Effects of Size and Stability of Native Fat Globules on the Formation of Milk Gel Induced by Rennet

Rennet‐induced gelation crucially impacts cheese structure. In this study, effects of the size and stability of native fat globules on the kinetics of rennet‐induced coagulation were revealed by determining the caseinomacropeptide release rate and rheological properties of milk. Moreover, the mobility and stability of fat globules during renneting was revealed using diffusing wave spectroscopy and confocal laser scanning microscopy. By use of a 2‐stage gravity separation combined centrifugation scheme, native fat globules were selectively separated into small (SFG, D_4,3 = 1.87 ± 0.02 μm) and large fat globules (LFG, D_4,3 = 5.65 ± 0.03 μm). The protein and fat content of SFG and LFG milk were then standardized to 3.2 g/100 mL and 1.2 g/100 mL, respectively. The milk containing different sized globules were then subjected to renneting experiments in the laboratory. Reduction of globule size accelerated the aggregation of casein micelles during renneting, giving a shorter gelation time and earlier 1/l^* change. The gel produced from LFG milk was broken due to coalescent fat globules and generated coarser gel strands compared to the finer strands formed with SFG milk. Structural differences were also confirmed with a higher final storage modulus of the curd made from SFG milk than that from the LFG. In conclusion, the size of fat globules affects the aggregation of casein micelles. Moreover, fat globule coalescence and creaming during renneting, also affects the structure of the rennet gel. A better understanding of the size of globules effect on milk gelation could lead to the development of cheese with specific properties.     

Differences in particle characteristics and oxidized flavor as affected by heat-related processes of milk powder

Understanding the formation of oxidized flavor will be highly useful in the improvement of milk powder quality. Effects of preheating, concentration and spray-drying on the particle characteristics and the oxidized flavor stability of milk powder were investigated. The surface composition and free radicals were analyzed using x-ray photoelectron spectroscopy and electron spin resonance spectrometry, respectively. The concentrations of selected oxidized volatiles hexanal and 2-heptanone were determined using solid-phase microextraction gas chromatography-mass spectrometry. Levels of hexanal and 2-heptanone in fresh milk powder were higher than those in raw milk and heated milk, which drastically increased with increasing time of storage. Differences in the morphological observations, free fat, and surface composition of fresh milk powder were found among different heat-related processes. During storage, a radical (g value, a characteristic constant whose value serves to identify any given free radical, was 2.0054) was detected in milk powder. The specific population of the radical increased from 2.99 × 10⁷ at 3 mo to 1.23 × 10⁸ at 6 mo of storage. Addition of ascorbic acid in milk powder changed the type of radicals and reduced the oxidation off-flavor. According to the Pearson correlations, not the surface compositions but the morphological characteristics of milk powder particles should be considered in maintaining the stability of oxidized flavor in storage.     

Development and application of confocal scanning laser microscopy methods for studying the distribution of fat and protein in selected dairy products.

Confocal scanning laser microscopy (CSLM) methods were developed to identify fat and protein in cheeses milk chocolate and milk powders. Various fluorescent probes were assessed for their ability to label fat or protein in selected food products in situ. Dual labelling of fat and protein was made possible by using mixtures of probes. Selected probes and probe mixtures were then used to study (a) structure development of Mozzarella cheese during manufacture and ripening, and (b)) the distribution of fat and protein in milk chocolate made with milk powders containing varying levels of free fat. Microstructural changes in the protein and fat phases of Mozzarella cheese were observed at each major step in processing. Aggregation of renneted micelles occurred during curd formation; this was followed by amalgamation of the para-casein into linear fibres during plasticization. Following storage, the protein phase of the Mozzarella became more continuous; entrapping and isolating fat globules. Chocolate made with a high free-fat spray-dried powder blend showed a homogeneous fat distribution, similar to that of chocolate made with roller-dried milk. Chocolate made with whole milk powder containing 10 g free fat/100 fat showed a non-homogeneous fat distribution with some fat occluded within milk protein particles. These differences in fat distribution were related to Casson yield value and Casson viscosity of the chocolates.     

Short communication: effect of production variables on the cis-9, trans-11 conjugated linoleic acid content of cows' milk

Although there have been numerous studies investigating effects of nutrition and individual variation on the concentration of cis-9, trans-11 conjugated linoleic acid (rumenic acid; RA) in milk, there is limited information on relationships among RA content of milk and production variables. The objective of the current analysis was to examine the effects of production variables on RA content and desaturase index of milk fat. A total of 430 samples were collected from cows fed a commercial total mixed ration in winter and grazing in summer. Across a >6-fold range in production variables, RA content of milk ranged from 1 to 32 mg/g of fatty acids and desaturase index ranged from 0.03 to 0.15. Days in milk, milk yield, milk fat content, and milk fat yield had minimal or no effect on RA content of milk fat or desaturase index (R² values all <0.08). Thus, whereas nutrition and individual variation are major factors affecting RA content and desaturase index of milk fat, these values are minimally affected by days in milk, milk yield, milk fat content, and milk fat yield. Differences in these parameters do not need to be considered, therefore, when designing management strategies to increase RA content of milk fat.     

Concentration of furfuryl alcohol in fluid milk,dried dairy ingredients,and cultured dairy products

Maillard reactions occur in dairy products during heat treatment. Furfuryl alcohol (FA) may be found in dairy products as a result of Maillard reactions. The recent posting in California Proposition 65 indicates that FA may be carcinogenic, and for this reason it is crucial to accurately measure FA concentrations in dairy products. The objective of this study was to identify an extraction and quantitation method for FA from dairy products and to determine FA concentrations in milk, dairy powders, and cultured dairy products. Solvent-assisted flavor extraction, solid-phase microextraction, stir bar sorptive extraction with gas chromatography-mass spectrometry and triple quadrupole mass spectrometry were compared for recovery of FA. Internal standards for the quantitation of FA (2-methyl-3-heptanone, furfuryl-d₅ alcohol, 2,5-dimethylphenol, 5-methyl-2-furfuryl alcohol, and 5-methyl furfural) were also compared. Subsequently, fluid milk [high temperature, short time (HTST) and ultrapasteurized], whey protein isolates (3 mo–4 yr), whey protein concentrates (3 mo–4 yr), whole milk powders (1 yr), high and low heat skim milk powders (SMP; 0–8 yr), milk protein isolates (3 mo–3 yr), milk protein concentrates (3 mo–3 yr), Cheddar cheese (mild, medium, sharp, and extra sharp), mozzarella cheese (whole and part skim), cottage cheese (nonfat, low fat, and full fat), sour cream (nonfat, low fat, and full fat), traditional yogurt (nonfat, low fat, and full fat), and Greek-style yogurt (nonfat; n = 139 products total) were evaluated. Furfuryl alcohol was extracted from products by headspace solid-phase microextraction followed by gas chromatography-triple quadrupole mass spectrometry using a ZB-5ms column (30 m × 0.25 mm × 0.25 µm; Phenomenex Inc., Torrance, CA). Furfuryl-d₅ alcohol was used as an internal standard. Each food was extracted in triplicate. Ultrapasteurized milks had higher levels of FA than HTST milks (122.3 vs. 7.350 µg/kg). Furfuryl alcohol concentrations ranged from 0.634 to 26.55 µg/kg in whey protein isolates, 2.251 to 56.19 µg/kg in whey protein concentrates, 11.99 to 121.9 µg/kg in milk protein isolates, and 8.312 to 49.71 µg/kg in milk protein concentrates, and concentrations increased with powder storage. High heat SMP had higher concentrations of FA than low heat SMP (11.8 vs. 1.36 µg/kg) and concentrations increased with storage time. Concentrations of FA in Cheddar and mozzarella cheese ranged from 2.361 to 110.5 µg/kg and were higher than FA concentrations in cottage cheese or sour cream (0.049–1.017 µg/kg). These results suggest that FA is present at higher levels in dairy products that have been subjected to higher temperatures or have been stored longer. Sour cream and cottage cheese had lower levels of FA. Compared with other studies on food products with reported levels of FA, such as coffee (200–400 µg/g), dairy products have very low levels of FA.     

Effect of homogenisation on detection of milk protein content based on NIR diffuse reflectance spectroscopy

Investigating the effect of homogenisation on the prediction performance of protein content by using near-infrared (NIR) spectroscopy is helpful to improve protein determination precision. For this purpose, the influence of homogenisation on milk fat globules and NIR spectra was analysed firstly. Then, NIR spectra of eighty-seven cow milk samples before and after homogenisation were obtained. Multiplicative scatter correction was used to do spectral pretreatment. Uninformative variable elimination based on partial least squares (UVE-PLS) and successive projection algorithm was used to extract characteristic variables. Partial least squares regression (PLSR) and least squares support vector machine models were established. The results showed that homogenisation made milk fat globules be distributed evenly, decreased the size of fat globules and improved NIR spectral repeatability and prediction precision on protein content. The best model was PLSR-UVE-PLS, having good and excellent protein prediction ability for un-homogenised milk (RMSEP = 0.06 g/100 g, RPD = 2.69) and homogenised milk (RMSEP = 0.04 g/100 g, RPD = 3.59), respectively.     

The Microstructure and Physicochemical Properties of Probiotic Buffalo Yoghurt During Fermentation and Storage: a Comparison with Bovine Yoghurt

The physicochemical and rheological properties of yoghurt made from unstandardised unhomogenised buffalo milk were investigated during fermentation and 28 days of storage and compared to the properties of yoghurt made from homogenised fortified bovine milk. A number of differences observed in the gel network can be linked to differences in milk composition. The microstructure of buffalo yoghurt, as assessed by confocal laser scanning microscopy (CLSM) and cryo scanning electron microscopy (cryo-SEM), was interrupted by large fat globules and featured more serum pores. These fat globules have a lower surface area and bind less protein than the homogenised fat globules in bovine milk. These microstructural differences likely lead to the higher syneresis observed for buffalo yoghurt with an increase from 17.4 % (w/w) to 19.7 % (w/w) in the weight of whey generated at days 1 and 28 of the storage. The higher concentration of total calcium in buffalo milk resulted in the release of more ionic calcium during fermentation. Gelation was also slower but the strength of the two gels was similar due to similar protein and total solids concentrations. Buffalo yoghurt was more viscous, less able to recover from deformation and less Newtonian than bovine yoghurt with a thixotropy of 3,035 Pa.s^?1 measured for buffalo yoghurt at the end of the storage, at least four times higher than the thixotropy of bovine yoghurt. While the titratable acidity, lactose consumption and changes in organic acid concentrations were similar, differences were recorded in the viability of probiotic bacteria with a lower viability of Lactobacillus acidophilus of 5.17 log (CFU/g) recorded for buffalo yoghurt at day 28 of the storage. Our results show that factors other than the total solids content and protein concentration of milk affect the structural properties of yoghurt. They also illustrate the physicochemical reasons why buffalo and bovine yoghurt are reported to have different sensory properties and provide insight into how compositional changes can be used to alter the microstructure and properties of dairy products.     

Size distribution of fat globules in goat milk

Milk from French-Alpine goats and Holstein cows was obtained from a bulk tank immediately prior to analyses. Fat globule size was determined by laser particle size analysis. Individual globules of fat in goat milk ranged from 0.73 to 8.58 microm in diameter. The average diameter of particles based on volume to surface area ratio (dvs) was 2.76 microm and was less than the mean (dvs) of 3.51 microm for bovine milk, in which fat globules ranged from 0.92 to 15.75 microm in diameter. The specific surface area of particles in caprine milk was 21,778 cm2/ml, whereas the specific surface area of particles in bovine milk was 17,117 cm2/ml. Ninety percent of the total particles found in goat milk were less than 5.21 microm in diameter, whereas 90% of the total particles in bovine milk were less than 6.42 microm based on the volume frequency distribution. Dissociation of casein micelles by urea in goat whole and skim milk caused larger dvs values due to the effect of fat particles and reduced the specific surface area in both milks because the total number of detectable particles in both whole and skim milk was reduced.     

Influence of enzymatic cross-linking on milk fat globules and emulsifying properties of milk proteins

The enzyme transglutaminase (TGase) can modify dairy protein functionality through cross-linking of proteins. This study examined the effects of TGase treatment on milk fat globules and the emulsifying properties of milk proteins. The extent of TGase-induced cross-linking of caseins increased with incubation time, with no differences between whole and skim milk. Extensive clustering of fat globules in extensively cross-linked raw whole milk occurred on homogenisation at 400 or 800 bar. Considerably less clustering of fat globules was observed when recombined milk (90 g fat L^–1) was prepared from TGase-treated skim milk and homogenised at 400 or 800 bar. TGase treatment did not affect fat globule size in cream, but prevented coalescence of fat globules therein, possibly through cross-linking of milk fat globule membrane components. TGase-induced cross-linking of milk proteins affected their emulsifying properties and may increase the stability of natural milk fat globules against coalescence.     

The nutritional ingredients and antioxidant activity of donkey milk and donkey milk powder

The aim of this work was to shed light on the nutritional ingredients and antioxidant activity of donkey milk and powder. It indicated that basic components of donkey milk were closed to human milk, especially lactose. The fat content of donkey milk was lower than that of cow milk and human milk. The essential amino acids, fatty acids and taurine in donkey milk and powder were richer. The whey protein content of donkey milk was 49.08 g/100 g. The ratio of casein to whey protein in donkey milk and powder was 70.3:100. The cholesterol of donkey milk was 8.6 mg/100 g. Therefore, donkey milk and powder are typical low-fat and low-cholesterol foods. The precious values of donkey milk and powder are suitable calcium and phosphorus proportion, and strongly resistant to oxidation. In conclusion, donkey milk and powder are good supplementary of cow milk and powder, would be better for infant dietary.     

Milk fat globule membrane proteins are involved in controlling the size of milk fat globules during conjugated linoleic acid–induced milk fat depression

Milk fat globule membrane (MFGM) proteins surround the triacylglycerol core comprising milk fat globules (MFG). We previously detected a decrease in the size of fat globules during conjugated linoleic acid (CLA)-induced milk fat depression (MFD), and other studies have reported that some MFGM proteins play a central role in regulating mammary cellular lipid droplet size. However, little is known about the relationship between MFD, MFG size, and MFGM proteins in bovine milk. The aim of this study was to investigate the profile of MFGM proteins during MFD induced by CLA. Sixteen mid-lactating Holstein cows (145 ± 24 d in milk) with similar body condition and parity were divided into control and CLA groups over a 10-d period. Cows were fed a basal diet (control, n = 8) or control plus 15 g/kg of dry matter (DM) CLA (n = 8) to induce MFD. Cow performance, milk composition, and MFG size were measured daily. On d 10, MFGM proteins were extracted and identified by quantitative proteomic analysis, and western blotting was used to verify a subset of the identified MFGM proteins. Compared with controls, supplemental CLA did not affect milk production, DM intake, or milk protein and lactose contents. However, CLA reduced milk fat content (3.73 g/100 mL vs. 2.47 g/100 mL) and the size parameters volume-related diameter D_[4,3] (3.72 μm vs. 3.35 μm) and surface area-related diameter D_[3,2] (3.13 μm vs. 2.80 μm), but increased specific surface area of MFG (1,905 m²/kg vs. 2,188 m²/kg). In total, 177 differentially expressed proteins were detected in milk from cows with CLA-induced MFD, 60 of which were upregulated and 117 downregulated. Correlation analysis showed that MFG size was negatively correlated with various proteins, including XDH and FABP3, and positively correlated with MFG-E8, RAB19, and APOA1. The results provide evidence for an important role of MFGM proteins in regulating MFG diameter, and they facilitate a mechanistic understanding of diet-induced MFD.     

Isolated Milk Fat Globules as Substrate for Lipoprotein Lipase: Study of Factors Relevant to Spontaneous Lipolysis in Milk

Fat globules isolated from normal and from spontaneous milk samples were compared as substrates for purified lipoprotein lipase. Only slight differences were observed. Fat globules isolated from fresh warm milk were almost resistant to lipolysis. This included globules from milk prone to spontaneous lipolysis. Cooling made the globules accessible to rapid lipolysis even if they were from normal milk. Rewarming the fat globules did not reverse the process. Maximum rate of lipolysis (after rewarming) required fat globules be stored at 10°C or below for 5 to 10 h. Lipolysis at 4°C usually started after a lag time of 3 to 5 h, but with fat globules from spontaneous milk the lag time was shorter. Fat globules isolated from cold milk were a poor substrate at 4°C but were lipolyzed when warmed. When ¹²⁵I-labeled lipase was added to fresh warm milk, some of the lipase bound to the milk fat globules but it caused little lipolysis. Binding increased after cooling, as did lipolysis. Both binding of lipase and lipolysis were impeded by the presence of skim milk. Another way to make fat globules isolated from fresh warm milk susceptible to lipolysis was to treat them with chemicals known to remove proteins.     

Preparation and properties of probiotic concentrated yoghurt (labneh) fortified with conjugated linoleic acid

Milk of high conjugated linoleic acid (CLA) level (1.25 g per 100 g milk fat) was produced by inclusion of fish oil and rousted soy bean in the ration of Holstein cows as compared to 0.55 g per 100 g milk fat in the milk of animals receiving control diet. Milk of normal (control) and high CLA content (treatment) was spray‐dried. Labneh was made from 20 g L^?1 reconstituted milk using 3 mL per 100 mL yoghurt starter and 2 mL per 100 mL of probiotic cultures of Lactobacillus casei or Lactobacillus acidophilus. The control (C) and high CLA (T) labneh were analysed chemically and microbiologically, and their viscosities were determined during cold storage for 15 days. The fat content of labneh of high CLA was less than that of the control, but the total solids (TS) were unaffected by the CLA level. Labneh made with Lb. acidophilus had lower TS and higher acidity, exopolysaccharides and acetaldehyde contents and viscosity than that made with the use of Lb. casei. Labneh from the different treatments retained high counts of the added probiotic (>10⁸ cfu g^?1) throughout the storage period. The storage period had significant effects on all parameters determined.     

The manufacture of miniature Cheddar-type cheeses from milks with different fat globule size distributions

A novel 2-stage gravity separation scheme was developed for fractionation of raw, whole bovine milk into fractions enriched in small (SFG) or large (LFG) fat globules. The volume mean diameter of fat globules in SFG, LFG or control (CTRL) milk was 3.45, 4.68 and 3.58 microm, respectively. The maximum in storage modulus (index of firmness) decreased with increasing fat globule size for rennet-induced gels formed from SFG, LFG or CTRL milks. Miniature (20 g) Cheddar cheeses were manufactured using each of the 3 milks. There were no significant (P > 0.05) differences in the pH, moisture and fat in dry matter levels between cheeses made using any of the 3 milks, however, the fat content of the cheese made using SFG milk was approximately 1% lower than that of cheese made using LFG or CTRL milk in each of the 2 trials. Image analysis of confocal scanning laser micrographs of the cheeses illustrated that the star volume of fat globules in the cheeses decreased significantly (P < or = 0.05) as the size of fat globules in the milks used for cheesemaking was reduced. This indicates that it is possible to manipulate the size distribution of fat globules in Cheddar cheese by adjusting the fat globule size distribution of the milk used for cheese-making. The concentration of free fatty acids (FFA) increased in all cheeses during ripening. At 120 d of ripening, the concentration of FFA varied significantly (P < or = 0.05 and P < or = 0.001 for trials 1 and 2, respectively) with fat globule size, with cheeses made in trial 2 from LFG, SFG or CTRL milks having total FFA levels of 3391, 2820 and 2612 mg/kg cheese, respectively.     

Physicochemical Properties of Milk Fat Emulsions Stabilized with Bovine Milk Fat Globule Membrane

Milk fat globules (MFG) were reconstituted with milk fat globule membrane (MFGM) and milk fat (MF). Viscosity of the reconstituted MFG was highest at pH 5.0 and 4 min emulsifying, and rose with an increase of MFGM between 40–80 mg/g fat. Adsorbed protein/unit fat increased at acid pH with increase of MFGM. The composition of proteins adsorbed on the surface of MFG was not influenced by factors of reconstitution. The size and specific surface area of globules were influenced by emulsifying time, MFGM and MF concentrations, and pH. The size range of MFG prepared by standard method was 0.9–17 μm in diameter. Median diameter was 5 μm and specific surface area was 15,600 cm²/cm³ of emulsion.     

GRINDING SPRAY-DRIED MILK POWDER NEAR the GLASS TRANSITION TEMPERATURE

The fine grinding of chocolate is typically accomplished on five‐roll mills. Chocolate manufacturers consider milk powder, a component of milk chocolate, difficult to grind. Spray‐dried milk powders comprise a glassy lactose matrix in which fat globules, air vacuoles and protein are entrapped. the glassy‐rubbery transition in commercial milk powders usually lies between 60–70C, depending on the moisture content. A mixture of 60% wt/wt commercial whole milk powder, T_g～ 60C, and 40% wt/wt cocoa butter was ground in a three‐roll refiner at temperatures of 40, 50, 60, 70 and 75C. Below T_g the particles exhibited brittle fracture, while above T_g plastic deformation was evident and particles became highly asymmetric. the amount of fat liberated from the lactose matrix, so‐called free fat, particle density, and mean particle size increased with grinding temperature. However, the Casson yield value and plastic viscosity of finished “white chocolate” coatings, manufactured to a constant free fat content, increased with grinding temperature, suggesting an influence of particle shape on flow behavior.     

Development of the milk fat microstructure during the manufacture and ripening of Emmental cheese observed by confocal laser scanning microscopy

Changes in the physico-chemical properties and microstructure of milk fat globules were investigated during the manufacture and ripening of Emmental cheese. The measurement of fat globule size and apparent zeta-potential showed that they were slightly affected during cheese milk preparation, i.e. storage of cheese milk overnight at 4 °C and pasteurisation. After rennet-induced coagulation and heating of curd grains, coalescence caused the formation of large fat globules (i.e.>10 μm). The structure of fat in Emmental cheese was characterised in situ using confocal laser scanning microscopy (CLSM). The rennet-induced coagulation lead to the formation of a continuous network of casein strands in which fat globules of various sizes were entrapped. Heating of curd grains induced the formation of fat globule aggregates. Pressing of the curd grains resulted in the greatest disruption of milk fat globules, their coalescence, the formation of non-globular fat (free fat) and the release of the milk fat globule membrane (MFGM) material. This study showed that milk fat exists in three main forms in ripened Emmental cheese: (i) small fat globules enveloped by the MFGM; (ii) aggregates of partially disrupted fat globules and (iii) free fat, resulting from the disruption of the MFGM and allowing free triacylglycerols to fill voids in the protein matrix. The curd grain junctions formed in Emmental cheese were also characterised using CLSM: they are compact structures, rich in protein and devoid of fat globules.     

Cholesterol and Antioxidant Vitamins in Fat Fraction of Whole and Skimmed Dairy Products

The skimming procedure is a common practice in dairy industry, and skimmed products contain less fat, less cholesterol and less fat-soluble vitamins than whole products. The aim of this research is to verify if something else happens during the skimming process to these compounds in milk and dairy products. Experimental milk and cream samples, ranging from 0.1 to 51.5 g fat/100 g, have been studied for beta carotene, alfa-tocopherol and cholesterol contents. The degree of antioxidant protection (DAP), useful to estimate the potential oxidative stability of fat in foods, has been calculated, combining these values. The same analytical protocol has been also applied to commercial products (fat content ranging from 0.1 to 85.0 g/100 g). As was expected, there is a good linear correlation between these compounds and fat content in experimental and in commercial samples; nevertheless, the composition of milk fat changes differently. During skimming process, in the residual fat matter, cholesterol concentration increases while antioxidant compound concentration decreases or remains unchanged. Moreover, in experimental and in commercial milk and dairy, the DAP values show that the residual cholesterol is more susceptible to oxidation in skimmed than in whole products. This aspect is particularly important from a safety point of view: actually, cholesterol oxide ingestion can be harmful and should be avoided even in a small amount.     

Microstructural properties of fat during the accelerated ripening of ultrafiltered-Feta cheese

A commercial pregastric lipase was used to accelerate lipolysis of Iranian ultrafiltered-Feta (UF-Feta) cheese. Scanning electron microscopy images showed that with an increase in lipase levels from 2.0 to 6.0 g 100 kg⁻¹ of retentate, disruption of fat globules increased significantly. On day 3 of ripening and enzyme level of 2.0 g 100 kg⁻¹ of retentate, individual fat globules and fat aggregates were clearly observed on the cheese samples. An increase in the lipase level or ripening period resulted in an increase in the rate of disappearance of fat globules. After 20 days of ripening, no apparent fat globules were observed and fewer fingerprints and voids of free fat were detected, compared to when no enzyme was used.     

Effects of vegetable fats versus lard in milk replacers on feed intake, digestibility, and growth in Finnish Ayrshire bull calves

The aim was to study whether vegetable fat mixtures could be used instead of lard [15.2% in dry matter (DM)] in milk replacers without impairing the performance of Finnish Ayrshire bull calves (n = 58). The growth performance of the calves was measured before and after weaning from 14 d to 6 mo of age. The following 3 fat sources in a milk replacer were studied: 1) a mixture of palm, coconut, and rapeseed oil, 2) palm and coconut oil, and 3) lard. The calves were bucket-fed 2 L of milk replacer 3 times per day. The milk replacer contained 116 g of DM/L, resulting in an average DM intake of 4.8 g of DM/kg of body weight^0.75 (BW^0.75) during the 8-wk trial, after which the calves were weaned. All the calves had free access to water, commercial starter, and grass silage before weaning. The weaned calves had free access to water and grass silage and were given 3 kg/d (air-dry basis) of a commercial concentrate mixture. The concentrate was replaced by barley when the bulls were 4.5 mo old. There were no significant differences between the diets in feed intake and apparent diet digestibility. The health and BW of the calves were similar during the study. The feed conversion rate (kg of DM intake/kg of gain) before weaning was significantly greater for the lard diet compared with the 2 vegetable fat mixtures. After weaning, the feed conversion rate was slightly lower for the diet that included the palm, coconut, and rapeseed oil mixture than for the diet that included palm and coconut oil mixture. The study showed that the 2 mixtures consisting solely of vegetable oils were effective dietary components, thus providing 2 alternative fat mixtures of milk replacers, for use instead of lard in formulating commercial calf milk replacers.