Yellow Grease Research Articles

Apparent digestibilities of common feedstuffs for bluegillLepomis macrochirusand largemouth bassMicropterus salmoidesusing individual test ingredients

Apparent digestibility of dry matter and energy, and availability of amino acids from blood meal (BM), fish meal (FM), meat and bone meal (MBM), poultry by-product meal (PBM), soybean meal (SBM), corn, wheat and yellow grease (YG) were determined for bluegill Lepomis macrochirus (mean weight, 57 g), and likewise, but not for BM or wheat, for largemouth bass Micropterus salmoides (mean weight, 30 g). To avoid nutrient interaction from a reference diet, diets containing 98.5% (985 g kg−1) of test ingredients were used, except for semi-solid, YG which was mixed with corn to permit pelletization. Faeces were collected by a siphoning method. Apparent dry matter digestibility values ranged from 50% (corn) to 87% (BM) for bluegill and from 53% (MBM) to 76% (PBM) for largemouth bass. Apparent energy digestibility values ranged from 53% (corn) to 92% (BM) for bluegill and from 63% (MBM) to 93% (YG) for largemouth bass. Apparent digestibility of most amino acids exceeded 90% for evaluated protein sources, except for MBM which showed slightly lower values (80–90%) for both fishes. Isoleucine digestibility from BM was relatively low (82%) for bluegill. High digestibility values for SBM, PBM and BM, indicate good potential for replacing FM in diets for both fishes.

Effects of supplemental fat on growth performance and quality of beef from steers fed corn finishing diets1

To measure the effects of dietary fat on feedlot performance and carcass characteristics, and on beef appearance, moisture binding, shelf life, palatability, and fatty acid content, 126 crossbred beef steers (321.1 +/- 0.57 kg of BW) were allotted to a randomized complete block (3) design with a 3 x 2 + 1 factorial arrangement of dietary treatments. The main effects were level of yellow grease (0, 3, or 6%) and alfalfa hay (3.5 or 7%) in corn-based diets containing 15% potato by-product (PB). The added treatment was 6% tallow and 7% alfalfa in a barley-based diet containing 15% PB. Dry matter intake and ADG were not affected by diet; however, G:F and diet NE content increased linearly (P < 0.10) with yellow grease. Kidney, pelvic, and heart fat (2.0 to 2.3 +/- 0.07) and yield grade (2.8 to 3.1 +/- 0.09) increased linearly (P < or = 0.05) with yellow grease. Steers fed corn plus 6% yellow grease had lower (P < 0.05) beef firmness and beef texture scores but greater (P < 0.01) fat color score than those fed barley plus 6% tallow. Moisture retention of beef was not affected by dietary treatment, except purge score during retail storage, which was decreased linearly (P < 0.01) from 2.1 to 1.6 +/- 0.06 by level of yellow grease. Steaks from steers fed barley plus 6% tallow had greater (P < 0.05) shear force than those from steers fed corn plus 6% yellow grease, and beef flavor increased linearly (P < 0.05) from 6.2 to 6.7 +/- 0.11 as the level of yellow grease increased. Level of yellow grease linearly increased (P < 0.01) transvaccenic acid (TVA) by 61% and CLA content of beef by 48%. Beef from steers fed corn plus yellow grease had lower (P < 0.05) palmitoleic and oleic acids and greater (P < 0.05) linoleic, TVA, and CLA than beef from steers fed the barley-tallow diet. Feeding yellow grease increased diet energy content, which increased carcass fatness, and altered beef fatty acid content, which increased beef flavor without affecting moisture retention, shelf life, or cooking properties of the beef. Additionally, beef from steers fed corn plus 6% yellow grease was more tender and had more polyunsaturated fatty acid content and CLA than beef from steers fed barley plus 6% tallow.

Long-Term Feeding of Conjugated Linoleic Acid and Fish Oil to Laying Hens: Effects on Hepatic Histopathology, Egg Quality, and Lipid Components

The present study was conducted to investigate the effect of long-term feeding of conjugated linoleic acid (CLA) and fish oil on egg quality characteristics, production performance, liver pathology, and egg fatty acid content of laying hens. Single Comb White Leghorn laying hens (n = 112), 21 wk old, were placed in cages and randomly assigned to 4 diets (28 hens/diet, 4 replicates of 7 hens) containing 3.0% yellow grease (control), 2.75% yellow grease + 0.25% CLA (YG-CLA), 2.5% yellow grease + 0.25% CLA + 0.25% fish oil (YG-CLA-FO), and 2.75% yellow grease + 0.25% fish oil (YG-FO). The experimental diets were fed for 12 mo. Eggs were collected daily for 12 mo. Feed consumption, hen-day egg production, and feed efficiency were monitored. At the end of the trial, hepatic tissue was collected for histopathology. No effect of diet was found on feed consumption, hen-day egg production, feed efficiency, egg weight, yolk weight, shell weight, or Haugh unit. The YG-CLA and YG-CLA-FO diets produced an increase in CLA and saturated fatty acids in the egg and liver tissue with a concomitant reduction in monounsaturated fatty acids (P < 0.05). Feeding YG-CLA-FO and YG-FO increased the n-3 fatty acids in egg yolk and liver of hens (P < 0.05). No difference was observed in the number of fat vacuoles in the liver tissue. The total fat content of hepatic and abdominal fat pads did not differ among treatments (P > 0.05). Regardless of the diet, as the hens aged, egg weight, yolk weight, and egg total fat increased, and shell weight decreased (P < 0.05). These data demonstrate that eggs with increased n-3 fatty acids and CLA can be generated by minor diet modifications without affecting the production performance or health of birds.

Biodiesel engine performance and emissions in low temperature combustion

Engine performance and emission comparisons were made between the use of soy, Canola and yellow grease derived B100 biodiesel fuels and an ultra-low sulphur diesel fuel in the high load engine operating conditions. Compared to the diesel fuel engine-out emissions of nitrogen oxides (NO x ), a high-cetane number (CN) biodiesel fuel produced comparable NO x while the biodiesel with a CN similar to the diesel fuel produced relatively higher NO x at a fixed start of injection. The soot, carbon monoxide and un-burnt hydrocarbon emissions were generally lower for the biodiesel-fuelled engine. Exhaust gas recirculation (EGR) was then extensively applied to initiate low temperature combustion (LTC) mode at medium and low load conditions. An intake throttling valve was implemented to increase the differential pressure between the intake and exhaust in order to increase and enhance the EGR. Simultaneous reduction of NO x and soot was achieved when the ignition delay was prolonged by more than 50% from the case with 0% EGR at low load conditions. Furthermore, a preliminary ignition delay correlation under the influence of EGR at steady-state conditions was developed. The correlation considered the fuel CN and oxygen concentrations in the intake air and fuel. The research intends to achieve simultaneous reductions of NO x and soot emissions in modern production diesel engines when biodiesel is applied.

Conjugated Linoleic Acid and Fish Oil in Laying Hen Diets: Effects on Egg Fatty Acids, Thiobarbituric Acid Reactive Substances, and Tocopherols During Storage

The effects of incorporating conjugated linoleic acid (CLA) and fish oil in laying hen diets on egg CLA, n-3 fatty acid, tocopherol, and TBA reactive substances (TBARS) during 60 d of storage were investigated. Hens were fed corn-soybean meal-based diets containing 3% yellow grease (YG), 2.75% yellow grease + 0.25% CLA (YG-CLA), 2.5% yellow grease + 0.25% CLA + 0.25% fish oil (YG-CLA-FO), or 2.75% yellow grease + 0.25% fish oil (YG-FO). Eggs were collected and stored at 4° C up to 60 d. On storage d 0, 20, 40, and 60, eggs (n = 8) from each treatment were selected randomly, and tocopherol and TBARS contents were measured. Egg total lipid and fatty acids were determined on d 0 and 60 of storage. Feeding YG-CLA-FO led to a 5.4 and 7.7% reduction in egg total lipids on d 0 and 60 (P < 0.05) when compared with YG eggs. The YG-CLA and YG-CLA-FO diets led to a 12% increase in egg saturated fatty acids compared with YG eggs. The content of monounsaturated fatty acids were lower (> 19%) in YG-CLA and YG-CLA-FO compared with YG. Egg n-3 was highest in YG-FO eggs and lowest in YG eggs (P < 0.0001). Storage over 60 d led to a 20 and 67% depletion of CLA in the YG-CLA and YG-CLA-FO eggs (P < 0.0001). A 29% reduction was observed in the total n-3 fatty acid content of YG-CLA-FO eggs at d 60 of storage when compared with d 0 of storage (P < 0.0001). Diet and storage increased TBARS (P < 0.0001), which was highest in YG-CLA eggs at 60 d of storage. The YG-CLA and YG-CLA-FO diets reduced α and γ-tocopherol contents at all days of storage compared with YG eggs (P < 0.05). Regardless of diet, egg storage for 40 d or longer depleted egg tocopherol contents (P < 0.05). These data demonstrate that healthy eggs with increased n-3 fatty acids and CLA can be generated by minor diet modifications, but added tocopherol supplementation may be needed to reduce lipid peroxidation when n-3 or CLA is included in the hen diet.

Computational modelling of NO&lt;SUB align=right&gt;x emissions from biodiesel combustion

A detailed numerical spray atomisation, ignition, combustion and NOx formation model was developed for direct injection diesel engines using KIVA-3V code that could be applied to biodiesel fuels and this model was used to investigate the NOx emissions mechanisms of biodiesel compared with diesel fuel. In addition, computational modelling was applied to evaluate strategies for reducing NOx emissions from biodiesel combustion. The physical and thermodynamic properties of biodiesel used in the model were based on fatty acid composition. The model was verified with experimental data from an engine fuelled with diesel fuel, soyabean methyl ester, Yellow Grease Methyl Ester (YGME) and genetically modified soyabean methyl ester. Strategies for reducing NOx emissions from biodiesel combustion were evaluated with the aid of the model. Increasing spray cone angle, retarding start of injection, applying Exhaust Gas Recirculation (EGR) and charge air cooling were all effective approaches to reducing NOx emissions from biodiesel fuel.

Descriptive flavor analysis of bacon and pork loin from lean-genotype gilts fed conjugated linoleic acid and supplemental fat1

This study evaluated the combined effects of dietary CLA and supplemental fat (SF) source on organoleptic characteristics of bacon and pork loin samples in lean-genotype gilts (n = 144). Gilts (49.3 kg of BW) were randomly assigned to a 3 x 2 factorial design, consisting of SF [0% SF, 4% yellow grease (YG), or 4% tallow] and linoleic acid (LA; 1% corn oil or 1% CLA). Animals were slaughtered (113 kg) after a feeding period of 47 d. A trained sensory panel (n = 6 members) developed a flavor profile on commercially cured bacon samples (12 descriptors) and center-cut, boneless, pork loin chops (18 descriptors, using a 14-point, universal intensity scale). Bacon samples from pigs fed 4% SF were considered to have a sweeter flavor (4.07 +/- 0.07) than those fed 0% SF (3.89 +/- 0.07; P < 0.04). The intensity of salty flavor was greater in bacon samples from pigs fed LA (6.18 +/- 0.09) compared with those fed CLA (5.86 +/- 0.10; P < 0.04). The intensity of salty aftertaste of bacon was greater when LA was combined with YG (5.21 +/- 0.14; P < 0.07) or tallow (5.44 +/- 0.14; P < 0.01) than for LA alone (4.85 +/- 0.14, but SF combined with CLA was not different from CLA alone (fat x LA; P < 0.02). Sour flavor intensity tended to be lower in loin samples from pigs fed CLA than for those fed LA (1.60 vs. 1.73 +/- 0.06; P < 0.09). Samples from animals fed 4% tallow tended to have lower (P < 0.09) notes of astringent aftertaste (1.42 +/- 0.08) compared with those fed 0% SF (1.62 +/- 0.09) or 4% YG (1.66 +/- 0.09). Overall, the flavor differences for bacon and loin samples were minimal, with most means differing by 1 point or less on the 14-point intensity scale. The sensory panel results indicate consumer acceptance of bacon and pork products from pigs fed CLA will not likely differ from commodity pork products.

Analysis of a Two-Step, Noncatalytic, Supercritical Biodiesel Production Process with Heat Recovery

A two-step, noncatalytic process for the production of biodiesel is analyzed. The reaction of transesterification of triglycerides with methanol is carried out in supercritical conditions by adopting reaction temperatures of 250−300 °C, higher than the critical temperature of methanol (240 °C). Under these conditions, free fatty acids are converted into fatty acid methyl esters with similar or higher rates than the corresponding triglycerides, and therefore, the process can use high acidity, cheap feedstocks, like yellow grease or beef tallow. The reacting system is also tolerant to water, so it is much more robust than the acid or alkali catalyzed systems which need the removal of water or free fatty acids to prevent catalyst deactivation. In order to minimize the heat consumption and pumping power which are very high in the traditional one-step supercritical method, two reactors with intermediate glycerol removal are used and a heat recovery scheme composed of heat exchangers and adiabatic flash drums i...

Milk composition of Holstein, Jersey, and Brown Swiss cows in response to increasing levels of dietary fat

Milk composition is influenced by many factors that include nutrition, parity, stage of lactation and breed. The objective of this study was to determine the effect of increasing the level of dietary fat on the composition of milk from primiparous Holstein (H), Jersey (J) and Brown Swiss (S) cows. Twelve lactating cows, four from each breed, were utilized in a 4×4 Latin square design with 14-day experimental periods. All cows received a basal total mixed ration consisting of 490 g/kg chopped alfalfa hay and 510 g/kg concentrate. Dietary fat in the form of yellow grease was added at 0, 15, 30 and 45 g/kg of diet as-fed, replacing a portion of rolled barley grain. Milk yield was higher for H versus J and S, and there was a linear increase in 40 g/kg fat corrected milk yield with increasing level of supplemental fat in the diet. Diet did not affect dry matter intake, but intake was highest for H and lowest for J. Total milk N and casein N proportions in milk did not differ by breed, but both decreased linearly with increased supplemental fat. There were no differences in milk content of Ca, K, Mg and P by breed, but the concentration of Mg linearly increased, and P decreased, with increasing supplemental fat. J milk fat had higher proportions of short-chain and medium-chain FA versus H and S milk fat, while S milk had the highest long-chain FA and J the lowest. For short-chain FA, J milk fat was highest in C4:0, C6:0 and C8:0. Milk fat content of C18:1 cis 9 & cis 10 was highest for S and lowest for J with H intermediate. C18:1 cis 9 & cis 10 increased linearly with increasing supplemental fat. Breed had no effect on C18:0, C18:2 and C18:3 concentrations, but C18:0 increased and C18:2 and C18:3 decreased with increasing supplemental fat. C18:2 cis 9 & trans 11 did not differ by breed, but increased linearly with increased supplemental fat. The ratio of C18:1 cis to C18:0 was highest for S and lowest for J, suggesting possible differences in mammary desaturase activity. Finally, J milk fat had larger fat globules than those of H and S, and fat globules also tended to increase in size with increasing level of supplemental fat. Results indicate that nutrition and breed can be used as practical means to modify the composition of milk fat.

The production of fatty acid isopropyl esters and their use as a diesel engine fuel

AbstractBiodiesel is an alternative fuel for diesel engines that consists of the monoalkyl esters of vegetable oils or animal fats. Currently, most biodiesel consists of methyl esters, which have poor cold‐flow properties. Methyl esters of soybean oil will crystallize and plug fuel filters and lines at about 0°C. However, isopropyl esters have better cold‐flow properties than methyl esters. This paper describes the production of isopropyl esters and their evaluation in a diesel engine. The effects of the alcohol amount, the catalyst amount, and two different catalysts on producing quality biodiesel were studied. Both sodium isopropoxide and potassium isopropoxide were found to be suitable for use in the transesterification process. A 20∶1 alcohol/TG molar ratio and a catalyst amount equal to 1% by weight (based on the TG amount) of sodium metal was the most cost‐effective way to produce biodiesel fuel. The emissions from a diesel engine running on isopropyl esters made from soybean oil and yellow grease were investigated by comparing them with No. 2 diesel fuel and methyl esters. For nitrogen oxide emission, the difference between the biodiesel produced from soybean oil and yellow grease was greater than the difference between the methyl and isopropyl esters of both feedstocks. The other emissions from using isopropyl esters were about 50% lower in hydrocarbons, 10–20% lower in carbon monoxide, and 40% lower in smoke number when compared with No. 2 diesel fuel.

Performance and exhaust emissions of a biodiesel engine

In this study, the applicabilities of Artificial Neural Networks (ANNs) have been investigated for the performance and exhaust-emission values of a diesel engine fueled with biodiesels from different feedstocks and petroleum diesel fuels. The engine performance and emissions characteristics of two different petroleum diesel-fuels (No. 1 and No. 2), biodiesels (from soybean oil and yellow grease), and their 20% blends with No. 2 diesel fuel were used as experimental results. The fuels were tested at full load (100%) at 1400-rpm engine speed, where the engine torque was 257.6 Nm. To train the network, the average molecular weight, net heat of combustion, specific gravity, kinematic viscosity, C/H ratio and cetane number of each fuel are used as the input layer, while outputs are the brake specific fuel-consumption, exhaust temperature, and exhaust emissions. The back-propagation learning algorithm with three different variants, single layer, and logistic sigmoid transfer function were used in the network. By using weights in the network, formulations have been given for each output. The network has yielded R 2 values of 0.99 and the mean % errors are smaller than 4.2 for the training data, while the R 2 values are about 0.99 and the mean % errors are smaller than 5.5 for the test data. The performance and exhaust emissions from a diesel engine, using biodiesel blends with No. 2 diesel fuel up to 20%, have been predicted using the ANN model.

Effects of chemical hydrogenation of supplemental fat on relative apparent lipid digestibility in finishing swine1,2

Four experiments were conducted to evaluate lipid digestibility in finishing swine fed chemically hydrogenated fats. Dietary chromic oxide was used as an inert marker to measure the apparent digestibility of supplemental fat (SF) that consisted of fully hydrogenated (FH), partially hydrogenated (PH), or PH products blended with other fat sources. In Exp. 1, diets containing 5% SF (as-fed basis) comprising 100, 66.7, 33.3, or 0% FH animal fat (iodine value = 2.5), with the balance contributed by soy oil, were fed to gilts (n = 24). Apparent digestibility increased linearly (-12.0, 26.0, 61.2, and 72.6%; P < 0.001) as the amount of FH fat in the diet decreased, suggesting the digestibility of FH to be near zero. Experiment 2 (2 x 4 factorial; n = 48) evaluated diets containing 5% (as-fed basis) blended fat (FH tallow and yellow grease) to achieve iodine values of 20, 30, 40, or 50 compared with PH tallow with identical iodine values. Digestibility of diets formulated with PH tallow was greater than those containing blended fat (73.4 vs. 67.2%; P < 0.01), especially at lower iodine values (interaction; P < 0.10). In Exp. 3, digestibility was measured in pigs (n = 96) fed 5% (as-fed basis) PH choice white grease with iodine values of 20, 40, 60, or 80. Increasing iodine value did not alter digestibility (66.2, 69.2, 68.2, and 69.7%). Experiment 4 investigated digestibility (n = 32) of diets formulated with 8% (as-fed basis) PH fat (iodine value 20 or 50) with 0.10% lysolecithin as an emulsifier. Lipid digestibility was 14.5% greater in the 8% SF diet with an iodine value of 50 compared with the diet with an iodine value of 20 (79.15 vs. 69.12%; P < 0.001), but lysolecithin was without effect. These experiments indicate that partial hydrogenation is superior to blending unsaturated fat with saturated fat sources and that digestibility is not greatly affected by decreasing the iodine value via partial hydrogenation.

Temperature‐dependent kinematic viscosity of selected biodiesel fuels and blends with diesel fuel

AbstractThe kinematic viscosities of four biodiesel fuels—two natural soybean oil methyl esters, one genetically modified soybean oil methyl ester, and one yellow grease methyl ester—and their 75, 50, and 25% blends with No. 2 diesel fuel were measured in the temperature range from 20 to 100°C in steps of 20°C. The measurements indicated that all these fuels had viscosity‐temperature relationships similar to No. 2 diesel fuel, which followed the Vogel equation as expected. A weighted semilog blending equation was developed in which the mass‐based kinematic viscosity of the individual components was used to compute the mixture viscosity. A weight factor of 1.08 was applied to biodiesel fuel to account for its effect on the mixture viscosity. The average absolute deviation achieved with this method was 2.1%, which was better than the uncorrected mass average blending equation that had an average absolute deviation of 4.5%. The relationship between the viscosity and the specific gravity of biodiesel fuels was studied. A method that could estimate the viscosity from the specific gravity of biodiesel fuel was developed. The average absolute deviation for all the samples using this method was 2.7%. The accuracy of this method was comparable to the weighted mass‐based semilog blending equation.

Effects of dietary fish oil, soy-acid oil, and yellow grease on growth and hepatic lipidosis of hybrid tilapia fry

The objective of this study was to compare the effects of dietary lipids on growth and liver histopathology of hybrid tilapia, Oreochromis niloticus x O. aureus, fry (6.0 g). Fish were fed one of six diets containing 8.4% fish oil (control), 8.4% soy-acid oil, 8.4% yellow grease, 5.6% yellow grease plus 2.8% soy-acid oil, 2.8% yellow grease plus 4.6% soy-acid oil, or 4.2% soy-acid oil plus 4.2% yellow grease for 60 days. Growth was similar in all groups and retarded in compari- son to earlier studies. Lipid accumulation as well as microvesicular (foamy degeneration) and macrovesicular degeneration in the liver were histopathologically detected.

SPRAY, IGNITION, AND COMBUSTION MODELING OF BIODIESEL FUELS FOR INVESTIGATING NOX EMISSIONS

The objective of this research was to develop a detailed numerical spray atomization, ignition, and combustion model for direct-injection diesel engines using KIVA3V code that could be applied to biodiesel fuels for investigating NOx emissions. Several modified or recalibrated submodels were incorporated into KIVA3V, including a KH-RT spray breakup model, a Shell ignition model, and a single-step kinetic combustion model. This modified model was applied to a John Deere 4045T direct-injection diesel engine fueled by a soybean methyl ester, a yellow grease methyl ester, and No. 2 diesel fuel. The output of the model was in close agreement with the experimental measurements of cylinder pressure and heat release rate from this engine. It was predicted from the modeling results that the two biodiesel fuels had shorter ignition delay and higher overall cylinder temperatures than diesel fuel. The in-cylinder spray analysis indicated that the soybean methyl ester had slightly longer penetration than diesel fuel, but the yellow grease methyl ester had shorter penetration than diesel fuel. Fewer particle numbers were predicted for the two biodiesel fuels. Both soybean methyl ester and yellow grease methyl ester had more widespread high-temperature distribution areas than diesel fuel, which could account for the increases in NOx emissions typically measured for biodiesel fuels.

Effects of supplemental fat on growth performance and quality of beef from steers fed barley-potato product finishing diets: II. Fatty acid composition of muscle and subcutaneous fat1

One hundred sixty-eight crossbred steers (317.1 +/- 1.0 kg) were used to evaluate the effects of supplemental fat in finishing diets on the fatty acid composition, including the 9,11 isomer of conjugated linoleic acid, of beef. Steers were allotted within three weight blocks to a randomized complete block design with a 3 x 2 + 1 factorial arrangement of dietary treatments. Main effects were level of yellow restaurant grease (RG; 0, 3, and 6%), and level of alfalfa hay (AH; 3.5 and 7%) with an added treatment containing 6% tallow (T) and 7% AH in barley-based diets containing 15% potato by-product and 7% supplement (all dietary levels are on a DM basis) fed for an average of 165 d. Fatty acids of the LM and s.c. fat from four randomly selected steers per pen were quantified using GC after methylation with sodium methoxide. Dietary treatment did not (P > 0.10) affect total fatty acid (FA) content of the LM (143 +/- 5.2 mg/g) or fat (958 +/- 7.9 mg/g). Myristic acid increased linearly (P < 0.01) with increasing RG from 3.1 to 3.7 +/- 0.1 g/100 g of FA in muscle. Stearic acid increased linearly (P < 0.05) as RG increased in the diet, from 11.4 to 12.9 +/- 0.4 g/100 g of FA in LM and from 9.9 to 12.2 +/- 0.3 g/100 g of FA in fat. Compared with T, steers fed 6% RG had more (P < 0.05) oleic acid in LM (42.7 vs. 40.3 +/- 0.5 g/100g FA) and in fat (43.0 vs. 40.9 +/- 0.5 g/100g FA). The cis-9, trans-11 conjugated linoleic acid (CLA) increased quadratically (P < 0.01) with increasing dietary RG in LM from 0.45 to 0.64 to 0.62 +/- 0.03 g/100 g of FA and increased in fat from 0.61 to 0.84 to 0.83 +/- 0.04 g/100 g of FA. Moreover, cis-9, trans-11 CLA was higher (P < 0.05) in fat from steers fed RG compared with T (0.81 vs. 0.69 +/- 0.04 g/100 g of FA), and tended to be higher (P = 0.07) in muscle (0.62 vs. 0.54 +/- 0.03 g/100 g of FA. Feeding yellow restaurant grease increased content of cis-9, trans-11 CLA in beef without an increase total FA content.

Effects of supplemental fat on growth performance and quality of beef from steers fed barley-potato product finishing diets: I. Feedlot performance, carcass traits, appearance, water binding, retail storage, and palatability attributes1

To measure the effects of dietary fat on feedlot performance, carcass characteristics, and beef appearance, moisture binding, shelf life, and palatability, 168 crossbred beef steers (317 +/- 1.0 kg) were allotted randomly, within weight blocks, to a randomized complete block design with a 3 x2 + 1 factorial arrangement of dietary treatments. Main effects were level of yellow restaurant grease (RG; 0, 3, or 6%) and level of alfalfa hay (AH; 3.5 or 7%), with the added treatment of 6% tallow and 7% AH in barley-based diets containing 15% potato by-product and 7% supplement fed for 165 d (all dietary levels on a DM basis). Dietary treatment did not (P >0.10) affect DMI, LM area, beef brightness, or beef texture. Level of RG linearly increased (P <0.05) ADG from 1.48 to 1.60 kg/d, diet NE(m) from 2.4 to 2.6 Mcal/kg, diet NE(g) from 1.7 to 1.9 Mcal/kg, and internal fat from 2.1 to 2.4%. Level of RG linearly increased (P <0.05) G:F from 0.184 to 0.202, but decreased (P <0.05) beef firmness score from 3.0 to 2.8 and fat luster score from 3.1 to 2.8. Level of AH did not (P >0.10) affect any of the measurements; however, AH interacted with level of RG on fat thickness and yield grade (linear; P <0.05), as well as marbling score and percentage of carcasses grading USDA Choice (quadratic; P <0.05). Fat thickness and yield grade increased with increasing RG level in 3.5%, but not in 7%, AH diets. In steers fed 3.5% RG, marbling scores and percentage of carcasses grading Choice were greatest when fed with 3.5% AH, and least when fed 7% AH. Steers fed tallow had lower marbling scores (P = 0.01) and percentage of carcasses grading Choice (P = 0.066) than those fed RG. Retail storage attributes, including visual and instrumental color, decreased during storage (P <0.01), but were not (P >0.10) affected by diet. Trained sensory panel scores for initial tenderness increased quadratically (P = 0.07) as dietary RG increased, but diet did not (P >0.10) affect drip loss, cooking loss, or trained sensory panel scores for sustained tenderness, initial and sustained juiciness, and beef flavor. Therefore, RG increased diet energy, improved performance, and increased carcass fatness; however, dietary fat and AH did not affect most measurements of water retention, color stability, or palatability of beef.

Relationship between body weight and level of fat supplementation on fatty acid digestion in feedlot cattle.

Eight Holstein steers with cannulas in the rumen and proximal duodenum were used in a split-plot design experiment to evaluate the interaction of body weight (175 vs. 370 kg) and level of fat supplementation (0, 3, 6, and 9% yellow grease) on characteristics of digestion and feeding value of fat in finishing diets. Dry matter intake was restricted to 2% of BW. There were no interactions between BW and level of fat supplementation (P > 0.10) on ruminal or total-tract digestion. Level of supplemental fat decreased (linear, P < 0.01) ruminal digestion of OM and NDF, and increased (linear, P < 0.05) ruminal N efficiency. There were no treatment effects (P > 0.10) on postruminal digestion of OM, NDF, and N. There tended to be an interaction (P < 0.10) between BW and level of fat supplementation on postruminal starch digestion. Increasing level of fat supplementation increased postruminal digestion of starch in heavier steers but did not affect starch digestion in lighter steers. There were no interactions (P > 0.10) between BW and level of fat supplementation on postruminal fatty acid digestion. Increasing level of fat supplementation decreased (linear, P < 0.01) postruminal fatty acid digestion, which was due to a decreased (linear, P < 0.01) postruminal digestion of C16:0 and C18:0. Supplemental fat decreased (linear, P < 0.01) total-tract digestion of OM and NDF. The estimated NEm (Mcal/kg) of yellow grease averaged (linear, P < 0.01) 6.02, 5.70, and 5.06 for the 3, 6, and 9% of level supplementation, respectively. We conclude that intestinal fatty acid digestion (FAD, %) is a predictable function (r2 = 0.89; P < 0.01) of total fatty acid intake per unit body weight (FAI, g/kg BW): FAD = 87.560 - 8.591FAI. Depressions in fatty acid digestion with increasing level of intake were due primarily to decreased intestinal absorption of palmitic and stearic acid. Level of fatty acids intake did not appreciably affect intestinal absorption of unsaturated fatty acid. Changes in intestinal fatty acid digestion accounted for most of the variation in the NE value of supplemental fat.

BIODIESEL BLEND DETECTION WITH A FUEL COMPOSITION SENSOR

Biodiesel is an alternative diesel fuel consisting of the alkyl monoesters of fatty acids from vegetable oils and animal fats. Biodiesel can be used in diesel engines as a pure fuel or in blends with petroleum–based diesel fuel. To maintain optimum performance and meet emission regulations, it may be necessary to measure the composition of blended fuels and adjust the fuel injection timing and other injection parameters during operation. The objective of this study was to investigate the suitability of using a commercial Flexible Fuel Composition Sensor for the detection of biodiesel composition in biodiesel/diesel fuel blends. Twelve different biodiesel fuel samples were tested including pure esters and esters from soybean oil, tallow, lard, canola oil, and yellow grease. The sensor produced a frequency output between 58.75 and 60.23 Hz for all of the biodiesel samples. Six different diesel fuel samples were also tested including commercial No. 1 diesel fuel and EPA emission certification fuel. All of the diesel fuel samples gave frequencies between 51.84 and 52.62 Hz. The frequency output of the sensor was linearly proportional to the percentage of biodiesel in the blend. The 7.14–Hz average difference from diesel fuel to biodiesel is sufficient to use this fuel composition sensor for blend detection of biodiesel blended fuels.

A PILOT PLANT TO PRODUCE BIODIESEL FROM HIGH FREE FATTY ACID FEEDSTOCKS

Biodiesel is an alternative diesel fuel consisting of the alkyl monoesters of fatty acids from vegetable oils or animalfats. Currently, most biodiesel is made from soybean oil, methanol, and an alkaline catalyst. However, there are large amountsof fats and oils that are unsuitable for human consumption that could be converted to biodiesel at lower cost. The problemwith processing these waste oils is that they often contain large amounts of free fatty acids that cannot be converted to biodieselusing an alkaline catalyst. These free fatty acids react with the alkaline catalyst to produce soaps that inhibit the separationof the biodiesel, glycerin, and wash water. Previous research has developed a process for pretreating these high free fatty acidfeedstocks using acid catalysts, which do not form soaps. The objective of this study was to construct a pilot plant to producebiodiesel from a wide variety of feedstocks including those with high free fatty acids. A 190 L batch pilot plant has been builtthat can process high free fatty acid feedstocks using an acidcatalyzed pretreatment followed by an alkalinecatalyzedtransesterification. Case studies of pilot plantscale production of biodiesel from soybean oil, yellow grease with 9% free fattyacids, and brown grease with 40% free fatty acids are presented. The effect of varying the reaction parameters is discussed,and the separation and washing processes are described. Estimates of the fuel cost using different feedstocks are alsoprovided.