Influence of conventional and Kosher slaughter techniques in cattle on carcass and meat quality

Abstract

The aim of this study was to evaluate and compare the influence of conventional and Kosher slaughter techniques in cattle on carcass and meat quality parameters. The conventional slaughter was done using a pneumatic captive bolt gun to stun the animals before sticking, while Kosher slaughter was done by sticking the animals and then stunning them with a 0.22 calibre cash special captive bolt gun, 20 seconds later. The animals (n=311) were randomly assigned into 4 treatment groups, namely; slaughter method (SM) (main group, sub-divided into: conventional slaughter technique (CST) and Kosher slaughter technique (KST)); electrical stimulation (ES), sub-divided into: electrically stimulated (ES) and non-stimulated (NES); gender (G), sub-divided into: male (M) and female (F); fat code (FC), sub-divided into: FC-2 and FC-3 (i.e. lean to medium fatness). The quality attributes evaluated were blood loss (BL), drip loss (DL), cooking loss (CL), presence of blood in the trachea (BLT), blood splash in the lungs (BS), shear force (SF), colour (L*, a* and b*), pH and temperature profile over 24 hours and the effect of subcutaneous fat thickness (SCF). Animals were mainly steers in the “A” age group with an average slaughter weight of about 400 kg. Different crossbreeds of Bonsmara, Brahman and Nguni cattle were used, which is typical of cattle slaughtered in South Africa. Blood loss, blood in trachea and blood splash were evaluated using 311 animals (CST, n=141; KST, n=170) but for the other parameters, smaller numbers were used because of the hectic nature of the trials. Evaluation of BL, BLT and BS were done in the abattoir and pH and temperature readings were also taken at 45 mins, 3, 6, 12 and 24 hrs post-mortem between the 10th and 11th rib on the m. longissimus dorsi which was where the carcasses were sampled for the meat quality analyses. The results of this study revealed that there was no significant difference (p> 0.05) in % blood loss between the conventional and the Kosher group but the conventionally slaughtered group had a slightly higher bleed-out. Fat code had a significant (p= 0.0475) influence on %BL, with FC-2 (2.42%) group bleeding out slightly more than FC-3 (2.24%). For % drip loss, there were no significant differences (p> 0.05) between all the treatment groups except for fat code (p= 0.0242), with FC-3 (2.95%) samples exuding more water than FC-2 (2.42%) meat samples. In terms of % cooking loss, there was a significant difference (p= 0.0004) between the slaughter methods, with meat samples from the conventional method (22.11%) exuding more water than the meat from Kosher group (18.16%). For blood in trachea, there was a highly significant difference (p< 0.0001) between the slaughter methods, with the Kosher-slaughtered animals having significantly more blood in the tracheas than the conventional group. Similarly, for % blood splash, the Kosher-slaughtered group also had a significantly (p< 0.0001) higher amount of splash than the conventional group. In terms of shear force, analyses showed significant difference between the SM with the Kosher meat (42.99) appearing more tender (p= 0.0005) compared to the meat from conventionally slaughtered animals (53.54). Electrical stimulation also had a significant influence, with meat from the ES group (43.27) being significantly (p< 0.0001) more tender compared to the NES group (61.15). For subcutaneous fat thickness, there were no significant differences (p> 0.05) in all the treatments save for fat code, with FC-3 group (6.38) having thicker fat cover (p= 0.0004) than FC-2 (4.44) which was anticipated. In terms of colour, there was a significant difference (p< 0.0001) between slaughter methods for the L* value (lightness). Meat samples from the Kosher-killed animals (46.08) were lighter than the conventionally killed ones (35.40). Samples from the females (48.29) were also significantly lighter (p= 0.0057) than the males’ (37.79). For a* value (redness), there was a significant difference (p< 0.0001) between the slaughter methods. The conventional group meat (15.58), were redder than the Kosher meat (10.40). Gender effect was also significant (p< 0.05), with meat from the males (13.81) appearing redder than the females’ (11.25). For b* value (yellowness), significant difference (p< 0.0001) was also found between the slaughter methods. The Kosher meat samples (-6.49) appeared yellower than those from conventional slaughter (0.26). FC-3 samples (-2.36) were also significantly (p= 0.0112) yellower than the FC-2 samples (-3.05). For pH, analyses revealed a significant difference (p< 0.0380) at 45 minutes post-mortem (pm) between slaughter methods. The kosher carcasses (pH= 6.43) had a slightly higher pH compared to the conventionally slaughtered carcasses (6.33). The ES carcasses (pH=6.16) also had a significantly lower (p< 0.0001) pH compared to the NES carcasses (pH=6.89). At 3hrs pm, only electrical stimulation showed a significant influence (p< 0.0001). The ES carcasses (pH= 5.72) were lower than the NES group (pH= 6.49). At 6hrs, only electrical stimulation still showed a significant influence (p< 0.0001), with the ES carcasses (5.56) still having a faster decline compared to the NES group (pH= 6.01). At 12hrs, the ES group (pH= 5.61) still had a significantly (p= 0.0008) lower pH than the NES group (pH= 5.82). At 24hrs, only the slaughter method showed a significant influence (p= 0.0314) in carcass pH, with the Kosher carcasses (pH= 5.53) having a slightly lower pH compared to the conventionally slaughtered ones (pH= 5.56). The latter difference is probably not of any practical significance and could be ignored. Temperature at 45 minutes pm showed a significant difference (p= 0.0248) between the slaughter methods with the carcasses from Kosher slaughter (36.500C) having a slightly lower temperature compared to those slaughtered conventionally (37.220C). At 3hrs pm, the carcasses from Kosher slaughter (30.060C) had a significantly higher (p= 0.0005) temperature than the conventional group (27.050C). The female carcasses (31.260C) also had significantly higher (p< 0.05) temperature compared to the male carcasses (27.890C). The FC-2 carcasses (28.190C) also had a significantly lower temperature (p= 0.0149) compared to FC-3 (30.110C) which was anticipated due to lower temperature decline in those with lower subcutaneous fat. At 6hrs pm, the conventionally slaughtered carcasses (14.710C) still showed a significantly faster decline (p< 0.0001) compared to those slaughtered by Kosher (20.16). FC-2 carcasses also showed a significantly (p= 0.0104) lower temperature (16.680C) compared to FC-3 (18.740C). At 12 hrs pm, the conventionally slaughtered carcasses (4.720C) still had a significantly (p< 0.0001) lower temperature compared to the Kosher group (10.240C). The FC-2 group (6.690C) also had a significantly (p= 0.0011) lower temperature compared to the FC-3 group (8.890C). Finally at 24 hrs after slaughter, slaughter method still showed a highly significant influence (p< 0.0001) with the conventionally slaughtered carcasses having a much lower temperature (-0.420C) compared to the Kosher group (3.060C). The male’ carcasses (0.620C) also had significantly lower (p< 0.05), ultimate temperature compared to carcasses from the females (2.990C). There was also a significant difference (p< 0.05) between the fat codes, with the FC-2 carcasses (1.010C) showing a lower temperature, compared to the FC-3 (1.710C) carcasses. Copyright