2002 Poultry Science Association, Inc.
EFFECT OF ELECTRICAL STIMULATION AND FEED WITHDRAWAL ON BROILER GASTROINTESTINAL CONTENT AND INTESTINAL PH, AND INTESTINAL BREAKING STRENGTH OF BROILER BREEDERS J. K. NORTHCUTT,1 R. J. BUHR, and J. A. DICKENS USDA, ARS, Russell Research Center, P.O. Box 5677, Athens, GA 30604-5677 Phone: (706) 546-3592 FAX: (706) 546-3633 e-mail:
[email protected]
Primary Audience: Primary Audience: Poultry Processing Plant Management, Quality Control Personnel, Researchers
SUMMARY Commercial poultry processors that use electrical stimulation (ES) systems to accelerate rigor mortis and resolution of rigor for early cut-up and deboning of meat have suggested that these systems also cause cloacal voiding of excreta during bleeding. Cloacal voiding would be advantageous to processors because it reduces available material for carcass contamination during evisceration. The present study used market-aged broilers and broiler breeders to evaluate effects of ES and feed withdrawal on gastrointestinal contents, intestinal tissue pH, and intestinal breaking strength. ES (200 V AC, 60 Hz pulsed 2 s on, 1 s off for 60 s) was found to have no effect on gastrointestinal contents or intestinal tissue pH of broilers. Gastrointestinal contents for full-fed broilers were 2.6- to 3-fold greater (51 to 57 g feces or ingesta), based on weight of filled intestines, than gastrointestinal contents of broilers held without feed. Intestinal breaking strength of roosters was 20 to 26% greater than intestinal breaking strength of hens, by as much as 160 g (jejunal) to 200 g (ileal). ES had no effect on viscera weight, ileal breaking strength, or jejunal breaking strength, with the exception of jejunal breaking strength for hens, which was 14% higher in ES hens as compared to non-stimulated hens. The increased intestinal strength for ES hens (14%) was less than the strength difference observed between sexes (20 to 26%) and, thus, would not provide a processing advantage. Key words: electrical stimulation, feed withdrawal, intestinal contents, pH, intestinal strength 2002 J. Appl. Poult. Res. 11:1–5
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To whom correspondence should be addressed.
JAPR: Research Report
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DESCRIPTION OF PROBLEM Before cut-up and deboning of poultry, processors typically hold or age meat on the carcass or breast half for 4 to 24 h to minimize meat toughness [1, 2, 3, 4]. The aging process is extremely costly for plants, requiring additional refrigerated storage space, electricity for refrigeration, storage bins, labor, and delays in filling customer orders [5, 6]. For this reason, there has been considerable effort expended toward the development of methods that reduce the amount of carcass aging time necessary to achieve acceptable poultry meat tenderness. One such method is electrical stimulation (ES), which has been implemented commercially to allow broiler processors to cut-up and debone meat immediately after carcass chilling without affecting meat tenderness [7, 8, 9, 10, 11, 12, 13]. ES is a rigor-accelerating process that involves application of electrical current in the form of pulses to an animal carcass shortly after death. These electrical pulses stimulate the muscle to contract and relax, which accelerates the depletion of energy stored in the muscles (glycogen and adenosine triphosphate or ATP), hastening the development and resolution of rigor mortis. Li et al. [7] published a comprehensive review and evaluation of ES in poultry. Sams [4, 12] has addressed the commercial implementation of ES in processing plants, and Hirschler and Sams [6] have addressed the production costs (installation and operation) of commercial-scale ES. ES systems are usually categorized based on the applied current amperage being low or high. ES systems using low current apply 200 mA or less per bird, and ES systems using high current apply 350 to 500 mA per bird [12]. Both ES systems induce muscle contraction; however, high amperage systems produce contractions with such force that the muscle contraction actually tears structure [8]. Low and high current ES systems have been used commercially in the U.S. and Brazil [12]. Some poultry processors have reported that the skeletal muscle contraction induced during ES results in cloacal voiding and improves a plant’s ability to meet the USDA Escherichia coli and Salmonella performance standards established in the Pathogen Reduction, Hazard
Analysis and Critical Control Point (HACCP) System regulation [14]. Based on these observations, the objective of the present study was to determine the relationship between ES, feed withdrawal, broiler intestinal pH, broiler gastrointestinal tract contents, and jejunal and ileal breaking strength in breeders.
MATERIALS AND METHODS EXPERIMENT 1 In each of two replications, 24 commercial male broilers were obtained from a local grower, transported to the university research facility, and divided into four pens containing pine shavings for litter. After an acclimation period of 3 d, pens of broilers were assigned to one of two feed withdrawal (FW) groups: 0 h FW or 12 h FW. Broilers held without feed for 12 h before processing remained on litter with access to water for the first 4 h, followed by 8 h of holding in coops. Full-fed broilers remained in pens with access to feed and water until 15 min before processing at which time they were cooped and transported less than 1 km to the pilot plant facility. Immediately before processing, broilers were weighed and processed in groups of four, using two birds from each FW group. Broilers were electrically stunned, head to shanks, in a brine stunner with voltage set at 50 V alternating current (AC) for 10 s and a current of approximately 33 mA. Stunned broilers were transferred to restraining cones to minimize clonic convulsions and were bled for 90 s by severing both carotid arteries and at least one jugular vein, or after bleeding for 30 s, one bird from each FW group was electrically stimulated (200 V AC, 60 Hz pulsed 2 s on, 1 s off for a total of 60 s). During ES, observations of noticeable evacuation were recorded and are presented in the text. All of the carcasses were scalded for 2 min at 52.5 C and were mechanically defeathered for 30 s. The external opening of the cloaca of each bird was clamped with a hemostat, and the bird’s abdominal and thoracic cavity was opened. Another hemostat was placed above the proventriculus, and the gastrointestinal tract was excised intact. Full viscera were weighed from clamp to clamp after removal of the heart, liver, gall
NORTHCUTT ET AL.: ELECTRICAL STIMULATION AND FEED WITHDRAWAL bladder, spleen, gizzard fat, and fat pad. After this initial weight, the tract was opened, wiped clean with towels, and reweighed. The pH of the small intestinal was measured in duplicate with 2.5-g samples taken from both sides of the Meckel’s diverticulum and following the method of Jeacocke [15]. The experimental design was a 2 × 2 factorial arrangement of the treatments for length of feed withdrawal (0 or 12 h) and ES (stimulated or not stimulated). Data were analyzed using the GLM procedure of SAS software to test the main effects as well as the interaction of feed withdrawal and ES. Means were separated using Tukey’s studentized range test option of the GLM procedure at a significance level of P < 0.05 [16]. EXPERIMENT 2 In each of two replications, 20 hens and 20 roosters were obtained from university flocks at 46 wk of age, transported
