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Some Observations Concerning the Period of Fasting Poultry Before Slaughter1
Some Observations Concerning the Period of Fasting Poultry Before Slaughter1 JAMES M. GWIN, GEORGE W. NEWELL AND MORLEY A. JULL
University of Maryland, College Park, Md.
T
HE effect of fasting broilers and fryers has been studied to determine a fasting period best suited to commercial operations. Many current poultry texts and bulletins recommend the withholding of feed from birds for twenty-four hours before slaughter. Commercial processors, and especially those in the broiler areas, follow the practice of slaughtering birds that have been full fed (fed up to time of slaughter) or have had feed withheld for periods of from only one to six hours. Many commercial processors operate without definite knowledge or rules relating to the proper length of the fasting period. They often follow the established commercial practice in their area without definite data to support their opinions. Many producers and small processors follow the long-established recommendation of a twenty-four hour fasting period, which, according to the results reported herein, indicates that it is an uneconomical practice and a much longer time than needed to accomplish the desired results. Schwarz and Teller (1924), as quoted by Heuser (1945), found great variations in the time that feed remains in the crop of the bird. Keith, Card, and Mitchell (1927) 1
Scientific paper No. A206. Contribution No. 2123 of the Maryland Agricultural Experiment Station (Department of Poultry Husbandry). Coordinated with Northeastern Poultry Marketing Studies.
observed the same condition. They also found that increasing the moisture content of the feed decreased the time required to move it through the crop. Heuser (1945) confirms the findings of both groups and gives a further explanation of the factors involved. He believes that the rate of movement of the feed from the crop is influenced by the amount of feed consumed, the period of time since the bird received feed, the individual bird differences, the mechanical condition of the feed, and the moisture content of the feed. Heuser (1947) reports that soft feed has been known to pass through the intestinal tract of a bird within two to three hours after ingestion. MATERIALS AND METHODS
A total of 190 cage and floor-grown broilers and fryers were used in three tests. Special effort was made to subject the birds to conditions similar to those existing during transporting, holding, and fattening in commercial broiler processing plants. The birds were first divided into lots of equal numbers and moved to fattening batteries. They were permitted to remain in these batteries with wet mash before them for approximately one full day. They were then weighed individually. During the following 24 hours, the wet mash was withdrawn according to predetermined fasting periods for different lots.
229
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on May 30, 2015
(Received for publication August 18, 1948)
230
JAMES M. GWIN, GEORGE W. NEWELL AND MOELEY A. JULL
All birds were given water when the wet mash was removed. At the conclusion of the 24-hour period, the birds were again weighed, slaughtered, and dressed on commercial dressing equipment. The intestinal tract was removed from each bird and individually weighed. All food and liquid was then removed from the intestinal tract, and weights were made to determine the quantity present.
period, the weight loss per bird averaged 75.2 grams. Approximately one-third of this was loss of food from the intestinal tract. The remaining two-thirds was loss of body weight. Converting this to dressing plant figures, it would mean a loss of about 125 pounds per thousand birds or approximately two ounces per bird. The primary purpose of withholding feed from birds is to empty the intestinal tract in order to save time in eviscerating or to prevent fecal matter from oozing from the dressed birds during the market-
The full-fed birds received wet mash from the start of the experiment until they were removed for weighing and slaughter. These birds showed the greatest average gain in body weight, but the weight of the contents of their intestinal tracts averaged less than in the one and two-hour fasted lots. This is accounted for by excessive water consumption on the part of the latter two groups. When commercial dressers slaughter full-fed birds, they are "milked" and "vented" as a part of the dressing operation. "Milking" is the proc-
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on May 30, 2015
ing process. It was found that it is not practical to withhold feed for the period of time required to completely empty the intestinal tract. The ceca appears to remain full longer than the other parts of the intestinal tract. In this connection, it was observed that in the birds from which feed had been withheld for 24 hours, the cecas contained almost as much material as was found in the cecas of the full-fed birds. It will be noted in Table 1 that more RESULTS material was found in the intestinal tract Table 1 shows the average change in of the birds that had been fasted five and live weight according to fasting period and six hours than in those that had been the average amount of feed remaining in fasted only three and four hours. This is the intestinal tract at the end of the 24- accounted for by the fact that after about hour period. three or four hours of fasting, the birds started drinking large quantities of water TABLE 1.—The effects offasting on live weight and on to appease their hunger. It was observed the amount of feed remaining in the intestinal tract that the intestinal tracts of the birds that weight had fasted for five and six hours contained Average live Average of feed remainweight change ing in intestinal the most liquid material. The practice of Fasting period per drinking water to appease hunger gradubird during after 24-hour period tract ally decreases. The period of excessive slaughter drinking varies widely with individual Grams Grams birds and is probably related to existing 24-hour fast -75.2 21.6 6-hour fast + 7.5 40.2 room temperature. This also accounts in 5-hour fast +10.1 37.6 part for the average gain in body weight of +11.3 4-hour fast 30.5 +16.1 31.5 3-hour fast the birds that underwent the five and six+20.5 49.0 2-hour fast hour fast periods. Considerable variation +22.3 49.5 1-hour fast +44.3 43.9 Full-fed (no fast) was found in the individual birds of these groups, with several showing a slight When feed was withheld for a 24-hour weight loss.
PERIOD OF FASTING POULTRY BEFORE SLAUGHTER
It is recognized that commercial dressers frequently encounter conditions that make it necessary to kill full-fed birds. These conditions may be the result of a sudden change in killing schedule, emergency orders, or miscalculations between the killing and fattening rooms. In cases of this kind, the "milking" and "venting" methods must be employed. If the birds are to be eviscerated in the same plant, the material in Table 1 indicates that the full-fed method may offer some weight advantages. GENERAL DISCUSSION The results obtained indicate that the average bird will lose about ^ of its intestinal contents during the first 3 to 4 hours of fasting. A slight increase in intestinal content will usually occur during the next three hours due to the increased intake of water. There will then be a gradual decrease until approximately 50 percent of the intestinal contents have been expelled at the end of a 24-hour period. The 3- to 4-hour fasting period will normally empty the crop and reduce the pressure on the intestines to the point
where they will withstand the normal handling in the course of the marketing process. Thus, according to the results of this experiment, the best fasting period would appear to be between 3 and 4 hours. This would reduce the contents of the intestinal tract by about § and would not produce excessive losses in body weight. The average weight changes between the one and six-hour fasting periods show a gradual decrease, but the differences are slight and are not statistically significant. However, a significant difference exists between those on full feed and those on a 24-hour fast and between both of these groups and all others. Although no attempt was made in this experiment to measure the amount or significance of moisture, it is acknowledged that it plays an important part, both in weight and appearance of the product. An experiment similar to this that would withhold water as well as feed should produce some interesting results. SUMMARY Under the conditions of this experiment, the long-established recommendation of a 24-hour fasting period is far too long and uneconomical; however, the slaughter of full-fed birds may offer some weight advantages to those who kill for immediate consumption. For best results in marketing practically all dressed poultry, the withholding of feed from three to four hours appears to be the most practical fasting period. REFERENCES
Heuser, G. F., 1945. The irate of passage of feed from the crop of the hen. Poultry Sci. 24: 20-24. , 1947. Feeding Poultry. John Wiley & Sons, Inc. New Yofky'New York. Keith, M. H.,"H. E. Card, and H. H. Mitchell, 1927. The rate of passage of food through the digestive tract of the hen. Jour. Agr. Res. 34: 759-769. ;--
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on May 30, 2015
ess of squeezing the excessive mash and moisture from the crop by pressure that forces it from the mouth of the dead bird. "Venting" consists of squeezing the vent and forcing out the excessive fecal matter. The relatively small amount of fecal material that can be pressed from the full-fed birds is usually not enough to prevent additional quantities from oozing out of the birds that are placed in the lower layers of the conventional barrel or crate of iced poultry. This results in an objectionable unsanitary condition. Birds with full intestines are a trade hazard on a normal market, but in times of light supply and heavy demand, the killing of full-fed birds is a common trade practice.
231
University of Maryland, College Park, Md.
T
HE effect of fasting broilers and fryers has been studied to determine a fasting period best suited to commercial operations. Many current poultry texts and bulletins recommend the withholding of feed from birds for twenty-four hours before slaughter. Commercial processors, and especially those in the broiler areas, follow the practice of slaughtering birds that have been full fed (fed up to time of slaughter) or have had feed withheld for periods of from only one to six hours. Many commercial processors operate without definite knowledge or rules relating to the proper length of the fasting period. They often follow the established commercial practice in their area without definite data to support their opinions. Many producers and small processors follow the long-established recommendation of a twenty-four hour fasting period, which, according to the results reported herein, indicates that it is an uneconomical practice and a much longer time than needed to accomplish the desired results. Schwarz and Teller (1924), as quoted by Heuser (1945), found great variations in the time that feed remains in the crop of the bird. Keith, Card, and Mitchell (1927) 1
Scientific paper No. A206. Contribution No. 2123 of the Maryland Agricultural Experiment Station (Department of Poultry Husbandry). Coordinated with Northeastern Poultry Marketing Studies.
observed the same condition. They also found that increasing the moisture content of the feed decreased the time required to move it through the crop. Heuser (1945) confirms the findings of both groups and gives a further explanation of the factors involved. He believes that the rate of movement of the feed from the crop is influenced by the amount of feed consumed, the period of time since the bird received feed, the individual bird differences, the mechanical condition of the feed, and the moisture content of the feed. Heuser (1947) reports that soft feed has been known to pass through the intestinal tract of a bird within two to three hours after ingestion. MATERIALS AND METHODS
A total of 190 cage and floor-grown broilers and fryers were used in three tests. Special effort was made to subject the birds to conditions similar to those existing during transporting, holding, and fattening in commercial broiler processing plants. The birds were first divided into lots of equal numbers and moved to fattening batteries. They were permitted to remain in these batteries with wet mash before them for approximately one full day. They were then weighed individually. During the following 24 hours, the wet mash was withdrawn according to predetermined fasting periods for different lots.
229
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on May 30, 2015
(Received for publication August 18, 1948)
230
JAMES M. GWIN, GEORGE W. NEWELL AND MOELEY A. JULL
All birds were given water when the wet mash was removed. At the conclusion of the 24-hour period, the birds were again weighed, slaughtered, and dressed on commercial dressing equipment. The intestinal tract was removed from each bird and individually weighed. All food and liquid was then removed from the intestinal tract, and weights were made to determine the quantity present.
period, the weight loss per bird averaged 75.2 grams. Approximately one-third of this was loss of food from the intestinal tract. The remaining two-thirds was loss of body weight. Converting this to dressing plant figures, it would mean a loss of about 125 pounds per thousand birds or approximately two ounces per bird. The primary purpose of withholding feed from birds is to empty the intestinal tract in order to save time in eviscerating or to prevent fecal matter from oozing from the dressed birds during the market-
The full-fed birds received wet mash from the start of the experiment until they were removed for weighing and slaughter. These birds showed the greatest average gain in body weight, but the weight of the contents of their intestinal tracts averaged less than in the one and two-hour fasted lots. This is accounted for by excessive water consumption on the part of the latter two groups. When commercial dressers slaughter full-fed birds, they are "milked" and "vented" as a part of the dressing operation. "Milking" is the proc-
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on May 30, 2015
ing process. It was found that it is not practical to withhold feed for the period of time required to completely empty the intestinal tract. The ceca appears to remain full longer than the other parts of the intestinal tract. In this connection, it was observed that in the birds from which feed had been withheld for 24 hours, the cecas contained almost as much material as was found in the cecas of the full-fed birds. It will be noted in Table 1 that more RESULTS material was found in the intestinal tract Table 1 shows the average change in of the birds that had been fasted five and live weight according to fasting period and six hours than in those that had been the average amount of feed remaining in fasted only three and four hours. This is the intestinal tract at the end of the 24- accounted for by the fact that after about hour period. three or four hours of fasting, the birds started drinking large quantities of water TABLE 1.—The effects offasting on live weight and on to appease their hunger. It was observed the amount of feed remaining in the intestinal tract that the intestinal tracts of the birds that weight had fasted for five and six hours contained Average live Average of feed remainweight change ing in intestinal the most liquid material. The practice of Fasting period per drinking water to appease hunger gradubird during after 24-hour period tract ally decreases. The period of excessive slaughter drinking varies widely with individual Grams Grams birds and is probably related to existing 24-hour fast -75.2 21.6 6-hour fast + 7.5 40.2 room temperature. This also accounts in 5-hour fast +10.1 37.6 part for the average gain in body weight of +11.3 4-hour fast 30.5 +16.1 31.5 3-hour fast the birds that underwent the five and six+20.5 49.0 2-hour fast hour fast periods. Considerable variation +22.3 49.5 1-hour fast +44.3 43.9 Full-fed (no fast) was found in the individual birds of these groups, with several showing a slight When feed was withheld for a 24-hour weight loss.
PERIOD OF FASTING POULTRY BEFORE SLAUGHTER
It is recognized that commercial dressers frequently encounter conditions that make it necessary to kill full-fed birds. These conditions may be the result of a sudden change in killing schedule, emergency orders, or miscalculations between the killing and fattening rooms. In cases of this kind, the "milking" and "venting" methods must be employed. If the birds are to be eviscerated in the same plant, the material in Table 1 indicates that the full-fed method may offer some weight advantages. GENERAL DISCUSSION The results obtained indicate that the average bird will lose about ^ of its intestinal contents during the first 3 to 4 hours of fasting. A slight increase in intestinal content will usually occur during the next three hours due to the increased intake of water. There will then be a gradual decrease until approximately 50 percent of the intestinal contents have been expelled at the end of a 24-hour period. The 3- to 4-hour fasting period will normally empty the crop and reduce the pressure on the intestines to the point
where they will withstand the normal handling in the course of the marketing process. Thus, according to the results of this experiment, the best fasting period would appear to be between 3 and 4 hours. This would reduce the contents of the intestinal tract by about § and would not produce excessive losses in body weight. The average weight changes between the one and six-hour fasting periods show a gradual decrease, but the differences are slight and are not statistically significant. However, a significant difference exists between those on full feed and those on a 24-hour fast and between both of these groups and all others. Although no attempt was made in this experiment to measure the amount or significance of moisture, it is acknowledged that it plays an important part, both in weight and appearance of the product. An experiment similar to this that would withhold water as well as feed should produce some interesting results. SUMMARY Under the conditions of this experiment, the long-established recommendation of a 24-hour fasting period is far too long and uneconomical; however, the slaughter of full-fed birds may offer some weight advantages to those who kill for immediate consumption. For best results in marketing practically all dressed poultry, the withholding of feed from three to four hours appears to be the most practical fasting period. REFERENCES
Heuser, G. F., 1945. The irate of passage of feed from the crop of the hen. Poultry Sci. 24: 20-24. , 1947. Feeding Poultry. John Wiley & Sons, Inc. New Yofky'New York. Keith, M. H.,"H. E. Card, and H. H. Mitchell, 1927. The rate of passage of food through the digestive tract of the hen. Jour. Agr. Res. 34: 759-769. ;--
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on May 30, 2015
ess of squeezing the excessive mash and moisture from the crop by pressure that forces it from the mouth of the dead bird. "Venting" consists of squeezing the vent and forcing out the excessive fecal matter. The relatively small amount of fecal material that can be pressed from the full-fed birds is usually not enough to prevent additional quantities from oozing out of the birds that are placed in the lower layers of the conventional barrel or crate of iced poultry. This results in an objectionable unsanitary condition. Birds with full intestines are a trade hazard on a normal market, but in times of light supply and heavy demand, the killing of full-fed birds is a common trade practice.
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