 53 41 V 11 8 3 554
Cross-bred pen
%
No.
J.
43.0 33.3 5.7 8.9
143 IS 51 19 7
— 10.5 35.6 13.3 4.9
47 4 698
32.9 2.8 —
6.5 2.4
— 32.2 3 days
34.9 7 days
EXPERIMENT 1. SUSCEPTIBLE CHICKS EXPOSED TO A FIELD STRAIN OF INFECTIOUS BRONCHITIS VIRUS
Seven hundred and fifty White Leghorn pullet chicks were hatched on March 28, 1953, from two infectious bronchitis susceptible parent flocks. The chicks were wing-banded at hatching time in six groups of 125 each, with all birds in each group having the same wing-band number. On the day of hatching, one group wing-band number (1), was delivered to the farm of a cooperator, and exposed through the eye to a strain of infectious bronchitis (Steele),
A 15.5% protein intake was maintained while on range, and a 17% protein ration was supplied after housing. This was ac-
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on May 4, 2015
with empty follicles as a proof of ovulation. Yolk fluid and concretions in the body cavity also bore out the theory that ovulation was taking place directly into the body cavity, rather than into the infundibulum. Examination of the oviduct itself found it considerably less than normal in length, and in many cases non-patent, as Cole and Hutt (1952) had found in certain nonlayers. These abnormalities of production in field cases, found consistently over a period of four years, and over a very wide area, prompted the authors to attempt to reproduce the syndrome experimentally, in an effort to determine the age beyond which damage to the flock would not warrant its disposal.
isolated the previous year from flocks in the same county. The virus used was undiluted allantoic fluid of 3rd egg passage of the I. B. strain (Steele). All other groups were held in batteries in Owatonna, Minnesota, until the time for exposure to the virus. The exposures were made at 1, 4, 8, 11, 15 and 18 days of age, of groups with wing-band numbers 1, 2, 3, 4, 5, and 7 respectively. No other vaccination was administered to this flock during its lifetime. During the first 48 hours, in all cases, steel cut corn was fed, after which a good 20% protein commercial starter was fed. Temperature in the battery and in the brooder house was maintained at 90° for the first week and an abundance of feeder and watering space was supplied. Respiratory symptoms were first observed on the fifth day, after exposure of the first group. These symptoms, typical of infectious bronchitis, then appeared in each of the remaining groups about 36 hours after their exposure. Serum-neutralization tests for LB. made at 13 weeks of age gave a serum neutralization index of 1,000 or greater. Hemagglutination inhibition tests for Newcastle disease were negative. Twenty-six chicks died from all causes during the first 3 weeks, twenty of which were attributed to infectious bronchitis. This loss of chicks was not proportionate to age at time of exposure. One hundred and twenty-five birds were lost in their tenth week, by smothering during a rainstorm. No disease was evident in the flock until maturity; a few birds showed respiratory symptoms of gapping and, on autopsy, plugs were found in bronchi and lower trachea; about 25 birds were lost from this cause. Predatory animals accounted for the remainder of the loss.
759
INFECTIOUS BRONCHITIS IN CHICKS
I
flge
-J
6*
at
II
--
•—
Time, of Exposure.,
Pays
FIG. 1. Relationship of age of exposure to infectious bronchitis virus and non-layers at maturity.
every day, others in "clutches" that were characteristic of mediocre or poor layers. Some birds typically entered the nest 2 or 3 times a day, in a futile effort to lay. Of 52 non-layers autopsied, 33 were found to have non-patent oviducts. The incidence of this condition, within each group of non-layers, decreased, generally speaking, with increased age at time of exposure to the infective agent. The incidence of all non-layers also tended to decrease with increased age at time of exposure (Figure 1). Measurements of the infundibulum, magnum, isthmus, uterus, and vagina of the 52 non-layers autopsied were made. The non-layers with non-patent oviducts were
TABLE 2.—Results of trapnesting and autopsy of chickens exposed to 13. at an early age Wing-band number No. wing-banded Age at time of exposure to virus Died from infectious bronchitis Trapped birds in group No. non-layers Non-layers % of group No. birds with incomplete oviducts % of non-layers with incomplete oviducts % of group with incomplete oviducts % of non-layers with complete oviducts
4 125
2 125
3 125
4 days
8 days
11 days
15 days
18 days
2 59 9
6 61 9
26.6
15.3
14.8
1 51 3 5.9 0
3 54 5 9.3 2
00.0 00.0
40.0
8
6
2 56 5 8.9 2
71.4 18.9
88.9 13.6
66.7
40.0
7.6
1.7
9.8 5.0
7.1 1.8
15
5 125
7 125
1 25 day 7 79 21
5.9
5.6 3.7
Downloaded from http://ps.oxfordjournals.org/ at Universite de Sherbrooke on May 4, 2015
complished by the use of a 26% protein commercial supplement on range and during the first two months after housing. At this time the ration was changed to a commercial 20% protein mash with corn and oats hand fed. Observations. The first egg was laid at S months of age, from which time production slowly increased to a peak of 70% at seven months. After this time, production leveled off at 64%, about which level it remained until the flock reached 9 months of age. As it is customary that this strain of layer reach an 80% to 90% rate of lay at from seven to eight months of age, it became apparent to the authors that a certain amount of damage to the reproductive system might have been incurred at the time of exposure to the virus. On December 29, all individuals still carrying wing-bands were leg-banded with a colored band on one leg and a numbered band on the other. For example, group 1, wing-band 1, all carried red leg bands, but were distinguished individually by their numbered bands of 1 to 79. On January 2, trapnesting was begun and continued for 7 days. After a pause of one week, trapping was carried on for another 4 days. Results are shown in Table 2. The activity of a number of the flock in visiting the nest without producing an egg was again observed, as described in previous reports. Some frequented the nest
760
D. I. BROADFOOT, B. S. POMEROY AND W. M. SMITH, JR.
TABLE 3.—Measurements of the various segments of the oviducts from non-layers Group'" d i b X m cm. 5.1 4.1 7.4 6.7 6.1 7.9 6.2 9.0
M
<«num cm.
10.3 10.2 12.6 13.3 31.8 15.4 15.6 33.0
Isthmus
cm. 9.0 8.0
10.6 13.8 15.8 9.4
11.1 10
Uterus
cm. 2.6 3.7 3.7 4.5 5.2 3.7 3.9
10-12
Va
«ina
cm.
2.5 4.0 3.4 3.5 4.9 3.0 4.3 12
* Romanoff and Romanoff, 1949.
EXPERIMENT 2. SUSCEPTIBLE CHICKS EXPOSED TO I.B. INTRANASAL VACCINE
Because of the possibility of carriers among the recovered birds and danger of spread of infectious bronchitis to a nonexposed control group, no control group was used on the same farm. However, a similar experiment, using an attenuated virus (commercial LB. vaccine, Salsbury), was conducted on a nearby farm. This flock, consisting of 8 groups, similarly exposed at 3 and 4 day intervals, were from the same parent flocks as those used in the first flock. This flock attained a peak production of 94% at iy2 months of age. Trapping of this flock showed no significant difference in rate of lay for each group, and only one non-layer was detected. Serum neutralization tests showed immunity to infectious bronchitis, and exposure to a virulent strain of LB. virus at 11 months resulted in some mild respiratory symptoms, but no decrease in rate of lay. In addition, another flock of the same parentage were within 2,000 feet of the experimental flock on a neighboring farm. This flock reached a production peak of 85%, and maintained an 80% rate of lay for 4 months. These birds were not trapnested, as the rate of lay was considered normal. DISCUSSION
It is not the purpose of this paper to establish the manner in which infectious bronchitis at an early age produces the described syndrome and lesions. The experiment does, however, confirm the observations by the writers that infectious bronchitis was the agent responsible in the
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found to have considerably shortened oviducts (Table 3) with varying amounts of yolk material in the body cavity. Nineteen non-layers with patent oviducts had generally less yolk material among the intestines than non-layers with non-patent oviducts, with entire oviducts shorter and showing less glandular development than normal. In all but one bird, the ovaries were active, with 4 to 9 ova greater than 1.5 cm. in diameter. A few birds also had a large number of ova from .75 to 1.25 cm. in diameter, suggesting over-stimulation possibly by the reabsorption of yolk material from the body cavity. Patent oviducts found in non-layers were shorter than normal and did not show the normal, non-glandular, translucent ring which demarks the border between the magnum and isthmus. This lack of sharp demarcation between segments made accurate measurement of the various segments difficult. In the non-patent oviducts, the caudal portion of the isthmus and the cephalic portion of the uterus were absent, their outline occasionally visible on the membrane of the mesasalpinx. In most of these, the sac-like remnant of the magnum was glandular, but the uterine wall was non-glandular, translucent, and cystic, containing a clear fluid with what appeared to be floating concretions of mucin fibers resembling the chalazae of a normal egg. The magnum contained no fluid. In seven non-layers the right oviduct had become
cystic, one having reached the length of 17.5 cm. and a width of 5 cm. This had occurred in the only bird whose ovary showed resorbing yolks and inactivity at time of autopsy. Typical non-patent oviducts are shown in Figures 2, 3, and 4.
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INFECTIOUS BRONCHITIS IN CHICKS
2
Fie. 3
FIG.
4
Figures 2, 3, and 4 show the cystic, non-patent condition of the oviduct found in non-layers. Note the active condition of the ovary and the sac like occlusions of the oviduct. In Figure 2, no trace of the anterior portion could be detected. Figure 3 shows a similar condition but with more development of the magnum. Figure 4 shows a portion of the magnum fairly well developed, non-patent anteriorly and joining the caudal portion of the oviduct only by the mesasalpinx, against which the outline of an infantile portion of the oviduct was faintly visible.
many field cases reported previously. These observations include those made on flocks of hybrid, standard-bred, and cross-bred birds, as well as crosses of inbred birds. The authors do not discount the possibility of a similar, or identical condition occurring to a considerably lesser degree in an unexposed population, nor the possibility that sire differences may have a decided bearing on such an occurrence. It would also be logical to expect that sire differences could have a considerable effect on the extent to which the infective agent would damage a flock, as not all birds are damaged. It is postulated, however, that the appearance of the syndrome and lesions in the experimental flock was entirely brought about by the exposure of the virulent I.B. virus as birds of identical breeding in another flock trapnested were unaffected by exposure to an attenuated commercial I. B. vaccine virus. A third flock of full sisters which served as controls and
were not trapnested, attained such high production that trapping was considered impractical. The presence of varying amounts of yolk material in the body cavities of all nonlayers, suggests to the authors the malfunctioning of the anterior oviduct, resulting in the failure of the infundibulum to engulf the yolk. This theory is also put forth by Cole and Hutt, 1952. This inability seemed evident whether or not the oviduct was patent. Alternately the infundibulum might have engulfed the yolk normally and later disgorged it by antiperistalsis with the same result. The embedding of yolk concretion showing concentric layers into the fat of the abdominal wall and mesentery, would suggest that at least some ova were dropped without the rupturing of the yolk membrane. Heavy layers of oily abdominal fat may have been caused by resorbing yolk material. The urge to nest is apparently not
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FIG.
762
D. I. BROADFOOT, B. S. POMEROY AND W. M. SMITH, JR.
POULTRY SCIENCE INDEX A subject matter index of volumes 1 to 20 inclusive, is available from C. B. Ryan, SecretaryTreasurer, Poultry Science Association, Texas A. and M. College System, College Station, Texas, at $1.00 per copy.
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brought on entirely by the presence of a ably greater in chicks exposed at 1 and 4 shelled egg in the lower oviduct, as those days than in chicks exposed at 15 and 18 individuals in which such a condition was days. These permanent abnormalities may impossible showed normal nesting habits. take the form of (1) a non-patent oviduct; Warren and Scott (1935) found increased (2) a patent oviduct of less than normal motility of the lower oviduct at ovulation, length, having no demarcation between the which would lead to the belief that the ab- magnum and isthmus, and of less than normal birds visited the nest at time of normal diameter and glandular developovulation. ment; or (3) cysts in the wall of the oviRecent observations with experimental duct or supporting ligament. The incidence groups of chicks from bronchitis immune of abnormality of the oviduct decreased, and non-immune sources indicate that pas- generally, with increasing age at exposure. sive immunity may protect the young Live non-layers, regardless of the type of chicks from the development of abnormal abnormality, were almost impossible of oviducts when exposed to a virulent field differentiation from normal layers. Apstrain of LB. parent good health, bright combs, depigmentation, handling qualities and capacity SUMMARY AND CONCLUSIONS did not distinguish non-layers from normal Groups of chicks of the same parentage layers. and age were exposed to a field isolated The activity of the ovary was apparently strain (Steele) of infectious bronchitis not decreased, but may have been stimuvirus, at ages ranging from 1 to 18 days, lated, in some cases, to produce an excesat 3 and 4 day intervals. This was done in sive number of immature ova. an effort to reproduce the syndrome of A commercial attenuated infectious bronnon-patent oviducts found in flocks of chitis vaccine was found to have almost no layers where field cases of infectious bron- tendency to produce similar abnormalities. chitis had appeared during the first few REFERENCES days of life. The same, or similar, autopsy findings Broadfoot, D. I., B. S. Pomeroy and W. M. Smith, Jr., 19S4. Effects of infectious bronchitis were noted on examining non-layers in this on egg production. J. Amer. Vet. Med. Assoc. study as were detected by the writers in 124: 128-130. previous field cases. Careful examination Cole, R. K., and F. B. Hutt, 19S2. Normal ovulaof 52 non-layers from the six age groups tion in non-laying hens. Poultry Sci. 3 3 : 481492. led to the conclusion that exposure of susceptible baby chicks during the first 18 Romanoff, A. L., and A. J. Romanoff, 1949. The Avian Egg, John Wiley and Sons, Inc., New days of life to the virulent field strain York, N.Y. (Steele) of infectious bronchitis virus can Warren, D. D.. and H. M. Scott, 193S. The time cause permanent abnormalities of the eggfactor in egg formation. Poultry Sci. 14: producing organs. This effect was consider19S-207.