Yellow Grease Research Articles

Production of Biodiesel from WVO Using Small Scale Continuous Ultrasonic Processor

There is a need in the USA to decrease dependency on fossil fuels. One alternative fuel that has gained much popularity in the past few years is biodiesel. Biodiesel can be produced using vegetable oil, waste vegetable oil (WVO), animal fat and yellow grease as raw materials. However, the process of converting a batch of WVO into usable biodiesel is time consuming, requires a human operator to run the system, and necessitates the performance of a chemical titration for each batch of biodiesel produced. In the first phase of this project, the processor was designed and built by the senior design students utilizing a programmable logic controller (PLC) in conjunction with pumps, valves, temperature sensors, etc. to completely handle the production of biodiesel with minimum operator interaction. This was the first step toward continuous flow processor and the elimination of the titration process. In the second phase of this project, the students integrated a small Hielscher Ultrasound continuous processing unit to the automated system. This paper presents the newly developed system and demonstrates the design aspects of the automated biodiesel production processor using a PLC and ultrasonication (continuous processing) as well as how the chemical titration procedure for each batch is eliminated.

Life‐cycle analysis of sustainable aviation fuel production through catalytic hydrothermolysis

AbstractCatalytic hydrothermolysis (CH) is a sustainable aviation fuel (SAF) pathway that has been recently approved for use in aircraft fuel production. In alignment with broader sustainable aviation goals, SAF production through CH requires a quantitative assessment of carbon intensity (CI) impacts. In this study, a current‐day life‐cycle analysis (LCA) was performed on SAF produced via CH to determine the CI. Various oily feedstocks were considered, including vegetable oils (soybean, carinata, camelina and canola) and low‐burden oils and greases (corn oil, yellow grease and brown grease). Life‐cycle inventory data were collected on all processes within the CH LCA boundary: feedstock cultivation and/or collection, preprocessing, hydrothermal cleanup and CH, biocrude refining, fuel transportation and end use through combustion. Baseline results show that the CH‐produced SAF can be generated with CI reductions ranging from 48 to 82% compared with conventional jet fuel. Modest improvements to CI can be achieved through incremental changes to the brown grease CH process, such as relaxing the dewatering specification and implementing renewable natural gas and electricity, which could decrease the CI from 22.9 to 7.9 g CO2e/MJ. Total CH fuel production potential was also assessed on the basis of current or near‐future feedstock availability and CI. The total biofuel production potential of CH (SAF and renewable fuel co‐products) in the US sums to approximately 3487 million gallons per year, with 97% of these volumes having a CI below 50% of that for petroleum jet fuel. The study shows that from an LCA perspective, CH offers a viable SAF pathway that is comparable with existing SAF pathways like hydroprocessed esters and fatty acids.

Biodiesel production from transesterified yellow grease by ZSM-5 zeolite-supported BaO catalyst: process optimization by Taguchi’s experimental design approach

Methanolysis of yellow grease (YG) was performed to synthesize its corresponding methyl ester (YGME) using BaO loaded on ZSM-5 (BaO/ZSM-5) as a heterogeneous base catalyst that was prepared via metallic solution hydrolysis method and characterized using N2 adsorption–desorption (BET), surface basicity, XRD, TGA/DTA, SEM, FTIR and Raman techniques.### The Taguchi design approach was utilized to optimize the transesterification process factors, and among the parameters studied, calcination temperature was found to have a significant influence on YGME yield. At 70 ℃ for 3 h, a YGME yield of 95.9 ±0.94\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pm 0.94$$\\end{document}% was obtained using a methanol/YG molar ratio of 15:1 and 1 g (2 wt.% of YG used) of BaO/ZSM-5 sample calcined at 700 ℃. The BaO/ZSM-5 catalyst was reused six times with only a 15% decrease in activity.

Comparative energy value of cooked grease recovered from rinse-trap water lines used as dietary fat source for feedlot lambs

The objective of this experiment was to compare the effects of dietary supplementation with cooking grease recovered from rinse-trap water lines (rinse-trap grease; RTG) versus conventional supplemental fats (tallow; TL, and yellow grease; YG) on 84-d growth performance, dietary energy, and carcass traits of feedlot lambs. Forty-eight Pelibuey × Katahdin lambs (27.7 ± 3.4 kg) were assigned in a randomized complete block design to evaluate: 1) basal diet without supplemental fat (Control); 2) 4% TL; 3) 4% YG, and 4) 4% RTG. Supplemental fats replaced maize in the control diet. Rinse-trap grease contained greater moisture (16.5 vs 0.92%) and impurities (3.6 vs 0.56%), and less total fatty acid (64.90 vs 89.60%) than that of conventional fats (TL and YG). Daily weight gain and gain efficiency were similar for control and RTG supplemental lambs, whereas ADG and gain efficiency were greater for lambs fed conventional fats than control or RTG-supplemented lambs. Both dietary net energy (NE) as well as ratio of observed-to-expected dietary NE were 4% greater for lambs supplemented with conventional fats vs RTG. Supplemental fat increased fat deposition but did not affect any other carcass measures or non-fat visceral mass. Estimated NE value for RTG was 57% of the average NE value (6.11 Mcal/kg) of tested conventional fats. Supplementation with RTG does not affect diet acceptability, and accordingly, is a suitable energy source for feedlot lambs. However, due to its lower total fatty acid content, its energy value is much lower than conventional supplemental fats.

Improving yields, compatibility and tailoring the properties of hydrothermal liquefaction bio-crude using yellow grease

Low quality waste feedstocks like food wastes, waste fats, manures etc. offer huge potential for replacing an appreciable quantity of petroleum crude. Owing to high water content of some of these feedstocks, hydrothermal liquefaction is the preferred route for its transformation. The present work performed in a continuous pilot scale hydrothermal liquefaction system studies the influence of yellow grease on the yields and quality of bio-crude, properties of bio-crude/blends, and its compatibility with petroleum fractions. Blends of food waste, yellow grease, and algae were used as feedstocks. Key fuel properties such as density and viscosity of bio-crudes and its blends with diesel and butanol were evaluated. Compatibility of different bio-crudes with petroleum fraction was investigated using microscopy imaging of blends of bio-crude and commercial diesel. Enhanced yields of bio-crude and lower asphaltene content were observed with the addition of waste lipids in the form of yellow grease while also decreasing the viscosity and density of bio-crude. Bio-crude from food wastes showed regions of compatibility at higher bio-crude concentrations while lower concentrations of bio-crude were incompatible. A combination of feedstock mix and blending of bio-crude could be used to improve the properties and compatibility of bio-crude for specific end-use devices and processes.

Roughage level and supplemental fat for newly received finishing calves: effects on growth performance, health, and physiological responses.

This experiment evaluated the effects of roughage levels and supplemental fat on intake, growth performance, health, and physiological responses of newly received finishing cattle during 58-d receiving period. A total of 72 crossbred steers (initial body weight [BW] = 200 ± 13 kg) were used in a randomized complete block design with a 2 × 2 factorial arrangement of treatments, consisting of two roughage levels (wheat hay at 30% [R30] or 60% [R60]; dry matter [DM] basis) and two levels of supplemental fat (yellow grease at 0% [-FAT; no additional fat] or 3.5% [+FAT]; DM basis). Upon arrival, calves were individually weighed, blocked by off-truck shrunk BW, and assigned to 24 soil-surfaced pens (three calves per pen). Shrunk BW was also collected on day 58 for the calculation of average daily gain (ADG). Throughout the study, calves were assessed for bovine respiratory disease (BRD). Effects of roughage level × supplemental fat interaction were only observed for diet particle size distribution and estimated physically effective neutral detergent fiber (peNDF) of diets (P ≤ 0.10). Adding fat to R60 diets tended to increase the percentage of particles retained in the 8-mm screen (P = 0.06) and the estimated peNDF (P = 0.10), but did not affect R30 diets. Dietary roughage level did not affect DM intake (DMI; P = 0.85). Calves-fed R30 tended to have greater ADG and final BW than calves-fed R60 (P ≤ 0.08). Gain efficiency (gain:feed ratio; G:F) was greater for calves-fed R30 than calves-fed R60 (P = 0.01). Dietary roughage level did not affect morbidity and mortality (P ≥ 0.11). Supplemental fat did not affect DMI (P = 0.6) but tended (P = 0.09) to increase ADG compared to -FAT diets. The G:F was greater for calves-fed +FAT than -FAT (P = 0.03). The +FAT diet tended (P = 0.10) to increase the number of retreatments against BRD compared to -FAT, although the total number of antimicrobial treatments required to treat sick calves (P = 0.78) and the mortality rate (P = 0.99) were not affected by supplemental fat. Feeding +FAT diet tended (P ≤ 0.09) to increase plasma concentration of cortisol and immunoglobulin-G compared to -FAT. In summary, feeding 30% roughage diets or adding 3.5% yellow grease (DM basis) as supplemental fat increased G:F during the feedlot receiving period.

The addition of different oils in the diet regulates the expression of adipocytokine signaling genes in sheep longissimus dorsi muscle.

Nutrition is an important factor that regulates the expression of several genes. The aim of this work was to analyze the effects of diets containing additions of different oils on the regulation of the adipocytokine signaling gene expressions in sheep longissimus dorsi muscle. Forty males and non-neutered sheep were kept in individual cages and fed under four different treatments: control treatment (concentrate and forage) and the other three treatments containing the concentrate and forage plus 4% oil (yellow grease, soybean and palm oils). After slaughter, samples of the longissimus dorsi muscle were collected. RNA extraction followed by Real Time PCR for five adipocytokine signaling genes. ANOVA was performed followed by the Dunnett's test (0.01). The normalized expressions of the ACLY gene were not significant between treatments to control, but for the ALDOC gene, all oil-supplemented treatments were significantly downregulated relative to the control treatment. The DUSP gene was not significantly expressed between the oil-supplemented treatments to control treatment. The ENPP1 gene was significantly upregulated with the addition of palm oil and yellow grease and the FASN gene was only significantly expressed in soybean oil-supplemented treatment to control treatment. It was concluded that the addition of different oils in the sheep diet regulated the expression of most genes for up or down, which can influence the metabolic pathways responsible for the fatty acid biosynthesis in the sheep longissimus dorsi muscle.

The economic feasibility of microalga to produce commercial biodiesel and reduce carbon dioxide emissions in Malaysia

Malaysia signed the Paris Agreement and agreed to lower its greenhouse gas (GHG) emissions by finding sustainable, renewable energy sources. One potential candidate is biodiesel made from the microalga, Chlorella vulgaris. Accordingly, this paper examines the economic feasibility of Malaysian agriculture to supply algal biodiesel and mitigate GHG emissions in Malaysia. The Malaysian Agriculture and Plantation Greenhouse Gas Model are employed for this purpose. The model contains the major agricultural commodities of Malaysia and forecasts market prices and quantities between 2024 and 2064. The simulation results indicate that the algal farms must sell algal biodiesel for a minimum price of USD0.66 per liter. The Malaysian government would pay a subsidy of USD0.14 per liter. The algal farms could supply 227.72 million liters in 2024 which grows to 277.37 million liters by 2064. The algal farms also dry the leftover slurry and sell it to the animal feed markets. The dried slurry contains protein and would help Malaysia reduce animal feed imports. Furthermore, Malaysia also produces biodiesel from palm oil and yellow grease. The algal, palm, and yellow grease biodiesel could reduce diesel tailpipe emissions by 0.11 million metric tonnes in 2024, which grows to 0.25 million tonnes by 2064. In addition, alga consumes the flue gas from coal and electric power plants and further reduces CO2 emissions by 1.06 million tonnes in 2024, which grows to 1.29 million tonnes in 2064. At last, an expanding biodiesel industry raises agricultural prices slightly and boosts agricultural employment.

Yellow and brown grease—characteristics of compression-ignition engine

This papers presents the results of analysis done on a compression-ignition engine supplied with methyl ester of rapeseed oil (Yellow Grease), methyl ester of goose fat (Brown Grease) and pure diesel. The analysis included the engine characteristics, emissions and fuel consumption. Results also include chromatographic analysis for all of the three fuels. Additional evaluation was done on a vehicle idling and under load.

Feasibility of Using Tabagwang Waste Shells as Catalyst in the Production of Biodiesel from Yellow Grease

Heterogeneous catalytic transesterification of yellow grease, commonly known as used cooking oil, utilizing the calcium oxide derived from waste shells of Jagora asperata, locally known as tabagwang, was carried out to produce biodiesel. Waste tabagwang shells were prepared and calcined at 900°C for 4 hours under static air to obtain CaO. The prepared CaO was used as a catalyst in the transesterification of used cooking oil. Reaction conditions such as temperature (45°C and 60°C), catalyst loading (2% and 10%), and methanol-to-oil molar ratio (6:1 and 9:1) were considered to evaluate the feasibility of the catalyst in terms of percent yield. For the given set of parameters, the largest yield of 4.85 mL biodiesel, corresponding to 9.70%, was obtained at temperature of 45°C, catalyst loading of 2%, and methanol-to-oil ratio of 9:1. Using a two-level factorial design, an optimum yield of 10.06% was calculated with the following conditions: temperature, 47.06°C; catalyst loading, 2.03%; methanol-to-oil molar ratio, 8.93:1.

The Research on Characteristics of CI Engine Supplied with Biodiesels from Brown and Yellow Grease

The effect of three kinds of fuels used to supply a diesel engine on its characteristics, fuel consumption, and emissions was studied. The fuels comprised pure diesel, a blend of diesel with 6% of methyl ester of yellow grease in the form of rapeseed oil, and a blend of diesel with methyl ester of brown grease in the form of goose fat. The chromatographic analysis was conducted for these fuels, and the results are presented. Two tests, comprising measurement of fuel consumption and engine emissions, were conducted on a vehicle with a diesel engine operating under zero load and under full load. The engine’s characteristics, including both power and torque versus speed, were determined under full engine load. The results of these tests are presented in this paper. The results indicated that the use of different methyl ester-based biodiesel blends with the same content of diesel to supply the diesel engine resulted in different fuel consumption and emissions of the engine not only in comparison to the supply of pure diesel but between biodiesels analyzed.

Highly efficient tantalum-zirconium oxide catalysts for biodiesel production from higher water and FFA containing soybean oil or yellowgrease feedstocks

Mesoporous tantalum-zirconium oxide (TZ) solid acid catalysts were synthesized by sol-gel method and employed in the biodiesel production from higher water (2.0 and 4.0 wt%) and palmitic acid (20.0 wt%) added soybean oil (SBO) or yellow grease feedstocks. Characterization of TZ catalysts were done by using BET-surface area, XRD, Raman spectroscopy, XPS and NH3-TPD techniques. Only 35.0% methyl palmitate and 14.0% SBO fatty acid methyl ester (FAME) yield was obtained on bare ZrO2 at 180 °C. Addition of tantalum to ZrO2 significantly improved the yield of methyl palmitate (95.0%) and SBO FAME (88.6%) at 180 °C. The greater ester yield on TZ catalysts was associated with improved acidity due to the presence of Ta–O–Ta, TaO and Zr–O–Ta species which readily interacted with methanol and triglycerides. Further, 20.0 mol.% tantalum loaded zirconium oxide catalyst (20TZ) exhibited consistent biodiesel yield upto two recycles of feed containing 2.0 wt% of added water and 20 wt% PA in SBO. It is noteworthy that, 80.0% yellow grease FAME formation was observed on 20TZ catalyst at 180 °C. The results emphasize, TZ solid acid catalysts are highly efficient compared to polyoxometalates and or sulphated zirconium oxide solid acid catalysts for biodiesel production from higher water and free fatty acid containing feedstocks.

Feeding value of supplemental fat as a partial replacement for steam-flaked corn in diets for Holstein calves during the early growing phase.

In calf-fed Holstein steers, the early growing phase is characterized by very high relative dry matter intake (DMI) accompanied with lower-than-expected efficiency of energy utilization. Although fat is commonly supplemented in growing–finishing diets, the comparative feeding value has not been investigated during the initial receiving–growing period. Eighty-four Holstein calves (127.7 ± 2.1 kg body weight) were used to evaluate the effects of including 3.5% of supplemental yellow grease (YG) in the diet on characteristics of growth performance and dietary energy utilization of calves during the early growth phase. Morbidity and mortality were not affected by dietary treatments. Yellow grease supplementation did not affect DMI, but tended to increase average daily gain (4.6%; P = 0.07), and increased (P ≤ 0.03) gain efficiency (5.8%) and dietary net energy for maintenance (NEm) and gain (NEg) by 4.1% and 5.3%, respectively. Based on performance data, the estimated NE value of supplemental YG was 4.67 and 3.68 Mcal/kg for NEm and NEg, respectively. These values are consistent with current tabular values assigned for vegetable oils (4.75 and 3.51 Mcal/kg), but markedly less (16.6%) than NEm value assigned for YG (5.60 Mcal NEm/kg; NASEM, 2016. Nutrient requirements of beef cattle. 8th ed. Washington (DC): National Academy Press.).

Intravenous-Accelerated Saline Particles to Unblock Partially Clogged Blood Vessels Using a Microcontroller

This research assesses the speed of saline fluid in vein vessels using venipuncture medical kit as well as DC submersive pumps that are being controlled by a microcontroller. The microcontroller is monitored and governed using a software IDE interface installed on a powerful laptop. Saline solution is being pumped through a medical syringe at variable speeds up to a maximum of 18.39 cm/second to the vein. The novel technique in this research is the usage of two pumps called Pump 1 and Pump 2. Pump 1 is used to physically model the flow of “blood” in human vein and the second pump (Pump 2) is used to generate the accelerated saline particles that are used to break the yellow grease that is placed on the inside of the vein’s wall. A tiny brush is briefly dipped into yellow grease, and then it is used to place one layer (one turn) of yellow grease on the inside of the vein’s wall, and then this procedure is repeated to place consecutive layers of yellow grease onto the inside of the wall of the vein vessel using a tiny brush. It was found that accelerated saline particles can in fact destroy fats that are built up inside the veins’ walls.

Techno-economic Analysis and Life-Cycle Analysis of Renewable Diesel Fuels Produced with Waste Feedstocks

Wet waste feedstocks represent an important category of resources that could be utilized to produce biofuels. Diversion of the wet waste resources from going through conventional waste management practices to utilization as feedstocks for energy production also benefits from avoided cost and pollutant emissions of waste management and disposal. This study investigates the economic and environmental implications of producing bioblendstocks for mixing controlled compression ignition engines from two waste-to-fuel pathways: hydroprocessed esters and fatty acids (HEFA) from yellow grease and swine manure hydrothermal liquefaction (HTL) followed by biocrude upgrading. Detailed process models were developed for both pathways, which informed the techno-economic analysis and life-cycle analysis. Conventional swine manure management practice was also modeled in detail as the business-as-usual scenario for the swine manure HTL pathway. The estimated minimum fuel selling prices were $1.22/gasoline liter equivalent (GLE) and $0.94/GLE for the yellow grease to HEFA and swine manure HTL pathways, respectively. The life-cycle greenhouse gas (GHG) emissions of the two pathways were 11.2 and −33.3 g of CO2e/MJ, respectively, for the yellow grease to HEFA and swine manure HTL pathways. The credits of avoided emissions from conventional swine manure management were the main reason for the negative GHG emissions of the swine manure HTL pathway. The marginal GHG emissions abatement costs were estimated to be $116–$270/tonne CO2e and $5–$103/tonne CO2e for the yellow grease HEFA and swine manure HTL pathways, respectively, for a diesel price ranging between $0.5/GLE and $0.9/GLE. Since the yellow grease HEFA pathway is already commercialized, it can benefit from the $200/tonne carbon credit in the California Low Carbon Fuel Standard market, which could help the yellow grease HEFA pathway to achieve near-zero marginal GHG emissions abatement cost.

Techno-economic analysis of catalytic hydrothermolysis pathway for jet fuel production

The aviation industry is moving towards increasing the use of renewable fuels to reduce its environmental impact and find alternative supply chains for aviation fuel. Analyzing the technical and economic viability of sustainable aviation fuel (SAF) conversion pathways provides critical understanding and new insight toward long-term sustainability and commercialization of SAF. This study reviews the catalytic hydrothermolysis (CH) pathway for sustainable aviation fuel production and conducted a detailed techno-economic analysis to determine the economic viability of SAF production from four selected feedstocks - carinata oil, soybean oil, yellow grease, and brown grease. Economic analyses were performed for ‘nth plant’ (mature technology) to assess process costs and sensitivity on minimum selling price (MSP) of SAF. Without incentives, the MSP of SAF produced from soybean oil, carinata oil, yellow grease, and brown grease are $1.50/L, $1.32/L, $1.19/L for and $1.00/L respectively. Regardless of feedstock, the MSP is shown to be more sensitive to the yield of SAF and feedstock cost, than to capital and supplementary costs. Based on the analysis, the CH process is a promising technology to convert renewable oils to SAF, however the projected MSP requires incentives to achieve parity with petroleum jet fuel.

Renewable Feedstocks Present New and Complex Opportunities

Renewable Feedstocks Present New and Complex Opportunities

Biofuel Options for Marine Applications: Technoeconomic and Life-Cycle Analyses.

This study performed technoeconomic and life-cycle analyses to assess the economic feasibility and emission benefits and tradeoffs of various biofuel production pathways as an alternative to conventional marine fuels. We analyzed production pathways for (1) Fischer-Tropsch diesel from biomass and cofeeding biomass with natural gas or coal, (2) renewable diesel via hydroprocessed esters and fatty acids from yellow grease and cofeeding yellow grease with heavy oil, and (3) bio-oil via fast pyrolysis of low-ash woody feedstock. We also developed a new version of the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) marine fuel module for the estimation of life-cycle greenhouse gas (GHG) and criteria air pollutant (CAP) emissions of conventional and biobased marine fuels. The alternative fuels considered have a minimum fuel selling price between 2.36 and 4.58 $/heavy fuel oil gallon equivalent (HFOGE), and all exhibit improved life-cycle GHG emissions compared to heavy fuel oil (HFO), with reductions ranging from 40 to 93%. The alternative fuels also exhibit reductions in sulfur oxides and particulate matter emissions. Additionally, when compared with marine gas oil and liquified natural gas, they perform favorably across most emission categories except for cases where carbon and sulfur emissions are increased by the cofed fossil feedstocks. The pyrolysis bio-oil offers the most promising marginal CO2 abatement cost at less than $100/tonne CO2e for HFO prices >$1.09/HFOGE followed by Fischer-Tropsch diesel from biomass and natural gas pathways, which fall below $100/tonne CO2e for HFO prices >$2.25/HFOGE. Pathways that cofeed fossil feedstocks with biomass do not perform as well for marginal CO2 abatement cost, particularly at low HFO prices. This study indicates that biofuels could be a cost-effective means of reducing GHG, sulfur oxide, and particulate matter emissions from the maritime shipping industry and that cofeeding biomass with natural gas could be a practical approach to smooth a transition to biofuels by reducing alternative fuel costs while still lowering GHG emissions, although marginal CO2 abatement costs are less favorable for the fossil cofeed pathways.

Correlating the cloud point of biodiesel with its fatty acid methyl ester composition: Multiple regression analyses and the weighted saturation factor (wSF)

Biodiesel is an alternative fuel that is typically composed of fatty acid methyl esters (FAME) from transesterification of fats or plant oils with methanol. When blended with conventional diesel fuels, biodiesel improves combustion quality and reduces harmful exhaust emissions. On the other hand, biodiesel has poor cold flow properties that can compromise its use during cold weather in moderate temperature climates. In the present study, nine mathematical models were proposed to calculate the cloud point (CP) of biodiesel based on the concentrations and melting properties of the FAME components. Experimental data were compiled for four biodiesel fuels made from canola, palm and soybean oils and yellow grease (CaME, PME, SME and YGME) plus 24 binary admixtures of these fuels. Four models were inferred from multiple regression analysis of CP as functions of Xi = (MPixi; MPi = melting point and xi = mole fraction of the FAME species). These models yielded high correlation coefficients (R2 ≥ 0.997) and low absolute average deviations (AAD) ≤ 0.60 K from analysis of calculated (CPcalc) versus measured data. The results helped to identify species that influenced the CP of FAME mixtures. Five additional models based on the weighted saturation factor (wSF) index as an independent variable for correlating the CP of biodiesel were inferred. The indices were calculated as weighted sums of Xi terms for species present in the FAME mixtures. Both an arbitrarily assigned weight factor (wi) and the MPi of the pure FAME species were used to calculate the wSF indices. The wSF index-based models were developed from regression analysis of FA profile and experimental CP data for the 28 FAME mixtures. Four models yielded R2 = 0.968–0.977 and AAD ≤ 0.73 from analysis of CPcalcversus measured CP data.

Yellow grease in sheep diets: intake and digestibility

ABSTRACT This study aimed to assess the effects of yellow grease supplementation on the intake, digestibility, and nitrogen balance in sheep. Twenty Santa Inês lambs with a mean age of 95 ± 10 d and body weight of 19.29 ± 3.17kg were evaluated in a completely randomized design. The diets were supplemented with oil at concentrations of 0, 20, 40, 60, and 80 gkg-1 of dry matter (DM) of the concentrate. The diets were based on roughage and concentrate (50:50). The experimental period lasted 19 d and included 14 adaptation days and five collection days for the total supplied diet, orts, feces, and urine. Supplementation with yellow grease had no significant effect on the intake of DM, crude protein (CP), neutral detergent fiber (NDF), or non-fiber carbohydrates (NFC). However, the ether extract (EE) intake increased linearly with supplementation of yellow grease. Moreover, no effect was observed for DM, CP, NDF, and NFC digestibility and nitrogen balance. EE digestibility increased linearly with the yellow grease dietary supplementation. Thus, sheep dietary supplementation with yellow grease may be used at a level of up to 80 gkg-1 of DM of concentrate without impairing nutrient intake and digestibility.