Epsilon Archive for Student Projects

Abstract

Meat quality is of importance regarding several characteristics like meat colour, visible fat and price, which is important for the consumers when buying meat at the store. Temperature and pH-decline postmortem is of great importance when discussing the quality of the meat. There are several factors along the whole production line that will influence the pH- and temperature decline that occur postmortem, which in turn have an effect on meat quality in the final product. Such factors could be feeding regimes pre-slaughter, age and breed, but also handling of the animals that might cause stress on farm, during transport and at the abattoir. The purpose of this study was therefore to investigate how pH- and temperature decline occurs in beef carcasses at a specific abattoir to investigate if the slaughter process is optimized or can be optimized to ensure a good final meat quality. The present study included 21 bulls, 11 heifers and 13 dairy cows that were slaughtered at two different occasions in the winter season. The carcasses were hanged in the Achilles tendon and half of the carcasses were electrical stimulated. The blood lactate was measured in the exsanguination blood, and the pH- and temperature meters were inserted into the left semimembranosus muscle, which registered values every tenth minutes for 24 hours. The results of the study showed that most of the carcasses reached pH 6 at high muscle temperatures, which increases the risk for heat-shortening and PSE. To ensure that pH 6 is reached at desirable muscle temperatures it is important to evaluate the slaughter process at the abattoir, so that animals are in a calm and suitable environment to reduce stressors before slaughter but also that the carcasses enter the coolers fast enough. No differences were seen regarding temperature- and pH-decline during the first 24 hours between sexes, but the muscle temperature at 24 hours postmortem (p=0.0417) were significantly higher for cows compared to heifers and bulls. Fat score had a positive correlation (r=0.64) to muscle temperature, which means that higher fat scores result in higher muscle temperatures in the carcasses. No differences were seen regarding the electrical stimulation for all parameters tested. However, the lairage time, overnight or not, showed that animals that stayed overnight had higher lactate concentration (p=0.0070) in exsanguination blood compared to animals slaughtered the same day due to different animal material in the groups. All bulls slaughtered stayed overnight, the cows were slaughtered the same day as arrival, and the heifers occurred in both groups. Bulls had a higher blood lactate concentration (p=0.0002) compared to heifers and cows, which is the explanation for the differences regarding lairage times´ effect on blood lactate concentration. But there were no differences in pH- and temperature decline between lairage times. According to the blood lactate results, animals may have reacted differently to the pre-slaughter situation, and some may have been more stressed/excited than others, it could therefore be of importance to evaluate if there are some steps pre-slaughter that can be optimized to reduce stress/excitement for the animals. Results from this study will be used to discuss optimization of the slaughter process at the specific abattoir