Interspecific and intraspecific variation in proximate, mineral, and fatty acid composition of milk in Old World fruit bats (Chiroptera: Pteropodidae)

We examine the effect of body mass on milk composition among Old World fruit bats, including Pteropus pumilus (0.175 kg), Pteropus rodricensus (0.265 kg), Pteropus hypomelanus (0.571 kg), and Pteropus vampyrus (1.133 kg). We describe intra- and interspecific differences in the proximate composition of milk among these four species and the minerals and fatty acids in the milk of the latter two species. There were no differences between species in the concentrations of dry matter, fat, or lactose in milk. However, there were significant, although small, differences in the protein content of milk among species, with protein being significantly greater in P. rodricensus than in P. pumilus and P. hypomelanus and protein being significantly less in P. hypomelanus than in P. rodricensus and P. vampyrus. There were no differences in mineral content between P. hypomelanus and P. vampyrus in milk minerals, but minor differences were evident in fatty acids 12:0, 14:0, 18:0, 18:1n11, and 18:2n6. Our findings suggest that milk composition is relatively constant across lactation for most proximate, mineral, and fatty acid components. We found a significant increase in dry matter and energy across lactation in the concentration of dry matter and energy in P. pumilus and fat in P. hypomelanus. In P. hypomelanus, we found a significant increase in the concentration of fatty acids 10:0 and 20:1n9 and a significant decrease in Iso15 and 20:1n7. No other differences associated with day of lactation were found. These findings suggest that milk composition is generally similar within the genus Pteropus, despite a 6.5-fold difference in body mass between species that we evaluated.     

Indigestion in Young Calves

Increasing the lactose content of different milk replacers or milk diets by approx. 30 % of the dry matter increased the frequency of diarrhoea the first 10–12 days in young calves on all occasions in 5 experiments comprising 120 calves. For all diets taken together, this effect was highly significant. Total daily intakes of lactose amounted to 200–480 g. When lactose was given on top of the milk rations, the growth rate increased significantly, whereas the growth rate was usually insignificantly reduced when lactose replaced other nutrients in milk diets or milk replacers, their levels of protein and fat becoming low. Albumin and total protein in blood plasma were significantly lower when the dietary protein level was low. Milk replacers with 20 or 40 % whey powder, replacing skim milk powder, performed equally well, but gave significantly less growth than the old-fashioned feeding of whole milk-skim milk. Intake of hay and barley and a number of clinical and histological or pathological parameters did not vary consistently with dietary level of whey powder or lactose. Feeding whole milk all the time resulted in low intake of hay and barley and poorly developed forestomachs, but high dressing-out %. Substituting soya for part of the skim milk powder in milk replacers gave abomasal content with no curds. In most cases, pH in the rumen appeared to be nearly up to neutral until the calves ate ground barley, about 1 month old.     

The survival of Staphylococcus epidermidis in raw milk with different somatic cell count

The antibacterial activity of an individual quarter milk sample cannot be evaluated by the number of somatic cells in milk and number of S. epidermidis cells surviving (-0,509, the most bactericidal. This was shown to be due to the fact that the strain of Staphylococcus epidermidis Se 25 is very sensitive to complement and also sensitive to cell free skimmed milk. A second stimulation of the udder enhances significantly the cell response to the stimulant. A negative and highly significant correlation coefficient exists between the number of somatic cells in milk and number of S. epidermidis cells surviving (0.509, P less than or equal to 0.01).     

SIGNIFICANCE OF THE CHEMICAL COMPOSITION OF THE SECRETING AND DRY MAMMARY GLAND TO MILK SECRETION

The results herein presented furnish exact critical evidence for one more stage in milk secretion. Cows producing up to 30 pounds of milk at one milking are shown to have the lactose equivalent of all this milk in the udder when milking commences. The average excess of lactose found in the udder after subtracting the amount necessary for the contained milk is equal to 2.1 pounds. This represents the milk retained in the udder when the cow is believed to be dry. These conclusions are further supported by the fact that no sugar is found in the udder in the quiescent state. The study of the total composition of the udder as fat, ash, nitrogen, and lactose, and of the contained milk shows that there is a large excess of fat, ash, and nitrogen in proportion to that necessary for milk formation. The excess of udder lactose over the milk lactose is much less. The lactose would therefore appear to be formed from some element in the blood, probably dextrose, only as needed for the formation of milk. The composition of the dry udder is quite different in certain respects from that of the actively secreting gland. It builds up a fat reserve of a quite different Reichert-Meissl number from that of butter-fat. It has no sugar, its ash content is reduced, and the nitrogen content is like that of the secreting gland.     

Lowering the milk lactose content in vivo: potential interests,strategies and physiological consequences

Lactose is the major sugar present in milk and an important osmotic regulator of lactation. It is digested by intestinal lactase, an enzyme expressed in new-borns. Its activity declines following weaning. As a result, adult mammals are normally lactose-intolerant and more than 75% of the human adult population suffers from lactase deficiency. A reduction in milk lactose content could be beneficial for nutritional but also agricultural and industrial purposes (less volume to transport, better milk coagulation, less effluent production). Several attempts to create transgenic mice producing milk with modified carbohydrate compositions have recently been described. Depending on whether these modifications resulted from an alteration of lactose synthesis or from lactose hydrolysis, striking physiological differences are observed.     

The survival of Staphylococcus aureus in raw milk with different cell count

The antibacterial activity of the individual udder quarter milk sample cannot be evaluated by the number of somatic cells. Milk with the highest number of cells is not always the most bactericidal. However, when the data were obtained from a material large enough for statistical calculations, negative and highly significant correlation coefficient (-0.465, P less than or equal to 0.01) between number of somatic cells in milk and number of bacteria surviving in it, and negative and significant correlation coefficient (-0.203, P 0.05) between number of somatic cells in milk and number of bacteria surviving in whey, were found. Results of the analysis of variance demonstrated highly significant differences as regards number of cells and bacteria surviving in milk and in whey between cows, quarters and stimulation time. Nevertheless, among ten investigated cows, three cows with high cell count and high antibacterial activity in milk and whey, highly reacting to stimulant, were found.     

THE DETERMINATION OF ESCHERICHIA COLI I IN SEA WATER

SUMMARY: For the determination of Escherichia coli I in sea water lactose broth frequently gave higher presumptive and confirmed counts than MacConkey's broth. In the presumptive count there were 53 cases where lactose broth gave larger numbers than MacConkey's broth, with 11 equal counts, and only 25 cases with smaller counts ( P =0·00137). After confirmation the corresponding numbers of cases were 39, 10 and 27 ( P =0·134).
In the samples giving most probable numbers (MPN) of less than 100 E. coli /100 ml lactose broth was superior to MacConkey's broth ( P =0·021). At higher MPN values both media were satisfactory, but with highly polluted water MacConkey's broth might give better recoveries due to the suppression of high concentrations of non-coli-aerogenes bacteria.
Samples stored for 24 or 48 hr before testing gave higher presumptive recoveries when examined with lactose broth than with MacConkey's broth, the values for P being 0·028 and 0·0027 respectively.
It appears that lactose broth without inhibitory ingredients could be used with advantage in the examination of sea water.     

Evolution of milk oligosaccharides and lactose: a hypothesis

Mammalian milk or colostrum contains up to 10% of carbohydrate, of which free lactose usually constitutes more than 80%. Lactose is synthesized within lactating mammary glands from uridine diphosphate galactose (UDP-Gal) and glucose by a transgalactosylation catalysed by a complex of β4-galactosyltransferase and α-lactalbumin (α-LA). α-LA is believed to have evolved from C-type lysozyme. Mammalian milk or colostrum usually contains a variety of oligosaccharides in addition to free lactose. Each oligosaccharide has a lactose unit at its reducing end; this unit acts as a precursor that is essential for its biosynthesis. It is generally believed that milk oligosaccharides act as prebiotics and also as receptor analogues that act as anti-infection factors. We propose the following hypothesis. The proto-lacteal secretions of the primitive mammary glands of the common ancestor of mammals contained fat and protein including lysozyme, but no lactose or oligosaccharides because of the absence of α-LA. When α-LA first appeared as a result of its evolution from lysozyme, its content within the lactating mammary glands was low and lactose was therefore synthesized at a slow rate. Because of the presence of glycosyltransferases, almost all of the nascent lactose was utilized for the biosynthesis of oligosaccharides. The predominant saccharides in the proto-lacteal secretions or primitive milk produced by this common ancestor were therefore oligosaccharides rather than free lactose. Subsequent to this initial period, the oligosaccharides began to serve as anti-infection factors. They were then recruited as a significant energy source for the neonate, which was achieved by an increase in the synthesis of α-LA. This produced a concomitant increase in the concentration of lactose in the milk, and lactose therefore became an important energy source for most eutherians, whereas oligosaccharides continued to serve mainly as anti-microbial agents. Lactose, in addition, began to act as an osmoregulatory molecule, controlling the milk volume. Studies on the chemical structures of the milk oligosaccharides of a variety of mammalian species suggest that human milk or colostrum is unique in that oligosaccharides containing lacto-N-biose I (LNB) (Gal(β1 → 3)GlcNAc, type I) predominate over those containing N-acetyllactosamine (Gal(β1 → 4)GlcNAc, type II), whereas in other species only type II oligosaccharides are found or else they predominate over type I oligosaccharides. It can be hypothesized that this feature may have a selective advantage in that it may promote the growth of beneficial colonic bacteria, Bifidobacteria, in the human infant colon.     

Subspecies and body size allometry affect milk production and composition, and calf growth in red deer: comparison of Cervus elaphus hispanicus and Cervus elaphus scoticus

Studies comparing lactation in wild mammals have shown that maternal weight scales with offspring weight, milk production, or its energy. However, no study appears to have scaled milk composition with maternal or offspring weight. Although diet affects milk composition and production, their effects in biological studies have almost never seemed to be controlled. In this study, we compare two subspecies of red deer, Scottish deer, Cervus elaphus scoticus (10 lactations), and Iberian deer, Cervus elaphus hispanicus (14 lactations), kept under the same diet and housing to assess differences in hind and calf weights and their trends, milk production and composition, and their allometric relationships. Scottish hinds were heavier, and calf weight and gains were greater than Iberian ones, with greater milk production and milk protein content, but they did not differ in fat or lactose content. Calf birth weight, milk production, and protein content showed significant allometric relationships with maternal weight, but no relationship was found for fat, lactose, or any of these variables with calf birth weight. Protein content correlated with calf birth weight, and calf weight trend depended on milk protein production rather than on that of fat or lactose. Protein may be the most important milk component to explain growth and milk composition differences between closely related mammals.     

Bacteriological Examination of Seawater: Observations on Factors Affecting the Performance of Media

The performance of MacConkey broth and minerals modified glutamate lactose medium was examined in a series of experiments. It was found that the addition of seawater with or without antibacterial activity and the addition of 3·2% NaCl solution to double strength media all had similar harmful effects on their performance. Also a concentration of 3·2% NaCl in ordinary lactose broth caused a great decrease ( P =0·02) in the number of tubes containing coliform organisms. It is concluded that the high salt content of seawater interferes with lactose fermentation by coliforms. This interference was found to be so great that the number of tubes in which coliform organisms and Escherichia coli were detected, dropped from 2·5 to 3·5 times when an equal volume of seawater was added to double strength MacConkey and glutamate media. The results of the last experiment suggest that for best performance of the media, the volume ratio of seawater to medium should be equal or less than 1/10. Also glutamate medium was superior to MacConkey broth ( P <0·001), especially in the detection of E. coli .     

Relationships between fertility, peak milk yields and lactational persistency in dairy cows

Peak milk yield, lactational persistency and conception rates were studied using 5928 lactation records of high milk-producing cows at three California dairies. Log-linear analysis was used to study relationships between peak milk yield, lactational persistency, dairy of origin, lactation number and conception rates in 3850 completed lactations. Cows with peak milk yields greater than the median (38.2 kg milk per day) were less likely to have conceived in one or two breedings than cows with peak milk yields lower than or equal to the median. Cows with a higher than median (0.755) lactational persistency were less likely to have conceived in one or two breedings than cows with a lactational persistency lower than or equal to the median. Dairy of origin had a significant effect on the probability of conceiving in one or two breedings. Cows in the first lactation were more likely than those in subsequent lactations to conceive in one or two breedings. This retrospective study demonstrated that subfertility is associated with high peak lactational yields in high milk-producing California cows.     

Utilization of Lactose, Glucose, and Galactose by a Mixed Culture of Streptococcus thermophilus and Lactobacillus bulgaricus in Milk Treated with Lactase Enzyme

The mechanism responsible for an increased rate of acid production when yogurt starter cultures are grown in milk treated with lactase enzyme was investigated by studying carbohydrate utilization and acid development by a pure culture of Streptococcus thermophilus and a mixed yogurt starter culture consisting of S. thermophilus and Lactobacillus bulgaricus. In milk containing glucose, galactose, and lactose, glucose and lactose (but not free galactose) were fermented. Fermentation of lactose in control milk was accompanied by the release of free galactose, with the result that carbohydrate utilization was less efficient than in treated milk. This phenomenon also occurred when lactose was fermented by S. thermophilus in broth culture. Carbohydrate utilization by the mixed yogurt culture was more rapid when the lactose in milk was partially prehydrolyzed. Our results suggest that the more rapid acid development that took place when a mixed yogurt starter culture was grown in milk containing prehydrolyzed lactose was the result of a more rapid and efficient utilization of carbohydrate by S. thermophilus when free glucose in addition to lactose was available for fermentation. The evidence presented also suggests that uptake and utilization of glucose and lactose by S. thermophilus are different in broth and milk cultures.     

A novel combined thermometric and amperometric biosensor for lactose determination based on immobilised cellobiose dehydrogenase

A novel method for lactose determination in milk is proposed. It is based on oxidation of lactose by cellobiose dehydrogenase (CDH) from the basidiomycete Phanerochaete chrysosporium, immobilised in an enzyme reactor. The reactor was prepared by cross-linking CDH onto aminopropyl-silanised controlled pore glass (CPG) beads using glutaraldehyde. The combined biosensor worked in flow injection analysis (FIA) mode and was developed for simultaneous monitoring of the thermometric signal associated with the enzymatic oxidation of lactose using p-benzoquinone as electron acceptor and the electrochemically generated current associated with the oxidation of the hydroquinone formed. A highly reproducible linear response for lactose was obtained between 0.05 mM and 30 mM. For a set of more than 500 samples an R.S.D. of less than 10% was achieved. The assay time was ca. 2 min per sample. The sensor was applied for the determination of lactose in dairy milk samples (milk with a fat content of 1.5% or 3% and also "lactose free" milk). No sample preparation except dilution with buffer was needed. The proposed method is rapid, suitable for repeated use and allows the possibility to compare results from two different detection methods, thus providing a built-in quality assurance. Some differences in the response observed between the methods indicate that the dual approach can be useful in mechanistic studies of redox enzymes. In addition, a dual system opens up interesting possibilities for studies of enzyme properties and mechanisms.     

A comparison of milk composition in Myotis lucifugus and Eptesicus fuscus (chiroptera: vespertilionidae)

Milk composition in two species of insectivorous bats (Myotis lucifugus and Eptesicus fuscus) was determined. No significant differences in fat, lactose, protein, or energy content were evident during the lactation period for M. lucifugus. The percentage of fat, lactose, and protein averaged 13.5, 3.3, 7.4, respectively, for M. lucifugus, and 16.4, 2.5, 6.2, respectively, for E. fuscus. Energy content of milk averaged 7.32 kJ/g for M. lucifugus and 8.37 kJ/g for E. fuscus. The percentage of lactose in milk from M. lucifugus was significantly greater than in E. fuscus, but there were no significant interspecific differences in percentages of fat or protein. The two species also differed significantly in content of five out of nine fatty acids.     

Are free glucose and glucose-6-phosphate in milk indicators of specific physiological states in the cow?

A total of 3200 milk samples from Holstein and Jersey cows were analysed for free glucose and glucose-6-phosphate (G6P) by an enzymatic-fluorometric method that requires no pre-treatment. The cows were primiparous as well as multiparous, and samples were taken throughout the entire lactation period. In addition, lactose, protein, fat, citrate and β-hydroxybutyrate were determined and comparisons between these variables were made. Data were analysed using GLM model for the effect of parity, breed, time from last milking and stage of lactation on variations in parameters in milk. Pearson’s correlations were generated between milk variables. P<0.05 was considered significant. Concentration of free glucose and G6P were on average 331 and 81 μM, respectively. Time from last milking (stay in the gland cistern) did not increase the concentration of these monosaccharides, indicating that they are not hydrolysis product from lactose post secretion, but rather reflecting the energy status of the mammary epithelial cells pre-secretion. Wide variation in range of these metabolites, that is, from 90 to 630 μM and 5 to 324 μM, for glucose and G6P, respectively, was observed. During the first 21 weeks in milk, free glucose increased whereas G6P decreased. Concentration of free glucose in milk is greater for primiparous than multiparous cows and greater for Holstein than Jersey cows. Concentration of G6P was not affected by parity or breed. The use of free glucose and G6P as indicators of physiological conditions and risk of disease is warranted for use as potential biomarkers for in-line surveillance systems on-farm.     

Composition of the milks of the bottlenose dolphin (Tursiops trucatus) and the Florida manatee (Trichechus manatus latirostris)

Milk samples from four individual bottlenose (Tursiops truncatus) and two Florida manatees (Trichechus manatus latirostris) of known lactation stages were analyzed for protein, carbohydrate and lipid composition, as well as for activity levels of alpha-lactalbumin, the regulatory protein of lactose synthase. The milk from both species had relatively high protein and lipid levels, as reported previously for other marine mammals. The major proportion of the lipid was in the form of triglycerides. Dolphin milk contained an average of 2.2% neutral sugars, which was essentially all in the form of lactose, as determined by several criteria. Manatee milk samples contained 0.6% of neutral sugars, and a larger proportion (about 2%) of amino sugars. Lactose was not detected by enzymatic assay or paper chromatography, but HPLC analysis indicated the presence of low levels of lactose together with two components that were tentatively identified as oligosaccharides. alpha-Lactalbumin activity, determined by assay with bovine galactosyltransferase, was found in both dolphin and manatee milk. The level in dolphin milk was comparable with that found in bovine and other milk, but the level in the manatee was less than 10% of that in the dolphin.     

Evolution of milk oligosaccharides: Origin and selectivity of the ratio of milk oligosaccharides to lactose among mammals

BackgroundThe carbohydrate fraction of mammalian milk is constituted of lactose and oligosaccharides, most of which contain a lactose unit at their reducing ends. Although lactose is the predominant saccharide in the milk of most eutherians, oligosaccharides significantly predominate over lactose in the milk of monotremes and marsupials.Scope of reviewThis review describes the most likely process by which lactose and milk oligosaccharides were acquired during the evolution of mammals and the mechanisms by which these saccharides are digested and absorbed by the suckling neonates.Major conclusionsDuring the evolution of mammals, c-type lysozyme evolved to α-lactalbumin. This permitted the biosynthesis of lactose by modulating the substrate specificity of β4galactosyltransferase 1, thus enabling the concomitant biosynthesis of milk oligosaccharides through the activities of several glycosyltransferases using lactose as an acceptor. In most eutherian mammals the digestion of lactose to glucose and galactose is achieved through the action of intestinal lactase (β-galactosidase), which is located within the small intestinal brush border. This enzyme, however, is absent in neonatal monotremes and macropod marsupials. It has therefore been proposed that in these species the absorption of milk oligosaccharides is achieved by pinocytosis or endocytosis, after which digestion occurs through the actions of several lysosomal acid glycosidases. This process would enable the milk oligosaccharides of monotremes and marsupials to be utilized as a significant energy source for the suckling neonates.General significanceThe evolution and significance of milk oligosaccharides is discussed in relation to the evolution of mammals.     

MacConkey and Glutamate Media in the Bacteriological Examination of Seawater

Confirmatory tests were made in 4807 positive tubes of MacConkey broth. It was found that when an equal volume of seawater was added to a double strength MacConkey broth only 88% of the tubes contained coliform organisms (12% false-positive reactions); when, however, the ratio of the volume of seawater to broth was 1/5 or less, coliform organisms were found in 93·5% of the positive tubes (6·5% false-positive reactions). Glutamate medium gives a higher rate of false reactions than MacConkey broth when an equal volume of seawater is added to double strength medium. When the volume ratio of seawater to glutamate medium is equal to or less than 1/5, then the minerals-modified lactose glutamate medium gives better results than MacConkey broth in the coliform and especially in the Escherichia coli count. The difference is statistically significant.
It is thus concluded that for the bacteriological examination of seawater the volume ratio of water to medium should be 1/5 or less and also that glutamate medium is the medium of choice.     

Effects of niacin on milk yield,milk composition,and blood components of dairy cows in hot weather

Twenty multiparous Friesian cows, 90 ± 30 days postpartum, were allocated to two groups of ten cows according to calving date, lactation number and daily milk yield, and assigned randomly to one of two diets in a cross-over experiment. The experimental diet consisted of concentrate and maize silage in the proportions 1:1 (dry matter basis) containing either 0 or 10 g niacin per cow per day, which was handmixed into the concentrate. The diets were offered individually as total mixed rations in two equal proportions at 09:00 and 20:00 h in amounts sufficient to ensure 10% refusals. Dry matter, metabolisable energy and crude protein intakes, as well as milk yield, milk protein proportion and yield, milk lactose, total solids and solids-not-fat proportions were not affected by niacin supplementation. In contrast, niacin supplementation increased milk fat proportion and yield. No differences were observed in blood serum concentrations of glucose, total protein, triglycerides, cholesterol, Na, K, Ca, P or Mg. However, the serum concentration of urea was lower when the cows were supplemented with niacin.     

Polymorphisms of <Emphasis Type="Italic">STAT5A</Emphasis> gene and their association with milk production traits in Holstein cows

The STAT5A gene was studied as a candidate gene for five milk production traits (milk yield at 305 days, protein percentage, fat percentage, lactose percentage and dry matter percentage) in Holstein cows. According to the sequence of bovine STAT5A gene, two pairs of primers (P1 and P2) were designed to detect polymorphisms of STAT5A gene in 401 Holstein cows by PCR-RFLP and PCR-SSCP. The results showed that the products amplified by primers P1 and P2 displayed polymorphisms. For P1, three genotypes (AA, AG, and GG) were detected, and the frequency of AA/AG/GG was 0.252/0.486/0.262, respectively. Sequence analysis revealed a single nucleotide substitution A–G at 14217 bp (GenBank NC_007317) of bovine STAT5A gene while compared GG genotype with AA genotype. The differences of the least squares means for the four milk production traits (milk yield at 305 days, fat percentage, lactose percentage and dry matter percentage) between AA, AG and GG were not significant (P > 0.05). Least squares mean of protein percentage for AG or GG was significantly higher than that for AA (P < 0.05); the difference of the least squares mean for protein percentage was not significant between AG and GG (P > 0.05). For P2, three genotypes (CC, CT, and TT) were detected in Holstein cows, and the frequency of CC/CT/TT was 0.751/0.234/0.015, respectively. Sequencing revealed an insertion CCT at 17266 (NC_007317) of bovine STAT5A gene while compared CC genotype with TT genotype. The differences of the least squares means for the three milk production traits (protein percentage, lactose percentage and dry matter percentage) between CC, CT and TT were not significant (P > 0.05). Least squares mean of milk yield at 305 days for TT or CT was significantly higher than that for CC (P < 0.05); the difference of the least squares mean for milk yield at 305 days was not significant between TT and CT (P > 0.05). Least squares mean of fat percentage for CC or CT was significantly higher than that for TT (P < 0.05); the difference of the least squares mean for fat percentage was not significant between CC and CT (P > 0.05). The results preliminarily indicated that allele G of A14217G polymorphic site of STAT5A gene is a potential DNA marker for improving protein percentage in dairy cattle, 17266indelCCT polymorphic site of STAT5A gene is a potential DNA marker for improving milk yield at 305 days and fat percentage in dairy cattle.