The qualitative characteristics, lipids and chemical composition of the meat of 35 Nellore young bulls were analyzed. These bulls had an average slaughter weight and fat thickness of 532.17±30.2 kg, and 7.00 mm, respectively. Significant differences were found only in the meat's water holding capacity (WHC), which was higher for animals fed with fresh linseed oil. More conjugated linoleic acid (CLA) was found in the meat of animals fed with unprotected soybean oil, while better omega-6/omega-3 ratios were noted for those fed unprotected linseed oil. The addition of different vegetable oils to the bulls' diet (soybean or linseed, either protected or not protected from rumen digestion) did not interfere with the qualitative characteristics of their meat while improving the lipid composition of the longissimus muscle. Of the oils examined, unprotected linseed oil most improved the omega-6/omega-3 ratio, thus producing the healthiest meat for human consumption.

-The objective was to evaluate the addition of vegetable oils protected or not from rumen degradation in the diet of feedlot-finished young bulls and their effects on performance and carcass characteristics. Thirty-five Nellore males of 402.69±14.90 kg initial weight and 18±2 months of age were utilized. The animals were confined for 96 days, after 28 days of adaptation, and slaughtered at 532.17±30.25 kg. Experimental diets were: control (715 g total digestible nutrients -TDN/kg of dry matter -DM), with addition of soybean oil or fresh linseed oil, and with the addition of the same oils protected from rumen degradation (765 g TDN/kg DM). All diets were formulated with the same amount of protein and with a roughage:concentrate ratio of 40:60, with sugarcane as the only roughage. The addition of oil, regardless of the type and processing, resulted in greater body weight gain (1.17 and 1.41 kg/animal/day), better feed (0.11 and 0.14 kg weight gain/kg DM ingested) and protein efficiency (0.86 and 1.09 kg weight gain/kg crude protein ingested), heavier carcasses (280.3 and 298.0 kg), with better yield (54.5 and 55.5%) and thicker subcutaneous fat (5.1 and 7.5 mm backfat thickness) and with heavier prime cuts, for control diet and the other treatments, respectively. The use of soybean or linseed oil protected or not from rumen degradation only changed the intake of a few nutrients and carcass yield and depth. Thus the addition of energy sources in the diet is beneficial for finishing feedlot bulls. For this addition, either soybean or linseed oils can be used, and the processing of these oils is only useful to facilitate the mixing with the other ingredients of the diet.

The aim of the present study was to assess the qualitative and chemical characteristics of a shoulder muscle (triceps brachii muscle, medial head (TBm)) of 15 Nellore × Canchim steers and 14 heifers of the same cross fed diets containing 80% concentrate on a dry-matter (DM) basis and increasing concentrations of linseed oil (1%, 3.8% and 5.2% of DM). A randomised incomplete-block design, divided on the basis of initial bodyweight, in a 3 × 2 factorial scheme (oil concentration and animal sex) was used. Oil concentrations were evaluated by linear and quadratic regression. The finishing period lasted for 96, 110 or 138 days, until the average weight of each block reached 500 kg. At 24 h postmortem, TBm samples were taken to evaluate quality traits and chemical composition. Meat from steers was significantly (P < 0.05) brighter than was heifer meat (brightness (L*) = 39.55 vs 36.28). The addition of linseed oil up to 5.2% improved the pH value of TBm in heifers (6.07, 6.22 and 5.77). No significant (P > 0.05) influence was observed for linseed oil addition up to 5.2% of DM or animal sex on the chemical characteristics of TBm, estimated activity of Δ9-desaturase and elongase, and atherogenic and thrombogenic indices. However, the increasing inclusion of linseed oil in the diet of crossbred cattle increased (P < 0.05) conjugated linoleic acid (0.46, 0.66 and 0.73 g/100 g total fatty acids), α-linolenic acid (0.39, 0.69 and 1.31 g/100 g total fatty acids for steers; 0.36, 0.79 and 0.76 g/100 g total fatty acids for heifers), γ-linolenic acid (0.07, 0.10 and 0.24 g/100 g total fatty acids), and the sum of n-3 fatty acids. The increasing inclusion of linseed oil also increased the ratio of polyunsaturated fatty acids to saturated fatty acids and decreased the ratio of n-6:n-3 fatty acids (11.68, 6.43 and 5.26 for steers; 10.69, 6.93 and 6.03 for heifers). Supplementation of finishing cattle with linseed oil is an effective means to increase n-3 fatty acid concentration in forequarter muscle.

ABSTRACT. This study evaluated the chemical and lipid composition of uncooked or cooked loin (Longissimus thoracis) and rump (Biceps femoris) in samples of 2.54 cm thick from 35 carcasses of Nellore young bulls finished in feedlot for 96 days and slaughtered at an average weight of 532.17 ± 30.25 kg and 24 months of age. The rump had the lowest level of protein and ash (18.57 and 0.90%, respectively) and the highest level of ether extract compared to loin (3.37 and 1.90%, respectively). Higher levels of cholesterol were found in rump compared to loin (40.91 e 30.93 mg 100 g -1 , respectively). The uncooked loin showed lower content of saturated fatty acids and higher content of polyunsaturated fatty acids. The best values for the omega-6: omega-3 ratio was observed in the uncooked beef. In the present study, the loin was healthier due to the higher amount of polyunsaturated fatty acids compared to rump. Cooking the meat decreases the levels of polyunsaturated fatty acids, omega-3, omega-6 and the omega-6: omega-3 ratio.Keywords: Conjugated linoleic acid, cholesterol, ether extract, meat cuts, protein.Composição química e lipídica de diferentes cortes cárneos in natura ou assados de tourinhos alimentados com fontes de óleo RESUMO. Objetivou-se avaliar as diferenças na composição química e lipídica do contrafilé (Longissimus thoracis) e da picanha (Biceps femoris) in natura ou assados de bovinos alimentados com diferentes fontes de óleo. Para isto, foram utilizadas amostras, seccionadas em bifes de 2,54 cm, do contrafilé e da picanha, provenientes de 35 carcaças de tourinhos da raça Nelore, confinados por 96 dias e abatidos com peso médio de 532,17 ± 30,25 kg e 24 meses de idade. A picanha apresentou os valores mais baixos de proteína e cinzas (18,57 e 0,90%, respectivamente). No entanto, os maiores teores de extrato etéreo também foram encontrados para este corte comparado ao contrafilé (3,37 e 1,90%, respectivamente). Maiores teores de colesterol foram encontrados na picanha em relação ao contrafilé (40,91 e 30,93 mg 100 g -1 , respectivamente). O contrafilé in natura apresentou menores teores de ácidos graxos saturados e maiores quantidades de ácidos graxos poli-insaturados. Para as relações dos ácidos graxos ômega-6: ômega-3, os melhores valores foram encontrados na carne in natura. O contrafilé, no presente estudo, mostrou-se mais saudável pela maior quantidade de ácidos graxos poli-insaturados que a picanha. Assar a carne diminui os teores de ácidos graxos poli-insaturados, ômega-3 e ômega-6, além da relação ômega-6: ômega-3.Palavras-chave: Ácido linoleico conjugado, colesterol, extrato etéreo, cortes cárneos, proteína.