ISRAEL JOURNAL OF
VETERINARY MEDICINE
VOLUME 54 (1), 1999
TITLE: THE SCIENTIFIC APPROACH TO RESOLVING CONFLICTS
BETWEEN VETERINARY SCIENCE AND SHECHITA.
AUTHOR: L.S. Shore
Dept. of Hormone Research, Kimron Veterinary Institute
P.O.B 12, 50250 Bet Dagan, Israel
Summary
Scientific research in veterinary science and halacha in the last 100 years
has centered on four areas: physiology of shechita, problems of food quality
resulting from the laws of kashrut, identification of piscine species, and
reducing traifot caused by veterinary intervention and modern animal
husbandry
Introduction
Scientific and experimental approaches to halachic problems of veterinary
interest prior to the present century may be divided into four categories: (a)
Direct observations: this includes performing animal dissections (Rabbanu
Shimshon, 11th century; Rosh, 12th; Ravid, 12th ; R. (Rabbi). Y. Eybshutz,
17th; (for references see 1-4), physiological experiments (R. Y. Lamperinti,
18th; R. Y. Landau, 18th ) and incidence surveys (R. Y. Iserlin, 15th); (b)
Use of general scientific literature (R. Y. Lipshutz, 19th; Malbim, 19th; R. Y.
Epstein, 19th); (c) Formal requests to scientific bodies (London Bet Din, 19th;
R. Eybshitz, 17th, [5]); and (d) Reliance on the minhag of Rabbi Shlomo Luria
that diseased animals should be considered non-kosher even though there
are no halachic problems. In its most developed form, this minhag was used
to forbid any animal with a disease or abnormality, which was known to be
fatal in sheep, cattle, or poultry and the ritual slaughterer was obligated to
declare the meat non-kosher (even if the information was from a non-Jewish
authority). The use of the minhag of Rabbi Shlomo Luria fell into disuse at the
beginning of this century as it was considered that nowadays there are
government veterinary regulations which forbid the slaughter of sick animals
(4).
In 1894, the Orthodox Jewish Society in Frankfurt published an
extraordinary document containing the opinions of over a hundred prominent
European physiologists and veterinarians supporting the merits of shechita
(6). Among the most prominent were Rudolf Virchow (1821-1906), Ernst
Hoppe-Seyler (1825-1895), and Emil Du Bois-Reymond (1818-1896). At
about the same time, the earliest scientific publications dealing with shechita
written by a physician, Isaac Dembo, (1847?-1906) appeared (7,8) and the
work was dedicated to Bois-Reymond. Two other papers, one dealing with the
degree of exsanguination (Goltz, 1890) and the other on the measurement of
ECG after slaughter appeared at this time (Kirilow, 1893), but the papers by
Dembo had much more impact in giving the impression that kosher meat was
of better quality (9). Until the early 1950’s, there was little further interest in
the scientific community in this kind of research. For example, one of the
major technical developments, the
Weinberg slaughtering pen, was developed by a tailor, apparently solely on
his own initiative (10,11). All these efforts were spurred by the campaign,
which continues today, to outlaw shechita on humanitarian grounds.
Modern scientific work (since 1960) on halachic problems of veterinary
interest has been primarily concerned with (a) the physiology of shechita; (b)
problems caused by halachic requirements in the preparation of food defeathering and salting; (c) identification of species, and; (d) iatrogenic
“treifa” - halachic problems caused by veterinary medicine and modern ways
of raising animals - veterinary surgery, immunization, and factory farming.
Physiology of Shechita
There are three basic issues with respect to the physiology of shechita: (a)
the stress of the restraining methods; (b) pain perception during and after the
incision, and (c) latency of the onset of complete insensibility. These topics
have been the subject of extensive reviews (12-14). Most recently, Dr.
Levinger (9) published a book, Shechita in the Light of the Year 2000, which
gives a comprehensive review of the work done in this field.
As mentioned above, the pioneering author in the scientific defense of
shechita was Isaac A. Dembo (7,8). His major contribution was to show that
shechita does not cause more pain than any other technique. This work was
continued by Levinger (9,15-17), who was and continues to be the leading
authority on veterinary problems of Kashrut. Levinger attempted to define the
loss of sensibility and the time of death by measuring the corneal reflexes, the
drop in blood carotid and vertebral arterial pressure, and the heart rate and
respiratory rate using the best available instrumentation.
Subsequent
investigations were centered on the determination of death as measured by
loss of sensibility by electroencephalograms (EEG) (“brain death”) (18,19);
electrocorticograms (ECoG) and evoked cortical potentials (20,21);
metabolites and blood gases (22); and cortisol and beta endorphin levels
(18,23).
The problem in some cattle of a prolonged consciousness after the initial
cutting has been a cause of great concern and has been a major argument
against shechita, especially in Australia and New Zealand. The problem has
been related to the unique artery, “rete mirabile epiduris” , in cattle which
allows blood to reach the brain from the vertebral column even when the
carotid arteries are occluded or cut (12,24). However, this structure was found
to have great anatomical variation and it is highly improbable that significant
amounts of blood can reach the brain by this pathway (9,25). (The rete
mirabile was considered by Galen to be the center of the soul and this belief
persisted till the mid-14 th century when it was demonstrated this structure
does not exist in man [26]). Furthermore, several investigators were unable to
demonstrate differences in time to loss of consciousness between cattle and
sheep (which do not have a caudal rete) (19,20,27). The most recent research
has shown that by using the proper slaughter apparatus (with the cow
standing upright with a properly designed head restraint) and with proper
handling, the cow is apparently unaware of the throat being cut and collapses
in 10 to 15 seconds (13). The rise in cortisol levels in head-restrained animals
was minimal (23). However, the lack of a basic understanding of what
constitutes consciousness and pain in animals makes evaluation of this work
difficult. Perhaps the techniques of positron emission topography combined
with brain scanning and electromagnetic transducers for measuring blood flow
will someday provide such an understanding.
A related problem is occlusion of the carotid artery which would not allow
rapid loss of blood from the brain. It is not known what factors cause the
spasmodic occlusion of the artery; it is believed to be related to stretching of
the carotid and can be greatly reduced by correct slaughter procedures (13).
It has generally been assumed by many consumers that kosher meat is of a
better quality than non-kosher meat (9). (About 75% of purchasers of kosher
deli products in the US are not Jewish [28]). Dembo (8) suggested that this is
due to the greater degree of exsanguination, which is affected by a variety of
factors such as breed and age. Attempts to demonstrate that shechita results
in better quality of meat, as measured by hemoglobin concentration, pH,
water content or bacterial count, have been inconclusive (9, 29-31).
Recently it was demonstrated that the commonly used pneumatic bolt gun
injects brain tissue into lung (32) and other organs (T. Garland, personal
communication). Whether this injected brain material could actually result in
the spread of bovine spongiform encephalopathy (BSE) is highly speculative.
Defeathering
Warm scalding (58÷C) or steam defeathering (62÷C without immersion) are
prevalent industrial methods for defeathering. However, this presents the
halachic problem of “cooking” the meat prior to the removal of blood so that
cold scalding (maximal 7C÷) is used in the kosher meat industry. This
presents two problems: (1) poor defeathering and (2) employment of
additional defeathering machinery with resultant mechanical damage to the
skin.
In spite of research into the mechanism of feather attachment (33-36), the
problem of poor defeathering remains. Methods to improve defeathering by
cervical transection (35) or use of papain (34) have not been adopted by the
industry. Recently, there has been shown some renewed interest in a
modified cervical transection technique (M. Zaks, personal comm.).
Damage to the carcass
Extensive work on bacterial contamination and the method of defeathering
has recently been reported (37-41). The authors found striking differences in
skin topography using scanning electron microscopy and immunoflorescent
dyes when various methods were compared. Conventional defeathering (hot
scalding) results in a smooth skin surface to which bacteria are only loosely
attached. However rough surfaces, in which bacteria become entrapped or
embedded, are produced by both steam spraying and kosher defeathering.
These rough surfaces are very different from each other. The rough surface
produced by kosher defeathering is a result of the partial delamination of the
epidermis during the extended picking procedures. The surface produced by
steam spray defeathering is due to the total removal of the epidermis and
exposure of collagen in the dermis. However, in various reports (37,38), there
were fewer salmonella positive birds following koshering than following steam
or hot scalding defeathering, depending the conditions of the experiment. On
the other hand, Listeria (a bacterium which is salt and cold resistant)
contamination was higher in one kosher plant, which was related to the salting
process.
Two additional problems of carcass damage are skin tears (42) and skin
discoloration due to hemorrhage. Although the industry has conducted
projects to reduce these defects, these studies have not been reported in the
general scientific literature. These problems are of great economic importance
in countries with special classifications for the appearance of the carcass.
Salting
The amount of salt in chicken meat varies greatly depending on the halachic
stringency of the slaughterhouse and the site of sampling (43). In general, the
salt content in kosher poultry is about 4 times above the level for non-salted
poultry. The breast was found to have much less salt than the thigh and leg
(44). Soaking poultry meat in fresh water does not appreciably reduce the
salt content (about 15%) (45). On the other hand, salting of red meat does not
greatly increase the salt content as the salt penetrates less than 1 cm (J.
Regenstein, personal comm.). Recently, the problem of pollution by high salt
effluents from slaughterhouses has become a concern.
Identification of species
Identification of species has primarily centered on fish. The main problem is
whether the fish has “kosher” scales (ctenoid or
cycloid as opposed to ganoid or placoid) at some point in its life cycle and
whether the scales can be removed with reasonable force without tearing the
skin. Levinger (17) and Atz (46) have published extensive lists of kosher and
non-kosher fish. A related problem is the extent to which non-kosher fish are
caught and kept on board with kosher fish and this was the subject of a recent
industrial survey of tuna fishing. Although it was demonstrated 200 years ago
(47) that chemical methods can be used to determine the degree to which
scales can be removed, this technique has not met with wide acceptance.
(The debate about whether swordfish or eels are kosher has engendered
some scientific discussion, but is primarily a halachic concern.)
Iatrogenic “traifot”
Some of the various veterinary procedures which can result in traifot have
been reviewed by Levinger (17,48). It is not known today what the effect of
veterinary intervention is on the slaughterhouse incidence of traifot. Recently
there was a great deal of discussion on traifot caused by veterinary surgery,
primarily in cases of left displaced abomasum and bloat. The problem is
related more to the production of “Chalav Yisrael” milk than to post-mortem
traifot. The syndrome of left displaced abomasum has increased in recent
years both in the US and Europe, probably due to the higher nutritional level
associated with high milk yielding cows (49,50) . In Israel it may be related to
extensive use as feed of industrial surpluses, such as molasses. However,
Israeli veterinarians are well aware of the problem and perform surgery using
the “Dutch” method, which does not cause traifot. Interestingly, most (80%)
cases of displace abomasum in Israel occur after the switch from wheat silage
to corn silage and corn-based feeds which occurs before Passover (U. Bargai,
personal communication). Whether wheat silage is really hamatz, has been
the subject of a recent work by Zaks et al. [51].
Immunization
The problem of immunization causing traifot has been a subject of heated
debate between the Rabbinical and Veterinary communities in Israel for some
time. Although generally the inoculations are harmless, inoculations in the
thigh, neck, or wing have been reported to cause some local damage (52).
Fortunately, the invention of “in ovo” injection of vaccines (53) promises to
overcome this problem. This process, which has only recently become
commercially available, is being adopted by Israeli hatcheries.
The extent to which traifot in cattle are caused by modern husbandry is
largely unknown. In surveys performed in Israel in 1970-1971, the two
principal types of traifot in cattle were found to be foreign objects causing
perforation of the stomach wall and lung adhesions (16). The problem of
foreign object perforation can be greatly reduced by the placement of
magnets in the reticulum (54). Although magnets are widely used in Israel, the
extent that this has reduced traifot has not been documented.
Damage to the esophagus in force-fed geese was the subject of some
studies by Levinger (55,56). He found that attention to optimal pressure, the
correct length of the tube and the nature of the material used for tubing can
greatly reduce the damage to the esophagus. In chickens, the problem of leg
inflammation, which causes damage to tendons of the lower leg (Zomet
Hagidim), has received major attention from the Israeli Rabbinical
establishment. It is believed that this is a result of raising chickens on wire
floors, since the syndrome is not seen in chickens raised on deep litter.
Industrial surveys in Israel indicate that in some flocks the incidence of
damaged tendons can reach 15-20% (57).
In summary, scientific studies dealing with veterinary problems in the kosher
meat and poultry industry today can be characterized as sporadic, generally
out-of-date, and grossly underreported. Attempts by Dr. Levinger in Israel in
the early 1970’s to develop a scientific basis for research into these problems
was not continued due to lack of funding. Considering that the rapidly growing
kosher food market is one of the great success stories of recent decades, this
policy, or lack of it, on the part of funding agencies can at best be
characterized as short sighted. This is especially so as the kosher meat
industry must meet the new environmental, hygienic, and food quality
requirements which will seriously challenge its profitability in the near future
(58).
Scientific research on problems of halacha of veterinary interest is just one
area of halachic problems of concern to the veterinarian. Other topics of
interest include: cruelty to animals, treatment of animals on Shabbat and
Holidays, halachic requirements in raising and slaughtering livestock (e.g.
firstborn calf, milking on Shabbat) and problems of concern to the kosher
consumer (e.g. parasites in fish, blood spots in eggs).
Acknowledgments
I would like to thank Dr. Y. Klinger, Director of the Kimron Veterinary
Institute, Dr. J. Regenstein, Cornell University and Dr. I. Levinger for their
invaluable assistance in the preparation of this document.
References
1. Shore, A.: The role of animal dissections in determining Jewish Law.
BDD 4: 73-80, 1997. (In Hebrew).
2. Shore, A.: Identification of the first born calf. Halichot Sadeh 104:
51-55, 1997. (In Hebrew).
3. Shore, A.: Unusual animals and their description by the expounders
of the Mishneh and Talmud in the modern period. Korot 12: 7-15,
1996-1997. (In Hebrew).
4. Shore, L.S.: Efforts by Jewish Communities to Prevent Zoonoses,
Torah U-Madda. 1998. (In press).
5. Eybshutz, Y.: (1690-1767), Kartei U’Palti 40, Vienna. 1821. (In
Hebrew).
6. Vorst‫ה‬
orthodoxen Judenthums. Gutachen: Gutachten der hervorragendsten
Physiologen and Veterin‫ה‬r‫ה‬
‫ה‬cten. Buchbinderei
von Louis Golde, Frankfurt am Main. 1894.
7. Dembo,
I.A.:
Anatomisch-physiologische
Grundlagen
der
verschiednene methoden des Viehschlachtens. Saint-Petersburg.
1892.
8. Dembo, I. A.: The Jewish method of slaughter compared with other
methods. Kegan Paul, Trench and Trubnen, London. 1894.
9. Levinger, I.M.: Shechita in the light of the year 2000. Critical review
of the scientific aspects of methods of slaughter and shechita. Maskil
L’David, Jerusalem. 1995.
10. Hall, T.C.: Demonstration of a new Jewish method of casting and
slaughtering animals for food. Vet. Rec. 7: 765-766, 1927.
11. Hobday, F.: The Weinberg cattle-casting pen for Jewish
slaughtering. Vet. J. 83: 460-462, 1927.
12. Blackmore, D.K. and Delany M.W.: Slaughter of Stock Pub. 118.
Cont. Education. Massey University, Palmerston North New
Zealand. 1988.
13. Grandin, T. and Regenstein, J.M.: Religious slaughter and animal
welfare: a discussion for meat scientists. Meat Focus International 3:
115-123, 1994.
14. Munk, M.L. and Munk, E.: Shechita: Religious and Historical
Research on the Jewish Method of Slaughter and Medical Aspects
of Shechita. Gur Aryeh, Jerusalem. 1976.
15. Levinger, I.M.: Untersuchugen zum Sch‫ה‬chtproblem (Thesis),
16. Levinger, I.M.: Trephot in Animals - Theory and Practice. Torah
Institute for Research in Agriculture, Jerusalem. 1973. (In Hebrew).
17. Levinger, I.M.: Kosher Food from Animals. Torah Institute for
Research in Agriculture, Jerusalem, pp. 95-175, 1975. (In Hebrew).
18. Dunn, C.S.: Stress reactions of cattle undergoing ritual slaughter
using two methods of restraint. Vet. Rec. 126: 522-525, 1990.
19. Schulze, W., Schultze-Petzold, H., Hazem, A.S. and Gross, R.:
‫ה‬ubung)
sowie
religionsgestzlichen (“Sch‫ה‬chtschnitt”) Sclachtung von Schaf und
Kalb. Dtsch. Tier‫ה‬rztl. Wochenschr. 85:62-66, 1978.
20. Gregory, G. and Wotton, S.D.: Time of loss of brain responsiveness
following exsanguination in calves. Res. Vet. Sci. 37: 141-143,
1984.
21. Daly, C.C., Kallweit, E. and Ellendorf, F.: Cortical function in cattle
during slaughter: conventional captive bolt stunning followed by
exsanguination compared with shechita slaughter. Vet. Rec. 122:
325-329, 1988.
22. Bager, F., Braggins, T.J., Devine, C.E., Graafhus, A.E., Mellor, D.J.,
Taener, A. and Upsdell, M.P.: Onset of insensibility in calves:
Effects of electropletic seizure and exsanguination on the
spontaneous electrocortical activity and indices of cerebral
metabolism. Res. Vet. Sci. 52: 162-173, 1992.
23. Tume, R.K. and Shaw, F.D.: Beta endorphin and cortisol
concentration in plasma of blood samples collected during
exsanguination of cattle. Meat Science 31: 211-217, 1992.
24. Baldwin, B.A. and Bell, F.R.: Blood flow in the carotid and vertebral
arteries of the sheep and calf. J. Physiol. 167: 448-462, 1963.
25. Levinger, I.M. and Appel, N.: The anastomoses between the
vertebral artery and the rete mirabile epidurale in cattle. Refuah Vet.
23: 241244, 1966.
26. Brazier, M.A.: The historical development of neurophysiology. In:
Handbook of Physiology Section I: Neurophysiology Vol. 1, Amer.
Physiol. Soc.: Washington DC. pp.1-58. 1959.
27. Nangeroni, L.L and Kennett, P.D.: An electroencephalographic
study of the effect of shechita slaughter on cortical function of
ruminants. Report, Ithaca University, New York. 1963.
28. Judy, J.A.: Kosher consumers: Not who you think they are. Deli
Business Fall 1997: 51-54. 1997.
29. Kalweit E., Ellendorf F., Daly, C. and Smidt D.: Physiological
reactions during slaughter of cattle and sheep with and without
stunning. Dtsch. Tier‫ה‬rztl. Wschr. 96: 89-92, 1989.
30. Vimini, R.J., Field, R.A., Riley, M.A., Williams, J.C., Miller, G.J. and
Knigel, W.G.: Influence of delayed bleeding after stunning on beef
muscle characteristics. J. Anim. Sci. 56: 608-615, 1983.
31. Warriss, P.D.: Exsanguination of animals at slaughter and the
residual blood content of meat. Vet. Rec. 115: 292-295, 1984.
32. Garland, T., Bauer, N. and Bailey M. Jr.: Brain emboli in the lungs
of cattle after stunning. Lancet 348: 610, 1996.
33. Angel, S., Hyams, M. and Levinger I.M.: Scanning electron
microscope study of the feather follicle wall attachment in chickens.
Brit. Poultry Sci. 23: 247-249, 1982.
34. Angel, S., Hyams, M. and Levinger, I.M.: Loosening of the feather
follicle attachment by subcutaneous application of crude papain.
Brit. Poultry Sci. 23: 251-255, 1982.
35. Levinger, I.M. and Angel, S.: Effect of spinal cord transection on
feather follicle release in the slaughtered broiler. Brit. Poultry Sci.
18: 169-172, 1977.
36. Levinger, I.M., Angel, S. and Hyams, M.: Possible control
mechanisms of feather follicle movement in the pectoral tract of the
chicken. Vet. Res. Comm. 9: 153-162, 1985.
37. Clouser, C.S., Doores, S., Mast, M.G. and Knabel, S.J.: The role of
defeathering in the contamination of turkey skin by Salmonella
species and Listeria monocytogenes. Poultry Sci. 74: 723-731,
1995.
38. Clouser, C.S., Knabel, S.J., Mast, M.G. and Doores, S.: Effect of
type of defeathering system on Salmonella cross-contamination
during commercial processing. Poultry Sci. 74: 732-741, 1995.
39. Kim, J-W. and Doores, S.J.: Influence of three defeathering
systems on microtopography of turkey skin and adhesion of
Salmonella typhimurium. Food Prot. 56: 286-292, 1993.
40. Kim, J-W. and Doores, S. J.: Attachment of Salmonella typhimurium to
skins of turkey that had been defeathered: scanning electron microscopic
examination. J. Food Protection 56: 395-400, 1993.
41. Kim, J-W., Knabel, S.J. and Doores, S.J.: Penetration of Salmonella
typhimurium into turkey skin. J. Food Protection 56: 292-296, 1993.
42. Granot, I., Pines, M., Plavnick, I., Wax, E., Hurwitz, S. and Bartov, I.: Skin
tearing in broilers in relation to skin collagen: effect of sex, strain and diet.
Poultry Sci. 70: 1928-1935, 1991.
43. Angel, S. and Weinberg, Z.G.: Variation in salt content in broiler parts
from different kosher dressing plants in Israel. Poultry Sci. 65: 481-480,
1986.
44. Angel, S., Weinberg, Z.G. and Jaffe R.: Salt content of kosher chicken
parts studied under controlled conditions. J. Food Qual. 11: 365-373, 1989.
45. Burns, E.R. and Neubort, S.: Sodium content of kosher meat. JAMA 252:
2960, 1984.
46. Atz, J.W.: Appendix: Properly scaled fishes and non-kosher fishes. In:
Lipshultz, Y.: Kashruth, A comprehensive background and reference guide
to the principles of Kasruth. Mesorah, Brooklyn, NY, pp. 139-160. 1988.
47. Landau, Y.: (1713-1793), Nodeh B’yehudah, second section, #28, Vilna.
1904. (In Hebrew).
48. Levinger, I.M.: Milk from Trepha Cows. Tehudat Kashrut 4: 35-36, 1994.
(In Hebrew).
49. Coppock, C.E.: Displaced abomasum in dairy cattle: etiological factors. J.
Dairy Sci. 57: 926-933, 1973.
50.
Vorkommen von Labmagenverlangerungun (dislocatio abomasi) in
Milchrinderbest‫ה‬nden. Tier‫ה‬rztlich-Umschau. 47: 320-326, 1992,
51. Zaks, M., Klein, Y., Vanit, H., Cohen, A. and Leshem, Y.: Wheat silage is
not necessarily Chametz. Halichot Sadeh 101: 61-69, 1996. (In Hebrew).
52. Mutalib, A. and Boyle, C.R.: Influence of site of inoculation on inactivated
vaccines on the immune response in chickens. Avian Dis. 38: 857-860,
1994.
53. Ahmad, J. and Sharma, J.M.: Protection against hemorrhagic enteritis and
Newcastle disease in turkey by embryo vaccination with monovalent and
bivalent vaccines. Avian Dis. 37: 485-491, 1993.
54. St‫צ‬ber, M., Fischer, W. and Taffe, B.: Neues aus der Buiatrik:
‫ה‬figmagneten (Modell
Rinderklinik Hannover). Praktische Tierarzt 70: 65-66, 1988.
55. Levinger, I.M.: Treifot in fowl: appearance, incidence and causes. Torah
U’Madah 3: 23-28, 1973. (In Hebrew).
56. Leveinger, I.M.: Ability of the (goose) esophagus to withstand force
feeding. Torah U’Madah 1: 35-38, 1975.
57. Ben Zvi, Y.: Tzomet hagidim in chickens. Tehudat Kashrut 11: 3-7, 1996.
(In Hebrew).
58. Krizner, K. and Aylward, L.: Inspection under the microscope. Meat
Marketing & Technology, Sept., 1995
ISRAEL JOURNAL