Meadus, W. J., Duff, P., Rolland, D., Aalhus, J. L., Uttaro, B., and Dugan, M. E. R. 2011. Feeding docosahexaenoic acid to pigs reduces triglycerides in blood and induces gene expression for fat oxidation in liver and adipose but not in muscle. Can. J. Anim. Sci. 91: 601–612. The essential fatty acids required in diets of humans are linoleic acid (18:2n-6:LA) and α-linolenic acid (18:3n-3: ALA), and these can be elongated and desaturated to form long-chain omega-6 or omega-3, respectively. Even though not considered essential, consumption of long-chain omega-3 fatty acid is recommended for health benefits, including protection against cardiovascular disease. The omega-3 fatty acid, docosahexanoic acid (DHA), was supplemented in pig diets as a dried biomass of the microalgae Schizochytrium to see if there are unique physiological changes associated with DHA feeding. Pigs were fed a diet with 330 mg (low), 3600 mg (medium) or 9400 mg (high) DHA per day for the last 25 d before slaughter at market weight (∼110 kg). Blood triglycerides (TG) were assayed colormetrically and tissue samples were analyzed for gene expression patterns of RNA by quantitative real-time polymerase chain reaction. Fatty acids were analyzed by gas chromatography. Animal performance appeared to increase with DHA, as shown by a 14% improved feed:gain ratio of 2.74±0.27 (P<0.05). Blood triglycerides were reduced significantly from 0.40±0.23 mM to 0.20±0.09 mM. Pigs accumulated 14 times more DHA in their subcutaneous fat (SQ) (10.67 mg g−1) on the high diet compared with the control diet (0.75 mg g−1). Gene analysis showed that the expression of the fat oxidation biomarkers acyl CoA oxidase 1 (ACOX1), peroxisome proliferator-activated receptors alpha (PPARα) and gamma (PPARγ) were stimulated in the SQ and liver. The delta-6 desaturase (D6D) and elongase (Elov5), which are genes involved in the endogenous synthesis of DHA, were unchanged. Fatty acid synthase (FASN) was stimulated in the liver and muscle of pigs on the high DHA diet. Analysis of gene transcription activity suggested fat metabolism was stimulated in the liver and SQ fat, but the genes involved in the endogenous production of DHA remained unchanged.

López-Campos, Ó., Aalhus, J. L., Okine, E. K., Baron, V. S. and Basarab, J. A. 2013. Effects of calf- and yearling-fed beef production systems and growth promotants on production and profitability. Can. J. Anim. Sci. 93: 171–184. In each of 2 yr, 112 spring-born steers were used to evaluate the effect of calf-fed vs. yearling-fed with and without growth implant and β-adrenergic agonist on production parameters and economic potential. Steers were grouped into: (1) non-implanted feeders harvested at 11–14 mo of age, (2) growth implanted feeders harvested at 11–14 mo of age, (3) non-implanted feeders harvested at 19–23 mo of age, and (4) growth implanted feeders harvested at 19–23 mo of age. Production data were collected and economic evaluation was performed. Calf-fed steers grew slower (1.21 vs. 1.99±0.07 kg d−1) and had a poorer feed conversion ratio [5.32 vs. 4.99±0.34 kg dry matter intake (DMI) kg−1 gain] during the feedlot dietary adjustment period than yearling-fed. Calf-fed steers were more efficient than yearling-fed during the first 76–83 d (5.16 vs. 7.33±0.11 kg DMI kg−1 gain) and latter 48–79 d (5.69 vs. 14.28±1.50 kg DMI kg−1 gain) of the finishing period. Implanted steers were more efficient than non-implanted during the dietary feedlot adjustment period (4.80 vs. 5.52±0.15 kg DMI kg−1 gain), and during the first 76–83 d (6.05 vs. 6.44±0.11 kg DMI kg−1 gain) and latter 48–79 d of the finishing period (9.29 vs. 10.69±1.50 kg DMI kg−1 gain). Implanted steers grew 11.4–19.6% faster than non-implanted throughout the finishing period, while yearling-fed grew 11.1–12.9% faster during the first 76–83 d, but 49.1–64.4% slower during the last 48–79 d of the finishing period compared with calf-fed. Quality grade was improved for non-implanted steers, with 43.6% of yearling-fed and 35.7% calf-fed steers grading AAA. Adjusted net return was best for calf-fed implanted ($17.52 head−1), followed by calf-fed non-implanted ($−41.92 head−1), yearling-fed implanted ($−73.77 head−1), and yearling-fed non-implanted ($−99.65 head−1) production strategies. The results of the present study suggest that reducing age at slaughter combined with growth implant can increase profit and reduce risk, but growth implants can negatively affect the carcass quality.

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Juárez, M., Larsen, I. L., Klassen, M. and Aalhus, J. L. 2013. Canadian beef tenderness survey: 2001–2011. Can. J. Anim. Sci. 93: 89–97. A large survey across Canada was developed collecting retail beef samples in 2001 (702 steaks) and 2011 (602 steaks). The samples (strip loin, top sirloin, inside round and cross-rib steaks) were evaluated for instrumental tenderness using standard procedures for sampling, storage, cooking and texture evaluation. New equations were also developed in order to compare the results obtained in these studies with consumer thresholds developed in Canada and the United States of America. In general, retail steaks collected in 2011 weighed less and showed higher fat thickness than those from 2001. Regarding tenderness, a significant improvement was observed, especially for strip loin and top sirloin steaks between 2001 and 2011. Using US threshold categories, the percentage of “tender” samples improved for the strip loin (2001=89%; 2011=99%), top sirloin (2001=70%; 2011=87%), inside round (2001=52%; 2011=61%) and cross-rib (2001=65%; 2011=76%) steaks. Similarly, the percentage of “tough” samples shifted from 5, 8 27 and 13% for the strip loin, top sirloin, inside round and cross-rib steaks in 2001 to 1, 5, 13, and 8%, respectively, in 2011. Similar improvements were observed when using the more descriptive four-category Canadian threshold system. These improvements may be due to changes in the animal population, production systems, carcass processing and distribution/handling prior to display in Canada.

J. L. 2014. SHORT COMMUNICATION: Influence of some meat quality parameters on beef tenderness. Can. J. Anim. Sci. 94: 455Á458. Steaks from longissimus lumborum and semimembranosus muscles, aged 2 or 27 d, were obtained from a population of steers (n 0112) managed to produce a range in tenderness (shear force range from 2.57 to 17.2 kg). All available carcass (live weight, hot commercial weight, pH, temperature, marbling, rib-eye area) and meat (objective colour, cook loss, cook time, WarnerÁBratzler shear force, myoglobin content, proximate composition and collagen content) quality data were used for the analyses. Multivariate analyses determined which factors influenced tenderness between and within muscles, both before or after ageing. In unaged muscles, soluble collagen explained differences in tenderness among muscles, while factors related to the myofibrillar component explained differences within a muscle. In contrast, in aged muscles, total collagen content was related to tenderness among muscles and the percent soluble collagen content was related to tenderness differences within a muscle.