S. F. Bilgili1, E. T. Moran1, Jr. and J. S. Spano2
1Dept. of Poultry Science,
Auburn University,
Auburn, AL, USA
2Dept. of Pathobiology,
Auburn University,
Auburn, AL, USA
A close coordination is essential between the live production and processing phases within an integrated broiler production system to maintain a steady supply of live birds to the processing plant. In this study, blood chemistry of male and female broiler chickens from two diverse strain-crosses (fast-food and yield type) subjected to pre¬-slaughter transportation was assessed at 39 and 53 days of age.
At each age, feed was withdrawn 4 hours prior to catching and cooping. One-half of the coops (by strain-cross, sex, and replicate pen) were either held stationary for 10 hours, or subjected to a 6h transportation followed by a 4h of stationary holding prior to slaughter.
Blood chemistry profiles showed few differences due to age, strain-cross and sex. However, significant treatment effects were detected from transportation due to increased dehydration, hemoconcentration and protein catabolism.
Introduction
Market age broilers must be transported to the processing plant. To assure a steady and uninterrupted supply, a close coordination is essential between the production and plant personnel. In scheduling flocks for transportation, many factors must be taken into account, including feed withdrawal program, farm location (distance), catching time (day or night) and method (speed), weather conditions, plant holding capacity, and processing line-speed (birds per h). Minimizing stressors during this short pre¬slaughter phase is essential to reduce the likelihood for mortality (DOA), weight loss (shrink) and carcass and meat quality problems (Freeman et al., 1984 ; Kettlewell, 1989 ; Nico and Scott, 1990 ; Moran and Bilgili, 1995). Freeman (1984) outlined several potential stressors during this period, including handling, inversion, crating, confinement, social disruption, changes in micro and macro climate, fasting, air movement, vibration, and noise.
The purpose of this study was to compare the changes in blood profile of broilers either held stationary or subjected to active transportation, followed by a period of rest, prior to processing.
Material and Methods
Male and female broilers from two diverse strain-crosses (SC; fast-food and yield type) were reared to 53 days of age (four replicate pens per sex and SC; 16 pens total) on common feeding and management conditions. Both at 39 and 53 days of age, feed was removed for 4 hours (with water available) prior to catching. Seven birds were placed per coop (four marked coops per pen) for transport to the Pilot Processing Plant. One-half of the coops from each pen were placed on an open-bed trailer for transportation (TR), whereas the other half were held stationary (SH) at the plant for 10h.
Transportation treatment was 6h in length, followed by a 4 h rest prior to processing. Coops from each pen was processed sequentially, with alternating TR and SH treatments. Birds were electically stunned in water-bath stunner, and manually cut for exsanguination. Blood (5 ml) was collected from each bird into marked individual plastic tubes (10 birds per treatment per pen). Blood was allowed to clot and serum was separated by centrifugation (Spano et al., 1987). One ml of serum was pooled by treatment from each pen (32 pooled samples per age) and used for blood chemistry. Serum samples were then analyzed in duplicate by a Cobas Mira Chemistry Analyzer, using commercially available kits for glucose, total protein, uric acid, sodium, chloride, calcium, potassium, phosphorus, aspartate transferase (AST), creatine phosphokinase (CPK), gamma glutamyl transferase (GGT), lactate dehydrogenase (LDH), and serum alkaline phosphatase (SAP).
Data were analyzed, by age, as a 2x2x2 factorial arrangement of SC, sex, and transportation treatments by the General Linear Models Procedure of SAS (1988).
Results and Discussion
Select serum chemistry values of broiler chickens are presented by SC, sex, transportation treatments, and age in Tables 1-3. It is difficult to obtain baseline clinical chemistry values for broiler chickens, as these values have been shown to vary extensively with genetics (i.e., layer vs. broiler lines), feeding/fasting status, micro/macro climate, age, sex, physiological state, health status, as well as methods used in blood sampling and analysis (Bowes et al., 1989). Tables 1-3 summarize the blood chemistry of broilers by main effects of SC, sex, and transportation treatment at both market ages.
There were no significant two- or three-way interactions in this study (P>0.05). Few differences were observed in blood chemistry values due to SC (GGT at 6 wk and SAP at 8 wk of age), and sex (sodium and potassium at 6 wk and SAP at 6 and 8 wk of age). On the other hand, significant increases in serum uric acid, sodium, chloride, potassium, AST, CPK, and LDH, and decreases in serum phosphorus, GGT and SAP were detected for the TR treatment at both ages.
Serum AST, CPK, and LDH levels appeared to increase with age, whereas the glucose and SAP levels decreased from 39 to 53 d of age. Age related drop in serum glucose values in this study was unexpected and unexplainable. However, values this low have been reported in birds with spiking mortality syndrome (Davis and Vasilatos-Younken, 1995) and with mycotoxicosis (Espada et al., 1994).
Blood chemistry profiles obtained indicates that long transportation period (6 h) may be a stress factor in itself in pre-slaughter broilers. Subsequent rest period of 4h did not stabilize the effects of transportation in this study. Increases in serum enzyme levels, particularly CPK and LDH, are attributed to tissue damage; changes in uric acid, GGT and AST to alterations in energy metabolism (lipolysis and gluconeogenesis); and increases in serum electrolytes to hemoconcentration (dehydration). These alterations in blood chemistry are consistent with those reported in the literature for transported broilers (Halliday et al., 1977 ; Freeman et al., 1984 ; Cashman et al., 1989 ; Duncan, 1989 ; Mitchell et al., 1992 ; Yalcin et al., 2001).
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From Proceedings of the "XVI European Symposium on the Quality of Poultry Meat" and the "X European Symposium on the Quality of Eggs and Egg Products", Saint-Brieuc Ploufragan, France.
