Effect of diet on animal performance, lipid composition of subcutaneous adipose and liver tissue of beef cattle

Two trials were carried out with Brahman beef cattle to study animal performance and carcass characteristics as well as fatty acid composition of subcutaneous adipose and hepatic tissue, as influence by length of grain feeding period or a pasturing regimen. In trial 1, steers were allotted to three feedlot finishing periods (76, 104 and 146 days) after being backgrounded on pasture. Steers fed 76 days had greater average daily gains (P < 0·05) than steers fed 146 and 104 days, respectively. Carcasses of steers slaughtered after 146 days on feed had higher (P < 0·05) marbling scores, quality grades, fat over ribeye, quality yield and per cent kidney, pelvic and heart (KPH) fat than steers fed for 104 and 76 days. The proprortions of certain fatty acid of subcutaneous fat and liver tissue were influenced by the length of grain feeding. There was a marked increased in the proportion of oleic acid in both tissues as the steers remained longer in the feedlot and a higher percentage of total saturated fatty acids at 76 days than at the other two times. Quantitative separation of hepatic lipid classes by the Iatroscan revealed that phosphatidylcholine and phosphatidylethanolamine were the main components of the phospholipids. Presents as minor components were cardiolipin and sphingomyelin. No differences (P > 0.·05) in these individual subclasses of liver lipids or in triglycerides were observed between the feedlot groups. Liver polyunsaturated fatty acids (PUFA) were higher (P < 0·001) at 104 than 76 days. In trial 2, steers fed a concentrate diet gained faster (P < 0·05) than the pasture group after 138 days. Marbling scores, yield grade, quality grade, fat over ribeye and per cent KPH were higher (P < 0·01) for the concentrate group while fat color scores were higher (P < 0·01) for the pasture group. Liver fatty acid analysis of summed ω6 PUFAs of triglyceride, phosphatidylcholine, phosphatidylethanolamine were higher for the feedlot than the pasture group. Linoleic acid was higher (P < 0·05) in the TG and PC liver subclass of the feedlot animals while higher (P < 0·05) linolenic acid occurred in the pasture group.     

Influences of anatomical location and muscle quality on porcine lipid composition

Carcasses of sixty Lacombe and Lacombe cross swine fed the same high concentrate ration were selected to equally represent three muscle quality groups (pale soft exudative (PSE), normal and dark firm dry (DFD)). These carcasses were utilised to supply back and belly fat samples for the evaluation of the influences of muscle quality and anatomical location on fatty acid composition. Back fat samples had lower percentages of palmitic (C16:0) and stearic (C18:0) acids, long (≥ C18), and short (≤ C16) chain saturated fatty acids and total saturated fatty acids and higher percentages of oleic (C18:1) and linoleic (C18:2) acids, polyunsaturated fatty acids and total unsaturated fatty acids than belly fat samples. They also had a higher unsaturated fatty acid to saturated fatty acid ratio than belly fat samples. Carcasses with DFD hams and loins had lower percentages of palmitoleic (C16:1) and linoleic (C18:2) acids and polyunsaturated fatty acids in their back fat than those with PSE hams and loins. They also had higher (P < 0·05) percentages of myristic (C14: 0) and stearic (C18:0) acids and long chain saturated fatty acids (≥ C18) and lower percentages (P < 0·05) of palmitic (C16:0) and palmitoleic (C16:1) acids in their back fat than carcasses with normal hams and loins. Moreover, they had lower (P < 0·05) percentages of palmitoleic (C16:1) and linoleic (C18:2) acids and poly-unsaturated fatty acids in their belly fat than carcasses with normal and PSE hams and loins. The fact that the lipid composition of carcasses differed significantly among muscle quality groups is of considerable importance, since it implies that factors (stress) producing differences in muscle quality may also significantly influence the fatty acid composition-and thereby the physical properties of carcass lipids.     

Effect of castration and cryptorchidism on fatty acid content of ovine adipose tissue

Fatty acid analyses of perinephric and subcutaneous adipose tissue were made on 50 of Mehraban and Bakhriari breeds lambs to determine the effect of castration and cryptorchidism on ovine lipid composition. The level of stearic acid was significantly higher (p < 0·05) in cryptorchids than in wethers. Rams were also higher (p < 0·05) in the percentage of linoleic acid of the internal adipose tissue than wethers. The percentage of palmitic acid of subcutaneous tissue was higher (p < 0·05) in cryptorchid than rams. There was a tendency toward less saturated (palmitic and stearic) acids, but more unsaturated (oleic and linoleic) acids in rams than in wethers. The perinephric fat was more saturated than subcutaneous fat.     

Fatty acids in the subcutaneous adipose tissue of intensively fed SA Mutton Merino and Dorper wethers

Recent ambiguity about the role of animal fat in causing coronary heart disease, coupled with the controversy regarding the effect of various levels of energy nutrition on ruminant depot fats, prompted an investigation into the influence of high-energy nutrition, breed and slaughter weight on the fatty acid profiles of ruminants. Two isonitrogenous and isomineral diets containing 11·76 MJ ME/kg DM and 10·18 MJ ME/kg DM were fed to Dorper and SA Mutton Merino wethers of ± 20 kg to 37 and 43 kg live weight. Subcutaneous fat samples and feed samples were collected for fatty acid analysis. Treatment significantly affected the subcutaneous fatty acid profiles of wethers, which includes C15:0, C16:0, C17:0, C17:1, C18:0, C18:1, C18:2 and C18:3. Treatment also influenced the concentration of saturated and unsaturated fatty acids in the subcutaneous adipose tissue as well as the concentration of trans-fatty acids. The results obtained suggest that dietary energy levels may significantly affect the fatty acids in the subcutaneous fat of wethers. Breed differences, after correcting for carcass fatness, occurred in C16:0.     

Fatty acid composition of lipid in Longissimus dorsi muscle of Duroc and British Landrace pigs and its relationship with eating quality

The fatty acid composition of intramuscular fat from Duroc and halothane negative British Landrace pigs was determined and the relationships between fatty acid concentrations and aspects of eating quality were estimated from data on 160 pigs. Boars and gilts from each breed were performance tested on ad libitum or restricted feeding regimes with an average slaughter weight of 80 kg. Eating quality was assessed by ten experienced taste panelists.

Intramuscular fat of Duroc pigs had higher concentrations of saturated and mono-unsaturated fatty acids and lower concentrations of poly-unsaturated fatty acids than Landrace pigs. With increasing intramuscular fat content, concentrations of saturated and mono-unsaturated fatty acids increased and concentrations of poly-unsaturated fatty acids decreased and the rate of change in fatty acid concentrations was greater in Landrace pigs than in Duroc pigs.

Eating quality traits were generally improved as the concentration of mono-unsaturated fatty acids increased and poly-unsaturated fatty acids decreased.     

Cow colostrum and early milk enriched with eicosapentaenoic and docosahexaenoic fatty acid

The objective of the study was to explore whether it is possible to alter cow colostrum and early milk fatty acid composition with a low level of fat supplement, high in docosahexaenoic (DHA) and eicosapentaenoic (EPA) fatty acid. Diets included a control diet and a diet supplemented with DHA- and EPA-enriched fat supplement. Addition of fat supplement significantly decreased saturated fatty acids, C14:0 and C16:0 and increased the values of monounsaturated fatty acids, polyunsaturated fatty acids (PUFA), n3 fatty acids, EPA, DHA, C18:1n9cis and C18:1n11trans. The percentage of short-chain fatty acids significantly increased with the progress of lactation, while the percentage of PUFA, n3 and n6 significantly decreased. These results showed that fat supplement, high in DHA and EPA, modified the fatty acid profile of colostrum and milk fat and increased the proportion of beneficial fatty acids for human health.     

Effect of Muscle Condition Before Freezing and Simulated Chemical Changes During Frozen Storage on the pH and Colour of Beef

The effect of rigor temperature (RT, 35 versus 10°C), increased ionic concentration (MS, 0 versus 0·2% mixed salts), oxidized lipids (OL, 0 versus 1% added oxidized fat), increased free amino acids (FAA, 0 versus 0·3% added mixture of amino acids), fat content (FC, 0 versus 15% added fat) and excluding atmospheric gases (V, 0 versus 99·9% vacuum) on pH and colour of mince stored for one month at -20°C was studied using a complete 2(6) factorial design. Adding FAA increased the meat pH measured after storage (p<0·001). Meat lightness (Hunter L* value) was increased by increased fat content (p<0·001), higher rigor temperature (p<0·001) and oxidized lipids (p<0·05). Vacuum packing tended to preserve redness (Hunter a*) whereas the higher rigor temperature decreased redness (p<0·001). Vacuum packing (p<0·05) and increased fat content (p<0·001) increased yellowness (Hunter b*). The hue angle was lowered by increased salt concentration (p<0·01), increased free amino acids (p<0·01) and using vacuum packing (p<0·001), whereas it was raised (p<0·001) by increased fat content and higher rigor temperature. Various significant two-and three-way interactions are tabulated and discussed.     

Evaluation method for firmness and stickiness of porcine perirenal fat

The firmness and stickiness of chilled porcine fat at 4°C were evaluated with an Instron compression tester and compared with fatty acid composition. Firmness of cylindrical adipose samples was measured at a force producing a 70% deformation. Firmness values were correlated with refractive index data (r=-0.67), melting point data (r=0.77), and saturated fatty acids concentration data (r=0.72) of the extracted lipid, and with sensory scores data (r=0.89). The firmness value correlated with the concentration of C18:0 (r=0.73). The stickiness of comminuted fat samples was evaluated with the Instron using a fixed load at a compression force of 20N and crosshead speed of 1.5mm/s. Single regression analyses showed that the stickiness parameters, stretch and adhesiveness correlated negatively with the concentration of the saturated fatty acids data (r=-0.64, -0.52) but positively and weakly with the monounsaturated fatty acids data (r=0.28, 0.34). Multiple regression analysis improved their relationships. These results indicate that mechanical evaluation may be used to predict porcine fat texture and saturated fatty acids concentration.     

Colour of bovine subcutaneous adipose tissue: A review of contributory factors, associations with carcass and meat quality and its potential utility in authentication of dietary history

The colour of bovine subcutaneous (sc) adipose tissue (carcass fat) depends on the age, gender and breed of cattle. Diet is the most important extrinsic factor but its influence depends on the duration of feeding. Cattle produced under extensive grass-based production systems generally have carcass fat which is more yellow than their intensively-reared, concentrate-fed counterparts and this is caused by carotenoids from green forage. Although yellow carcass fat is negatively regarded in many countries, evidence suggests it may be associated with a healthier fatty acid profile and antioxidant content in beef, synonymous with grass feeding. Nonetheless, management strategies to reduce fat colour of grass-fed cattle are sought after. Current research suggests that yellow colour of this tissue is reduced if pasture-fed cattle are converted to a grain-based diet, which results in accretion of adipose tissue and dilution of carotenoids. Colour changes may depend on the initial yellow colour, the carotene and utilisable energy in the finishing diet, the duration of finishing, the amount of fat accumulated during finishing and the rate of utilisation of carotene from body fat. Differences in nutritional strategies which cause differences in fatty acid composition may be reflected by differences in fat colour and carotenoid concentration. Fat colour and carotenoids are prominent among a panoply of measurements which can aid the authentication of the dietary history and thus to some extent, the origin of beef, although this potential utility is complicated by the simultaneous rather than discrete use of forages and concentrates in real production systems.     

Fatty acid composition of the meat and fat of the one-humped camel (camelus dromedarius)

The fatty acid composition of lean raw meat taken from the hind leg of seven young (1-3 years of age) male one-humped camels (Camelus dromedarius) has been determined by capillary gas-liquid chromatography; fat samples taken from the hump of these seven camels were also analysed. The saturated fatty acids in the meat account for 51·5% of the total fatty acids, while the monosaturated and polyunsaturated chains constitute 29·9 and 18·6%, respectively. The major fatty acids in camel meat are palmitic (26·0%), oleic (18·9%) and linoleic (12·1%), with smaller amounts of other fatty acids, both normal and branched, that range in chain lengths from C(14) to C(22). The fatty acids of dromedary fat are dominated by saturated even-numbered chains with smaller amounts (5·4%) of odd-numbered normal and branched chains. The main fatty acid of the hump fat is palmitic (34·4%) followed by oleic (28·2%), myristic (10·3%) and stearic (10·0%).     

Organ weights, muscle composition and fatty acid profiles in lambs fed salbutamol: Effect of a 5-day withdrawal period

Lambs were fed ad libitum on a diet containing the β-adrenergic agonist salbutamol (2 ppm) for 38 days to investigate its effects on organ weights, muscle composition and fatty acid profiles. The influence of a 5-day withdrawal period was also assessed. The oral administration of salbutamol did not increase muscle weights and no differences were found in liver, heart and lung proportions. However, kidney weight was higher in the salbutamol-not-withdrawn animals. In treated animals fat and collagen levels decreased (P < 0.05), while protein increased (P < 0.05) in the semitendinosus (ST) muscle when compared to controls. However, no effects of the β-agonist treatment were found in the longissimus dorsi (LD) muscle. Intramuscular LD polyunsaturated fatty acids were higher (P < 0.05). Subcutaneous adipose tissue samples were higher (P < 0.05) in total unsaturated fatty acids and lower (P < 0.05) in total saturated fatty acids. All these changes in the fatty acid profiles of both intramuscular and adipose tissues were more marked after the 5-day salbutamol withdrawal period.     

Quantitative determination of saturated-, monounsaturated- and polyunsaturated fatty acids in pork adipose tissue with non-destructive Raman spectroscopy

The composition of dietary fat has received increased attention during the recent years because it influences human health. Seventy seven samples from pork adipose tissue and melted fat from the same tissue were measured with Raman spectroscopy. Gas chromatography analysis was conducted as reference. Iodine values (IV) ranged from 58.2 to 90.4 g iodine added per 100 g fat. Polyunsaturated fatty acids (PUFA) ranged from 7.8% to 31.7% and monounsaturated fatty acids (MUFA) from 35.2% to 51.5% of total fatty acids. When applied on pre-processed spectra of melted fat, partial least square regression (PLSR) with cross-validation gave a correlation coefficient (R) = 0.98, and root mean square error of cross-validation (RMSECV) = 1.4 for IV, using 3 PLS factors in the model. PUFA gave R = 0.98 and RMSECV = 1.0% of total fatty acids, using 5 PLS factors. MUFA were predicted with R = 0.96 and RMSECV = 1.0% of total fatty acids, using 9 PLS factors. On adipose tissue a model with 3 PLS factors gave R = 0.97 and RMSECV = 1.8 for IV. For PUFA, a model with 3 PLS factors gave R = 0.95 and RMSECV = 1.5% of total fatty acids. For MUFA a model with 6 PLS factors gave R = 0.91 and RMSECV = 1.5% of total fatty acids. The results indicate the feasibility to use Raman spectroscopy as a rapid and non-destructive method to determine IV, PUFA, MUFA and saturated fatty acids (SFA) measured directly on pork adipose tissue and in melted fat from the same tissue.     

Muscle glycogen level and meat quality in pigs of different halothane genotypes

The halothane genotype of 22 Polish landrace pigs was determined using halothane test and blood typing. Eight homozygous normal (NN), eight hetero-zygotes (Nn) and six homozygous recessive (nn) were identified. The levels of glycogen and lactate were measured in biopsy samples taken from the longissimus lumborum using a shot biopsy technique. pH (pH(1)) and IMP/ATP ratio (R) were determined at 30 min after slaughter, while pH, meat colour and water holding capacity were determined on the day after slaughter. The halothane genotype did not affect intra vitam glycogen level. The nn pigs had a higher R value and lower pH(1) than both Nn and NN animals. Heterozygous animals were intermediate between both homo-zygotes for biopsy lactate level and meat colour. The lactate content of biopsy samples was significantly correlated with pH(1) (r = -0·68; P < 0·01), R (r = 0·68; P < 0·01), meat colour (r = 0·57; P < 0·01) and water holding capacity (r = 0·45; P · 0·05).     

Determination of C22:5 and C22:6 marine fatty acids in pork fat with Fourier transform mid-infrared spectroscopy

Fatty acids in samples (n=74) of pork adipose tissue were measured with a Fourier transform mid-infrared (FT-MIR) spectrometer and by gas chromatography. The measured absorption spectra provided information to estimate partial least squares regression models for fatty acid groups, the iodine value and several fatty acids. The iodine values were predicted with correlation coefficient R=0.996 and root mean square error of cross-validation RMSECV=0.658. The sum of the two marine fatty acids of main interest, C22:5n3+C22:6n3, were predicted with R=0.982 and RMSECV=0.062. The K nearest neighbours procedure successfully classified the samples in three classes, depending on their proportions of marine fatty acids. Application of fat and absorption measurements were rapid, requiring less than 5 min of labour per sample. The results reported in this paper demonstrate that FT-MIR measurements can serve as a rapid method to determine marine fatty acids in pork fat.     

The fatty acid composition and intramolecular structure of triglycerides derived from different sites in the body of the sheep

Triglycerides were isolated from a number of different tissues obtained from six adult sheep; the tissues including internal fat depots (perinephric and mesenteric), subcutaneous fat depots (rump and chest) and the subcutaneous region of the metatarsal part of the hind limbs and of the pinnae of the ears. The fatty acid composition of these triglycerides was determined by gas-liquid chromatography and the intramolecular distribution of the acids was studied using pancreatic lipase to remove selectively the fatty acids esterified to the primary alcoholic groups (1- and 3-positions) of the glycerol molecules. Unsaturated fatty acids of the trans configuration were estimated by infra-red absorption analysis. In confirmation of earlier, less detailed, studies it was found that the triglycerides of the internal tissues contained a much higher proportion of saturated fatty acids (particularly stearic acid) than did those of the external tissues. In the most exposed tissues (legs, ears) oleic acid accounted for as much as 60-70% of the total fatty acids present. Trans fatty acid (almost entirely C₁₈ mono-unsaturated) was, like stearic acid, found in greatest concentration in the internal tissue triglycerides. Regardless of their location in the body all the triglycerides examined showed a similar pattern of intramolecular distribution of their major component acids; saturated acids (palmitic acid and stearic acid) were for the most part esterified in the 1- and 3-positions, and oleic acid was found predominantly esterified in the 2-position. Trans unsaturated acid, when present, showed a similar degree of preferential esterification in the 1- and 3-positions to that observed for stearic acid. It was tentatively concluded that long-chain fatty acids absorbed from the intestine influence primarily the composition of the triglycerides of internal adipose tissue.     

The effect of transport on some metabolic parameters and meat quality in pigs

Two groups of 40 castrated male pigs were selected at random in an abattoir from pigs arriving from two farms, situated 650 km (group A) and 180 km (group B) from the plant, respectively. The animals were kept in lairage overnight and slaughtered the following morning. At slaughter, samples of blood were collected to determine serum levels of some enzymes [lactic dehydrogenase (LDH), glutamic oxaloacetic transaminase (GOT) and glutamic phosphatase transaminase (GPT)]. Measurements of pH were then taken on the Longissimus thoracis at the level of the last rib 45 min, 3 h and 24 h post mortem. After overnight chilling of the sides at +2°C, a portion of the Longissimus thoracis was removed for colour and drip measurements. Results show that distance travelled affects pH values at 45 min and 24 h, group A presenting higher values than group B (P < 0·001). Drip loss did not differ significantly between the two groups, while group A showed lower values of L (?) and higher a (?) values than group B (P < 0·05 and P < 0·01, respectively), with no differences in the mean values of b (?). In group A, a higher value of LDH was observed (P < 0·001) than in group B. GOT and GPT showed no significant difference between the two groups. It is concluded that, although some significant effects of treatment were recorded on some quality traits, the magnitude of the differences are not considered of much practical significance.     

Prediction of the fatty acid composition of beef by near infrared transmittance spectroscopy

The intramuscular fat content and composition influence consumer selection of meat products. A study predicting the fatty acid (FA) profile of ground beef from the Longissimus thoracis of yearling bulls (n=100) using near infrared transmittance spectroscopy (NIT) was conducted. The samples were scanned using an Infratec 1265 Meat Analyzer which operates in transmittance mode from 850 to 1050nm. NIT technology was able to accurately predict (R(CV)(2) over 0.76) some prominent FAs such as C14:0, C16:0, C16:1cis9, C17:0, C18:1cis9 and C18:1cis11, and minor FAs like C13:0, C15:0, C17:1cis9 and C18:1cis13. When studying FA groups, NIT spectra were able to accurately predict saturated (R(CV)(2)=0.837), branched (R(CV)(2)=0.701) and monounsaturated (R(CV)(2)=0.852) FAs. In addition, NIT spectra provided useful information on the contents of conjugated linoleic acids (CLA) in beef. These results show the potential of NIT technique as a rapid and easy tool to predict the major FAs in beef, especially those located in triglycerides.     

Intramuscular fat and muscle fibre lipid contents in halothane-gene-free pigs fed high or low protein diets and its relation to meat quality

Immediately after exsanguination, samples were taken from M. longissimus dorsi (LD) and M. biceps fermorsi (BF) of halothane-gene-free Swedish Yorkshire pigs (entire males and gilts) fed a high-protein (18·5% crude protein, 0·96% lysine; n = 20) or a low-protein diet (13·1% crude protein, 0·64% lysine; n = 20). The lipid content, measured as triglyceride (TG), was analysed after the samples had been freeze-dried and dissected free from blood, fat and connective tissue. Fibre type composition (type I, IIA, IIB, IIC) was analysed by histochemical staining on all samples. In 14 samples of LD, representing the entire variation of the intramuscular fat content (IMF) among the 40 animals, fibre areas, lipid content and oxidative capacity within the fibre types were evaluated. IMF, meat colour and drip loss were measured in both muscles. Shear force was measured on cooked meat samples from LD. IMF was higher in both LD (2·5%) and BF (2·0%) from pigs on the low-protein diet compared with LD (1·5%) and BF (1·3%) from pigs on the high-protein diet. TG content did not differ between diets in BF but was higher in LD from pigs on low- vis-à-vis high protein diet. A significant correlation was seen in LD between IMF and TG content (r = 0·57; P < 0·001). Fibre type composition did not differ between pigs on the two diets. BF had a higher proportion of type I and IIA fibres and a lower proportion of IIB fibres, compared with LD. TG content in muscle was not correlated with fibre type composition or staining intensity for lipids and oxidative capacity. High staining intensity for lipid in LD was seen in all type I fibres and in some type IIA fibres. Meat quality parameters did not differ between groups except shear force, which was higher in pigs fed the high- vis-à-vis low-protein diet (4·7 and 4·0 kg/cm(2), respectively). Shear force was correlated significantly with TG content (r = -0·42; P < 0·01) and IMF (r = -0·43; P < 0·01) in LD. The results of this study show that lipids are stored mainly in type I fibres and in some type IIA fibres. Intracellular triglycerides account for only a small fraction of IMF. The results indicate that IMF and TG content in muscle fibres may be related to shear force.     

Ruminal fermentation characteristics and fatty acid profile of ruminal fluid and milk of dairy cows fed flaxseed hulls supplemented with monensin

Flaxseed hull, a co-product obtained from flax processing, is a rich source of n-3 fatty acids (FA) but there is little information on its value for dairy production. Monensin supplementation is known to modify biohydrogenation of FA by rumen microbes. Therefore, the main objective of the experiment was to determine the effect of feeding a combination of monensin and flaxseed hulls on ruminal fermentation characteristics and FA profile of ruminal fluid and milk. Four ruminally fistulated multiparous Holstein cows averaging 665 ± 21 kg body weight and 190 ± 5 d in milk were assigned to a 4×4 Latin square design (28-d experimental periods) with a 2×2 factorial arrangement of treatments. Treatments were: 1) control, neither flaxseed hulls nor monensin; 2) diet containing (dry matter basis) 19·8% flaxseed hulls; 3) diet with monensin (16 mg/kg dry matter); 4) diet containing 19·8% (dry matter basis) flaxseed hulls and 16 mg monensin/kg. Flaxseed hull supplementation decreased the acetate to propionate ratio in ruminal fluid and monensin had no effect. Concentrations of trans-18:1 isomers (trans9,trans11,trans13/14+6/8) and cis9,12,15-18:3 in ruminal fluid and milk fat were higher and those of cis9,12-18:2 in milk fat tended (P=0·07) to be higher for cows supplemented with flaxseed hulls than for cows fed no flaxseed hulls. Monensin had little effect on milk fatty acid profile. A combination of flaxseed hulls and monensin did not result in better milk fatty acid profile than when feeding only flaxseed hulls.     

Fibre‐optic method for estimation of bovine fat quality

Spectroscopy using remote surface, contact, insertion and transmission fibre‐optic probes and a sensor at wavelengths of 400 to 1100 nm was used for rapid estimation of the physio‐chemical characteristics of bovine fat. Surface reflectance of the adipose tissue was negatively correlated with the bovine fat colour score at many wavelengths and positively correlated with the contents of the polyunsaturated fatty acids at 400 to 650 nm (P < 0.05). Internal reflectance using an insertion probe at 445 to 1100 nm was positively correlated with melting point and negatively correlated with refractive index (P < 0.05). Internal reflectance using a contact probe tended to be related to saturated and monounsaturated fatty acid contents. Transmittance at almost all wavelengths was positively correlated with refractive index (P < 0.05). Internal reflectance of the intermuscular fat from 34 animals measured at a meat market was correlated (P < 0.01) with saturated fatty acid content (r = 0.72 at 650 nm) and with monounsaturated fatty acid content (r = ?0.69 at 650 nm). These results indicated the possibility of using fibre‐optic measurements, requiring 1 s in bovine adipose tissue, to evaluate the quality of depot fat and that the various types of probe can be used to evaluate different physiochemical characteristics of fat. Copyright © 2003 Society of Chemical Industry