. 2011. Modification of muscle inherent properties through age at slaughter, growth promotants and breed crosses. Can. J. Anim. Sci. 91: 635Á648. A 2 4 factorial experiment tested the interactions of slaughter age (12Á13 or 18Á20 mo), growth hormone use, b-adrenergic agonist (b-AA) use and breed cross [HerefordÁAberdeen Angus (HAA) or CharolaisÁRed Angus (CRA)] on the composition, fibre types, and connective tissue characteristics of m. semitendinosus (ST) and m. gluteus medius (GM) from 112 crossbred steers. Muscle weights increased with slaughter age, implantation and CRA genetics (PB0.05), but were not affected by ractopamine hydrochloride (RAC) (P 0.10). Animal age increased fast glycolytic (FG) and decreased fast oxidative glycolytic (FOG) fibre percentages by 7.2 and 6.6%, respectively, in the ST and increased slow oxidative (SO) and FOG fibre areas in both muscles (PB0.05). Cross-sectional areas of all fibre types were increased in the ST with implantation. In the GM, implantation increased SO (3.1%) and reduced FOG (3.2%) fibre percentages, while RAC reduced the SO (3.8%) and increased the FG (6.1%) fibre percentages (P B0.05). Only GM total collagen content increased with slaughter age (PB0.05), but collagen solubility decreased with slaughter age for both muscles (PB0.05). CRA genetics increased FG percentage in the GM of yearling-fed steers and increased moisture and protein and reduced fat contents of both muscles (PB0.05). In the muscles studied, IMP, slaughter age and animal genetics induced greater changes in muscle inherent properties than RAC.

Girard, I., Aalhus, J. L., Basarab, J. A., Larsen, I. L. and Bruce, H. L. 2012. Modification of beef quality through steer age at slaughter, breed cross and growth promotants. Can. J. Anim. Sci. 92: 175–188. A 23 factorial experiment tested the interactions of slaughter age (12–13 or 18–20 mo), growth implants use (Component E-S, TE-S), ractopamine hydrochloride (RAC) feed supplementation use and breed cross [Hereford–Aberdeen Angus (HAA) or Charolais–Red Angus (CRA)] on pH, temperature, objective colour measurements, relative myoglobin states, sarcomere lengths, shear force, and water losses of m. semitendinosus (ST) and m. gluteus medius (GM) from 112 crossbred steers. In the ST, age affected objective colour measurements by increasing chroma and decreasing lightness (L*) and hue angle (P<0.05). Metmyoglobin (MMB) content of the ST also increased with steer age (P<0.05). In the GM, yearling-fed steers had greater MMB content than calf-fed steers, while hue angle varied the opposite way (P<0.05). Other variations in meat colour and myoglobin contents were more complex in the GM than the ST as they involved three-way interactions between the different treatments. Shear force and purge loss of the ST increased with implantation (P<0.05) with no change in sarcomere length (P>0.05). Shear force standard deviation was similar for breed crosses when yearling-fed but greatest for CRA breed cross when calf-fed (P<0.05). In both muscles, purge loss was increased by RAC supplementation (P<0.05). RAC supplementation did not affect sarcomere length and shear force in both muscles (P>0.10). In the GM, shear force increased with age and with CRA genetics (P<0.05). Results indicated that producers seeking to reduce beef toughness should consider using British crossbreds, exclude the use of hormonal implants and slaughter process steers at 12 to13 mo of age.

Soladoye, P. O., Shand, P. J., Aalhus, J. L., Garie´py, C. and Jua´rez, M. 2015. Review: Pork belly quality, bacon properties and recent consumer trends. Can. J. Anim. Sci. 95: 325Á340. Several factors can affect pork belly quality and, subsequently, bacon quality. Going by the recent trends in the bacon market and bearing in mind the more choosy nature of the consuming populace, it is imperative to consider the factors that can affect or improve bacon quality, thereby sustaining the current market surge. In as much as both genetic and environmental factors have been identified as largely affecting muscle food quality, nutritional interventions also seem to be a very viable tool to improve the quality of meat and its products. Processing and storage methods can also affect bacon quality, including microbial quality, physicochemical attributes and palatability. Both objective and subjective measures have been explored in assessing belly quality, most of which use belly softness and fatty acid profile as yardsticks, whereas bacon quality has been widely assessed only subjectively in terms of fat quality and slice integrity. Although consumers' and producers' quality perceptions seem to be in conflict, it is the responsibility of all stakeholders in the bacon industries to come together in ensuring a balanced approach to satisfy both parties along the production chain.Key words: Belly softness, environmental factors, genetic factors, nutritional factors, bacon quality Soladoye, P. O., Shand, P. J., Aalhus, J. L., Garie´py, C. et Jua´rez, M. 2015. Article de synthe`se: La qualite´de poitrine de porc, les caracte´ristiques du bacon et les tendances re´centes des consommateurs. Can. J. Anim. Sci. 95: 325Á340. Plusieurs facteurs peuvent influencer la qualite´de poitrine de porc et donc, par conse´quent, la qualite´du bacon. Selon les tendances re´centes dans le marche´du bacon, gardant a`l'esprit la nature plus se´lective des consommateurs, il est impe´ratif de prendre en conside´ration les facteurs qui peuvent influencer ou ame´liorer la qualite´du bacon, et ainsi soutenir l'e´lan courant du marche´. Dans la mesure que les facteurs ge´ne´tiques et environnementaux ayant un effet sur la qualite´de viande ont e´teí dentifie´s, les interventions nutritionnelles semblent un outil viable pour ame´liorer la qualite´de la viande et de ses produits. Les me´thodes de traitement et d'entreposage peuvent aussi avoir un effet sur la qualite´du bacon, incluant la qualiteḿ icrobienne, les caracte´ristiques physico-chimiques et la palatabilite´. Des mesures objectives et subjectives ont e´teé xplore´es pour e´valuer la qualite´de poitrine, dont la plupart utilisent la douceur de la poitrine et le profil d'acides gras comme jalon, tandis que la qualite´du bacon est largement e´value´e seulement en termes subjectifs comme la qualite´du gras et l'inte´grite´de la coupe. Bien que la perception de qualite´des consommateurs et des producteurs semblent contradictoires, il est la responsabilite´de tous les intervenants des industries du bac...

No abstract

Hernández-Calva, L. M., He, M., Juárez, M., Aalhus, J. L., Dugan, M. E. R. and McAllister, T. A. 2011. Effect of flaxseed and forage type on carcass and meat quality of finishing cull cows. Can. J. Anim. Sci. 91: 613–622. Sixty-two cull cows were fed one of four diets in a 2×2 factorial arrangement, consisting of barley silage or grass hay with or without flaxseed to influence fatty acid composition. After slaughter, carcass grade, meat quality and sensory data were collected. Silage increased live (P=0.002) and carcass (P=0.001) weights of the cows as compared with hay. Muscle width (P=0.013) and score (P=0.010) and rib-eye area (P=0.002) were enhanced when silage was included in the diet, whereas supplementation with flaxseed increased (P=0.003) grade fat depth by 29%. Most subjective and objective retail evaluation traits in steaks from the left longissimus thoracis and ground meat were negatively affected (P<0.05) by the length of the retail display time. Moreover, dietary hay increased (P=0.015) the lean colour values in steaks and ground beef, which was corroborated by lower L* (P=0.009) and higher hue (P=0.010) in steaks and lower L* (P=0.049), chroma (P=0.005) in ground beef as compared with cows fed silage. A significant interaction between forage type and flax inclusion for thiobarbituric acid reactive substances (TBARS) (P=0.050) was observed. After sensory evaluation, steaks from cows fed silage had an increase (P=0.030) in beef flavour intensity when compared with cows fed hay, whereas inclusion of flaxseed in the diet decreased (P<0.001) beef flavour intensity in steaks from cows fed both forage sources. Sensory evaluation of ground beef found that hay-fed cows with flaxseed supplementation had decreased (P=0.03) beef flavour intensity, while the same effect was not observed in ground beef from cows fed silage with flaxseed. Results from this study show that inclusion of flaxseed in the diet reduced off-flavours in steak, but for ground beef this response depended on the source of forage in the diet.

Rodas-González, A., Juárez, M., Robertson, W. M., Larsen, I. L. and Aalhus, J. L. 2013. Characterization of Canadian grade standards and lean yield prediction for cows. Can. J. Anim. Sci. 93: 99–107. Commercial carcasses (n=120) were selected to benchmark the current Canadian grading system for cows (D1, D2, D3, D4;>50% ossification) in comparison to A/AA grades youthful carcasses [over (OTM) and under (UTM) 30 mo of age based on dentition but <50% ossification]. With the exception of the D3 and D4 grades, D1 and D2 carcass grades had similar carcass yield attributes compared with OTM and UTM carcasses; however, rib-eye area from UTM carcasses was the largest (P<0.05), followed by D1, D2 and OTM. As expected, both OTM and UTM grades had lower ossification scores (P<0.05); however, D4 grade showed the highest marbling score (P<0.05). For carcass composition, compared with all other grades, the D3 grade had the highest proportion of lean (P<0.05) due to a lower proportion of dissectible fat (P<0.05); however, it had the lightest carcass weight (P<0.05). Using simple measures of carcass characteristics (grade fat, rib-eye area, marbling and ossification) a prediction equation to estimate lean yield (R 2=0.825; Cp=4.31) could be used to more accurately assess carcass value in cows; however, validation of the equation on a separate population would be required before its application.

Mapiye, C., Dugan, M. E. R., Turner, T. D., Rolland, D. C., Basarab, J. A., Baron, V. S., McAllister, T. A., Block, H. C., Uttaro, B. and Aalhus, J. L. 2013. Short Communication: Erythrocytes assayed early ante mortem can predict adipose tissue and muscle trans-18:1 isomeric profiles of steers fed red clover silage supplemented with flaxseed. Can. J. Anim. Sci. 93: 149–153. Steers were fed a red clover silage-based diet with or without flaxseed to evaluate over time the effects of flaxseed supplementation on erythrocytes (ERC) trans(t)18:1 isomers composition and their relationships to adipose tissue and muscle t18:1 profiles at slaughter. Concentrations of most ERC t18:1 isomers in steers fed flaxseed increased (P<0.01) markedly in the first 2 mo and increased gradually thereafter. Strong (P<0.01) correlations of t9-, t10- and t11-18:1 isomers were observed from month 2 to 6 between ERC and beef tissues collected at slaughter from steers fed flaxseed. Findings suggest that ERC sampled as early as 2 mo into the feeding period can be indicative of variation in beef t18:1 isomeric profile at a later slaughter date when feeding red clover silage with flaxseed.

Avilés, C., Juárez, M., Larsen, I. L., Rodas-González, A. and Aalhus, J. L. 2014. Effect of multiple vacuum packs on colour development and stability in beef steaks. Can. J. Anim. Sci. 94: 63–69. The aim of this study was to compare the colour stability of steaks from longissimus dorsi muscle previously submitted to four treatments of vacuum packaging and aged for 15 d. Muscle portions were either vacuum packed and aged for 15 d (NRP), or repacked after 2 h (RP2h), 8 d (RP8d) and after 2 h and 8 d (RP2h+8d). Purge loss values from RP8d and RP2h+8d treatments were higher (P=0.019) than those from NRP and drip loss was higher (P=0.001) for RP2h and RP8d. Colour changes during a 30-min period of exposure to atmospheric oxygen immediately after opening the packages were similar for repackaged-aged steaks and NRP steaks (P>0.05). Nevertheless, colour stability during subsequent retail display under atmospheric air conditions was affected by the packaging treatment. The decrease in chroma values (P=0.043) and the increase in hue (P=0.011) between day 3 and day 6 was minimum for RP2h+8d, compared with NRP, RP2h and RP8d. Also, the proportion of pigment in the myoglobin form in these three treatments dramatically increased from day 3 to day 6, while no effect was observed for RP2h+8d (P=0.005). Similarly, the decrease over time in the proportion of pigment in the oxymyoglobin form in meat from the RP2h+8d treatment was much lower (P=0.002) than for the other three packaging treatments. Changes in colour stability associated with multiple vacuum packagings may confound results in experimental designs. Thus, if beef colour is to be evaluated, repeated vacuum packaging should be limited.