• Variation in the quality of meat from Irish steers at the time of slaughter.

      Moloney, Aidan P; Mullen, Anne Maria; Maher, S.C.; Buckley, D.J.; Kerry, Joseph P. (Teagasc, 01/01/2004)
      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.
    • What are the drivers of beef sensory quality using metadata of intramuscular connective tissue, fatty acids and muscle fiber characteristics?

      Listrat, Anne; Gagaoua, Mohammed; Andueza, Donato; Gruffat, Dominique; Normand, Jérome; Mairesse, Guillaume; Picard, Brigitte; Hocquette, Jean-François; Agence de l'Environnement et de la Maîtrise de l'Energie, France; European Union; et al. (Elsevier BV, 2020-10)
      The aim of this integrative study was to investigate the relationships between biochemical traits (total, insoluble and soluble collagens (TCol, ICol, SCol), cross-links (CLs), proteoglycans (TPGs), proportion of fiber types, total lipids (TLips), main fatty acids (FAs) families, the n-6/n-3 polyunsaturated FA (n-6/n-3PUFA) ratio and the sensory attributes scores (tenderness, juiciness, flavor) of two muscles from beef: Rectus abdominis (RA) and Longissimus thoracis (LT). For robust analysis, a database was prepared using samples from three studies from animals raised under different production systems. The analyses were performed either on each study separately or on pooled data per muscle after removing as many experimental effects as possible in each study. The CLs (across the muscles and studies) and, to a lower extent, type IIA muscle fibers (mainly for RA muscles), saturated FAs (SFAs), monounsaturated FAs (MUFAs) (for the LT muscles) were the components the most frequently associated with tenderness. The CLs, type IIA muscle fibers (mainly for the RA muscles), TLips, SFAs, MUFAs, conjugated linoleic acids (CLAs) and n-6/n-3 PUFA ratio (mainly for the LT muscles) were the components the most associated with juiciness. The TLips and CLAs (across the muscles and studies), SFAs, MUFAs (mainly for the LT muscles), CLs (mainly for the RA muscles) and TPGs (mainly for the LT muscles) were the components the most associated with flavor liking. The CLs, CLAs, TLips, SFAs, MUFAs, n-6/n-3 PUFA ratio, type IIA and I muscle fibers were the components the most frequently associated with the 3 sensory scores taken together. The SCol, TPGs and type IIX+B muscle fibers were little associated with the sensory scores taken together. The TCol, ICol and PUFAs were components the least associated with sensory scores. The data of this integrative study highlighted for the first time that the CLs were negatively involved in the determination of the three sensory traits mainly in the RA muscle. The muscle fibers in this integrative study had a weak impact on the variations in beef sensory traits. The type IIA and IIX+B muscle fibers were respectively negatively and positively associated with tenderness, negatively associated with juiciness and flavor. The type I muscle fibers were overall positively associated with juiciness and flavor and negatively or positively with tenderness and these associations were muscle and study-dependent. Overall, the TLips and FAs were positively associated with the sensory scores and the n-6/n-3 PUFA ratio was negatively associated with them.
    • What are the drivers of beef sensory quality using metadata of intramuscular connective tissue, fatty acids and muscle fiber characteristics?

      Listrat, Anne; GAGAOUA, Mohammed; Andueza, Donato; Gruffat, Dominique; Normand, Jérome; Mairesse, Guillaume; Picard, Brigitte; Hocquette, Jean-François; Agence de l'Environnement et de la Maîtrise de l'Energie; European Union; et al. (Elsevier, 2020-08-14)
      The aim of this integrative study was to investigate the relationships between biochemical traits (total, insoluble and soluble collagens (TCol, ICol, SCol), cross-links (CLs), proteoglycans (TPGs), proportion of fiber types, total lipids (TLips), main fatty acids (FAs) families, the n-6/n-3 polyunsaturated FA (n-6/n-3PUFA) ratio and the sensory attributes scores (tenderness, juiciness, flavor) of two muscles from beef: Rectus abdominis (RA) and Longissimus thoracis (LT). For robust analysis, a database was prepared using samples from three studies from animals raised under different production systems. The analyses were performed either on each study separately or on pooled data per muscle after removing as many experimental effects as possible in each study. The CLs (across the muscles and studies) and, to a lower extent, type IIA muscle fibers (mainly for RA muscles), saturated FAs (SFAs), monounsaturated FAs (MUFAs) (for the LT muscles) were the components the most frequently associated with tenderness. The CLs, type IIA muscle fibers (mainly for the RA muscles), TLips, SFAs, MUFAs, conjugated linoleic acids (CLAs) and n-6/n-3 PUFA ratio (mainly for the LT muscles) were the components the most associated with juiciness. The TLips and CLAs (across the muscles and studies), SFAs, MUFAs (mainly for the LT muscles), CLs (mainly for the RA muscles) and TPGs (mainly for the LT muscles) were the components the most associated with flavor liking. The CLs, CLAs, TLips, SFAs, MUFAs, n-6/n-3 PUFA ratio, type IIA and I muscle fibers were the components the most frequently associated with the 3 sensory scores taken together. The SCol, TPGs and type IIX+B muscle fibers were little associated with the sensory scores taken together. The TCol, ICol and PUFAs were components the least associated with sensory scores. The data of this integrative study highlighted for the first time that the CLs were negatively involved in the determination of the three sensory traits mainly in the RA muscle. The muscle fibers in this integrative study had a weak impact on the variations in beef sensory traits. The type IIA and IIX+B muscle fibers were respectively negatively and positively associated with tenderness, negatively associated with juiciness and flavor. The type I muscle fibers were overall positively associated with juiciness and flavor and negatively or positively with tenderness and these associations were muscle and study-dependent. Overall, the TLips and FAs were positively associated with the sensory scores and the n-6/n-3 PUFA ratio was negatively associated with them.