Fat-free Milk Research Articles

The Influence of Nonfat Dry Milk on the Sensory Properties, Viscosity, and Color of Lowfat Milks

Previous work demonstrated that an effective fat substitute for fat-free milk should make the color of the milk whiter, less green, and less blue. This change corresponds to the L, a, and b values of 81, −3.7, and 2.9, respectively, for milk with 2% added fat, based on L, a, and b values of 74, −6.7, and 1.1 for skim milk. The first candidate for a fat replacer was NDM. Addition of NDM (0 to 2% solids) did not impart the same sensory or color characteristics (L, a, and b values of 75.6, −6.5, and 1.9, respectively, for 2% NDM solids added to skim milk) as fat. However, the effect of addition of 2% NDM on the objective measure of viscosity was very similar to addition of 2% fat. Our results suggested that a fat substitute for fat-free milk needs to change the appearance attributes of the milk more than its tactile attributes and that addition of NDM alone is not an adequate fat substitute for use in skim milk.

The Influence of Fat on the Sensory Properties, Viscosity, and Color of Lowfat Milk

A sensory panel was trained to assess appearance, aroma, flavor, and textural attributes of milk containing various percentages of fat. The relative viscosity and color of the milk were also measured. Milk appearance had a profound effect on the perceived mouthfeel. There was a correlation of the L-value (whiteness), a-value (greenness), and b-value (blueness) for the milk with the perceived color and mouthfeel. As fat content was increased, the milk was whiter, less green, and less blue. Similarly, sensory scores for appearance and mouthfeel attributes increased as fat content increased from 0 to 2%. Panelists were given the samples under red lighting to mask the milk color. Under these conditions, the perceived mouth coating, residual mouth coating, and thickness of 2% fat milk were decreased from those of the same samples tested under normal light. Our results suggested that a fat substitute for fat-free milk needs to change the appearance more than the tactile attributes of the milk. A successful fat substitute should alter the color of fat-free milk such that the L-, a-, and b-values are approximately 81, –3.7, and 2.9, respectively, based on L-, a-, and b-values of 74, –6.7, and 1.1 for skim milk.

Níveis de progesterona em leite desnatado de vacas no período pós- parto e diagnóstico precoce de gestação

Foram avaliados os períodos pós-parto de vacas primíparas mestiças Gir x Caracu e Nelore x Caracu mantidas em regime extensivo de pastagem. Para a determinação dos níveis hormonais de progesterona, amostras de leite foram coletadas semanalmente até que os animais apresentassem o 1º estro perceptível, quando foram inseminadas artificialmente. Decorridos 21 dias da inseminação, amostras foram coletadas e dosadas para fazer o diagnóstico precoce de gestação. Os resultados mostraram início de ciclicidade ovariana com 9,89 semanas após o parto para vacas Gir x Caracu, com valores médios de progesterona de 0,28 nmol/l no dia do estro e 7,62 nmol/1 aos 21 dias após a inseminação. Para vacas Nelore x Caracu, o estro se deu com 12,08 semanas após o parto e com valores médios de progesterona de 0,46 nmol/l e 9.23 nmol/1 para o dia do estro e no 21º dia, respectivamente. Dez gestações de doze diagnosticadas no 21º dia foram confirmadas por palpação retal, tendo ocorrido um caso de mortalidade embrionária precoce. Outras três vacas foram inseminadas durante a fase luteínica. A eficiência na observação de estros foi de 52.94%, pois de 34 identificados pelos níveis hormonais, 18 foram percebidos visualmente. A variação entre os cruzamentos não alterou significativamente o nível de progesterona no dia do estro, tampouco no 21º dia após inseminação e também quanto ao período necessário ao reinício da atividade ovariana pós - parto.

Níveis de progesterona determinados por radioimunoensaio em plasma sangüíneo e leite desnatado de vacas da raça Gir (Bos indicus). Avaliações durante o ciclo estral. Diagnóstico precoce de gestação.

Foram estudados 17 ciclos estrais de 12 vacas da raça Gir, mantidas em regime extensivo de pastagens no Centro Intraunidade de Zootecnia e Indústrias Pecuárias "Fernando Costa", em Pirassununga, Estado de São Paulo. Para o estudo dos níveis de progesterona através de RIE, foram colhidas, 3 vezes por semana e aos 23 dias após a cobertura, amostras de leite e de plasma sangüíneo, totalizando, respectivamente, 137 e 138 amostras. Os resultados obtidos indicaram correlação entre amostras refrigeradas e congeladas de leite desnatado (r = 0,92), assim como entre leite desnatado e plasma sangüíneo (r = 0,63). Verificaramse, ainda, variações dos níveis de progesterona durante o ciclo estral, com baixos valores na fase folicular (inferiores a 1,49 nmol/l de leite desnatado) e picos de 15,60 a 21,30 nmol/l no plasma e 5,91 a 11,37 nmol/l, no leite desnatado durante a fase luteínica. Todos os resultados de prenhez e não prenhez, baseados na análise de progesterona, utilizando níveis discriminatórios de 9,54 nmol/l no plasma e 3,18 nmol/l no leite, foram confirmados por palpação retal. As falhas de detecção de cio foram da ordem de 17,2% (24 cios observados em 29 ocorridos)

Progesterone determinations and clinical examinations of reproductive organs in purebred and crossbred female Zebu cattle

Five experiments were undertaken to investigate variation in progesterone concentrations as related to the collection and handling of samples of milk and blood, to determine reference values for progesterone and to evaluate clinical findings in relation to progesterone data from pure- and crossbred Zebu cattle reared in the Peruvian tropics. Whole-milk progesterone concentrations obtained from 12 Holstein × Nellore pregnant cows at hourly intervals over a 24-h period were highest immediately after milking; this peak was followed by a sharp drop over the next 3 h. Milk-fat content from 28 Brown Swiss × Nellore pregnant cows increased from 2.4% before milking to 6.7% afterwards (P < 0.05), whereas progesterone concentrations in whole milk increased from 18.4 to 59.5 nmol/1 (P < 0.05). Progesterone concentrations in fat-free milk were stable, with the exception of the fore-milk sample, which was lower than subsequent samples collected during milking (P < 0.05). Blood samples collected from 23 purebred, pregnant Nellore cows, were divided into four aliquots, and plasma and serum were harvested periodically over the next 120 h of storage at +4°C, or in the shade at ambient air temperatures. The results indicate that blood samples can be stored unseparated at both temperatures studied for up to 3 h without severe loss of progesterone. Milk samples collected at different intervals during the luteal phase of the estrous cycle and during early and mid-pregnancy from crossbred cows showed no significant differences in progesterone concentrations between Days 9 to 13 of the cycle and Days 9 to 13 of gestation. Progesterone levels during advanced gestation were higher (P < 0.05). Out of 2,607 clinical examinations, the level of agreement between palpatory findings and progesterone determinations was 95.6 and 81.9% in diagnosing non-luteal and luteal structures, respectively. Significant differences in the level of agreement between palpators were found (P < 0.01). It is concluded that milk samples, preferably composite milk or strippings, must be consistently collected at the same stage of milking, and that centrifugation of blood samples should be done as soon as possible and not later than 3 h after collection.

Characterization of short luteal cycles in the early post-partum period and their relation to reproductive performance of dairy cows

The ovarian activity of primiparous and multiparous Israeli-Friesian dairy cows was monitored by progesterone (P 4) determination in fat-free milk twice weekly, beginning at calving and continuing until pregnancy was confirmed by palpation, but not later than 150 days post partum. The cows were observed for standing oestrus, thrice daily. Based on the distribution of progesterone concentrations concurrent with inseminations at behavioral oestrus resulting in conceptions or not, 0.5 ng/ml was taken as the dividing value between luteal and non-luteal origins of progesterone. Resumption of luteal activity occurred by 35 days post partum in 99% and 93% of the primiparous and multiparous cows, respectively. The rate of short luteal cycles (≤ 11 days) was about 54% in the first, 24% in the second and 20% in the third-fifth luteal cycles post partum. The duration of first luteal cycles was associated with post partum interval. Neither length nor maximum progesterone concentration of the cycle preceding insemination was associated with conception rate. The results indicate that short luteal cycles (≤ 11 days), whenever they occur, can be attributed to a functional corpus luteum and not to ovary malfunction.

Blood glucose and plasma insulin responses to fat-free milk and low-lactose fat-free milk in young type 1 diabetics.

The blood glucose and plasma insulin responses to test milk samples were studied in eight insulin-dependent diabetics. After an overnight fast, the subjects (aged 20-45 years) were given a breakfast containing two Weetabix biscuits (20 g carbohydrate) with 500 ml of either regular (S) fat-free milk (25 g lactose) or 500 ml of a new low-lactose (D) fat-free milk (3.75 g lactose and 4.25 g fructose). The regular morning insulin dose was omitted. Mean basal plasma glucose level was slightly higher before S milk (11.4 vs. 10.1 mmol/l). The peak increment in plasma glucose was higher in S milk (9.4 vs. 6.6 mmol/l). The rise was 83% above basal (S) vs. 65% (D). Although the final mean plasma glucose concentration was not significantly higher 3 h after S milk compared with D milk (17.9 vs. 14.3 mmol/l) the incremental area under the plasma glucose curve was much greater (p less than 0.001) with S milk than with D milk (1266 +/- 295 units vs. 909 +/- 242 units). No galactose was detectable in any sample and there was no difference in plasma beta-hydroxybutyrate levels. The results suggest that the low-lactose fat-free milk (D) may be suitable for diabetic diets and weight reducing diets due to the lower contribution of energy. The results suggest that fat-free milk does not exert a fast action on blood glucose concentration and therefore fat-free milk and especially low-lactose fat-free milk may also prove to be suitable for diabetic diets.

Postpartum ovarian activity, uterine involution and fertility in indigenous buffaloes at a selected village location in Sri Lanka

Reproductive events were monitored over a period of 30 months in a sample of 55 indigenous (Lanka) buffalo cows belonging to five farmers selected at random in a specific village in the dry zone low-country region of Sri Lanka. The animals were maintained under the existing traditional methods of extensive grazing management and low-intensity utilization for milk and draught power in a crop-livestock system. Annual calving rate was 87.2%, with 82.4% of all calvings occurring between December and March (peak calving season). Involution of the uterus, based on rectal palpation, was completed at an interval of (mean ± SD) 32.9 ± 8.2 days post-partum. The majority (70.8%) of first services postpartum were recorded between February and April. The interval from calving to first service was 57.3±49.2 days for 80 animals which calved during the peak calving season and 156.2 ± 95.6 days for eight animals calving outside the peak season (overall 66.4 ± 61.4 days, n = 88). The intervals to uterine involution and first service were correlated ( r=0.53, P < 0.01) and both were significantly influenced by month of calving, but not by age or parity of the cow. The interval from calving to palpation of the first corpus luteum was 52.3 ± 16.8 days, and to the first elevation of progesterone above 0.5 ng/ml of fat-free milk was 54.9 ± 17.9 days. Of the 36 cases where complete progesterone profiles and clinical data were available, first services were recorded in 27 (75%) before palpation of a corpus luteum or elevation of progesterone after calving, and conception to this service was confirmed in 24 (88.9%). Elevation of progesterone preceded first service in seven (19%); the resultant luteal phases were short in four and normal in three. Overall conception rate to first service was 77.7% and the number of services per conception was 1.29. The calving to conception intervals ranged from 23 to 502 days (mean 71.5 ± 66.2, mode 41–60, n = 82) and the calving intervals from 329 to 816 days (mean 384.9 ± 62.9, mode 351–370, n=79). These findings confirm that Lanka buffaloes are capable of maintaining high fertility under certain traditional systems of management. The major cause of long calving intervals was prolonged postpartum acyclicity, which occurred mainly in animals calving outside the peak calving season.

Fetal survival in the cow after pregnancy diagnosis by palpation per rectum

It is desirable to determine wheter a cow has failed to become pregnant as early as possible, preferably prior to 50 d after insemination. Although palpation per rectum has been the generally accepted method of pregnancy diagnosis in cattle, the procedure may be a significant iatrogenic cause of fetal attrition. In a study conducted at a North Florida dairy from January through June 1982, pregnancy was determined in 192 Holstein-Friesian cows by measuring low milk progesterone (P4) content on day of insemination (Day 0) and elevated P4 on Days 21 and 24. Pregnant cows were randomly assigned to a treatment and a control group. Cows in the treatment group (n = 85) were palpated per rectum twice between Days 42 and 46 after insemination. Cows in the control group (n = 107) were not palpated until both groups were palpated at Day 90. Palpation, done by two experienced clinicians, consisted of palpation of fetal fluid fluctuation, identification of the amniotic vesicle, and slipping of the chorioallantoic membranes. In both groups of cows fetal viability was monitored by milk P4 content. Last milk (5 to 15 ml) was collected from one front quarter on Days 0, 21, and 24 and twice weekly thereafter through Day 63. Milk was defatted by centrifugation and the fat-free milk progesterone content measured by a radioimmunoassay without extraction. The milk P4 test was 80.0% accurate in determining pregnancy in the palpated and nonpalpated cows. In the cows palpated on Days 42 to 46, pregnancy rates declined by 7.5% as determined by palpation at Day 90, or by 11.4% as determined by milk P4 content through Day 63 (both values P < 0.05). Cows that were not palpated on Days 42 to 46 showed a 1.9% increase or a 4.3% decline in pregnancy rates as determined by the same criteria. Before palpation, at Days 42 to 46, pregnancy rates were better in cows that were inseminated in winter (January to March) than in spring (April to June) (82.3% vs 61.6%; P < 0.05); P4 content was higher (winter > spring = 2.13 ng/ml vs 1.38 ng/ml; P < 0.05). First-lactation cows had higher P4 values on Days 21 and 24 than older cows (P < 0.01).

Blood glucose and plasma insulin responses to fat free milk and low-lactose fat free milk in healthy human volunteers.

The blood glucose and plasma insulin responses to test milk samples were studied in healthy normal volunteers. After an overnight fast the subjects were given 500 ml of either regular fat free milk (approximately 25 g lactose) or 500 ml of a new low-lactose fat free milk (3.75 g lactose and 4.25 g fructose). Blood glucose levels were not significantly altered after either milk sample, but plasma insulin responses were significantly elevated after milk consumption. The response was slightly but not significantly higher after regular fat-free milk than after the low-lactose fat free milk. The results suggest that fat free milk does not exert a fast effect on blood glucose concentration and therefore fat free milk and especially low-lactose fat free milk may prove to be suitable for diabetic diets.

A survey of reproductive performance in dairy herds. Characteristics of the patterns of progesterone concentrations in milk

ABSTRACTProgesterone concentrations were measured by radioimmunoassay in fat-free milk samples obtained three times weekly from calving until day 60 of pregnancy from over 700 cows in commercial dairy herds. Profiles of progesterone concentration during the ovulatory cycle and early pregnancy were also examined. In 94% of the animals cycling had commenced by 60 days post partum and a further 3% had shown some ovarian activity. In 34% of cows, the resumption of regular ovulatory activity was preceded by short periods of progesterone secretion which did not meet the criteria for a 'normal cycle’. Peaks of progesterone cross-reactivity (&gt;0·75 ng/1) were detected at the time of ovulation in proportionately 0·06 of all cycles. There was no relationship between the detection of oestrus and the length of the following progesterone cycle or the concentrations during that cycle. However, there was a tendency for the first progesterone cycle post partum to be more variable in length than later cycles (0·56 within the range 18 to 24 days compared with 0·70 of later cycles; P &lt; 0·001). Extension of the length of the luteal phase occurred in 58 second and later cycles (proportionately 0·141) following inseminations which did not result in calving. However, since the comparable figure for 1053 cycles where no insemination was given was 0·048, the overall figure for embryo mortality later than 24 days after insemination was estimated as 9·3%. Concentrations of progesterone in pregnant animals, compared to non-pregnant animals, and the distributions of luteal lengths between 8 and 21 days long following inseminations not resulting in calving could both be explained by early maternal recognition of pregnancy.

Blood glucose and serum insulin responses to breakfast including guar gum and cooked or uncooked milk in type 2 (non-insulin-dependent) diabetic patients.

The post-prandial blood glucose and serum insulin responses to test meals, each including 300 ml fat-free milk taken separately with the meal or premixed before cooking into the meal consisting of oatmeal porridge, were studied in 10 diet-treated Type 2 (non-insulin-dependent) diabetic subjects. The modifying effect of guar gum on the responses was also studied by supplementing both types of test meals with 5 g granulated guar gum taken at the beginning of the meal. The blood glucose response was higher after the meal which contained cooked milk than after the respective meal with milk taken separately. The guar gum supplementation attenuated the blood glucose response after the meals, but the effect was more pronounced after the meal containing cooked milk. Post-prandial serum insulin responses were similar after all test meals. The results suggest that cooking may facilitate the absorption of lactose from milk-containing foods, and that supplementation with guar gum may counteract this response.

The Effect of Time of Sampling in Relation to Time of Suckling on Milk Progesterone Levels in Beef Cows

Milk samples were collected directly from the teats of 20 pregnant Hereford × Friesian cows. Two samples were taken from each animal, one before and one immediately after suckling. Each sample was divided into two, one of which was spun to remove the fat. Progesterone, fat and protein levels were measured in the whole-milk samples and progesterone in the ‘fat-free’ samples. Progesterone and fat levels after suckling were significantly ( P < 0·001) higher than the levels before suckling. The mean values in whole milk for progesterone, fat and protein before and after suckling were 6·26 and 27·7 ng/ml, 0·68 and 7·32%, 3·24 and 3·00% respectively. Progesterone levels in the fat-free milk were 2·08 and 7·21 ng/ml before and after suckling respectively. It was concluded that time of milk sampling in relation to time of suckling was a critical factor in determining milk progesterone concentrations in beef suckler cows.

Human milk fibronectin: identification of fibronectin fragments by transfer of milk proteins from polyarcrylamide gels to nitrocellulose sheets

1. INTRODUCTION The term ‘Iibronectin’ describes a family of structural and immunologically related high-Mi, glycoproteins that are present in vertebrates in both the soluble and insoluble form. The soluble form has been observed in various biological fluids in- cluding plasma, cerebrospinal, amniotic and sin- ovial fluids, urine and seminal plasma [l-6]. The insoluble form is present in vertebrate tissue, intra- cellularly, and as an extracellular matrix compo- nent [7- 121. and the cream removed (fat-free milk). Aliquots were then respun at 90 000 X g for 30 min to remove casein (lactoserum). All samples were analyzed within 24 h after drawing. Rabbit monospecific and mouse monoclonal anti-human plasma fibronectin antibodies were prepared as in [2 1,221. Although little is known about the function of fibronectin in vivo, it has been shown to display many interesting features in vitro ([ 13-201 and ref- erences therein). The amount of Iibronectin ,pres- ent on the surface of transformed or neoplastic cells is generally greatly reduced with respect to their normal counterparts. Fibronectin promotes cell aggregation and cell substratum adhesivness, partially restores transformed tibroblasts to a more normal phenotype, promotes locomotion of certain types of cells and facilitates reticuloendothelial sys- tem clearance of particles. Here, we report that human milk contains fibro- nectin and other components of lower M, which are recognized by anti-Iibronectin antibodies. These lower

Milk prolactin is biologically active

Fat-free milk from cow and goat was chromatographed on Sephadex G-100 and the prolactin (PRL) activity of the fractions determined by radioimmunoassay (RIA). A single prolactin component was observed in 3 cow and 3 goat milk samples with a Vf/Vt ratio of approximately 0.5. Fractions in which PRL was detected by RIA and fractions on either side of the PRL peak were combined, dialyzed and freeze dried. The fractions were assayed for biological activity using the pseudopregnant rabbit mammary gland in organ culture; the degree of secretory response was evaluated histologically. Milk prolactin was biologically active. In the RIA cow milk PRL and one of 2 samples of goat milk PRL gave dose response curves parallel with the bovine PRL standard. In the bioassay the dose response curves for cow milk PRL and ovine PRL were parallel while goat milk PRL was parallel when the results were compared on a weight basis but not on the basis of prolactin content of the preparations assayed by RIA.

Cow milk fat interferes with prolactin radioimmunoassay

The concentration of prolactin (PRL) in fat-free cows milk was one-third that of whole milk while the values were similar for milk from the goat. A number of experiments were performed to determine if PRL was present in cow milk fat. The results indicate that cow milk fat introduces an artifact in the double antibody PRL RIA which overestimates the amount of prolactin in whole cow milk.

Milk progesterone measurement in dairy cows: Correlation with estrus and pregnancy determination

Progesterone levels in fore milk, determined by a highly specific radioimmunoassay, were compared for the assessment of estrus by a veteran herdsman and an experienced inseminator, in cows presented for insemination. In addition, an examination was made of the relative accuracy of using milk progesterone levels for the determination of pregnancy at 24, 40 and 44 days after insemination, as compared with rectal palpation at 45–50 days post-breeding. Fat-free fore milk progesterone levels were similar to jugular plasma levels at 24 days post-insemination and reached roughly 60% of the level of unextracted fore milk at this time. Accuracy of estrus diagnosis by herdsman, inseminator and milk progesterone level was 84%, 93% and 96%, respectively. For pregnancy diagnosis, milk progesterone determination in 85 cows showed 78% accuracy in predicting pregnancy and 100% accuracy in predicting non-pregnancy. At 40 days post-insemination false positives dropped to 10% and at 44 days only 7% of the cows were incorrectly diagnosed as pregnant. The false positives in this study were largely due to embryonic mortality as reflected by abnormal intervals of return to estrus. Two milk progesterone determinations, at 24 and either 40 or 44 days post-insemination ensure maximum reliability for early pregnancy diagnosis.

Untreated and formaldehyde treated skimmilk powder as a protein supplement for dairy cows

Twenty four high producing dairy cows were used in an experiment in which the value of fat free spray-dried milk powder, untreated or formaldehyde treated (0.4 g formaldehyde/100 g crude protein), was studied as a protein supplement in a protein deficient diet. The groups were: 1) Protein shortage group, 1) Untreated milk powder group and 3) Formaldehyde treated milk powder group. Rations were made for all groups from hay, grass silage, barley, oats and mineral and vitamin mixtures according to nutrient requirements excepting that of protein. In the rations of the protein shortage group 25 % of the DCP required for milk production was omitted. In the other groups this deficiency was filled with untreated or formaldehyde treated milk protein. The experiment lasted 15 weeks. The feed consumption and utilization, milk production and composition, and blood contents were determined. In eliminating the protein deficiency with fat free milk powder positive results were found in milk yields, the protein content of the milk and in the live weight of the cows. The differences in the utilization of untreated and formaldehyde treated milk powder were not significant. Only small amounts of formaldehyde (0.11 mg/kg milk), were found in the milk of the cows receiving formaldehyde treated protein. The values of the blood analyses remained within the normal ranges on all diets.

Utilization of untreated and formaldhyde treated skimmilk powder and skimmilk powder-barley pellets by ruminants

The utilization of spray-dried fat free milk powder in three different froms 1) untreated, 2) treated with formaldehyde (0.4 g formaldehyde/100 g crude protein) and 3) pelleted with barley meal (30 % milk powder and 70 % barley meal) was studied with three rumen-fistulated dairy cows according to a 3 x 3 Latin square. The effects of different treatments were investigated with respect to rumen fermentation, microbial determinations and milk and blood analyses. The basic feed in every diet consisted of hay, grass silage, barley, oats, mineral and vitamin mixtures. Feeding was according to nutrient requirement. In each diet 25 % of the DCP required for milk production was replaced with milk protein. The NH3 concentration in the rumen fluid was lowest on the pelleted diet followed by the formaldehyde treated and untreated skimmilk powder diets, the differences only being significant between the pelleted and untreated diets. The pH values were significantly higher on the pelleted diet than on the other diets. The VFA content of the rumen fluid was similar on the different diets. The total amount of rumen ciliates was highest on the untreated skimmilk powder diet and lowest on the pelleted diet. The quantity of bacteria was however lower on the untreated skimmilk powder diet than on the other diets. Bacteria constituted 72—88 % of the total microbe mass on the different diets. The total microbe mass consisted of the following percentages of rumen content on the different diets: untreated 3.3 %, formaldehyde treated 3.2 % and pelleted diet 2,9 %. No effects on the milk yields and blood contents were found with the different treatments of skimmilk powder. Milk protein-% was significantly higher on the untreated skimmilk powder diet than on the pelleted diet.

In vivoinhibition by specific lipids of ethanol production from glucose by the yeastTorulopsis glabrata

SUMMARYThe production of toxic levels of ethanol in the stomachs of neonatal ruminants resulting from fermentation of glucose by resident yeasts occurs only in the absence of fat from the diet. Daily levels of ethanol and numbers of viable yeast were measured on samples of stomach contents for 21-day periods. Milk fat was shown to control the ethanol production in lambs and calves (but notin vitroin culture), the quantitative nature of this control was demonstrated by experiments with cream using lambs. Nine dietary fats in commercial use homogenized in fat-free milk, a commercial catering ‘milk’, and an intravenous lipid feed were all tested in lamb-feeding experiments, compared with whole and separated milk, and an inert oily hydrocarbon, liquid paraffin.