Poult. Sci.
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Poult Sci 2007. 86:2029-2033
© 2007 Poultry Science Association
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PROCESSING, PRODUCTS, AND FOOD SAFETY

Feeding Turkeys a Highly Digestible Supplement During Preslaughter Feed Withdrawal

B. M. Rathgeber*,1, J. L. MacIsaac{dagger} and M. E. MacKenzie{ddagger}

* Crops and Livestock Research Centre, Charlottetown Prince Edward Island, Canada, C1A 7M8; {dagger} Atlantic Poultry Research Institute, Truro, Nova Scotia, B2N 5E3; and {ddagger} Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada, T6G 2P5

1 Corresponding author: rathgeberb{at}agr.gc.ca


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 REFERENCES
 
Standard commercial practice is to deny poultry access to feed 8 to 12 h prior to slaughter. Occasionally a flock of turkeys is marketed at several ages, and starvation can occur for birds that are not shipped. For this project multiple marketed female turkeys were fed a special diet (nutritive supplement) during the preslaughter feed withdrawal period to reduce live weight loss, bird stress, and grazing on manure. Three trials were conducted at the Nova Scotia Agricultural College using 60 female turkey poults for each of 8 pens for each trial. The birds were separated into 8 pens with 20 birds from half of the pens shipped at 63 d of age and all remaining birds shipped 1 wk later. Prior to shipping, feed was withdrawn, with half the pens receiving the supplement. The pens that had received supplement at 63 d of age received it again a week later along with half the pens not previously marketed. The supplement was only consumed in a significant quantity when it was new to the birds (~10 g/kg of bird). The carcass yield, based on the live weight before the conventional feed withdrawal period, was improved for birds that consumed the supplement. Microbiological profiles of the crops revealed that although the total number aerobic bacteria was not affected, birds ingesting the supplement had fewer Escherichia coli and coliforms present. Breast meat samples collected at 15 min postmortem and 24 h postmortem and measured for pH were not found to be different between the treatments. Because birds would only consume the supplement on the first exposure, this supplement is only effective for reducing live weight loss and microbial load of the crop in an all-in all-out management situation.

Key Words: turkey • feed withdrawal • yield • crop bacteria • processing


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 REFERENCES
 
The focus of this project is a modification to the traditional practice of preslaughter feed withdrawal for market-age commercial poultry. Appropriate management of the length of time off feed is crucial to obtain the intended benefits of this practice and minimize detrimental effects. Currently feed is withdrawn from the flock several hours prior to the initiation of catching and shipping to allow time for the contents of the digestive tract to pass through the bird. It is generally recommended that the time between feed removal and slaughter totals 8 to 12 h. Withdrawal periods longer than 12 h can result in reduced tensile strength of the intestine, increasing the risk of gut breakage (Bilgilli, 1988). Long withdrawal periods can also result in substantial weight loss, which reduces carcass yield (Veerkamp, 1986; Lyon et al., 1991).

A nutritive supplement administered during the normal preslaughter feed withdrawal period through existing feeding equipment was developed by previous researchers (Farhat et al., 2002). The high digestibility of this supplement may aid in clearing intestinal contents prior to slaughter while the bird continues to consume nutrients until placement in transport crates to minimize live weight losses.

The purpose of denied access to feed prior to slaughter is to reduce the incidence of carcass contamination; however, recent investigations with broiler chickens have indicated that feed withdrawal at the recommended times may contribute to an increased incidence of pathogenic bacteria on poultry carcasses. In the absence of feed, birds begin to consume the shavings or straw, as well as the manure associated with the bedding. Corrier et al. (1999) reported a 2-fold increase in consumption of manure 2 h after removal of feed. This translates into an increased risk for carcass contamination from leakage of ingesta stored in a modification of the esophagus known as the crop. Ramirez et al. (1997) reported an increased incidence of Salmonella in the crops of broiler chickens following 8 h of feed withdrawal compared with birds in the same facility that were on full feed.

In addition to increasing manure consumption, feed withdrawal also influences the integrity of the broiler intestinal tract. During feed withdrawal, the surface of the intestinal tract becomes smooth in appearance (Shamoto and Yamauchi, 2000, Tarachai and Yamauchi, 2000), and villi width, crypt depth, and mucus content decrease (Shamoto and Yamauchi, 2000; Thompson and Applegate, 2006). Alterations in the integrity of the intestinal tract could have implications for a commonly used practice in the Nova Scotia turkey industry known as multiple marketing, the practice of shipping a portion of the flock at several different times rather than the entire flock at once. Morphological changes of the intestinal villi during feed withdrawal periods may have an impact on the ability of unshipped birds to efficiently absorb nutrients when normal feeding resumes.

It is anticipated that consumption of the feed withdrawal supplement by multiple-marketed turkeys will provide benefits to the bird and the producer. Providing a source of nutrients during the normal preslaughter feed withdrawal period should reduce stressful behavior associated with prolonged absence of a feed supply, which may translate into reduced injuries and carcass damage caused by frantic birds. Reduced levels of stress for those birds being shipped may additionally influence meat quality. Stress can trigger the acceleration of postmortem rigor mortis development increasing the incidence of poor quality breast meat (McKee and Sams, 1997; Owens et al., 2000). Pietrzak et al. (1997) and Rathgeber et al. (1999a, b) have demonstrated that abnormally rapid postmortem metabolism increases the rate and extent of postmortem degradation of breast muscle proteins and significantly reduces the functionality of breast meat in further processed products. Increased paleness, decreased water holding capacity, and a poor texture are often used to describe products manufactured from breast meat harvested from turkeys exposed to preslaughter stress (McKee and Sams, 1997). In addition to reducing bird stress, the use of the nutritive supplement should ensure uninterrupted nutrient absorption for shipped birds and those retained for later shipment. For the producers, this should mean reduced weight loss prior to shipping, improved feed conversion for birds shipped at later dates, and a reduction in downgraded carcasses. A potential reduction in manure consumption in combination with emptied lower digestive tracts should reduce the incidence of carcass contamination during the slaughter procedure, improving the safety of the product for consumers. An improved microbiological profile of the processed carcass will make this product a key component of on-farm food safety programs for improving the safety of our food supply.

The objectives of this study were to evaluate the effects of a nutritive supplement offered during preslaughter feed withdrawal on intestinal morphology and meat quality and to determine the ability of this supplement to decrease crop enteropathogens (thus reducing the risk of carcass contamination during processing) and improve carcass yield of multiple-marketed turkey hens.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 REFERENCES
 
Three replicate trials were conducted at the Nova Scotia Agricultural College. In each trial, 480 female turkey poults were raised in 8 pens at a density of 0.18 m2/ bird. The birds were raised using standard management practices and were fed commercial turkey feed. At 63 d of age, one-third of the birds from half of the pens (80 birds) were shipped for processing (multiple-marketed). Six hours prior to catching, the feed was withdrawn from the pens containing birds to be multiple-marketed. Water remained available up until the birds were caught and placed in crates for both treatment groups. For half of these pens, a highly digestible nutritive supplement was made available to the birds in the feeder system for the first 5 h of the withdrawal period. The supplement was similar to FWS0 as described by Farhat et al. (2002). For this trial, Grain Processing Corporation (Muscatine, IA) supplied a supplement listed as 4440-KF-020C. The product is formulated based on a commercial carbohydrate source derived from controlled hydrolysis of cornstarch to yield a nonsweet, D-glucose polymer—maltodextrin. The maltodextrin has an approximate dextrose equivalent of 15 and sugar content of <6%. The formula consisted of 95.6% maltodextrin, 2.0% corn germ, 2.0% mono- and diglycerides, 0.36% NaCl, and caramel color added at 15 g/4,540 g of batch. The pellets were coated with tallow amounting to 3% of the weight of the product.

Following shipment of the first group of birds from the multiple-marketed pens, the feed was returned to the remaining birds, which were grown to 70 d of age. The same pens administered the nutritive supplement at 63 d of age received it once again during the 6-h precatching period at 70 d of age when all the remaining birds were shipped. This included the pens that did not have birds removed at 63 d of age. Nine hours in total had elapsed from the start of feed withdrawal to the time of slaughter. Timing of feed withdrawal was staggered 15 m between pens for the first shipment and 15 m between pairs of pens for the second shipment. The sequence of feed withdrawal was maintained at slaughter. Birds were processed in batches of 10. Therefore, one-half of each pen (or pair of pens for the second shipment) was processed after the birds were off feed 9 h; the second half was processed after 10 h off feed.

Each time birds were shipped 2 additional birds per pen were removed and euthanized. A section of the small intestine 5 cm on either side of the Meckel’s diverticulum was removed and frozen in liquid nitrogen. These samples were later prepared for evaluation of changes to intestinal morphology.

On each of the 2 slaughter dates, all birds were weighed prior to preshipping feed withdrawal and again prior to slaughter to determine the effect on live weight loss. Live shrink = [(live weight before conventional feed withdrawn –live weight before slaughter)/live weight before conventional feed withdrawn)] x100. Each bird was also weighed after evisceration to determine carcass yield. Carcass yield 1 = (eviscerated carcass weight/live weight before conventional feed withdrawn) x100. Carcass yield 2 = (eviscerated carcass weight/live weight prior to slaughter) x100.

The crops of 5 birds (first marketing day) and 3 birds (second marketing day) from each pen were removed during the evisceration process and transferred to sample bags and held on ice for microbiological analysis. At 15 min after the stunning of the birds, a breast meat sample (approximately 5 g) was removed and placed in liquid nitrogen.

A 1-g subsample of the breast muscle gathered at 15 min postmortem was homogenized in iodoacetate solution according to Northcutt et al. (1994), and the pH was measured to determine the rate of postmortem metabolism between treatments. Additionally, a 24-h postmortem breast muscle sample was removed from each processed carcass, and the pH was measured to determine the extent of postmortem lactic acid production.

The crops that were collected and held on ice at the slaughter facility were transported back to the Nova Scotia Agricultural College and shipped to the Prince Edward Island Food Technology center where the total number of aerobic bacteria, coliforms, E. coli, and Salmonella were determined per gram of tissue sampled. These bacteria were enumerated by techniques described by Rathgeber and Waldroup (1995).

Morphological evaluations of the cells lining the intestine were determined by examining frozen sections of the intestinal tract of selected birds. Thin sections of the intestinal tract were mounted on frost-free microscope slides, fixed and stained using a Hema 3 stain set (Protocol, Fisher Diagnostic, Middletown, VA). Each sample was viewed under a light microscope and rated on a scale of 0 to 4 for the loss of epithelial tissue along the villi of the digestive tract, where 4 represented the most extreme damage and 0 represented intact tissue.

All data were subjected to ANOVA using the mixed-model procedure of SAS Institute Inc. (1990). Bacterial numbers were transformed to log base 10 prior to analysis.


   RESULTS AND DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
REFERENCES
 
Feed Consumption, Live Shrink, and Processing Yield

First Shipment. Turkeys readily consumed the nutritive supplement after conventional feed was withdrawn (10.8 g per kg of live weight, average weight 4.8 kg per bird). Birds provided with supplement lost less weight prior to slaughter than those not on the supplement (P <0.0001); average live shrink was 4.4% for birds removed from feed and 2.7% for those provided supplement (standard error 0.2%). Holding half the birds from each pen for an additional hour did not significantly influence live shrink. Birds receiving supplement had higher carcass yields than those removed from feed (Table 1Go) based on live weight before conventional feed was withdrawn (P<0.05); the average percent carcass yield was 74.7% for birds removed from feed and 75.8% for those provided supplement (standard error 0.2%). Carcass yield based on live weight prior to slaughter was similar for both groups (average yield 78%), indicating that processing was consistent between the groups and that the supplemented birds retained BW rather than visceral weight.


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  		Table 1. Carcass yield of 63- and 70-d-old turkey hens denied feed or provided a feed supplement during the feed withdrawal period prior to shipping
 
Second Shipment. Turkeys for the second shipment that had not previously experienced the nutritive supplement readily consumed it after conventional feed was withdrawn (9.5 g per kg live weight, average weight 5.8 kg per bird). Multimarketed birds that had experienced the supplement the previous week consumed considerably less (1.8 g per kg of live weight, average weight 5.5 kg). Results discussed below do not include multimarketed birds because they did not consume a significant volume of supplement during the second exposure. The birds provided feed supplement lost less weight prior to slaughter than those not on the supplement (P <0.001); average live shrink was 4.9% for birds removed from feed and 3.6% for those provided supplement (standard error 0.2%). Northcutt et al. (2003) found that a similar nutritive supplement (commercial maltodextrin formulation) reduced live shrink when broilers were denied feed for 8 to 12 h before processing. Similar to the week before, holding the second group of birds for an additional hour did not significantly influence live shrink. The nutritive supplement did not improve carcass yield for birds at 70 d of age, based on live weight before feed withdrawal or based on weight before slaughter (Table 1Go).

Microbiological Analysis

The microbiological profile of crops from birds that were offered the supplement on both marketing days, but refused to eat a significant volume in the second shipment, was not significantly different from that of the control birds. Therefore, the data from these birds are not included in the following discussion. When the nutritive supplement was offered to birds that had not previously consumed the product, there was a significant reduction(~90%) in E. coli (P <0.01) and total coliforms (P <0.02) per gram of crop (Table 2Go). The total number of aerobic bacteria present in the crop was not affected by the consumption of the nutritive supplement. Salmonellae were not detected in any of the crops sampled. Hinton et al. (2002) found that following 12 h of feed withdrawal, a sucrose cocktail lowered crop pH, which may have reduced numbers of Salmonella and Campylobacter in crops of orally challenged broilers. Lower coliform numbers suggest that the highly digestible nutritive supplement in our study may be effective in reducing enteropathogen populations in the crops of broilers subjected to a 4-h feed withdrawal prior to slaughter. Although crop pH was not measured in this study, it is possible that the maltodextrin-based nutritive supplement reduced coliform numbers through a modification of crop pH. Greater coliform numbers in the crops of control fed birds may also indicate that these birds consumed litter following feed removal.


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  		Table 2. Crop bacteria cultured from 63- and 70-d-old turkey hens denied feed or provided a feed supplement during the feed withdrawal period prior to shipping
 
Intestinal Integrity and Meat Quality

The intestinal morphology of birds consuming the nutritive supplement was similar to that of those offered the control (average score 2.13). This suggests that the supplement is digested in the upper tract and does not enter the lower tract or that a 5-h feed withdrawal was not long enough to induce morphological changes in the intestines of birds offered the control diet. In this study, changes in intestinal morphology were measured objectively as the loss of epithelial tissue along the villi of the digestive tract. In a study by Thompson and Applegate (2006) villi height was unaffected in broilers withheld feed for 24 h, although villi width and crypt depth decreased with increasing feed withdrawal. Meat quality appeared to be unaffected by the nutritive supplement, as indicated by 15 min postmortem pH (6.05). Glycogen reserves also appeared to be unaffected by the nutritive supplement, as indicated by 24 h postmortem pH (5.80).

Multiple Marketing

Results of this study indicate that if turkey hens consume the nutritive supplement in preparation for shipping but are not shipped until a later date, they will consume only a small fraction of the product during the second exposure. This behavior may limit the usefulness of this supplement in repeated feeding situations such as the multiple marketing practice common in Nova Scotia. However, when turkeys are exposed to the nutritive supplement for the first time, it is effective in decreasing crop coliforms and reducing live shrink after a 4-h feed withdrawal and therefore has good potential for use in the turkey industry.


   ACKNOWLEDGMENTS
 
Thanks are extended to R. Masoodi, M. McConkey, and R. Mekers for technical assistance. The authors would like to thank EIEICO and Grain Processing Corp. for supplying the nutritive supplement. Funding was provided by the Poultry Industry Council, Canadian Turkey Marketing Agency, Technology Development and Agriculture & Agri-Food Canada.

Received for publication December 16, 2006. Accepted for publication May 21, 2007.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 REFERENCES
 
Bilgili, S. F. 1988. Research note: Effect of feed and water withdrawal on shear strength of broiler gastrointestinal tract. Poult. Sci. 67:845–847.[Web of Science][Medline]

Corrier, D. E., J. A. Byrd, B. M. Hargis, M. E. Hume, R. H. Bailey, and L. H. Stanker. 1999. Presence of Salmonella in the crop and ceca of broiler chickens before and after preslaughter feed withdrawal. Poult. Sci. 78:45–49.[Abstract/Free Full Text]

Farhat, A., M. E. Edward, M. H. Costell, J. A. Hadley, P. N. Walker, and R. Vasilatos-Younken. 2002. A low residue nutritive supplement as an alternative to feed withdrawal in broilers: Efficacy for gastrointestinal tract emptying and maintenance of live weight prior to slaughter. Poult. Sci. 81:1406–1414.[Abstract/Free Full Text]

Hinton, A., R. J. Buhr, and K. D. Ingram. 2002. Carbohydrate-based cocktails that decrease the populations of Salmonella and Campylobacter in the crop of broiler chickens subjected to feed withdrawal. Poult. Sci. 81:780–784.[Abstract/Free Full Text]

Lyon, C. E., C. M. Papa, and R. L. Wilson, Jr. 1991. Effect of feed withdrawal on yields, muscle pH, and texture of broiler breast meat. Poult. Sci. 70:1020–1025.[Web of Science]

McKee, S. R., and A. R. Sams. 1997. The effect of seasonal heat stress on rigor development and the incidence of pale, soft, exudative turkey meat. Poult. Sci. 76:1616–1620.[Abstract/Free Full Text]

Northcutt, J. K., R. J. Buhr, M. E. Berrang, and D. L. Fletcher. 2003. Effect of replacement finisher feed and length of feed withdrawal on broiler carcass yield and bacteria recovery. Poult. Sci. 82:1820–1824.[Abstract/Free Full Text]

Northcutt, J. K., E. A. Foegeding, and F. W. Edens. 1994. Water-holding properties of thermally preconditioned chicken breast and leg meat. Poult. Sci. 73:308–316.[Web of Science][Medline]

Owens, C. M., E. M. Hirschler, S. R. McKee, R. Martinez-Dawson, and A. R. Sams. 2000. The characterization and incidence of pale, soft, exudative turkey meat in a commercial plant. Poult. Sci. 79:553–558.[Abstract/Free Full Text]

Pietrzak, M., M. L. Greaser, and A. A. Sosnicki. 1997. Effect of rapid rigor mortis processes on protein functionality in pectoralis major muscle of domestic turkeys. J. Anim. Sci. 75:2106–2116.[Abstract/Free Full Text]

Ramirez, G. A., L. L. Sarlin, D. J. Caldwell, C. R. Yezak, M. E. Hume, D. E. Corrier, J. R. Deloach, and B. M. Hargis. 1997. Effect of feed withdrawal on the incidence of Salmonella in the crops and ceca of market age broiler chickens. Poult. Sci. 76:654–656.[Abstract/Free Full Text]

Rathgeber, B. M., J. A. Boles, and P. J. Shand. 1999a. Rapid postmortem pH decline and delayed chilling reduce quality of turkey breast meat. Poult. Sci. 78:477–484.[Abstract/Free Full Text]

Rathgeber, B. M., M. D. Pato, J. A. Boles, and P. J. Shand. 1999b. Rapid post-mortem glycolysis and delay chilling of turkey carcasses cause alterations to protein extractability and degradation of breast muscle proteins. J. Agric. Food Chem. 47:2529–2536.[Web of Science][Medline]

Rathgeber, B. M., and A. L. Waldroup. 1995. Antibacterial activity of a sodium acid pyrophosphate product in chiller water against selected bacteria on broiler carcasses. J. Food Prot. 58:530–534.[Web of Science]

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Tarachai, T., and K. Yamauchi. 2000. Effects of luminal nutrient absorption, intraluminal physical stimulation, and intravenous parenteral alimentation on the recovery responses of duodenal villus morphology following feed withdrawal in chickens. Poult. Sci. 79:1578–1585.[Abstract/Free Full Text]

Thompson, K. L., and T. J. Applegate. 2006. Feed withdrawal alters small-intestine morphology and mucus of broilers. Poult. Sci. 85:1535–1540.[Abstract/Free Full Text]

Veerkamp, C. H. 1986. Fasting and yield in broilers. Poult. Sci. 65:1299–1304.[Web of Science]





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