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Effect of Time of Feed Withdrawal and Killing Before Processing on Defeathering of Spent Hens1
EFFECT OF TIME OF FEED WITHDRAWAL AND KILLING BEFORE PROCESSING ON DEFEATHERING OF SPENT HENS' HAFIZ ANWAR AHMAD, D. A. ROLAND, SR?, and SYED S. SOHAIL 341 ADS Poultly Science Depament, Auburn University,AL 36849 Phone: (334) 844260.5 FAX: (334) 844-2641
I
One possible solution to this problem is DESCRIPTION OF PROBLEM the conversion of spent hens, along with other Laying hens generally remain in production for approximately65-75 wk. At the end of their first laying cycle, hens are either molted and returned to production or replaced. Producers decide whether to molt or replace hens based on egg price, cost of replacement pullets, and other associated factors. At the time this experiment was conducted, more hens were available for slaughter than the market could absorb due to an abundance of meat on the market [l].Therefore, instead of being able to sell spent hens, producers had to give them away or in some instances even pay for their removal.
poultry by-products, to a high protein, high energy feed ingredient through rendering [2]. One difficulty with this procedure is that unhydrolyzed feathers are indigestible and therefore may limit the use of such ingredients in animal feeds. Another concern is the cost of hauling live spent hens. It would be more economical to transport dead hens to rendering plants than live ones. There is concern, however, that the waiting period between killing and processing could adversely affect the removal of feathers during processing. This study was designed to determine the effect of feed removal prior to killing and of
1 Alabama Agricultural Experiment Station Journal Series No. 12-965194 2
To whom correspondence should be addressed
Downloaded from http://japr.oxfordjournals.org/ at Western Michigan University on May 5, 2015
Primary Audience: Egg Producers, Nutritionists, Renderers, Researchers, Poultrv Extension SDecialists
DEFEATHERING SPENT HENS
326
the waiting period between killing and processing on carcass yield and defeathering during processing.
RESULTSAND DISCUSSION EXPERIMENT 1 No significant difference was found in live body weight prior to feed withdrawal (Table 1). Time of feed withdrawal significantly influenced body weight of hens immediately prior to processing. Hens from which feed was withdrawn 48 hr before processing had significantly lower body weights, presumably because of longer feed withdrawal time compared to those from which feed was withdrawn 17 hr before processing. Hens in both treatment groups (48 hr and 17 hr) also had significantly lower body weights than hens of control group from which feed was not withdrawn. Consequently, the processed weight followed the same pattern. Feed withdrawal time had no significant effect on percent feather loss (feathers removed during processing) based either on live weight or body weight just prior to processing. Feather score (remaining feathers after processing) was significantly higher for hens from which feed was withdrawn 48 hr compared to those from which feed was withdrawn 17 hr before killing. Feather scores of both treatment groups (48 hr and 17 hr) were also significantly higher than that of control group: klling times (12 hr, 8 hr, 4 hr, and immediately prior to processing) had no significant effect on body weight of hens just prior to processing, processed weight, feather loss, or percent feather loss based either on live weight or body weight just prior to processing (Table 1). Live weight, feather score, and difference between live weight and body weight immediately prior to processing were significantly influenced by the killing times (Table 1). Hens killed 4 hr before processing had higher live weight than those killed 12 hr before processing. Body weights at other killing times were not different. Hens killed immediately prior to processing had the lowest feather score (feathers remaining after processing). There was a significant interaction in feather removal (feather loss) between feed withdrawal and killing time before processing. Hens from which feed was withdrawn 48 hr and killed just prior to processing lost the least amount of feathers compared to hens
MATERIALS AND METHODS
Downloaded from http://japr.oxfordjournals.org/ at Western Michigan University on May 5, 2015
lkro experiments were conducted using Dekalb@Delta hens. In Experiment 1,68-wkold hens were assigned to two treatment groups of 80 hens each. Feed was withdrawn from hens 48 hr or 17 hr prior to processing for Treatments 1 and 2, respectively. Chloroform was used to kill 20 hens each from Treatments 1 and 2 at 12 hr, 8 hr, 4 hr, and immediatelyprior to processing.Ten hens were killed immediately prior to processing without feed withdrawal. These hens were considered the control. All hens were wingbanded and weighed prior to feed withdrawal and were placed in cans (20 herdcan) after chloroforming. Hens were weighed before and after processing and remaining feathers were visually scored on a scale of one to five as follows: 1) free of feathers; 2) slight feathering on vent and shoulder; 3) moderate feathers on vent and wings; 4) feathers covering back and neck; 5) vent, back, and wings covered with feathers. In Experiment 2, 69-wk-old hens were assigned to three treatment groups of 10 hens each. Feed was withdrawn either 50 hr or 25 hr before processing for Treatments 1and 2 respectively, and all hens were chloroformed 5 hr before processing. Treatment 3 hens were killed immediately prior to processing without feed withdrawal. Criteria measured in Experiment 2 included body weight at the time of feed withdrawal; body weight just prior to processing; carcass weight immediately after processing and at 2 hr and 3 hr after processing; and weight of feathers remaining after processing (hand picked feathers). The hens were processed at the Auburn University Department of Poultry Science processing facility [3]. Hens were transported to the plant using plastic cages and were immediately transferred to the processing lines. All hens were visually observed and scored for any remaining feathers after processing.These feathers were removed by hand and weighed for subsequent analysis.Data were statistically analyzed [4] using the GLM procedure of SAS Institute [5].
Research Report AHMAD et al.
327
TABLE 1. Influence of feed withdrawal and killing time before processing on defeathering of spent hens (Experiment 1)
12 hr
Oh2 FWTXKT 48 hr x 12 hr 48 h r x 8 hr
48 h r x 4 hr 48hrxOhr'
17 hr x 12 hr 17 hrx 8 hr 17 hr x 4 hr 17 hrx 0 h 2
1
17Mb 179Tb
1842a 1774ab
I 1 I I
1575
1554
I I I I I I I
1571
I
1514
1494
I I I I
1462
1627 1621 1667 1637
I 1752 1805 1825 1800 1756 1789 1859 1735
I I I I I I I
I
1562
1691 1687 1762 1603
1566 1601 1593 1503 1501
1647 1631 1688 1537
'Body weight prior to feed withdrawal
'Body weight just prior to processing %eight immediately after processing %e
amount of feather lost during processing (B - C)
%'ercent
feather loss based on body weight just prior to processing (DWx 100)
'Percent feather loss based on live weight just prior to processing (D/A x 100) GDifferencebetween live weight and body weight (A - B) just prior to processing % h e experiment was analyzed as a 2 x 4 factorial. The control values, however, were only compared to the 48 hr and
17hr feed withdrawal times. [Atprocessing cc
Means with no common letter in a column are significantly different ( P < .OS)
'*P < .01;***Pc .001.
killed 12 hr, 8 hr, or 4 hr before processing. The situation was reversed for hens from which feed was withdrawn 17 hr before processing, however. In this case the hens killed immediately prior to processing lost a greater quantity of feathers than those killed 12 hr, 8 hr, or 4 hr before processing. We do not know the cause for this. However, visual feather score did not correspond to feather
loss for hens from which feed was withdrawn 48 hr that were killed immediately prior to
processing. Feather score indicated that fewer feathers, not more, remained after processing on hens from which feed was withdrawn for 48 hr and that were killed immediately prior to processing. In order to check this discrepancy and confirm the results, a second experiment was conducted.
Downloaded from http://japr.oxfordjournals.org/ at Western Michigan University on May 5, 2015
8 hr
4 hr
I I I 1 I I I I I I I I
JAPR DEFEATHERING SPENT HENS
328
I
prior to processing prevented complete feather removal from spent hens. Although the visual scoring of remaining feathers showed a significant difference among treatments, the total weight of unremoved feathers would probably be insignificant (less than 2.6 g). Withdrawing feed from spent hens prior to transporting to a rendering plant may save money in terms of one or two free eggs per hen, as hens can produce these eggs from their body reserves. Feed withdrawal, however, will yield lower carcass weight. Feed withdrawal and a waiting period between killing time and processing prevents the total removal of feathers. The amount of remaining feathers (less than 5% of total feathers), however, seems too small to cause any serious problems for digestibility of the rendered product [6].Fine-tuningthe processing equipment can make removal of even more feathers possible.
TABLE 2. Influence of feed withdrawal and killing time before processing on defeathering of spent hens (Experiment 2)
*Weight of live bird prior to feed withdrawal BBodyweight just prior to processing %eight immediately after processing %eight 2 hr after processing %'eight
3 hr after processing
'Remaining feather weight (hand picked) GTotal feather loss HAt processing 8-4
Meanswith no common letter in a column are significantly different (P c .05)
**P<.01; **'P<.001
Downloaded from http://japr.oxfordjournals.org/ at Western Michigan University on May 5, 2015
EXPERIMENT 2 As in Experiment 1, feed withdrawal time significantly influenced body weight of hens immediately prior to processing (Experiment 2; Table 2). Hens from which feed was withdrawn 50 hr before processing had significantly lower weight compared to those from which feed was not withdrawn before processing. This trend was also observed whether hens were weighed at processing or 2 hr or 3 hr after processing. Feed withdrawal time significantly influenced the quantity of manually recovered feathers. Hens from which feed was not withdrawn before processing yielded a significantly lower quantity of feathers than hens from which feed was withdrawn 50 hr or 25 hr before processing. Feather scoring showed a similar trend, and maximum score occurred in hens from which feed was withdrawn 50 hr before processing. Experiment 2 confirmed that feed kthdrawal
Research Report 329
AHMAD et al.
CONCLUSIONS AND APPLICATIONS
REFERENCES AND NOTES 1. Olejnik, B., 1995. Rendering appears to be solution to spent hen problem. Poultry Times 42(4):6. 2. Froning, G.W., 1995. Utilization of spent fowl. Egg Industry 100(3):22. 3. Hens were electrically stunned, bled for 90 sec, scalded at 57°C for 82 sec, and defeathered mechanically for 42 sec. Hens were weighed immediatelyafterprocessing. 4. Statistical procedure. EKperiment 1 data were subjected to 2 x 4 factorial analris of variance with two feed removal times and four killing times; the main effect
means of withdrawal times (48 hr and 17 hr) were compared only to data for the control group. Experiment 2 data were subjected to analysis of variance and means were further separated b multiple range test using the General Linear Model ((rLM) procedure of SAS.
5. SAS Instilulc, 1985. SAS User’sGuide: Statistics. SAS Institute, Inc., Cary, NC.
6. Ensminger, M.E,1992. Feeds and additives. Pages 9S-120 in: Poults Science. M.E. Ensminger, ed. Interstate Publishers, anwlle, IL.
Downloaded from http://japr.oxfordjournals.org/ at Western Michigan University on May 5, 2015
1. Withdrawing feed from hens prior to processing reduces carcass yield but provides one or two marketable eggs with no feed cost. 2. Longer feed withdrawal times result in more feathers remaining on processed hens. 3. Longer waiting periods between killing and processing result in more feathers remaining on processed hens. 4. Although longer feed withdrawal time and waiting period between killing and processing yields carcasses that appear to have substantially more feathers, less than 5% of total feathers actually remain on the carcasses. 5. The quantity of feathers that remain due to feed withdrawal and waiting period between killing and processing seems too small to cause any serious digestibility problems of the rendered product. 6. Feed withdrawal decreases feed cost but reduces carcass yield and prevents total feather removal from processed hens. Longer waiting between killing and processing also prevents complete defeathering of spent hens; the unremoved feathers, however, being less than 5% of the total feathers, seems too small an amount to cause any serious digestibilityproblems.
I
One possible solution to this problem is DESCRIPTION OF PROBLEM the conversion of spent hens, along with other Laying hens generally remain in production for approximately65-75 wk. At the end of their first laying cycle, hens are either molted and returned to production or replaced. Producers decide whether to molt or replace hens based on egg price, cost of replacement pullets, and other associated factors. At the time this experiment was conducted, more hens were available for slaughter than the market could absorb due to an abundance of meat on the market [l].Therefore, instead of being able to sell spent hens, producers had to give them away or in some instances even pay for their removal.
poultry by-products, to a high protein, high energy feed ingredient through rendering [2]. One difficulty with this procedure is that unhydrolyzed feathers are indigestible and therefore may limit the use of such ingredients in animal feeds. Another concern is the cost of hauling live spent hens. It would be more economical to transport dead hens to rendering plants than live ones. There is concern, however, that the waiting period between killing and processing could adversely affect the removal of feathers during processing. This study was designed to determine the effect of feed removal prior to killing and of
1 Alabama Agricultural Experiment Station Journal Series No. 12-965194 2
To whom correspondence should be addressed
Downloaded from http://japr.oxfordjournals.org/ at Western Michigan University on May 5, 2015
Primary Audience: Egg Producers, Nutritionists, Renderers, Researchers, Poultrv Extension SDecialists
DEFEATHERING SPENT HENS
326
the waiting period between killing and processing on carcass yield and defeathering during processing.
RESULTSAND DISCUSSION EXPERIMENT 1 No significant difference was found in live body weight prior to feed withdrawal (Table 1). Time of feed withdrawal significantly influenced body weight of hens immediately prior to processing. Hens from which feed was withdrawn 48 hr before processing had significantly lower body weights, presumably because of longer feed withdrawal time compared to those from which feed was withdrawn 17 hr before processing. Hens in both treatment groups (48 hr and 17 hr) also had significantly lower body weights than hens of control group from which feed was not withdrawn. Consequently, the processed weight followed the same pattern. Feed withdrawal time had no significant effect on percent feather loss (feathers removed during processing) based either on live weight or body weight just prior to processing. Feather score (remaining feathers after processing) was significantly higher for hens from which feed was withdrawn 48 hr compared to those from which feed was withdrawn 17 hr before killing. Feather scores of both treatment groups (48 hr and 17 hr) were also significantly higher than that of control group: klling times (12 hr, 8 hr, 4 hr, and immediately prior to processing) had no significant effect on body weight of hens just prior to processing, processed weight, feather loss, or percent feather loss based either on live weight or body weight just prior to processing (Table 1). Live weight, feather score, and difference between live weight and body weight immediately prior to processing were significantly influenced by the killing times (Table 1). Hens killed 4 hr before processing had higher live weight than those killed 12 hr before processing. Body weights at other killing times were not different. Hens killed immediately prior to processing had the lowest feather score (feathers remaining after processing). There was a significant interaction in feather removal (feather loss) between feed withdrawal and killing time before processing. Hens from which feed was withdrawn 48 hr and killed just prior to processing lost the least amount of feathers compared to hens
MATERIALS AND METHODS
Downloaded from http://japr.oxfordjournals.org/ at Western Michigan University on May 5, 2015
lkro experiments were conducted using Dekalb@Delta hens. In Experiment 1,68-wkold hens were assigned to two treatment groups of 80 hens each. Feed was withdrawn from hens 48 hr or 17 hr prior to processing for Treatments 1 and 2, respectively. Chloroform was used to kill 20 hens each from Treatments 1 and 2 at 12 hr, 8 hr, 4 hr, and immediatelyprior to processing.Ten hens were killed immediately prior to processing without feed withdrawal. These hens were considered the control. All hens were wingbanded and weighed prior to feed withdrawal and were placed in cans (20 herdcan) after chloroforming. Hens were weighed before and after processing and remaining feathers were visually scored on a scale of one to five as follows: 1) free of feathers; 2) slight feathering on vent and shoulder; 3) moderate feathers on vent and wings; 4) feathers covering back and neck; 5) vent, back, and wings covered with feathers. In Experiment 2, 69-wk-old hens were assigned to three treatment groups of 10 hens each. Feed was withdrawn either 50 hr or 25 hr before processing for Treatments 1and 2 respectively, and all hens were chloroformed 5 hr before processing. Treatment 3 hens were killed immediately prior to processing without feed withdrawal. Criteria measured in Experiment 2 included body weight at the time of feed withdrawal; body weight just prior to processing; carcass weight immediately after processing and at 2 hr and 3 hr after processing; and weight of feathers remaining after processing (hand picked feathers). The hens were processed at the Auburn University Department of Poultry Science processing facility [3]. Hens were transported to the plant using plastic cages and were immediately transferred to the processing lines. All hens were visually observed and scored for any remaining feathers after processing.These feathers were removed by hand and weighed for subsequent analysis.Data were statistically analyzed [4] using the GLM procedure of SAS Institute [5].
Research Report AHMAD et al.
327
TABLE 1. Influence of feed withdrawal and killing time before processing on defeathering of spent hens (Experiment 1)
12 hr
Oh2 FWTXKT 48 hr x 12 hr 48 h r x 8 hr
48 h r x 4 hr 48hrxOhr'
17 hr x 12 hr 17 hrx 8 hr 17 hr x 4 hr 17 hrx 0 h 2
1
17Mb 179Tb
1842a 1774ab
I 1 I I
1575
1554
I I I I I I I
1571
I
1514
1494
I I I I
1462
1627 1621 1667 1637
I 1752 1805 1825 1800 1756 1789 1859 1735
I I I I I I I
I
1562
1691 1687 1762 1603
1566 1601 1593 1503 1501
1647 1631 1688 1537
'Body weight prior to feed withdrawal
'Body weight just prior to processing %eight immediately after processing %e
amount of feather lost during processing (B - C)
%'ercent
feather loss based on body weight just prior to processing (DWx 100)
'Percent feather loss based on live weight just prior to processing (D/A x 100) GDifferencebetween live weight and body weight (A - B) just prior to processing % h e experiment was analyzed as a 2 x 4 factorial. The control values, however, were only compared to the 48 hr and
17hr feed withdrawal times. [Atprocessing cc
Means with no common letter in a column are significantly different ( P < .OS)
'*P < .01;***Pc .001.
killed 12 hr, 8 hr, or 4 hr before processing. The situation was reversed for hens from which feed was withdrawn 17 hr before processing, however. In this case the hens killed immediately prior to processing lost a greater quantity of feathers than those killed 12 hr, 8 hr, or 4 hr before processing. We do not know the cause for this. However, visual feather score did not correspond to feather
loss for hens from which feed was withdrawn 48 hr that were killed immediately prior to
processing. Feather score indicated that fewer feathers, not more, remained after processing on hens from which feed was withdrawn for 48 hr and that were killed immediately prior to processing. In order to check this discrepancy and confirm the results, a second experiment was conducted.
Downloaded from http://japr.oxfordjournals.org/ at Western Michigan University on May 5, 2015
8 hr
4 hr
I I I 1 I I I I I I I I
JAPR DEFEATHERING SPENT HENS
328
I
prior to processing prevented complete feather removal from spent hens. Although the visual scoring of remaining feathers showed a significant difference among treatments, the total weight of unremoved feathers would probably be insignificant (less than 2.6 g). Withdrawing feed from spent hens prior to transporting to a rendering plant may save money in terms of one or two free eggs per hen, as hens can produce these eggs from their body reserves. Feed withdrawal, however, will yield lower carcass weight. Feed withdrawal and a waiting period between killing time and processing prevents the total removal of feathers. The amount of remaining feathers (less than 5% of total feathers), however, seems too small to cause any serious problems for digestibility of the rendered product [6].Fine-tuningthe processing equipment can make removal of even more feathers possible.
TABLE 2. Influence of feed withdrawal and killing time before processing on defeathering of spent hens (Experiment 2)
*Weight of live bird prior to feed withdrawal BBodyweight just prior to processing %eight immediately after processing %eight 2 hr after processing %'eight
3 hr after processing
'Remaining feather weight (hand picked) GTotal feather loss HAt processing 8-4
Meanswith no common letter in a column are significantly different (P c .05)
**P<.01; **'P<.001
Downloaded from http://japr.oxfordjournals.org/ at Western Michigan University on May 5, 2015
EXPERIMENT 2 As in Experiment 1, feed withdrawal time significantly influenced body weight of hens immediately prior to processing (Experiment 2; Table 2). Hens from which feed was withdrawn 50 hr before processing had significantly lower weight compared to those from which feed was not withdrawn before processing. This trend was also observed whether hens were weighed at processing or 2 hr or 3 hr after processing. Feed withdrawal time significantly influenced the quantity of manually recovered feathers. Hens from which feed was not withdrawn before processing yielded a significantly lower quantity of feathers than hens from which feed was withdrawn 50 hr or 25 hr before processing. Feather scoring showed a similar trend, and maximum score occurred in hens from which feed was withdrawn 50 hr before processing. Experiment 2 confirmed that feed kthdrawal
Research Report 329
AHMAD et al.
CONCLUSIONS AND APPLICATIONS
REFERENCES AND NOTES 1. Olejnik, B., 1995. Rendering appears to be solution to spent hen problem. Poultry Times 42(4):6. 2. Froning, G.W., 1995. Utilization of spent fowl. Egg Industry 100(3):22. 3. Hens were electrically stunned, bled for 90 sec, scalded at 57°C for 82 sec, and defeathered mechanically for 42 sec. Hens were weighed immediatelyafterprocessing. 4. Statistical procedure. EKperiment 1 data were subjected to 2 x 4 factorial analris of variance with two feed removal times and four killing times; the main effect
means of withdrawal times (48 hr and 17 hr) were compared only to data for the control group. Experiment 2 data were subjected to analysis of variance and means were further separated b multiple range test using the General Linear Model ((rLM) procedure of SAS.
5. SAS Instilulc, 1985. SAS User’sGuide: Statistics. SAS Institute, Inc., Cary, NC.
6. Ensminger, M.E,1992. Feeds and additives. Pages 9S-120 in: Poults Science. M.E. Ensminger, ed. Interstate Publishers, anwlle, IL.
Downloaded from http://japr.oxfordjournals.org/ at Western Michigan University on May 5, 2015
1. Withdrawing feed from hens prior to processing reduces carcass yield but provides one or two marketable eggs with no feed cost. 2. Longer feed withdrawal times result in more feathers remaining on processed hens. 3. Longer waiting periods between killing and processing result in more feathers remaining on processed hens. 4. Although longer feed withdrawal time and waiting period between killing and processing yields carcasses that appear to have substantially more feathers, less than 5% of total feathers actually remain on the carcasses. 5. The quantity of feathers that remain due to feed withdrawal and waiting period between killing and processing seems too small to cause any serious digestibility problems of the rendered product. 6. Feed withdrawal decreases feed cost but reduces carcass yield and prevents total feather removal from processed hens. Longer waiting between killing and processing also prevents complete defeathering of spent hens; the unremoved feathers, however, being less than 5% of the total feathers, seems too small an amount to cause any serious digestibilityproblems.