Lipids have been used in ruminant feed to replace high amounts of grain for increasing the diet energy density, performance and meat quality. This study evaluated the qualitative characteristics of meat from feedlot heifers fed with sources of lipid supplements. Twenty-one crossbred heifers (¼Nelore × ¼Santa Gertrudis × ½Braunvieh) were used. Each heifer received 60 % forage with a base of corn silage and 40 % concentrate, resulting in 5.8 % lipid content in the total diet. The following sources of lipids were used: soybeans, protected fat and soybean oil. There were no differences on physical characteristics of meat samples from heifers fed with the lipid sources. Soybeans increased the concentration of linoleic acid, content of polyunsaturated fatty acid and activity of the Δ 9 -desaturase C16 enzyme in the Longissimus muscle. The use of soybean oil in the diet increased the oleic acid, monounsaturated fatty acid, total cis-and trans-fatty acids (C18:0) and the activity of the Δ 9 -desaturase C16 enzyme in the subcutaneous fat. Diets with soybean grain had greater deposition of linoleic and linolenic acids than diets with fat protected and greater presence of these essential fatty acids are associated to a better composition and meat quality.

The objective of this study was to evaluate the effects of sources of soybean oil [ground soybean (GS), soybean oil (SO) and calcium salts of soybean oil (CS)] on DM intake (DMI), ingestive behaviour and average daily gain (ADG) of heifers grazing marandu palisadegrass (Brachiaria brizantha cv. Marandu) supplemented in two frequencies [daily and 3 days a week (Monday, Wednesday and Friday -MWF)]. The experiment was conducted from July until November of 2007. Forty-two crossbred heifers (1/4 Nellore · 1/4 Santa Gertrudis · 1/2 Braunvieh), 17-months old and 297.1 kg AE 30.5 BW AE s.e.m., were used. Supplements were offered at 0.75% BW.day. Treatments were allocated in a completely randomised design and distributed in a factorial arrangement (3 · 2 -SO from three different sources and two supplementation frequencies). Total DMI was greater in August and October (2.2 kg DM/kg BW) than in November (1.5 kg DM/kg BW). There was an effect of SO source on total DM, herbage and nutrients intake, but no effects of supplementation frequency. The animals supplemented with SO had greater DMI (P < 0.05) than the ones fed GS and CS. Average daily gain (0.580 g) was not affected by supplement sources or feeding frequency. Therefore, GS and CS are more efficient supplements. Supplementation frequency altered grazing time differently according to source. The MWF treatment resulted in a decreased grazing time when GS and SO were fed. However, in days when supplements were not offered, grazing time was increased for GS and CS. It was concluded that a decreased frequency of supplementation may be implemented without effect on weight gain and will reduce labour and machinery costs.

-The objective of this study was to evaluate the effect of different lipid sources on nutrient intake, performance, development and carcass characteristics of heifers raised in confinement. Twenty-one crossbreed heifers (Nellore × Santa Gertrudis × Braunvieh) received 600 g/kg forage composed of corn silage and 400 g/kg concentrate with a 58.0 g/kg fat content in the total diet. The following lipid sources were used: soybeans, protected fat (Megalac-E ® ) and soybean oil. The experimental design was completely randomized, with three treatments and seven replicates, and the means were compared by the Tukey test at 5%. The protected fat diet resulted in a greater intake of dry matter (8.80 kg/d) when compared with the other diets. The animals that were fed the protected fat diet had a higher average daily weight gain and slaughter weight.Feed conversion and protein efficiency rate were not influenced by lipid sources. Carcass yield was not influenced by the different diets.

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