Muscle of dark and normal beef differs metabolically

Reduction in muscle glycogen triggered by adverse antemortem handling events alters postmortem energy metabolism and results in a high ultimate pH and dark, firm and dry beef, often referred to as 'dark-cutting'. However, the relationship between atypical dark (AT) beef, postmortem energy metabolism and underlying tissue characteristics remains somewhat unclear. Cattle harvested in the US and Canada representing normal (pH < 5.6), AT dark (pH 5.6-5.8) and dark cutting (DC; pH > 5.8) beef were analyzed for tissue characteristics related to energy metabolism. Results show AT dark beef is more oxidative but similar to normal beef in glycolytic potential and nucleotide abundance. Mitochondria DNA content (P < 0.05, Canada; P < 0.005, US) and oxidative enzymes for DC and AT dark beef were greater (P < 0.01; Canada and US) compared to normal beef. Myoglobin tracked (P < 0.01) with color classification. These findings show both DC and AT beef are inherently more oxidative and raise the possibility that more oxidative muscle may be more prone to develop dark beef.

Effects of immunocastration on the performance and meat quality traits of feedlot-finished Bos indicus (Nellore) cattle

This study aimed to evaluate the effects of immunocastration on the performance, testosterone concentration, carcass traits and meat quality of feedlot-finished Nellore cattle. Fifty-eight males (430 ± 36 kg bodyweight; 24 months old) were separated into three groups in a randomised complete design: surgically castration (n = 15), immunocastrated (anti-gonadotropin-releasing hormone (Bopriva®) vaccine, n = 21) and non-castrated (n = 22). The animals were housed in individual pens and fed ad libitum for 90 days with a common diet comprising 70% concentrate and 30% roughage (corn silage). The non-castrated animals had a greater average daily gain, feed efficiency, hot carcass weight and carcass yield than the surgically castrated and immunocastrated animals (P &lt; 0.05). Surgically castrated cattle grew faster and more efficiently than those castrated immunologically (P &lt; 0.05). The surgically castrated and immunocastrated animals had higher colour values L*, a* and b* and cooking loss than non-castrated animals (P &lt; 0.05). In conclusion, immunocastration decreased cattle performance compared with surgically castrated or non-castrated animals. However, immunocastration resulted in better meat quality compared with non-castrated, making it an alternative to surgical castration with no negative effects on animal welfare.