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Blood Loss by Chickens during Killing1
Blood Loss by Chickens During Killing1 GEORGE W. NEWELL 2 AND C. S. SHAFFNER
Poultry Department, University cf Maryland, College Park (Received for publication October 3, 1949)
I
1 Scientific Paper No. A255. Contribution No. 2190 of the Maryland Agricultural Experiment Station (Department of Poultry Husbandry). 2 Present address: College of Agriculture, University of Missouri, Columbia, Missouri.
ess. Newell and Shaffner (1950) have presented data showing the total quantity of blood in New Hampshire chickens of different weights and sex. Using the results as presented by them, the completeness of bleeding can be determined by comparing the actual loss of blood from an individual with the volume of blood calculated to be present in the same bird, This latter figure can be obtained by interpolation from their curves for blood volume. This report concerns a study of procedures which it was thought might influence the percentage of the total blood of the body that is lost in the dressing operation. MATERIALS AND METHODS
The simplest and most accurate method of determining blood loss proved to be by weighing the birds before and after bleeding. Since the birds were fasted for 12 hours previous to slaughter, little trouble was experienced from defecation or from regurgitation during the dying struggles; however, careful watch was kept and if any such loss occurred the bird was discarded. Three groups of 60 New Hampshire chickens each were killed by three different methods: (1) by severing the jugular vein by cutting through the skin of the throat similar to "Kosher" killing, although no attempt was made to be sure the trachea or esophagus was cut; (2) by severing the jugular vein in the conventional manner of inserting the knife into the mouth and also debrainihg the bird; (3) by beheading.
271
Downloaded from http://ps.oxfordjournals.org/ at Dalhousie University on May 17, 2015
N PROCESSIN G poultry for market, the total and relative amount of blood lost through bleeding has always been of interest from the economic standpoint as well as with respect to the appearance of the dressed poultry. Since a large percentage of the blood of the chicken's body is located in the small veins and capillaries, much of the blood remains in the body of the bird after death. This blood is present in the carcass of the bird when consumed, the larger blood vessels appearing as black strings. The accepted value for the loss of blood and feathers is 10 to 11 percent of the body weight. The loss due to blood alone is very seldom separated from total loss. Vernon (1923), quoting U.S.D.A. Bulletin 1052, shows a loss of 3.3 to 4.0 percent due to blood for hens and broilers, respectively. Mitchell, Card, and Hamilton (1926) report similar results for White Plymouth Rock hens and cockerels. Jull and Maw (1923), reporting on a study of 165 fattened roosters, found the blood loss to be 4.0 + 0.19 percent of the body weight. Vondell (1948) found that bleeding was complete in 50 seconds for a group of adult Rhode Island Reds and that in that length of time they had lost 3.4 percent of the body weight. These results gave no indication of the percentage of the total blood volume which was lost during the bleeding proc-
272
GEORGE W. NEWELL AND C. S. SHAFFNER
ator at 40° F. for 15 hours after which they were placed in a deep freezer at — 10°F. for five hours. I t was observed that the combs and feet of many of these birds were frozen upon removal from the crates, but otherwise no detrimental effects of the low temperature could be seen. Another group of 15 males and 12 females was placed in a room in which the temperature was held between 85° and 92°F. for 20 hours. A control group of 14 males and 9 females was held at ordinary room temperature (70°F.) for approximately the same length of time. All of these groups were killed by the "Kosher" method immediately upon removal from the respective rooms. RESULTS AND DISCUSSION The results of the test comparing blood loss by the different methods of killing are presented in Table 1. These results show that chickens lose between 35 and 50 percent of the blood of the body during the bleeding period. There is considerable variation among individuals regardless of the method of killing employed. In all cases the highest percentage of blood was lost by those chickens which were "Kosher" killed, and the least by those which were beheaded. The loss of blood TABLE 1.—The cubic centimeters of blood lost per 100 cc. of total blood volume by chickens killed by different methods Method of killing* Group
Kosher
Stuck
Beheaded
46.817.8 43.1±5.1
45.6±3.0 38.7±4.2
F-^ISSrot
48.3±5. 43.3±6.
45.4±5.9 43.6±4.8
41.6±S.O 35.7±2.4 38.9±6.1 40.4±4.6
Av. all males Av. all females
44.8±6.8 45.716.4
41.9±5.1 44.5±5.5
38.5±S.l 39.515.9
Av. all treated Av. all controls
47.616. 43.2±6.
45.514.7 41.1±4.8
40.115.9 37.914.6
Over-all average
45.316.3
43.215.8
39.015.6
* Thirty birds of each sex were killed by each method. t Treated birds had received 0.2 percent thiouracil plus 0.0022 percent thyroprotein in the ration for five weeks prior to killing.
Downloaded from http://ps.oxfordjournals.org/ at Dalhousie University on May 17, 2015
One-half of each group of birds available for this study had been on a ration containing 0.2 percent thiouracil plus one gram of thyroprotein per hundred weight for five weeks prior to killing. Newell and Shaffner (1950) have shown that birds on this type of ration contained relatively less blood per unit of body weight than untreated birds. Epinepherine, the active principle of the medulla of the adrenal gland, when injected intravenously causes the blood pressure to rise sharply and as it approaches its maximum, the heart beats are greatly slowed and strengthened. This effect occurs very rapidly and soon returns to normal. Epinepherine also produces a very powerful vasoconstriction, particularly in the peripheral capillaries and small veins. Thus, it was felt that with these effects increased bleeding as well as a blanching of the skin might result from the injection of epinepherine. The action of epinepherine injected subcutaneously is the same as when injected intravenously except that it is slower. Because of the danger of hemorrhage, it was decided to use the subcutaneous injection and wait for 30 minutes for the full effect to manifest itself. After the injection of epinepherine, observation of the birds indicated a nervous reaction in that they were continually picking and preening themselves. This was true at all of the levels of injection. Thirty minutes after the injection, the birds were killed by severing the jugular vein similar to "Kosher" killing. I t was thought that extremes in environmental temperature might shed some light on the cause of incomplete bleeding. To test the effect of holding temperature on completeness of bleeding, 14 New Hampshire males and 11 females, each weighing approximately 1600 grams, were placed in coops and held in a refriger-
BLOOD LOSS BY CHICKENS DURING KILLING
273
"Kosher"-killed birds exhibited greater variability in blood loss than the birds killed by either of the other two methods. This is probably because of the greater variation possible in making the cut by this method. Very little difference exists between the standard deviations for the blood loss of the two sexes, indicating that individual variation within each is about TABLE 2.—Grams of blood lost per 100 grams of live the same. weight of New Hampshire chickens The blood loss of the birds in this test, Method of killing calculated as a percentage of body weight, Group is shown in Table 2. Only slight differKosher Stuck Beheaded ences between sexes or methods of killing 4.0 4.1 3.6 were evident. The differences in blood loss 4.4 4.0 3.7 between the different methods of killing 3.2 3.8 3.6 follow closely the same data discussed on 4.0 4.0 3.6 blood loss as a percentage of total blood 4.1 3.9 Average 3.5 volume. The blood loss from the chickens inthe differences between the blood loss by jected with various levels of epinepherine either of these methods and by the be- is shown in Figure 1. There is a minimum headed birds is highly significant statistically to the one percent level. Females Blood loss percent tended to lose a higher percentage of their blood than males, although the difference is not statistically significant. I t has previously been pointed out that male ~"**^_ "have considerably more blood in relation \ to body weight than females. Since the \ S sex difference in blood loss as a percentS age of blood volume is small, this leads to the conclusion that loss of blood at death Hales is more closely related to the volume of _ Females blood in the body than to body weight. Throughout this test, the thiouraciltreated birds tended to lose a slightly higher percentage of the volume of the blood in the body than the untreated birds. However, this difference may have been due to error in correcting for the 0 .05 .XO .20 .30 .Ml .50 effect of the thiouracil treatment on blood Milliliters epinepherine solution (1-1000) per bird volume. FIG. 1. The percentage of the total blood of the As was stated earlier, there was con- body lost during the bleeding period following subsiderable individual variation in blood cutaneous injections of various levels of epinepheloss by all of the methods of killing. The rine.
by chickens which were killed by the conventional method of sticking and debraining agrees closely with that of the "Kosher"-killed birds. The difference between the blood loss of the "Kosher" method of killing and the stuck-and-debrained method of killing is not statistically significant. However,
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Downloaded from http://ps.oxfordjournals.org/ at Dalhousie University on May 17, 2015
**• {5SS
274
GEORGE W. NEWELL AND C. S. SHAFFNER
of 5 and a maximum of 8 birds represented in the average for each level. The control birds received no injection and all groups were comparable in age and weight. Males and females are represented by different lines although the difference between the sexes is not significant statistically. Examination of the graph presented in Figure 1 shows that there is very little difference in blood loss between the con-
Downloaded from http://ps.oxfordjournals.org/ at Dalhousie University on May 17, 2015
control room temperatures and least in those birds held in the cold room. Although the number of chickens in each group was rather small, additional studies with larger numbers might disclose an effect of environmental temperatures during the period of holding the birds in the feeding station prior to killing. General observations during all of these trials have indicated that coagulation of blood is not the determining factor on how TABLE 3.—Showing the blood loss by chickens held in completely bled the carcass of the bird hot, cold, and control room temperatures appears after death. The amount of bleedCc. blood loss ing seems to be more closely related to the No. per 100 cc. of p cessation of heart action. It was felt that birds total blood volume if anoxia leads to the cessation of the heart beat, super oxygenation might be 'Males 41.9±2.9 15 Females 12 47.3 ±2.8 effective in maintaining the action of the heart muscles a little longer and thus 14 39.6 + 5.0 'Males 11 Females 45.3 + 4.7 pump more blood from the body. In order to test the anoxia theory, two male birds 14 47.2 + 3.3 'Males 48.8 + 4.2 Females 9 each weighing approximately 1400 grams were forced to breathe in an atmosphere of pure oxygen for approximately two mintrols (0 level) and any of the levels of utes. The birds were killed by the epinepherine used: however, there ap"Kosher" method and again enclosed in a pears to be a tendency for the higher bag containing pure oxygen until bleedlevels of epinepherine to decrease blood loss. The vasoconstriction and the in- ing was complete. The blood loss from creased blood pressure which resulted these two birds was only 41 and 44 perfrom the injection of the epinepherine cent of the total blood volume, respecwas ineffective in causing either an in- tively. These values closely approximate crease in blood loss or an improved ap- those reported in other parts of this study. pearance of the dressed carcass. The results of the above trials indicate The cubic centimeters of blood lost that it is very difficult to increase appreper 100 cc. of total blood volume for the ciably the percentage of the total blood birds held at different environmental that is lost during the normal bleeding temperatures is shown in Table 3. operation. The decrease in blood loss by Although the extremes in environmental the birds that were beheaded probably temperatures did not increase the blood was the result of the severing of the loss, a careful study of some of the differ- nervous control to the heart and debrainences shown in Table 3 brings out some ing probably had a similar effect. It was interesting points. Individual variation in apparent throughout the trials that there blood loss was greatest in the group of was little correlation between the perchickens held in the cold room and least centage of blood loss and the appearance among those birds in the hot room. Blood of the bird as regards degree of bleeding. loss was greatest in those birds held at It is thus the feeling of the authors that
BLOOD LOSS BY CHICKENS DURING KILLING
much of the difference reported by dressing plants between the bleeding characteristics of different lots of birds is the result of differences in degree of fattening and perhaps amount of peripheral blood rather than an actual difference in the amount of blood lost. CONCLUSIONS
body when killed by any of the three methods tested. Epinepherine injections, extremes in environmental temperatures, and the breathing of pure oxygen prior to killing were ineffective in increasing the percentage of blood lost or improving the appearance of the dressed carcass of chickens. The amount of blood lost is more closely associated with total blood volume than with body weight. REFERENCES Jull, M. A. and W. A. Maw, 1923. Determinations of the dressed, drawn, and edible percentage of various kinds of domestic birds. Sci. Agr. 3: 329-338. Mitchell, H. H., L. E. Card and T. S. Hamilton, 1926. The growth of White Plymouth Rock chickens. 111. Agr. Exp. Sta. Bull. 278: 132. Newell, G. W. and C. S. Shaffner, 1950. Blood volume determinations in chickens. Poultry Sci. 29: 78-87. Vernon, W. M., 1923. Losses sustained in preparing poultry for the table. Poultry Sci. 3: 187-193. Vondell, J. H., 1948. Some factors in killing chickens. Feathered-fax. Jan. 15, 1948.
Downloaded from http://ps.oxfordjournals.org/ at Dalhousie University on May 17, 2015
Chickens lose between 35 and 50 percent of the total blood of the body during the bleeding phase of the killing operation with considerable individual variation in blood loss. With broilers, this corresponds to approximately 4 percent of the live weight. "Kosher"-killed birds and birds which were stuck and debrained lost significantly larger percentages of the blood in the body than did birds which had been decapitated. Males and females lost approximately the same percentage of the blood in the
275
Poultry Department, University cf Maryland, College Park (Received for publication October 3, 1949)
I
1 Scientific Paper No. A255. Contribution No. 2190 of the Maryland Agricultural Experiment Station (Department of Poultry Husbandry). 2 Present address: College of Agriculture, University of Missouri, Columbia, Missouri.
ess. Newell and Shaffner (1950) have presented data showing the total quantity of blood in New Hampshire chickens of different weights and sex. Using the results as presented by them, the completeness of bleeding can be determined by comparing the actual loss of blood from an individual with the volume of blood calculated to be present in the same bird, This latter figure can be obtained by interpolation from their curves for blood volume. This report concerns a study of procedures which it was thought might influence the percentage of the total blood of the body that is lost in the dressing operation. MATERIALS AND METHODS
The simplest and most accurate method of determining blood loss proved to be by weighing the birds before and after bleeding. Since the birds were fasted for 12 hours previous to slaughter, little trouble was experienced from defecation or from regurgitation during the dying struggles; however, careful watch was kept and if any such loss occurred the bird was discarded. Three groups of 60 New Hampshire chickens each were killed by three different methods: (1) by severing the jugular vein by cutting through the skin of the throat similar to "Kosher" killing, although no attempt was made to be sure the trachea or esophagus was cut; (2) by severing the jugular vein in the conventional manner of inserting the knife into the mouth and also debrainihg the bird; (3) by beheading.
271
Downloaded from http://ps.oxfordjournals.org/ at Dalhousie University on May 17, 2015
N PROCESSIN G poultry for market, the total and relative amount of blood lost through bleeding has always been of interest from the economic standpoint as well as with respect to the appearance of the dressed poultry. Since a large percentage of the blood of the chicken's body is located in the small veins and capillaries, much of the blood remains in the body of the bird after death. This blood is present in the carcass of the bird when consumed, the larger blood vessels appearing as black strings. The accepted value for the loss of blood and feathers is 10 to 11 percent of the body weight. The loss due to blood alone is very seldom separated from total loss. Vernon (1923), quoting U.S.D.A. Bulletin 1052, shows a loss of 3.3 to 4.0 percent due to blood for hens and broilers, respectively. Mitchell, Card, and Hamilton (1926) report similar results for White Plymouth Rock hens and cockerels. Jull and Maw (1923), reporting on a study of 165 fattened roosters, found the blood loss to be 4.0 + 0.19 percent of the body weight. Vondell (1948) found that bleeding was complete in 50 seconds for a group of adult Rhode Island Reds and that in that length of time they had lost 3.4 percent of the body weight. These results gave no indication of the percentage of the total blood volume which was lost during the bleeding proc-
272
GEORGE W. NEWELL AND C. S. SHAFFNER
ator at 40° F. for 15 hours after which they were placed in a deep freezer at — 10°F. for five hours. I t was observed that the combs and feet of many of these birds were frozen upon removal from the crates, but otherwise no detrimental effects of the low temperature could be seen. Another group of 15 males and 12 females was placed in a room in which the temperature was held between 85° and 92°F. for 20 hours. A control group of 14 males and 9 females was held at ordinary room temperature (70°F.) for approximately the same length of time. All of these groups were killed by the "Kosher" method immediately upon removal from the respective rooms. RESULTS AND DISCUSSION The results of the test comparing blood loss by the different methods of killing are presented in Table 1. These results show that chickens lose between 35 and 50 percent of the blood of the body during the bleeding period. There is considerable variation among individuals regardless of the method of killing employed. In all cases the highest percentage of blood was lost by those chickens which were "Kosher" killed, and the least by those which were beheaded. The loss of blood TABLE 1.—The cubic centimeters of blood lost per 100 cc. of total blood volume by chickens killed by different methods Method of killing* Group
Kosher
Stuck
Beheaded
46.817.8 43.1±5.1
45.6±3.0 38.7±4.2
F-^ISSrot
48.3±5. 43.3±6.
45.4±5.9 43.6±4.8
41.6±S.O 35.7±2.4 38.9±6.1 40.4±4.6
Av. all males Av. all females
44.8±6.8 45.716.4
41.9±5.1 44.5±5.5
38.5±S.l 39.515.9
Av. all treated Av. all controls
47.616. 43.2±6.
45.514.7 41.1±4.8
40.115.9 37.914.6
Over-all average
45.316.3
43.215.8
39.015.6
* Thirty birds of each sex were killed by each method. t Treated birds had received 0.2 percent thiouracil plus 0.0022 percent thyroprotein in the ration for five weeks prior to killing.
Downloaded from http://ps.oxfordjournals.org/ at Dalhousie University on May 17, 2015
One-half of each group of birds available for this study had been on a ration containing 0.2 percent thiouracil plus one gram of thyroprotein per hundred weight for five weeks prior to killing. Newell and Shaffner (1950) have shown that birds on this type of ration contained relatively less blood per unit of body weight than untreated birds. Epinepherine, the active principle of the medulla of the adrenal gland, when injected intravenously causes the blood pressure to rise sharply and as it approaches its maximum, the heart beats are greatly slowed and strengthened. This effect occurs very rapidly and soon returns to normal. Epinepherine also produces a very powerful vasoconstriction, particularly in the peripheral capillaries and small veins. Thus, it was felt that with these effects increased bleeding as well as a blanching of the skin might result from the injection of epinepherine. The action of epinepherine injected subcutaneously is the same as when injected intravenously except that it is slower. Because of the danger of hemorrhage, it was decided to use the subcutaneous injection and wait for 30 minutes for the full effect to manifest itself. After the injection of epinepherine, observation of the birds indicated a nervous reaction in that they were continually picking and preening themselves. This was true at all of the levels of injection. Thirty minutes after the injection, the birds were killed by severing the jugular vein similar to "Kosher" killing. I t was thought that extremes in environmental temperature might shed some light on the cause of incomplete bleeding. To test the effect of holding temperature on completeness of bleeding, 14 New Hampshire males and 11 females, each weighing approximately 1600 grams, were placed in coops and held in a refriger-
BLOOD LOSS BY CHICKENS DURING KILLING
273
"Kosher"-killed birds exhibited greater variability in blood loss than the birds killed by either of the other two methods. This is probably because of the greater variation possible in making the cut by this method. Very little difference exists between the standard deviations for the blood loss of the two sexes, indicating that individual variation within each is about TABLE 2.—Grams of blood lost per 100 grams of live the same. weight of New Hampshire chickens The blood loss of the birds in this test, Method of killing calculated as a percentage of body weight, Group is shown in Table 2. Only slight differKosher Stuck Beheaded ences between sexes or methods of killing 4.0 4.1 3.6 were evident. The differences in blood loss 4.4 4.0 3.7 between the different methods of killing 3.2 3.8 3.6 follow closely the same data discussed on 4.0 4.0 3.6 blood loss as a percentage of total blood 4.1 3.9 Average 3.5 volume. The blood loss from the chickens inthe differences between the blood loss by jected with various levels of epinepherine either of these methods and by the be- is shown in Figure 1. There is a minimum headed birds is highly significant statistically to the one percent level. Females Blood loss percent tended to lose a higher percentage of their blood than males, although the difference is not statistically significant. I t has previously been pointed out that male ~"**^_ "have considerably more blood in relation \ to body weight than females. Since the \ S sex difference in blood loss as a percentS age of blood volume is small, this leads to the conclusion that loss of blood at death Hales is more closely related to the volume of _ Females blood in the body than to body weight. Throughout this test, the thiouraciltreated birds tended to lose a slightly higher percentage of the volume of the blood in the body than the untreated birds. However, this difference may have been due to error in correcting for the 0 .05 .XO .20 .30 .Ml .50 effect of the thiouracil treatment on blood Milliliters epinepherine solution (1-1000) per bird volume. FIG. 1. The percentage of the total blood of the As was stated earlier, there was con- body lost during the bleeding period following subsiderable individual variation in blood cutaneous injections of various levels of epinepheloss by all of the methods of killing. The rine.
by chickens which were killed by the conventional method of sticking and debraining agrees closely with that of the "Kosher"-killed birds. The difference between the blood loss of the "Kosher" method of killing and the stuck-and-debrained method of killing is not statistically significant. However,
^ale, {g-a
""
—N.
Downloaded from http://ps.oxfordjournals.org/ at Dalhousie University on May 17, 2015
**• {5SS
274
GEORGE W. NEWELL AND C. S. SHAFFNER
of 5 and a maximum of 8 birds represented in the average for each level. The control birds received no injection and all groups were comparable in age and weight. Males and females are represented by different lines although the difference between the sexes is not significant statistically. Examination of the graph presented in Figure 1 shows that there is very little difference in blood loss between the con-
Downloaded from http://ps.oxfordjournals.org/ at Dalhousie University on May 17, 2015
control room temperatures and least in those birds held in the cold room. Although the number of chickens in each group was rather small, additional studies with larger numbers might disclose an effect of environmental temperatures during the period of holding the birds in the feeding station prior to killing. General observations during all of these trials have indicated that coagulation of blood is not the determining factor on how TABLE 3.—Showing the blood loss by chickens held in completely bled the carcass of the bird hot, cold, and control room temperatures appears after death. The amount of bleedCc. blood loss ing seems to be more closely related to the No. per 100 cc. of p cessation of heart action. It was felt that birds total blood volume if anoxia leads to the cessation of the heart beat, super oxygenation might be 'Males 41.9±2.9 15 Females 12 47.3 ±2.8 effective in maintaining the action of the heart muscles a little longer and thus 14 39.6 + 5.0 'Males 11 Females 45.3 + 4.7 pump more blood from the body. In order to test the anoxia theory, two male birds 14 47.2 + 3.3 'Males 48.8 + 4.2 Females 9 each weighing approximately 1400 grams were forced to breathe in an atmosphere of pure oxygen for approximately two mintrols (0 level) and any of the levels of utes. The birds were killed by the epinepherine used: however, there ap"Kosher" method and again enclosed in a pears to be a tendency for the higher bag containing pure oxygen until bleedlevels of epinepherine to decrease blood loss. The vasoconstriction and the in- ing was complete. The blood loss from creased blood pressure which resulted these two birds was only 41 and 44 perfrom the injection of the epinepherine cent of the total blood volume, respecwas ineffective in causing either an in- tively. These values closely approximate crease in blood loss or an improved ap- those reported in other parts of this study. pearance of the dressed carcass. The results of the above trials indicate The cubic centimeters of blood lost that it is very difficult to increase appreper 100 cc. of total blood volume for the ciably the percentage of the total blood birds held at different environmental that is lost during the normal bleeding temperatures is shown in Table 3. operation. The decrease in blood loss by Although the extremes in environmental the birds that were beheaded probably temperatures did not increase the blood was the result of the severing of the loss, a careful study of some of the differ- nervous control to the heart and debrainences shown in Table 3 brings out some ing probably had a similar effect. It was interesting points. Individual variation in apparent throughout the trials that there blood loss was greatest in the group of was little correlation between the perchickens held in the cold room and least centage of blood loss and the appearance among those birds in the hot room. Blood of the bird as regards degree of bleeding. loss was greatest in those birds held at It is thus the feeling of the authors that
BLOOD LOSS BY CHICKENS DURING KILLING
much of the difference reported by dressing plants between the bleeding characteristics of different lots of birds is the result of differences in degree of fattening and perhaps amount of peripheral blood rather than an actual difference in the amount of blood lost. CONCLUSIONS
body when killed by any of the three methods tested. Epinepherine injections, extremes in environmental temperatures, and the breathing of pure oxygen prior to killing were ineffective in increasing the percentage of blood lost or improving the appearance of the dressed carcass of chickens. The amount of blood lost is more closely associated with total blood volume than with body weight. REFERENCES Jull, M. A. and W. A. Maw, 1923. Determinations of the dressed, drawn, and edible percentage of various kinds of domestic birds. Sci. Agr. 3: 329-338. Mitchell, H. H., L. E. Card and T. S. Hamilton, 1926. The growth of White Plymouth Rock chickens. 111. Agr. Exp. Sta. Bull. 278: 132. Newell, G. W. and C. S. Shaffner, 1950. Blood volume determinations in chickens. Poultry Sci. 29: 78-87. Vernon, W. M., 1923. Losses sustained in preparing poultry for the table. Poultry Sci. 3: 187-193. Vondell, J. H., 1948. Some factors in killing chickens. Feathered-fax. Jan. 15, 1948.
Downloaded from http://ps.oxfordjournals.org/ at Dalhousie University on May 17, 2015
Chickens lose between 35 and 50 percent of the total blood of the body during the bleeding phase of the killing operation with considerable individual variation in blood loss. With broilers, this corresponds to approximately 4 percent of the live weight. "Kosher"-killed birds and birds which were stuck and debrained lost significantly larger percentages of the blood in the body than did birds which had been decapitated. Males and females lost approximately the same percentage of the blood in the
275