W. M. Robertson

The eating quality of Canadian pork and its relationship with intramuscular fat

This study was undertaken to assess the effect of various levels of intramuscular fat (IMF: <1%, 1.0-1.49%, 1.5-1.99%, 2.0-2.49% and 2.5-3.0%) produced from Canadian pigs on the eating attributes of pork loin. Sensory and instrumental eating attributes were determined on 85 pork loins (m. longissimus lumborum and thoracis). The following correlations were found between IMF and eating attributes: softness, -0.32 (P<0.01); initial tenderness, -0.31 (P<0.01); chewiness, -0.27 (P<0.01); rate of breakdown, -0.20 (P=0.07); juiciness, 0.17 (P>0.05); flavour intensity, 0.24 (P=0.02); off-flavour, 0.13 (P>0.05); mouth coating, 0.13 (P>0.05); amount of perceptible connective tissue, -0.02 (P>0.05), and instrumental tenderness (Warner-Bratzler shear force), -0.41 (P<0.001). As tenderness is considered the most important attribute that determines overall acceptance of pork, the threshold level of IMF for ensuring a positive eating experience was identified as a function of the attributes describing tenderness. Increasing the level of IMF past 1.5% did not change (P<0.05) the panelists scores for softness and initial tenderness. Average shear force, an instrumental measure of tenderness, was higher (P<0.05) at less than 1% IMF but did not change past 1.0% IMF (P>0.05). It is proposed that the threshold level of IMF that will ensure a pleasing eating experience is 1.5% IMF.

Feedlot performance, carcass composition and meat quality of free-range reared pigs

The effects of the housing system (confinement versus free-range) and season (summer versus winter) on growth performance, carcass composition and meat quality were determined from commercial pigs with known NN genotype at the halothane locus. Free-range-housed pigs reared from 25 to 105 kg required 16 ± 1.2 (SEM) more days to reach market weight compared with confinement-housed pigs. Housing did not affect feed requirements during the summer, but food consumption increased by 13.7% for free-range pigs during the winter. Confinement-reared pigs had a 0.75 ± 0.28 kg heavier commercial carcass weight than free-range-reared pigs. While there was no difference in carcass fat thickness, muscle depth was 2.4 ± 1.02 mm greater in free-range-reared pigs with increased predicted lean yield from 59.1 ± 0.24% to 59.8 ± 24%. Free-range-reared pigs had heavier butts, loins and hams, and lighter bellies, which increased their wholesale carcass value by 2.9%. Furthermore, they had greater dissected lean in the picnic (2...

Comparing Subcutaneous Adipose Tissue in Beef and Muskox with Emphasis on trans 18:1 and Conjugated Linoleic Acids

Muskox (Ovibos moschatus) are ruminant animals native to the far north and little is known about their fatty acid composition. Subcutaneous adipose tissue (backfat) from 16 wild muskox was analyzed and compared to backfat from 16 barley fed beef cattle. Muskox backfat composition differed substantially from beef and the most striking difference was a high content of 18:0 (26.8 vs. 9.77%). This was accompanied by higher levels of most other saturated fatty acids except beef had more 16:0. Muskox backfat also had a lower level of cis-18:1 and this was related to a lower expression of steroyl-CoA desaturase mRNA. Beef backfat had a higher level of total trans-18:1 (4.25 vs. 2.67%). The most prominent trans-18:1 isomers in beef backfat were 10t-18:1 (2.13%) and 11t-18:1 (0.77%) whereas the most prominent isomers in muskox backfat were 11t-18:1 (1.41%), 13t/14t- (0.27%) and 16t-18:1 (0.23%). The total conjugated linoleic acid (CLA) content was higher in beef backfat than muskox (0.67 vs. 0.50%) with 9c,11t-18:2 as the most abundant CLA isomer. The second most abundant CLA isomer in beef backfat was 7t,9c-18:2 (0.10%) whereas in muskox it was 11t13c-18:2 (0.04%). Muskox backfat had a higher content of 18:3n-3 and its elongation and desaturation products 20:5n-3, 22:5n-3 and 22:6n-3 and a lower n-6/n-3 ratio. Overall, the high forage diet of muskox seemed to produce a healthier fatty acid profile and highlighted the need to develop feeding strategies for intensively raising beef that will not negatively impacting fatty acid composition.

Evaluation of wheat or corn dried distillers’ grains with solubles on performance and carcass characteristics of feedlot steers

A study was conducted on crossbred steers (n = 275; 376 ± 24 kg) to evaluate performance and carcass quality of cattle fed wheat or corn dried distillers’ grains with solubles (DDGS). The control ration contained 86.6% rolled barley grain, 5.7% supplement and 7.7% barley silage (DM basis). The four treatments included replacement of barley grain at 20 or 40% of the diet (DM basis) with wheat or corn DDGS. Steers were slaughtered at a common end weight of 645 kg with 100 steers randomly (n = 20 per treatment) selected for determination of the retail yield of sub-primal boneless boxed beef (SPBBB). Data were analyzed as a completely randomized design using pen as the experimental unit. Feeding increasing levels of wheat DDGS led to a quadratic increase in dry matter intake (DMI) (P < 0.01), whereas increasing levels of corn DDGS led to a quadratic decrease in DMI (P = 0.01). Average daily gain was not influenced (P = 0.13) by feeding wheat or corn DDGS, but cattle fed corn DDGS exhibited a quadratic increas...

A novel approach to grading pork carcasses: computer vision and ultrasound.

A Computer Vision System prototype for grading pork carcasses was developed at the Lacombe Research System. The system consists of two components: ultrasound imaging to scan a cross-section of the loin muscle and video imaging to capture two-dimensional (2D) and three-dimensional (3D) images of the carcass. For each of the 241 carcasses (114 barrows and 127 gilts), salable meat yield was determined from a full cutout. Linear, two- and three-dimensional, angular and curvature measurements and carcass volume were derived from each image. Muscle area and fat thickness (7 cm off the mid-line) measured by ultrasound at the next to last rib site, together with 2D and 3D measurements provided the most accurate model for estimating salable meat yield (R(2)=0.82 and RSD=1.68). Models incorporating fat thickness and muscle depth measured at the Canadian grading site (3/4 last rib, 7 cm off the mid-line) with the Destron PG-100 probe, had the lowest R(2) and highest residual standard deviation (RSD) values (R(2)=0.66 and RSD=2.15). Cross-validation demonstrated the reliability and stability of the models; hence conferring them good industry applicability. The Lacombe Computer Vision System prototype appears to offer a marked improvement over probes currently used by the Canadian pork industry.

The influence of chilling rate and fat cover on beef quality

The economic advantages of rapid carcass chilling include reduced cooling time, increased carcass processing rate, and decreased shrink and drip losses; however, it may also reduce subsequent meat tenderness, especially in lean carcasses. The present study examined the effects of blast chilling and electrical stimulation on quality of longissimus lumborum (LL) and semimembranosus muscles from carcasses with a wide range in backfat thickness (0 to 69 mm). Despite promoting a wide range in postmortem pH and temperature decline, backfat thickness had a limited effect on meat quality. There was a decrease in the proportion of carcasses with very high (>35 N cm–2) shear values and a tendency (P = 0.12) for the average shear force to decrease in the LL as backfat depth increased. Unexpectedly, leaner carcasses had less shrink loss than fatter carcasses under blast chill conditions. While blast chilling resulted in slightly darker, tougher meat, electrical stimulation was able to reduce these effects. Neither ea...

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...

Evaluation of three ultrasound instruments, CVT-2, UltraFom 300 and AutoFom for predicting salable meat yield and weight of lean in the primals of pork carcasses

Three commercially available ultrasound instruments were evaluated using pigs representative of the Canadian pig population: CVT-2, UltraFom 300 and AutoFom. The reflectance probe HGP2 was utilized as the baseline instrument. Sampling was stratified by fat thickness. The original data set (n=236) was divided randomly into a calibration set (n=194 [85 barrows and 109 gilts]) to calibrate the instruments and a validation set (n=72[32 barrows and 40 gilts]) for validating the calibration models. For salable meat yield, RMSE values for the calibration models were: HGP2, 1.56; CVT-2, 1.57; UltraFom, 1.70; and AutoFom, 1.68. For lean (kg) in butt, picnic, loin and ham, and weight (kg) of the skinless, trimmed belly, RMSE for the calibration models was similar for all four instruments: respectively, 0.19-0.21, 0.21-0.23, 0.31-0.37, 0.35-0.40 and 0.35-0.36 kg. Validation results for predicting salable meat yield show that the improvement in precision and/or accuracy associated with the UltraFom 300 or AutoFom, over the baseline reflectance probe HGP2, was negligible whereas a definite advantage was observed for the CVT-2. However, validation results for predicting kg of lean in the primals did not show any clear advantage for the three commerciallly available ultrasound instruments over the baseline reflectance probe HGP2. Calibration and validation procedures showed that, if one was to base the assessment of these three ultrsound instruments uniquely on the precision and accuracy for predicting salable meat yield and/or kg of lean in the primals, any amelioration over the baseline reflectance probe HGP2 would have to be viewed as rather negligible; particularly for the UltraFom 300 or AutoFom.

Meat quality of heifers fattened to heavy weights to enhance marbling

Marbling is the primary factor affecting quality grades of youthful grain-fed cattle in the Canadian, American and Japanese grading systems. Cattle were fed for an extended period of time and to extreme slaughter weights to enhance marbling. The effects of slaughter weight, breed, nutrition, and grading site (12/13th rib-Canadian or 6/7th rib-Japanese) on meat quality were evaluated using 221 weaned heifer calves (exp. 1) and 216 yearling heifers (exp. 2) raised on high (HP) or moderate-high (MHP) planes of nutrition. Mean intramuscular fat concentration in longissimus muscle was 6.93, 8.94, and 9.86% at mean slaughter weights of 500, 590, and 680 kg, respectively (exp 1) and 6.84% and 9.02% at 590 and 680 kg (exp. 2). HP carcasses had more intramuscular fat and lower shear values and drip losses than MHP carcasses (P ≤ 0.05). Angus carcasses had more intramuscular fat and lower shear values than the other breeds studied. Holsteins on the HP diet produced tender meat with a high amount of intramuscular fa...

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.