M. Juárez

Relationship between collagen characteristics, lipid content and raw and cooked texture of meat from young bulls of fifteen European breeds.

Variations in texture were determined for 10 day aged raw and cooked Longissimus thoracis (LT) muscle from 436 bulls of 15 European cattle breeds slaughtered at an age of 13-16 months. Variations in texture were related to differences in pH 24 h post-mortem, sarcomere length, collagen characteristics and lipid content. The shear force of cooked meat samples varied from 43.8 to 67.4 N/cm². Simmental, Highland and Marchigiana cattle had the highest shear force values and Avileña-Negra Ibérica, Charolais, Casina and Pirenaica cattle had the lowest values. Cooked meat toughness showed a weak negative correlation to lipid content (P<0.001) but no correlation to collagen characteristics. Raw meat texture measured by compression correlated positively (P<0.001) with total and insoluble collagen. In conclusion, collagen characteristics showed correlation to raw meat texture but not to cooked meat toughness of LT muscle in European young bulls.

Effects of vitamin E and flaxseed on rumen-derived fatty acid intermediates in beef intramuscular fat☆

To elucidate the effects of dietary vitamin E with or without flaxseed on beef fatty acid composition, 80 feedlot steers were fed 4 diets: Control-E (451 IU dl-α-tocopheryl acetate/head/day), Control+E (1051 IU dl-α-tocopheryl acetate/head/day), Flax-E (10% ground) and Flax+E. Vitamin E had no effect on animal growth or carcass weight (p>0.05), while flaxseed-fed steers had greater average daily gain (p=0.007), final live weight (p=0.005) and heavier carcasses (p=0.012). Feeding flaxseed increased the total n-3 fatty acid content of beef and this response was further accentuated by the inclusion of high levels of vitamin E in the diet. Feeding flax increased levels of some 18:3n-3 partial hydrogenation products including c15- and t13/14-18:1 and several 18:2 isomers (p<0.001) but decreased t10-18:1 (p<0.001). Vitamin E enhanced intramuscular levels of 18:3n-3 and its biohydrogenation products leading to greater accumulations of total n-3 fatty acids in lean ground beef. The consequences of increasing the concentrations of partially hydrogenated products on human health have yet to be investigated.

Beef quality attributes as affected by increasing the intramuscular levels of vitamin E and omega-3 fatty acids

In order to investigate the effects of increasing beef n-3 fatty acid content and the protective effects of vitamin E antioxidant activity on meat quality characteristics, 80 feedlot steers were fed 4 different diets (control, high vitamin E, 10% ground flaxseed or high vitamin E-10% ground flaxseed). While dietary treatments had no effect (P>0.05) on meat composition or tenderness values, the increase in oxidation products was lower (P=0.046) in meat from vitamin E supplemented steers and higher (P=0.006) in meat from flaxseed fed animals. The increase in α-tocopherol tissue levels (P<0.001) in meat from animals fed flaxseed and increased dietary vitamin E resulted in the lowest drip loss values (P=0.013). As expected, display time had a large effect on retail traits in both steaks and patties (P<0.001). While retail traits of steaks were not affected by the dietary treatments (P>0.05), feeding flaxseed decreased (P<0.05) ground beef retail scores, which were not corrected by higher levels of dietary vitamin E. Finally, although no effect (P>0.05) was observed among treatments for sensory attributes in steaks, the correlations of a combined n-3:α-tocopherol ratio against retail and sensory attributes (P<0.05) suggest that increased n-3 fatty acids levels require increased dietary antioxidants, such as vitamin E to avoid negative effects on meat quality from a loss in oxidative stability.

Feeding wheat dried distillers grains with solubles improves beef trans and conjugated linoleic acid profiles.

In western Canada, ethanol is produced mainly from wheat. As the demand for wheat increases, so do grain prices, which in turn creates incentives for feeding reduced-cost distillers coproducts to livestock. Substitution of wheat dried distillers grains plus solubles (DDGS) for barley grain may also create opportunities for enhancing beef fatty acid profiles because reducing starch concomitantly increases dietary fiber and oil and may shift PUFA biohydrogenation toward a healthier trans and CLA profile. To study this potential, heifers were fed diets containing 0, 20, 40, or 60% wheat DDGS (DM basis) substituted for rolled barley (n = 24; 133-d finishing period). Adding DDGS increased dietary oil (from 1.9 to 3.7%), but dietary fatty acid compositions remained consistent. Feeding increasing amounts of DDGS linearly decreased total diaphragm fatty acids on a milligram per gram basis (P = 0.031). For both brisket fat and diaphragm, feeding increasing amounts of DDGS caused linear increases in percentages of 18:2n-6 (P = 0.001) and total n-6 fatty acids (P = 0.001) but did not change the concentrations of individual or total n-3 fatty acids. Feeding increasing amounts of DDGS did not change the content of total trans MUFA in either brisket fat or diaphragm but led to linear decreases in 10t-18:1 (P = 0.033, brisket fat; P = 0.004, diaphragm) and increases in 11t-18:1 (P = 0.005, brisket fat; P = 0.003, diaphragm). Feeding increasing amounts of DDGS also caused a linear increase in 9c11t-18:2 (P = 0.044, brisket fat; P = 0.023, diaphragm) and total CLA (P = 0.086, brisket fat; P = 0.039, diaphragm). Overall, feeding DDGS enhanced the fatty acid composition of beef by decreasing 10t-18:1 while increasing the major CLA isomer (9c,11t-18:2) and its precursor 11t-18:1.

Feeding co-extruded flaxseed to pigs: effects of duration and feeding level on growth performance and backfat fatty acid composition of grower-finisher pigs.

To examine the effect of co-extrusion on subsequent n-3 fatty acids in pig tissues, 8 pigs (barrows and gilts) were assigned to either a control treatment or one of nine treatments arranged in a 3 x 3 factorial design with 3 levels of co-extruded flaxseed (5%, 10% and 15%) and 3 durations of feeding (4, 8 and 12 weeks). Feed conversion improved slightly (P=0.01) with increasing dietary flaxseed but feeding flax for more than 8 weeks reduced average daily gain (P=0.02). In general, the duration and level of co-extruded flaxseed feeding affected (P<0.05) most fatty acids except for 22:6n-3 (P>0.05). Increasing the duration of flax feeding led to significant quadratic effects in backfat 18:3n-3 (P<0.001) and total n-3 fatty acids (P=0.002) when feeding 5% co-extruded flaxseed. Those increases were linear (P<0.001) when feeding 10% and 15% co-extruded flaxseed. Consequently feeding higher levels of flax for shorter periods vs. lower levels for longer periods appears to be more efficient at increasing n-3 fatty acids in pig backfat, but increases appeared to be less consistent. Moreover the addition of a 50:50 mix of extruded flax/peas to pig diets provided a highly available source of 18:3n-3 yielding n-3 fatty acid enrichments in backfat comparable to studies where extracted flaxseed oil was fed. Feeding flax co-extruded with field peas can be used to optimize consistent enrichments of n-3 fatty acids in back fat and relatively small amounts of this fat could be used to manufacture pork products to meet Canadian standards for n-3 fatty acid enrichment.

Extended ageing time and temperature effects on quality of sub-primal cuts of boxed beef

Most of the information indicating ageing improves tenderness has been collected on the loin and rib-eye muscles over relatively short ageing times, assuming that all muscles will react similarly. In the present study, the effect of extended ageing times on instrumental texture (56 d) and sensory characteristics (42 d) of six different beef sub-primals [striploin (SL), inside round (IR), outside round (OR), eye of round (ER), blade eye (BE) and chuck tender (CT)] was studied. The effects of two ageing temperatures (1 and 5°C) were also compared. In general, ageing increased tenderness (P   0.05) and resulted in a decrease in tenderness of OR (P < 0.05) until day 35, with a later increase after 42 d of ageing. Increasing ageing temperature (5°C) had limited effect on tenderness, but ageing time and temperature increases led to lower flavour and higher...

Dietary vitamin E inhibits the trans 10-18:1 shift in beef backfat.

Forty feedlot steers were fed a barley-grain-based finishing diet typical for western Canada, with two levels of supplementary vitamin E (468 or 1069 IU head-1 d-1) and the effect on backfat trans-18:1 isomeric profile was determined. Feeding 1068 IU vitamin E reduced the total trans-18:1 content in backfat (P < 0.01), as well as the percentage of trans 10-18:1 (P < 0.001), which are related to an increased risk for cardiovascular diseases. On the other hand, trans 11-18:1 (vaccenic acid) the precursor for cis 9,trans 11-18:2 (rumenic acid), which have several purported health benefits, increased (P < 0.01). Vitamin E could, therefore, be used to decrease trans-18:1 in beef and improve its isomeric profile.Key words: Beef, trans fatty acid, vaccenic acid, vitamin E

Associations between DGAT1, FABP4, LEP, RORC, and SCD1 gene polymorphisms and fat deposition in Spanish commercial beef

The objective of the present study was to assess the frequency distribution of markers in the diacylglycerol acyltransferase (DGAT1), fatty acid binding protein 4 (FABP4), leptin (LEP), retinoic acid receptor-related orphan receptor C (RORC), and stearoyl-CoA desaturase (SCD1) genes in a Spanish commercial crossbred population (n = 286) produced in southwest Spain. We have also evaluated the association of these 5 major SNP with backfat thickness (BFT) and intramuscular fat (IMF) to use them routinely in the industry (if the associations are confirmed) due to their ease of use. The KK genotype of the DGAT1 gene was associated (P = 0.046) with the greatest BFT value. Bulls presenting the GG genotype for SNP in the FABP4 gene showed greater values for the percentage of IMF (P = 0.030), which means an increase of 0.155% IMF per copy of the G allele of this marker (P = 0.009). A significant association was found between the RORC: g.3290T > G marker and the percentage of IMF. The GG genotype of the RORC: g.3290T > G marker showed the lowest IMF percentage (P = 0.025). The specific associations found in this study not only provide information about the involvement of these genes in the fat deposition at different levels in the southwestern Spain cattle population, but can also serve as a tool to improve certain meat quality attributes through Marker Assisted Selection. However, sensory studies are needed to explore further the usefulness of these genes in meat quality and the impact on the actual palatability of the beef.

Trans-18:1 and conjugated linoleic acid profiles after the inclusion of buffer, sodium sesquicarbonate, in the concentrate of finishing steers

Ninety-six European crossbred steers were fed a barley-based finishing diet for differing lengths of time (34-104 days) to investigate if adding dietary buffer (sodium sesquicarbonate at 1.5% as fed) could improve the trans-18:1 (GC-FID) and CLA (Ag(+)-HPLC-DAD) content and isomeric profile of beef produced. Results indicate that the addition of buffer to diets of cattle fed high concentrate diets has limited effects on the overall fatty acid composition of backfat and muscle tissues. However, buffer addition can help to prevent a 10t- shift by maintaining a better (higher) 11t-/10t-18:1 ratio in both meat and backfat during the first 30-60 days of feeding a high grain diet. Over time, however, the effect is lost becoming equal in tissues from animals with or without buffer addition to their diets.

Enhancing pork loin quality attributes through genotype, chilling method and ageing time.

The experiment was conducted to examine opportunities for enhancing pork quality through the use of post-mortem ageing when combined with different chilling regimes. Large White (LW, n=24) and Duroc×Large White (Duroc, n=24) barrows were slaughtered and alternate carcass sides were either conventionally or blast-chilled. The longissimus thoracis et lumborum muscle was dissected from the carcass sides (24h post-mortem) and trimmed of cover fat. Three sections (15cm length) were vacuum packaged and assigned to 2, 7 or 14days of ageing (2°C) randomized within muscle location. Blast-chilled meat had lower purge (P=0.009) and drip (P=0.0009) losses and higher hue (P=0.02) than conventionally chilled meat. However chilling by conventional or blast-chilling methods had no effect on sensory characteristics (P>0.1). When breeds were compared, meat from Duroc barrows had lower moisture (P<0.0001) and higher intramuscular fat content (P<0.0001), L∗ (P=0.0003) and hue (P=0.007) values than LW. Overall tenderness (P=0.005), juiciness (P=0.0007) and palatability (P<0.0001), as well as flavour intensity (P<0.0001) and desirability (P<0.0001) values were higher and undesirable flavours were lower (P<0.0001) for meat from Duroc pigs, when compared with LW. Ageing increased purge loss (P<0.0001), L∗ (P<0.0001), hue (P<0.0001), chroma (P<0.0001) and content of protein (P=0.002), with corresponding decreases (P<0.0001) in drip loss and moisture content. Instrumental (P<0.0001) and sensory (initial, P<0.0001 and overall, P<0.0001) tenderness increased from day 2 to 14. Therefore independent of chilling method, ageing improved quality of pork loins. Moreover ageing had greater effect on tenderness, while breed had greater effect on flavour which may be related to differences in intramuscular fat content.