PUBLICATION DATE: 11/09/2007
SOURCE: Univ. of Arkansas Cooperative Extension Service
Experimental market research has shown that beef consumers equate eating quality with value and that superior eating quality not only increases the likelihood that consumers will purchase beef but also increases the prices they are willing to pay to obtain the level of eating satisfaction they desire. One source of inherent tenderness variation, often overlooked in the design of beef tenderness management systems, is sex classification (heifer vs. steer). Despite the fact that heifers typically produce carcasses with higher marbling scores and more desirable USDA quality grades, product tenderness usually favors steers.
• Calpastatin and Early Postmortem Tenderization: Fresh beef naturally tenderizes during postmortem storage at refrigerated temperatures (aging). This natural tenderization process is caused by the degradation of specific structural proteins in muscle fibers by enzymes that reside in skeletal muscle tissue. The specific enzyme responsible for most of the protein degradation during the early postmortem period is μ-calpain. Degradation of proteins by μ-calpain is regulated by a specific enzyme inhibitor called calpastatin. When calpastatin´s inhibitory activity is low, μ-calpain actively degrades key protein structures within the muscle cells, causing the muscle to lose structural integrity and tenderize as it ages. Conversely, when calpastatin activity is high, degradation of structural proteins by μ-calpain is limited, which reduces the extent of tenderization.
The longissimus tissue from heifers has a higher 24-hour calpastatin activity than longissimus muscle tissue from steers. As a result, longissimus steaks from heifers were tougher than steaks from steers. Data suggest that beef produced by heifers tenderizes more slowly than beef from steers and, therefore, requires a longer postmortem aging period to attain a comparable level of tenderness.
• Temperament and Reaction to Pre-Harvest Stress: Heifers and steers differ in temperament and, therefore, react differently to pre-slaughter stress. Heifers are not only more temperamental than steers but also produce a greater number of carcasses with slightly dark lean color compared with steers.
Recent research suggests that avoiding stress immediately prior to harvest is important for assuring acceptable beef tenderness. Therefore, gentle handling of slaughter cattle during transport and immediately before harvest is important for assurance of final product quality. Because of their excitability, it is especially important to exercise careful handling practices when transporting heifers.
• Hormonal Effects (Endogenous Hormones): Information concerning hormonal effects on beef tenderness is limited; however, existing evidence suggests that higher circulating estrogen levels of Beef Cattle Research Update 6 September 2007 heifers may contribute to their tendency to produce beef that is tougher than beef produced by steers.
• MGA in Finishing Diets for Heifers: A widely used approach for suppressing estrus and reducing estrogen-induced behavioral problems among finishing heifers is dietary supplementation with melengestrol acetate. Research suggests that feeding MGA is not detrimental to beef tenderness.
MGA has no withdrawal requirement. To avoid beef quality problems, heifers should not be removed from MGA-supplemented diets for periods longer than 24 hours prior to harvest. Heifers receiving diets that include MGA normally show signs of estrus within two to seven days of MGA withdrawal. The stress associated with behavioral estrus, following withdrawal from MGA-supplemented diets, can result in an abnormally high frequency of dark cutting carcasses and decreased product tenderness.
• Hormonal Implants: Recent research suggests that both number and potency of hormonal implants administered to heifers during the finishing period can influence tenderness of the final product. Use of a single finishing implant for heifers seems to have little effect on tenderness; however, use of two successive finishing implants has been shown to significantly increase longissimus WBSF. Moreover, existing evidence suggests that not all two-implant programs for finishing heifers have detrimental effects on tenderness. Implant/reimplant programs that involve some of the more potent combination implants are the only ones that have been found to elicit negative effects on tenderness in heifers. Implant effects on tenderness tend to be most pronounced for the first few days postmortem and, then, gradually diminish as length of the postmortem aging period is extended.
Correspondingly, increased toughness observed among re-implanted heifers receiving relatively potent implants seems to be largely mitigated by aging for 21 days or longer. Re-implanting of heifers also has been shown to reduce marbling score, which can be detrimental to both tenderness and flavor. Heifers receiving two comparatively potent finishing implants often produce reduced numbers of carcasses grading Choice and Prime, whereas less aggressive implant programs tend to have minimal effects on quality grade performance.
Key Points: Managing Heifers to Minimize Beef Tenderness Problems
• Beef produced by heifers is more likely to be tougher than beef from steers.
• Compared to steers, heifers are more excitable and, therefore, are more likely to exhibit stress-related meat quality problems (dark lean color and reduced tenderness). When shipping heifers, extra precautions should be taken to avoid aggressive handling, excitement or physical exertion before, during or following transport to the processing plant.
• Finishing diets that include MGA can be used to suppress estrus and improve growth performance of heifers without negatively affecting beef tenderness. Heifers should not be removed from MGA-supplemented diets for periods longer than 24 hours prior to harvest.
• The number and potency of finishing implants can influence beef tenderness and carcass quality grade. For heifers requiring two finishing implants, use of two successive high-potency implants should be avoided.
• Beef produced by heifers tenderizes more slowly during storage and requires a longer postmortem aging period than beef from steers to attain a comparable level of tenderness. Based on existing research information, postmortem aging periods of at least 21 days are recommended for heifer beef.
By Tatum et al., Colorado State University.
PUBLICATION DATE: 11/09/2007
SOURCE: Univ. of Arkansas Cooperative Extension Service
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SOURCE: Univ. of Arkansas Cooperative Extension Service
Experimental market research has shown that beef consumers equate eating quality with value and that superior eating quality not only increases the likelihood that consumers will purchase beef but also increases the prices they are willing to pay to obtain the level of eating satisfaction they desire. One source of inherent tenderness variation, often overlooked in the design of beef tenderness management systems, is sex classification (heifer vs. steer). Despite the fact that heifers typically produce carcasses with higher marbling scores and more desirable USDA quality grades, product tenderness usually favors steers.
• Calpastatin and Early Postmortem Tenderization: Fresh beef naturally tenderizes during postmortem storage at refrigerated temperatures (aging). This natural tenderization process is caused by the degradation of specific structural proteins in muscle fibers by enzymes that reside in skeletal muscle tissue. The specific enzyme responsible for most of the protein degradation during the early postmortem period is μ-calpain. Degradation of proteins by μ-calpain is regulated by a specific enzyme inhibitor called calpastatin. When calpastatin´s inhibitory activity is low, μ-calpain actively degrades key protein structures within the muscle cells, causing the muscle to lose structural integrity and tenderize as it ages. Conversely, when calpastatin activity is high, degradation of structural proteins by μ-calpain is limited, which reduces the extent of tenderization.
The longissimus tissue from heifers has a higher 24-hour calpastatin activity than longissimus muscle tissue from steers. As a result, longissimus steaks from heifers were tougher than steaks from steers. Data suggest that beef produced by heifers tenderizes more slowly than beef from steers and, therefore, requires a longer postmortem aging period to attain a comparable level of tenderness.
• Temperament and Reaction to Pre-Harvest Stress: Heifers and steers differ in temperament and, therefore, react differently to pre-slaughter stress. Heifers are not only more temperamental than steers but also produce a greater number of carcasses with slightly dark lean color compared with steers.
Recent research suggests that avoiding stress immediately prior to harvest is important for assuring acceptable beef tenderness. Therefore, gentle handling of slaughter cattle during transport and immediately before harvest is important for assurance of final product quality. Because of their excitability, it is especially important to exercise careful handling practices when transporting heifers.
• Hormonal Effects (Endogenous Hormones): Information concerning hormonal effects on beef tenderness is limited; however, existing evidence suggests that higher circulating estrogen levels of Beef Cattle Research Update 6 September 2007 heifers may contribute to their tendency to produce beef that is tougher than beef produced by steers.
• MGA in Finishing Diets for Heifers: A widely used approach for suppressing estrus and reducing estrogen-induced behavioral problems among finishing heifers is dietary supplementation with melengestrol acetate. Research suggests that feeding MGA is not detrimental to beef tenderness.
MGA has no withdrawal requirement. To avoid beef quality problems, heifers should not be removed from MGA-supplemented diets for periods longer than 24 hours prior to harvest. Heifers receiving diets that include MGA normally show signs of estrus within two to seven days of MGA withdrawal. The stress associated with behavioral estrus, following withdrawal from MGA-supplemented diets, can result in an abnormally high frequency of dark cutting carcasses and decreased product tenderness.
• Hormonal Implants: Recent research suggests that both number and potency of hormonal implants administered to heifers during the finishing period can influence tenderness of the final product. Use of a single finishing implant for heifers seems to have little effect on tenderness; however, use of two successive finishing implants has been shown to significantly increase longissimus WBSF. Moreover, existing evidence suggests that not all two-implant programs for finishing heifers have detrimental effects on tenderness. Implant/reimplant programs that involve some of the more potent combination implants are the only ones that have been found to elicit negative effects on tenderness in heifers. Implant effects on tenderness tend to be most pronounced for the first few days postmortem and, then, gradually diminish as length of the postmortem aging period is extended.
Correspondingly, increased toughness observed among re-implanted heifers receiving relatively potent implants seems to be largely mitigated by aging for 21 days or longer. Re-implanting of heifers also has been shown to reduce marbling score, which can be detrimental to both tenderness and flavor. Heifers receiving two comparatively potent finishing implants often produce reduced numbers of carcasses grading Choice and Prime, whereas less aggressive implant programs tend to have minimal effects on quality grade performance.
Key Points: Managing Heifers to Minimize Beef Tenderness Problems
• Beef produced by heifers is more likely to be tougher than beef from steers.
• Compared to steers, heifers are more excitable and, therefore, are more likely to exhibit stress-related meat quality problems (dark lean color and reduced tenderness). When shipping heifers, extra precautions should be taken to avoid aggressive handling, excitement or physical exertion before, during or following transport to the processing plant.
• Finishing diets that include MGA can be used to suppress estrus and improve growth performance of heifers without negatively affecting beef tenderness. Heifers should not be removed from MGA-supplemented diets for periods longer than 24 hours prior to harvest.
• The number and potency of finishing implants can influence beef tenderness and carcass quality grade. For heifers requiring two finishing implants, use of two successive high-potency implants should be avoided.
• Beef produced by heifers tenderizes more slowly during storage and requires a longer postmortem aging period than beef from steers to attain a comparable level of tenderness. Based on existing research information, postmortem aging periods of at least 21 days are recommended for heifer beef.
By Tatum et al., Colorado State University.
PUBLICATION DATE: 11/09/2007
SOURCE: Univ. of Arkansas Cooperative Extension Service
News from the sector07/01/2009 | Cows´ body temperature drives their behaviorage
06/09/2009 | VéO® Field-Validated Benefits: Optimization of Feed Intake & Stress Management
06/08/2009 | Engormix.com in Alltech´s International Symposium
06/08/2009 | Despite economic crisis, SIAL China 2009 was successful
06/05/2009 | Engormix.com invests in the North American, European and Eastern agro-industry Send to a friend Who saw this news? (127)Comments: (0) Post a comment
Copyright ® 1999-2009 Engormix.com - All Rights Reserved.
ENGORENEWS GDC 20090920