THE EFFECT OF PERIOD FROM CATCHING OF TURKEYS TO SLAUGHTERING ON BREAST MEAT PSE INCIDENCE LUCIE KUPCIKOVA, VOJTECH ANDERLE, MARTINA LICHOVNIKOVA Department of Animal Breeding Mendel University in Brno Zemedelska 1, 613 Brno CZECH REPUBLIC lucie.kupcikova@mendelu.cz Abstract: The experiment involved 24 flocks of turkeys. Ten flocks were slaughtered within one hour after catching while fourteen flocks were transported to the slaughter for 8 1 km and the period between catching and slaughtering was 3 4 hours. The determination of PSE was done by staff visually and by palpation and they decisions were confirmed by water losses. The incidence of PSE meat was higher (P<.5) for turkeys slaughtered within 1h after catching (5.7% vs. 1.4%). The loss of water for PSE free meat ranged from 1.1 to 13.1%, whereas PSE meat reached values from 14.2 to 15.6%, the differences were significant (P<.5). It was confirmed that experienced staff at slaughter can very precisely and quickly recognize PSE meat visually and by palpation. Key Words: turkeys, growth, PSE meat, turkey meat production INTRODUCTION The consumption of turkey meat in the Czech Republic is annually around 2 kg per person but especially breast meat belongs to quality dietary meat. Given that heavy turkey hybrids with high carcass yield are currently used for fattening it is not necessary to fatten the high number of animals to cover the demand for this meat. Therefore it is important to greatly reduce stress and its adverse effect on the animals which can cause lower carcass yield of breast meat and possibly lead to the occurrence of defects meat PSE (pale, soft, exudative) and the subsequent confiscation was the most valuable parts of the turkey s carcass. The muscle showing pale color, fine texture and exudative character was firstly described in pork. The occurrence of these symptoms is mainly in white meat with predominance of white myofibrils. Based on these findings the abbreviation PSE (pale, soft, exudative) was accepted for such meat defects even for poultry meat. However the term PSE is still debated because the causes causing PSE differ for pigs and poultry mainly in genetic background, therefore for poultry expression PSE-like is also used. The halogen screening method, which have been used for the detection of sensitive pigs to stress and consequently prone to PSE, does not work in turkeys or broilers (Fujii et al. 1991, Ingr 23). PSE meat defect arises primarily as a result of stress. During fattening there is no significant stressful situations, however the situation is changed at the end of the fattening period when the animals are caught to the cages and transported to the slaughterhouse and here they are handled again (Ingr 23). This stress starts a very rapid progress of degradation of ATP and glycogen to lactic acid and inosine and the ph drops in one hour postmortem to 5.8 or lowers (Ingr 23). Fast glycogenolysis releases a lot of energy and it increases muscle temperature up to +43 C (Ingr 23, Chae et al. 27). Increased acidity and temperature of the muscle causes partial denaturation of the muscle proteins, which results in deterioration of water holding capacity of the meat. All meat quality characteristics show great variability and in this spirit PSE defects are manifested in intensity from barely noticeable to very significant (Ingr 23). Owens et al. (29) reported that the incidence of PSE meat on slaughters in the USA is in the range from 5 to 4%. Breeders in USA are also the largest producers of turkeys and turkey meat and therefore this defect meat causes considerable financial losses, which are estimated at up to 2 million dollars annually. In the EU the incidence of this defect is quite high, nearly 4% (Barbut et al. 25). Petracci et al. (29) sum the main possible causes of poultry PSE-including genetics, seasons, stress factors and conditions before slaughtering. 245 P age
Breast muscle exhibiting PSE defect is not suitable for direct consumption, because of water level, softness and paleness. PSE meat can be used for processing, canning or in sausage production but with less water holding capacity it is necessary to mix the meat with the meat of standard quality (Skřivan et al. 2). Carcass quality and breast meat yield is also affected by transport and particularly by transport cages size and its design. There is risk of breast meat of other body turkey parts damage due to the lack of space among the animals. Other factors which include hanging, stunning, undercutting, bleeding, scalding, plucking and storing meat can also affect carcass yield and breast meat quality (Skřivan et al. 2, Smith and Northcutt 29). The aim of the experiment was to determine the effect of period from catching to slaughtering including transport on occurrence of PSE breast meat in turkey. MATERIAL AND METHODS Twenty-four flocks were included in the evaluation of PSE incidence in turkey, both sex hens and toms. Ten flocks (2 46 turkeys) were fattened in the halls near the slaughterhouse. These animals were slaughtered within one hour after catching in the hall. The remaining 14 flocks (3 784 turkeys) were transported from farms 8 1 km distant when the period from catching to slaughtering ranged between 3 4 hours. The effect of both periods from catching to slaughtering and sex on the PSE incidence in breast meat was evaluated. The live weight of turkeys, carcass weight, PSE meat weight and breast muscle weight were measured too. The determination of PSE meat was done by two methods. First, visually and by palpation was done by staff in the slaughter that has long time experience with PSE. Correctness of the staff assessment was judged by laboratory control by water holding capacity (see Figure 1). Figure 1 Evaluation of PSE by staff (PSE free right side and PSE left side) Photographer Iveta Vdolčeková Water holding capacity (WHC) was determined in samples of the breast meat which were visually assessed as PSE by staff. The samples were taken from the caudal part of the deep breast muscle weighting 5 g, 24 hours post mortem. PSE free meat was assessed too. The samples were homogenized, 2 g of the meat were inserted between two papers Watman No. 2 and between two glass plates and loaded weight 5 g for 5 minutes. The samples were weighted before and after the treatment and percentage of water loss was calculated (Grau and Hamm 1953). There were done two observations, in the first 2 samples of PSE free and 16 samples of PSE were analyzed for WHC and in the second one 15 PSE free and 3 samples of PSE were analyzed. Water loss was expressed by mean and standard error of mean. Variability of the measurement was characterized by the coefficient of variation. For the evaluation of the effect of sex end transport on the observed characteristics Kruskal-Wallis one-way analysis of variation and the Mann-Whitney U test were used. Statistical analysis was performed using the UNISTAT 5.1 (Unistat Ltd, England). RESULTS AND DISCUSSION The period from turkey catching to slaughtering (4 hours vs. 1 hour) had significant effect on PSE incidence (P<.5). Table 1 shows the higher incidence of PSE meat defects in turkeys slaughtered 246 P age
within 1 hour from catching compared turkeys that were transported from a distance 8 1 km. PSE meat incidence ranged in turkeys slaughtered in one hour at a level of 5.7% while in turkeys slaughtered in 3 4 hours the level was 1.4%. Figure 2 shows the incidence of PSE in each flocks and there is a noticeable higher incidence of PSE meat in all flocks slaughtered within one hour after removal from halls. The sex of turkeys had no statistically significant effect (P>.5) on the incidence of PSE meat which shows Table 2. The results of water loss in both observations are shown in Table 3. The staff right decision about meat (PSE or PSE free) was confirmed by water losses according to Grau and Hamm (1953). The PSE free samples had statistically significantly lower water loss (P<.5) compared to PSE samples in both cases. This observations demonstrated that employees thanks connection with acquired practice are able precisely recognize the PSE meat just by quick palpation (P<.5). Table 1 Influence of period from catching to slaughtering on the incidence of PSE meat defects in turkeys [%] PSE breast meat Period Average ± SE* v x Till 1 h 5.7 ±.42 a.23 Till 4 h 1.4 ±.15 b.4 a, b - means of the same order designated by different letters are significantly different (P<.5) Table 2 Effect of turkey sex on PSE meat incidence [%] PSE breast meat Group Average ± SE* v x Turkey cockerels 2.8 ±.63 a.63 Turkey hens 3.4 ±.66 a.78 a, b - means of the same order designated by different letters are significantly different (P<.5) Figure 2 The incidence of PSE meat in all observed flocks [%] PSE meat [%] 9 8 7 6 5 4 3 2 1 Transport free Flocks Figure 3 show sum of live weight, carcass weight and breast meat weight in all flocks according to the period from catching to slaughtering. It is clear, that more animals were transported from distance 8 1 km. On the other hand, figure 4 shows the absolute weight of PSE meat for both periods. Notwithstanding the live weight of turkeys slaughtered within one hour was lower about 16.5t (Figure 3), the weight of PSE was much higher for these birds (337 kg vs. 19 kg, Figure 4). 247 P age
Table 3 Water losses of PSE and PSE free as determined by staff [%] Water losses Observation Breast meat Average ± SE* v x 1. PSE free 13.1 ±.47 a.16 PSE 15.6 ±.72 b.18 2. PSE free 1.1 ±.86 a.33 PSE 14.2 ±.43 b.16 a, b - means of the same order designated by different letters are significantly different (P<.5) The effect of time from catching to slaughtering on the incidence of PSE also discussed Owens et al. (2). They used for PSE meat determination ph and breast meat temperature as other possible factors characterizing PSE meat and they showed that breast meat of transported turkeys had significantly higher ph in 2 hours and 24 hours after slaughter. These authors however did not notice the difference in the loss of water. In contrast the authors Marques et al. (216) point out the significant influence of transport lasting two hours, the time from catching to slaughtering, on turkey stress, expressed by gene expression in the liver, which corresponds with our results. Hoof (1979) showed that with increasing length of turkey transport decreased the levels of glycogen and ATP, which can be connected with lower incidence of PSE in turkey after longer transport. They measured the glycogen and ATP levels after 4 hours of transport (26 km). Figure 3 The monitored carcass parameters depending on the period from catching to slaughtering [kg] Thousand 45 4 35 3 25 2 15 1 5 44.2 27.7 28.5 18.7 5.8 8.3 1 h 4 h 1 h 4 h 1 h 4 h Live weight 1 h Live weight 4 h Carcass weight 1 h Carcass weight 4 h Breast meat 1 h Breast meat 4 h Live weight Carcass weight Breast meat Figure 4 PSE breast muscle weight to about 1 hour to 4 hours to defeat of the total weight of the breast muscle turkey hens and turkey cockerels in the period [kg] kg 4 35 3 25 2 15 1 5 1 h 4 h PSE meat weight PSE meat weight 1 h PSE meat weight 4 h Owens et al. (29) reported that the incidence of PSE meat on slaughters in the USA is in the range from 5 to 4%. Breeders in USA are also the largest producers of turkeys and turkey meat and 248 P age
therefore this meat defect causes considerable financial losses, which are estimated at up to 2 million dollars annually. In the EU this defect is found in meat quite often nearly 4% (Barbut et al. 25). CONCLUSION The period from catching to slaughtering had statistically significant effect (P<.5) on incidence of PSE breast meat in turkey. The incidence of PSE meat was higher for turkeys slaughtered within 1h after catching, namely 5.7%. In contrast the incidence of PSE meat in turkey slaughtered within 3 4 hours was 1.4%. The influence of sex was no statistically significant (P>.5). The loss of water for PSE free meat ranged from 1.1 to 13.1%, whereas PSE meat reached values from 14.2 to 15.6%, the differences were significant (P<.5). It was confirmed that experienced staff at slaughter can very precisely and quickly recognize PSE meat visually and by palpation. ACKNOWLEDGEMENT The authors would like to thank the IGA IP 26/216 FA MENDELU project financial support. REFERENCES Barbut, S., Zhang, L., Marcone, M. 25. Effects of pale, normal, and dark chicken breast meat on microstructure, extractable proteins, and cooking of marinated fillets. World's Poultry Science Journal, 84(5): 797 82. Chae, H.S., Singh, N.K., Yoo, Y.M., Ahn, C.N., Jeong, S.G., Ham, J.S., Kim, D.H. 27. Meat Quality and Storage Characteristics Depending on PSE Status of Broiler Breast Meat. Asian-Australasian Journal of Animal Sciences, 2(4): 582 587. Fujii, J., Otsu, K., Zorzato, F., Leon, S., Khanna V.K., Weiler J.E., O`Brien P.J. and MacLennan D.H. 1991. Identification of Mutation in Porcine Ryanodine Receptor Associated with Malignant Hyperthermia. Science, 253(518): 448 451. Grau, R., Hamm, R. 1953. Eine einfache Methodz zur Bes-trimming der Wasserbindung im Muskel. Naturwissenschaften, 4: 29 3. Hoof, J.V. 1979. Influence of ante- and peri-mortem factors on biochemical and physical characteristics of turkey breast muscle. Veterinary Quarterly, 1: 29 32. Ingr, I. 23. Atypické zrání a kažení masa. Český svaz zpracovatelů masa [online]. Available at: http://www.cszm.cz/clanek.asp?typ=1&id=895. [216-7-27]. Marques, A.T., Lecchi, C., Grilli, G., Giudice, Ch., Nodari, S.R., Vinco, L.J., Ceciliani, F. 216. The effect of transport stress on turkey (Meleagris gallopavo) liver acute phase proteins gene expression. Veterinary Science, 14: 92 95. Owens, C.M., Alvarado, C.Z, Sams, A.R. 29. Research developements in pale, soft, and exudative turkey meat in North America. World's Poultry Science Journal, 88(7): 1513 1517. Owens, C.M., Sams, A.R. 2. The influence of transportation on turkey meat quality. World's Poultry Science Journal, 79(8): 124 127. Petracci, M., Bianchi, M., Cavani, C. 29. The European perspective on pale, soft, exudative conditions in poultry. World's Poultry Science Journal, 88(7): 1518 1523. Skřivan et al. 2. Drůbežnictví 2. Agrospoj, 22 s. Smith, D.P., Northcutt, J.K. 29. Pale poultry muscle syndrome. World's Poultry Science Journal, 88(7): 1493 1496. 249 P age