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Variation in the quality of meat from Irish steers at the time of slaughter.
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01/01/2004
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Moloney, A.P., Mullen, A.M., Maher, S.C., Buckley, D.J., Kerry, J.P., Variation in the quality of meat from Irish steers at the time of slaughter. End of Project Report, Teagasc, 2004.
Abstract
There is no information on the variation in quality, in particular
tenderness, that exists in Irish Beef nor is there information on the
variation that would remain if optimum practices were imposed at
all stages of the beef production chain. Evaluation of the success of
measures to improve beef consistency requires information on
existing variation and the minimum variation achievable.The objectives
of this project were (i) to establish the variation that exists in
the quality of meat from Irish cattle, (ii) to quantify the minimum
variation in meat quality that can be achieved in a practical beef production
system, (iii) to determine the effects and mechanisms of
additional sources of variation.
The conclusions from this project are:
• The M. longissimus dorsi (loin) was found to be more variable
than the M. semimembranosus (topside) for most quality
attributes examined (tenderness, sarcomere length and pH).
The scale of variation within the loin was similar to that
reported by the other research groups within the EU and US.
Heifers were more variable than steers for most attributes,
while there was no consistent classification effect on the
variability of meat quality attributes.
• Tenderness was equally variable in meat from genetically similar
steers, managed similarly, compared to commercial steers
randomly selected from a factory lairage but matched for
weight and grade.This was likely a result of both groups being
crossbred beef cattle of similar age, fat score, carcass weight
and managed identically post-mortem. However, variation in
tenderness of both groups was less than that observed in
a survey of commercial throughput (experiment 1). This
decrease is attributed to better pre-and-post-slaughter handling
practices.
• The data suggest that selection of sires (within a breed) with
better than average conformation has no deleterious effect on the eating quality of beef of their progeny.A more comprehensive
comparison of sires within a breed and between
breeds is required to confirm the generality of this conclusion.
• In a comparison of genotypes, gender and slaughter weights,
there was no evidence that variation around the mean value
for tenderness differed between breeds or liveweights after
14 days ageing. Bulls were more variable than steers for some
quality traits but the variation in tenderness was similar for
bulls and steers after 14 days ageing.
• While optimising the management of animals during the pre
and post-slaughter period reduced variation in tenderness,
some residual variation remained. A large percentage of the
residual variation in tenderness (Warner Bratzler shear force)
after 2 and 7 days post-mortem was explained by proteolysis
(breakdown of myofibrillar proteins).Variation in tenderness
(Warner Bratzler shear force) after 2 days post-mortem was
largely explained by phosphates (energy) and proteolysis,
while sensory tenderness was largely explained by phosphates
and glycolytic potential.
• Further work is required to reduce residual variation in Irish
beef and to determine the causes of this variation.