Martin R. L. Scheeder

Meat quality of Angus, Simmental, Charolais and Limousin steers compared at the same intramuscular fat content

Meat quality and marbling properties of Angus, Simmental, Charolais and Limousin steers (4×16) were compared at an average intramuscular fat content (IMF) of 3.25% in the M. longissimus dorsi. The steers were fattened on a forage-based diet until the desired, ultrasonically estimated IMF content was reached which resulted in considerably different growth and carcass characteristics. The Angus group showed a growth rate similar to Simmental and Charolais while Limousin grew slower, became oldest and provided the heaviest carcasses and best conformation. Angus carcasses showed the lowest weight but the highest fatness score. Marbling was equal for all breeds. Angus and Charolais provided pale meat with low haem iron content. Angus and Limousin beef was more tender on sensory assessment than Simmental beef, corresponding to differences found in shear force (non-significant) and myofibrillar fragmentation index measured at 48 h post mortem. Flavour was similar among breed groups while juiciness was highest for Limousin and lowest for Angus. The juicier beef simultaneously showed the highest drip but the lowest cooking losses. In conclusion, clear differences in meat quality were observed between breeds despite similar IMF contents.

The influence of cooking and fat trimming on the actual nutrient intake from meat.

The effects of cooking and trimming of visible fatty tissue on the content of fat, fatty acids, minerals and vitamins was studied in six meat cuts (beef rib-eye and brisket, pork neck steak and belly, veal chop and rolled breast) in order to improve the estimates of the actual nutrient intake from meat. Cooking decreased the absolute fat content by about 17.9-44.4% and therefore concomitantly influenced the content of different fatty acids. The trimming of visible fatty tissue additionally decreased the fat content by about 23.8-59.1%. Calcium, sodium, potassium, magnesium and phosphorus decreased during cooking in all cuts and cooking processes, while iron and zinc were found to increase in beef. All vitamins decreased during cooking, with thiamine showing the highest losses, from 73% up to 100%. In conclusion, the cooking and trimming of meat cuts considerably affected the nutrients in various ways and to different degrees, which should be taken into account when the nutrient intakes of meat are estimated.

Quality of retail beef from two grass-based production systems in comparison with conventional beef

Seventy beef strip loins (Longissimus dorsi) were sampled, originating from labels prescribing pasturing (PS, suckler beef; PF, finished steers or heifers), from conventional production (CH, heifers; CB, young bulls), and from a label producing intensively fattened young bulls (LB) and prescribing specific husbandry conditions but not grazing. Samples were purchased in autumn and spring (1:1) from 33 retail stores in northeastern Switzerland. Colour was lightest in LB beef, while PS displayed the least intensive red. Shear force was low in pasture beef, with PF showing the lowest variability. Pasture beef was richer in n-3 fatty acids than beef of all other origins. The n-6/n-3 ratio was consistently below 2 in pasture beef, while it ranged above 5 in LB, and also in CH and CB when purchased in spring. Prescribing year-round feeding of grass products and the use of steers or heifers therefore guarantees n-3 enriched beef, which can be at least as tender as conventional beef.

Fatty acid composition, cooking loss and texture of beef patties from meat of bulls fed different fats

The effect of fatty acid composition on the properties of patties standardised to contain 15% fat was studied. Patties were made of beef from 36 Brown Swiss bulls fed on six different diets with five of them containing additional fats to achieve a high variability in body lipid composition. When the feed contained fullfat oilseeds (rapeseed, sunflower seed, linseed), the proportions of some nutritionally favourable fatty acids were increased in the patties. Patties made from the meat of bulls fed linseed and coconut oil could be distinguished in a sensory triangle test from most other groups. Cooking loss and instrumental texture properties showed no relation to fatty acid composition of patties. Cooking only slightly decreased the proportion of saturated fatty acids in favour of polyunsaturated fatty acids. In conclusion, widely differing dietary fats can be fed to bulls without risking major effects on texture of beef patties.

Effects of Feeding Pigs Increasing Levels of C 18:1 Trans Fatty Acids on Fatty Acid Composition of Backfat and Intramuscular Fat as well as Backfat Firmness

Forty Large White pigs were fed from 30kg to 103kg body mass on diets supplemented with 6% of pure high-oleic sunflower oil (HO) or HO plus increasing amounts of partially hydrogenated rape seed oil (HR; 1.85%, 3.70%, 5.55%), containing high levels of j 6 to j 11 C 18:1 trans fatty acid isomers. Increasing dietary C 18: trans fatty acids resulted in a linear increase in C 18:1 trans fatty acids and conjugated linoleic acid (cis-9, trans-11 CLA) in backfat (BF) as well as in neutral lipids (NL) and phospholipids (PL) of M. long. dorsi. Thus, the rate of bioconversion of trans vaccenic acid (TVA) into CLA and incorporation of C 18:1 trans and CLA into pig adipose tissue was not limited up to 25g total C 18:1 trans fatty acids including 3.3g of TVA perkg feed. BF was higher in C 18:1 trans fatty acids and CLA than M. long. dorsi NL and PL. In BF and NL the sum of saturated fatty acids (SFA) increased with increasing dietary amounts of HR, while in PL SFA were reduced. Thus, according to their physical properties, C 18:1 trans fatty acids partly replaced SFA in PL. Firmness of backfat was also significantly increased (P<0.05) with increasing amounts of HR in feed.

Influence of different fats in pig feed on fatty acid composition of phospholipids and physical meat quality characteristics.

Two feeding experiments (i, ii) were conducted to investigate the influence of different dietary fats on the fatty acid (FA) composition of phospholipids as well as meat quality in pigs. In each experiment 12 x 4 siblings of Swiss Landrace or Large White breed were allocated to one of four feeding treatments according to sex, breed, and litter and fattened from about 25 to 105 kg liveweight. Pigs were fed a control diet (barley, wheat, soybean meal) or the control diet supplemented with 7% pork fat, 4.95% olive oil or 3.17% soybean oil (i) or 5% of olein or stearin fraction of pork fat or hydrogenated fat (ii). The dietary FA composition was reflected in the FA composition of phospholipids in M. long, dorsi and triceps brachii. However, the unsaturated to saturated ratio was not affected by the dietary intake of polyunsaturated FAs and was only slightly increased by the olive oil supplementation. Trans FAs including conjugated linoleic acid were incorporated into phospholipids only to a small extent. The dietary altered fatty acid composition of phospholipids did not cause any effect on pH, cooking loss, texture, or colour of pork, but meat quality as well as the proportion of saturated FA, arachidonic acid, and n-3 fatty acids were significantly influenced by genetic effects.

Dietary C18:1 trans fatty acids increase conjugated linoleic acid in adipose tissue of pigs

The effect of dietary C18:1 trans fatty acids on back fat composition in pigs was investigated with special emphasis on conjugated linoleic acids (CLA). A total of 12 × 4 siblings of Large White and Swiss Landrace breed were housed in groups and fattened from 22 to 103 kg live weight. Pigs were fed a control diet (barley, wheat, soybean meal) or experimental diets which consisted of the control diet with a 5% replacement of olein or stearin fractions of pork fat, or partially hydrogenated fat. The hydrogenated fat was rich in C18:1 trans fatty acids but contained only negligible amounts of CLA. In contrast olein and stearin fractions contained far less C18:1 trans fatty acids but some CLA. In the control diet no C18:1 trans fatty acids and only traces of CLA were detected. The partially hydrogenated fat led to the highest CLA content in back fat (0.44%). Intermediate amounts of CLA were measured in pigs fed the fractionated pork fat (0.22/0.23%). In pigs fed the control diet, also small amounts of CLA were detected. The results indicate that CLA may be produced by endogenous Δ9-desaturation out of dietary trans vaccenic acid in pigs.

Effect of Dietary Mono- and Polyunsaturated Fatty Acids on the Fatty Acid Composition of Pigs' Adipose Tissues

In two experiments with growing-finishing pigs six different dietary fats were added to a conventional diet (control - C) to study the effects of dietary monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) on the fatty acid composition of backfat and kidney fat at similar amounts of double bonds in feed (Exp. 1:7% pork fat - PF, 4.95% olive oil - OO, 3.17% soybean oil - SO) or a constant amount of 5% of processed fats (Exp. 2: partially hydrogenated fat - SAT, fractionated pork fats: olein - OLE, stearin - STE). Compared with the control, PUFA were only slightly increased in backfat of pigs fed PF, OLE, STE or OO, although dietary PUFA intake was up to 70% higher. With SO PUFA were significantly increased in adipose tissues, predominantly at the expense of MUFA. Consequently, a non-linear relationship was found between PUFA intake and proportion in backfat. MUFA were incorporated at the expense of SFA, therefore, adipose tissues of OO fed animals were lowest in SFA. Despite comparable amounts of double bonds in feed (Exp. 1), the degree of unsaturation measured as fat score (sum of double bonds) was in the order SO > OO > PF > C. In contrast, the proportion of SFA was C > PF = SO > OO. Regarding the decisive role of SFA for fat consistency it may be concluded that MUFA should also be considered in feeding recommendations for pigs. Furthermore, in case of a high dietary supply of MUFA, a simple index of double bonds might not be sufficiently conclusive to judge pig fat quality.

Determination of fatty acid composition and consistency of raw pig fat with near infrared spectroscopy

For the production of high quality meat products, processors demand firm pig fat. About 20 years ago, Swiss slaughter houses established a titrimetric method to determine the so-called fat score (an index of double bonds in the fat) as a quality control measure. Since 2005, an NIR method has been applied to determine the fat score in two processing plants. The use of toxic solvents and reagents was thus avoided and the work needed considerably reduced. The result, nevertheless, is an unspecific measure of the sum of double bonds. The aim of this study was to evaluate the potential of determining the fatty acid composition more specifically or even to predict fat consistency traits directly in pig fat without extracting the lard. For this purpose a total of 155 samples of pig fat was scratched from the outer layer of the backfat at the slaughter line according to the official fat score method. The collected fat was mixed with a rotor-stator homogeniser, before NIR spectra were recorded. The fatty acid composition was analysed using gas chromatography and the solid fat content was measured by differential scanning calorimetry. The proportion of saturated fatty acids (SFA), monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) was validated with relative standard errors of prediction (SEP) of 0.9%, 1.6% and 4.7% and coefficients of determination (r2) of 0.98, 0.88 and 0.96, respectively. The validation of the proportion of very long chain PUFA resulted in a SEP of 7.6% and an r2 of 0.88. The solid fat content (at 10°C and 20°C) was also estimated with sufficient precision and accuracy (n = 80; SEP=2.9% and 3.2%, r2 = 0.94 and 0.96, respectively). NIR, therefore, provides the potential to establish more specific measures for pig fat quality than the original fat score method.

Comparative evaluation of rumen-protected fat, coconut oil and various oilseeds supplemented to fattening bulls. 2. Effects on composition and oxidative stability of adipose tissues.

The effects of five different dietary fat supplements on fatty acid composition and oxidative stability of subcutaneous and kidney fat were evaluated in 36 Brown Swiss bulls and compared to a low fat diet in a monofactorial design. The following fat supplements were provided as additional fat at 30 g per kg feed dry matter: crystalline rumen‐protected fat, coconut oil, and three types of crushed whole oilseeds (rapeseed, sunflower seed and linseed). Adipose tissues reflected differences (P < 0.05) in dietary fatty acid composition although to a lower extent. Using protected fat, which contained elevated levels of trans fatty acids, and sunflower seed, containing a high proportion of linoleic acid, significantly increased C18:1 trans fatty acid proportion in the adipose tissues. The use of sunflower seed increased conjugated linoleic acid. The oilseeds resulted in lower amounts of C16:0 in favour of C18:0. Except for linseed, all fat supplemented groups improved oxidative stability of adipose tissues as compared with control. This was explained by lower proportions of unsaturated fatty acids in adipose tissue (protected fat), by elevated α‐tocopherol contents (rapeseed, sunflower seed) or by a combination of both (coconut oil). Fat colour remained unaffected by treatments. Compared to other fat supplements oilseeds, especially sunflower seed and rapeseed, can therefore be recommended to be fed to bulls in order to increase the proportions of C18 unsaturated fatty acids in adipose tissues and to maintain or improve oxidative stability.