By James Magolski, PhD on 11/12/2012
Beef tenderness is one of the most researched attributes of cooked beef. This continued focus is due to the vast number of factors influencing tenderness and the consumer’s demand for a tender product.
Research has shown that increased stress in the feedlot, during transportation and at the slaughterhouse can lead to an overall decreased tenderness. These negative quality traits influence the producer’s bottom line and the consumer’s willingness to purchase beef.
Beef cattle stress and temperament
The measurement of beef cattle temperament is still a novel topic within the livestock industry, and therefore one specific measurement of temperament has yet to be widely accepted by researchers and industry leaders. Today most measurements are subjective, allowing for human error or biased results. Published methods used include genetic markers, exit velocity, pen score, chute score, catch score, hair whorl position, vocalization and blood lactate concentration.
Livestock stress is an inevitable consequence of transferring animals from farm to slaughter. However, the measurement and understanding of the effects of specific pre-slaughter stressors on meat quality is difficult to comprehend due to the inherent variation across animal’s arriving at the plant, as well as the complex nature of the conversion of muscle to meat. One means of measurement found to be insightful includes recording vocalization of cattle prior to stun and then measuring blood lactate concentrations at exsanguination as an indication of animal stress and metabolic activity.
Animal Welfare Concerns
Almost all cattle vocalization events are the direct result of some stressful event, including the use of electric prods, falling, excessive squeezing of the chute or missed stuns. It is also understood that animals that are more stressed just prior to slaughter undergo a faster rate of anaerobic metabolism. Currently there is minimal published research evaluating the relationship between blood lactate and stress in beef cattle; however it has been reported that elevated concentration of circulating blood lactate are associated with increased stress.
A recent study reported temperament scores including chute score, capture score and vocalization just prior to harvest correlated (P < 0.03) with blood lactate concentration at time of exsanguination; with the strongest correlation between vocalization and blood lactate. Furthermore, cattle that did not vocalize just prior to harvest had a significantly (P = 0.001) lower blood lactate concentration compared to cattle that exhibited excessive vocalization (9.53 vs. 12.99 mmol/ L respectively).
In 2009 the kosher market contained more than 150,000 retail products representing a $200 billion industry. Even with strong demand for all goods including beef, the method of kosher slaughter by exsanguination of cattle without stunning has long been a topic of debate for its deviation in harvest method compared to captive bolt stunning. Currently there is mixed data with regard to kosher slaughter’s impact on animal welfare.
Generally speaking, cattle slaughtered by the kosher method remain conscious for 17 to 85 seconds after a proper throat cut compared to immediate unconsciousness with captive bolt stunning. To reduce this prolonged consciousness, some beef slaughter facilities have elected to follow the throat cut with a captive bolt stun to reduce animal activity and blood splash.
Religious slaughter is also a meat quality issue
Although animal welfare has been the primary discussion point for kosher slaughter, recently collected data suggests that it may also be a meat quality issue. These differences in meat quality could be attributed to many different observed measurements that deviate from the traditional expectations associated with captive-bolt stunning.
Time to unconsciousness is different between the two methods, and during this time animal stress and muscular activity may be affecting end product quality. Kosher-slaughtered cattle are also restrained differently than captive bolt cattle, which may result in increased stress just prior to death. Cattle stunned with the captive bolt method have their nose positioned downward, while the kosher method requires their nose to be elevated to expose the neck. While much meat quality research is focused on minimizing pre-slaughter stress, this process may be a stress influencer previously unmeasured.
Data collected on the Longissimus thoracis from kosher and captive bolt slaughtered heifers showed that kosher-slaughtered heifers exhibited higher (P < 0.01) L*, a*, b* and Warner-Bratzler shear force values than that of captive bolt stunned heifers. The reported decrease in tenderness of the kosher slaughtered cattle was 0.5 kg. There was also a tendency for kosher slaughtered heifers to have a reduced cook loss compared with captive bolt slaughtered cattle, suggesting a possible change in muscle pH and water-holding capacity.
One note that seems to be left out of the general conversation when discussing kosher slaughter is its unintentional impact on the commercial cattle market. More than half the volume of the kosher harvested beef in the U.S. is marketed through the commercial beef chain. Hindquarters are not marketed as kosher due to the muscles association with the siatic nerve while forequarters not passing final inspection are also sold through the conventional market. It is therefore important to understand how slaughter method will influence beef quality and palatability as the industry continues to focus on consumer acceptability.
Conclusion
Current data suggests a positive relationship between feedlot temperament measurements and blood lactate concentration at time of slaughter, suggesting that an animal’s stress response in the feedlot is similar to their response at the slaughterhouse.
Slaughter method can have an impact on meat quality and palatability, as strip steaks from kosher slaughter heifers had increased L*, a*, and b* values, decreased Warner-Bratzler shear force values, and reduced cook loss. Further research evaluating potential changes in muscle structure and overall meat quality as a result of the kosher method is needed to understand the implications of this alternative slaughter method.
