Structural determination of the oligosaccharides in the milk of an Asian elephant (Elephas maximus)

Characteristics of gut microbiota in captive Asian elephants (Elephas maximus) from infant to elderly

Gut microbiota play an important role in the health and disease of Asian elephants, however, its characteristics at each stage of life have not been thoroughly investigated in maintaining and regulating health of elephants. This study, therefore, aimed to characterize the profiles of the gut microbiota of captive Asian elephants from infants to the elderly. Gut microbiota were identified by 16S rRNA sequencing from the feces of captive Asian elephants with varying age groups, including infant calves, suckling calves, weaned calves, subadult and adult elephants, and geriatric elephants. The diversity of the gut microbiota was lowest in infants, stable during adulthood, and slightly decreased in the geriatric period. The gut microbiota of the infant elephants was dominated by milk-fermenting taxa including genus Bifidobacterium of family Bifidobacteriaceae together with genus Akkermansia. The fiber-fermenting taxa such as Lachnospiraceae_NK3A20_group were found to be increased in suckling elephants in differential abundance analysis by Analysis of Compositions of Microbiomes with Bias Correction (ANCOM-BC). The gut microbiota profiles after weaning until the adult period has been uniform as indicated by no significant differences in beta diversity between groups. However, the composition of the gut microbiota was found to change again in geriatric elephants. Understanding of the composition of the gut microbiota of captive Asian elephants at various life stages could be beneficial for promoting good health throughout their lifespan, as well as ensuring the welfare of captive elephants.

Creation of a milk oligosaccharide database, MilkOligoDB, reveals common structural motifs and extensive diversity across mammals

The carbohydrate fraction of most mammalian milks contains a variety of oligosaccharides that encompass a range of structures and monosaccharide compositions. Human milk oligosaccharides have received considerable attention due to their biological roles in neonatal gut microbiota, immunomodulation, and brain development. However, a major challenge in understanding the biology of milk oligosaccharides across other mammals is that reports span more than 5 decades of publications with varying data reporting methods. In the present study, publications on milk oligosaccharide profiles were identified and harmonized into a standardized format to create a comprehensive, machine-readable database of milk oligosaccharides across mammalian species. The resulting database, MilkOligoDB, includes 3193 entries for 783 unique oligosaccharide structures from the milk of 77 different species harvested from 113 publications. Cross-species and cross-publication comparisons of milk oligosaccharide profiles reveal common structural motifs within mammalian orders. Of the species studied, only chimpanzees, bonobos, and Asian elephants share the specific combination of fucosylation, sialylation, and core structures that are characteristic of human milk oligosaccharides. However, agriculturally important species do produce diverse oligosaccharides that may be valuable for human supplementation. Overall, MilkOligoDB facilitates cross-species and cross-publication comparisons of milk oligosaccharide profiles and the generation of new data-driven hypotheses for future research.

Primary Structure of Glycans by NMR Spectroscopy

Glycans, carbohydrate molecules in the realm of biology, are present as biomedically important glycoconjugates and a characteristic aspect is that their structures in many instances are branched. In determining the primary structure of a glycan, the sugar components including the absolute configuration and ring form, anomeric configuration, linkage(s), sequence, and substituents should be elucidated. Solution state NMR spectroscopy offers a unique opportunity to resolve all these aspects at atomic resolution. During the last two decades, advancement of both NMR experiments and spectrometer hardware have made it possible to unravel carbohydrate structure more efficiently. These developments applicable to glycans include, inter alia, NMR experiments that reduce spectral overlap, use selective excitations, record tilted projections of multidimensional spectra, acquire spectra by multiple receivers, utilize polarization by fast-pulsing techniques, concatenate pulse-sequence modules to acquire several spectra in a single measurement, acquire pure shift correlated spectra devoid of scalar couplings, employ stable isotope labeling to efficiently obtain homo- and/or heteronuclear correlations, as well as those that rely on dipolar cross-correlated interactions for sequential information. Refined computer programs for NMR spin simulation and chemical shift prediction aid the structural elucidation of glycans, which are notorious for their limited spectral dispersion. Hardware developments include cryogenically cold probes and dynamic nuclear polarization techniques, both resulting in enhanced sensitivity as well as ultrahigh field NMR spectrometers with a 1H NMR resonance frequency higher than 1 GHz, thus improving resolution of resonances. Taken together, the developments have made and will in the future make it possible to elucidate carbohydrate structure in great detail, thereby forming the basis for understanding of how glycans interact with other molecules.

African Elephant Milk Short Saccharide and Metabolite Composition and Their Changes over Lactation

Elephant milk composition is unique, as are its changes over lactation. Presented here is the milk non-dedicated metabolite composition of three African elephants. Their lactation times are overlapping and span day one to thirty months. Metabolites were identified and quantified by ¹H nuclear magnetic resonance spectroscopy. Lactose and short oligosaccharides are a large component of the metabolites, with lacto-N-difucohexaose I as the major oligosaccharide. These were followed by metabolites of lipids, amino acids, and the citric acid cycle. The content of lactose, lacto-N-difucohexaose I, 2'-fucosyllactose, and some unidentified oligosaccharides decrease over lactation, while that of difucosyllactose and other unidentified ones increase. The high content of glutamate, as a glucogenic amino acid, supported the uprated synthesis of saccharides by the milk gland cells. The content of succinate and choline increase over lactation, indicating higher energy expenditure and phospholipid synthesis during later lactation.

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

BACKGROUND

The 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 REVIEW

This 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 CONCLUSIONS

During 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 SIGNIFICANCE

The evolution and significance of milk oligosaccharides is discussed in relation to the evolution of mammals.

The Dynamic Changes of African Elephant Milk Composition over Lactation

Simple Summary

The composition of elephant milk differs from all other mammals, as well as between Asian and African elephants. The changes of this milk composition during lactation is also unique. Apart from the major sugar being lactose, sugars also occur as longer chains. With progressed lactation, the content of the lactose decreases, and oligosaccharides become the major sugar component. The content of protein, minerals, and fat also increase during lactation, resulting in an increase in total energy. The fatty acid composition changes during lactation to a high content of saturated acids. Vitamin E occurs at low levels in this milk, and vitamins A, D3, and K occur in trace amounts. The combined data of 14 African elephants over 25 months of lactation are presented. The reported changes may contribute to improving the management strategies of captive African elephants to optimize the nutrition, health, and survival of elephant calves.

Abstract

The combined data of milk composition of 14 African elephants over 25 months of lactation are presented. The milk density was constant during lactation. The total protein content increased with progressing lactation, with caseins as the predominant protein fraction. The total carbohydrates steadily decreased, with the oligosaccharides becoming the major fraction. Lactose and isoglobotriose reached equal levels at mid lactation. The milk fat content increased during lactation, as did the caprylic and capric acids, while the 12 carbon and longer fatty acids decreased. The fatty acid composition of the milk phospholipids fluctuated, and their total saturated fatty acid composition was low compared to the triacylglycerides. The milk ash and content of the major minerals, Na, K, Mg, P, and Ca, increased. Vitamin content was low, Vitamin E occurred in quantifiable amounts, with traces of vitamins A, D3, and K. The energy levels of African elephant milk did not change much in the first ten months of lactation, but they increased thereafter due to the increase in protein and fat content. The overall changes in milk composition appeared to be in two stages: (a) strong changes up to approximately 12 months of lactation and (b) little or no changes thereafter.

Chemical structures of oligosaccharides in milks of the American black bear (Ursus americanus americanus) and cheetah (Acinonyx jubatus)

The milk oligosaccharides were studied for two species of the Carnivora: the American black bear (Ursus americanus, family Ursidae, Caniformia), and the cheetah, (Acinonyx jubatus, family Felidae, Feliformia). Lactose was the most dominant saccharide in cheetah milk, while this was a minor saccharide and milk oligosaccharides predominated over lactose in American black bear milk. The structures of 8 neutral saccharides from American black bear milk were found to be Gal(β1-4)Glc (lactose), Fuc(α1-2)Gal(β1-4)Glc (2'-fucosyllactose), Gal(α1-3)Gal(β1-4)Glc (isoglobotriose), Gal(α1-3)[Fuc(α1-2)]Gal(β1-4)Glc (B-tetrasaccharide), Gal(α1-3)[Fuc(α1-2)]Gal(β1-4)[Fuc(α1-3)]Glc (B-pentasaccharide), Fuc(α1-2)Gal(β1-4)[Fuc(α1-3)]GlcNAc(β1-3)Gal(β1-4)Glc (difucosyl lacto-N-neotetraose), Gal(α1-3)Gal(β1-4)[Fuc(α1-3)]GlcNAc(β1-3)Gal(β1-4)Glc (monogalactosyl monofucosyl lacto-N-neotetraose) and Gal(α1-3)Gal(β1-4)GlcNAc(β1-3)Gal(β1-4)Glc (Galili pentasaccharide). Structures of 5 acidic saccharides were also identified in black bear milk: Neu5Ac(α2-3)Gal(β1-4)Glc (3'-sialyllactose), Neu5Ac(α2-6)Gal(β1-4)GlcNAc(β1-3)[Fuc(α1-2)Gal(β1-4)GlcNAc(β1-6)]Gal(β1-4)Glc (monosialyl monofucosyl lacto-N-neohexaose), Neu5Ac(α2-6)Gal(β1-4)GlcNAc(β1-3)[Gal(α1-3)Gal(β1-4)GlcNAc(β1-6)]Gal(β1-4)Glc (monosialyl monogalactosyl lacto-N-neohexaose), Neu5Ac(α2-6)Gal(β1-4)GlcNAc(β1-3){Gal(α1-3)Gal(β1-4)[Fuc(α1-3)]GlcNAc(β1-6)}Gal(β1-4)Glc (monosialyl monogalactosyl monofucosyl lacto-N-neohexaose), and Neu5Ac(α2-6)Gal(β1-4)GlcNAc(β1-3){Gal(α1-3)[Fuc(α1-2)]Gal(β1-4)[Fuc(α1-3)]GlcNAc(β1-6)}Gal(β1-4)Glc (monosialyl monogalactosyl difucosyl lacto-N-neohexaose). A notable feature of some of these milk oligosaccharides is the presence of B-antigen (Gal(α1-3)[Fuc(α1-2)]Gal), α-Gal epitope (Gal(α1-3)Gal(β1-4)Glc(NAc)) and Lewis x (Gal(β1-4)[Fuc(α1-3)]GlcNAc) structures within oligosaccharides. By comparison to American black bear milk, cheetah milk had a much smaller array of oligosaccharides. Two cheetah milks contained Gal(α1-3)Gal(β1-4)Glc (isoglobotriose), while another cheetah milk did not, but contained Gal(β1-6)Gal(β1-4)Glc (6'-galactosyllactose) and Gal(β1-3)Gal(β1-4)Glc (3'-galactosyllactose). Two cheetah milks contained Gal(β1-4)GlcNAc(β1-3)[Gal(β1-4)GlcNAc(β1-6)]Gal(β1-4)Glc (lacto-N-neohexaose), and one cheetah milk contained Gal(β1-4)Glc-3'-O-sulfate. Neu5Ac(α2-8)Neu5Ac(α2-3)Gal(β1-4)Glc (disialyllactose) was the only sialyl oligosaccharide identified in cheetah milk. The heterogeneity of milk oligosaccharides was found between both species with respect of the presence/absence of B-antigen and Lewis x. The variety of milk oligosaccharides was much greater in the American black bear than in the cheetah. The ratio of milk oligosaccharides-to-lactose was lower in cheetah (1:1-1:2) than American black bear (21:1) which is likely a reflection of the requirement for a dietary supply of N-acetyl neuraminic acid (sialic acid), in altricial ursids compared to more precocial felids, given the role of these oligosaccharides in the synthesis of brain gangliosides and the polysialic chains on neural cell adhesion.

VITAL SIGNS AND FIRST OCCURRENCES IN NORMAL AND ABNORMAL NEWBORN ASIAN ELEPHANT ( ELEPHAS MAXIMUS) CALVES

Sixteen years of medical records documenting 19 births within a herd of Asian elephants ( Elephas maximus) at a private facility in the southeastern United States were reviewed. Of the 19 calves, 11 were normal at birth, requiring no additional veterinary care, and eight were abnormal, requiring veterinary care immediately or within the first week of birth. Descriptive statistics were used to evaluate morphometrics, vital signs, and behavioral milestones in newborn calves both normal and abnormal. Blood work and urinalysis results from all calves were compared to values for adult elephants. Medical management of abnormal calves is described. All calves had faster heart rates and respiratory rates than did adult elephants, but rectal temperatures were the same. Calves were precocious with regard to sitting and standing but could be very slow to nurse. The most-common medical conditions of newborn calves were umbilical abnormalities and problems associated with nursing. Two calves required cardiopulmonary resuscitation after birth but made full recoveries. Some conditions were not apparent at birth but were recognized a few hours or days later. Following veterinary intervention, six of the eight calves made full recoveries, suggesting that early identification and treatment of problems can greatly decrease mortality. This is the first report of multiple veterinary and behavioral parameters in normal and abnormal neonatal Asian elephants from a facility with a calf survival rate above 90%. This information may be helpful to other elephant-holding facilities in providing care to their newborn elephant calves.

Elephant's breast milk contains large amounts of glucosamine

Hand-reared elephant calves that are nursed with milk substitutes sometimes suffer bone fractures, probably due to problems associated with nutrition, exercise, sunshine levels and/or genetic factors. As we were expecting the birth of an Asian elephant (Elephas maximus), we analyzed elephant’s breast milk to improve the milk substitutes for elephant calves. Although there were few nutritional differences between conventional substitutes and elephant’s breast milk, we found a large unknown peak in the breast milk during high-performance liquid chromatography-based amino acid analysis and determined that it was glucosamine (GlcN) using liquid chromatography/mass spectrometry. We detected the following GlcN concentrations [mean ± SD] (mg/100 g) in milk hydrolysates produced by treating samples with 6M HCl for 24 hr at 110°C: four elephant’s breast milk samples: 516 ± 42, three cow’s milk mixtures: 4.0 ± 2.2, three mare’s milk samples: 12 ± 1.2 and two human milk samples: 38. The GlcN content of the elephant’s milk was 128, 43 and 14 times greater than those of the cow’s, mare’s and human milk, respectively. Then, we examined the degradation of GlcN during 0–24 hr hydrolyzation with HCl. We estimated that elephant’s milk contains >880 mg/100 g GlcN, which is similar to the levels of major amino acids in elephant’s milk. We concluded that a novel GlcN-containing milk substitute should be developed for elephant calves. The efficacy of GlcN supplements is disputed, and free GlcN is rare in bodily fluids; thus, the optimal molecular form of GlcN requires a further study.

Characterization of casein and alpha lactalbumin of African elephant (Loxodonta africana) milk

The current research reports partial characterization of the caseins and α-lactalbumin (α-LA) of the African elephant with proposed unique structure-function properties. Extensive research has been carried out to understand the structure of the casein micelles. Crystallographic structure elucidation of caseins and casein micelles is not possible. Consequently, several models have been developed in an effort to describe the casein micelle, specifically of cow milk. Here we report the characterization of African elephant milk caseins. The κ-caseins and β-caseins were investigated, and their relative ratio was found to be approximately 1:8.5, whereas α-caseins were not detected. The gene sequence of β-casein in the NCBI database was revisited, and a different sequence in the N-terminal region is proposed. Amino acid sequence alignment and hydropathy plots showed that the κ-casein of African elephant milk is similar to that of other mammals, whereas the β-casein is similar to the human protein, and displayed a section of unique AA composition and additional hydrophilic regions compared with bovine caseins. Elephant milk is destabilized by 62% alcohol, and it is speculated that the β-casein characteristics may allow maintenance of the colloidal nature of the casein micelle, a role that was previously only associated with κ-casein. The oligosaccharide content of milk was reported to be low in dairy animals but high in some other species such as humans and elephants. In the milk of the African elephant, lactose and oligosaccharides both occur at high levels. These levels are typically related to the content of α-LA in the mammary gland and thus point to a specialized carbohydrate synthesis, where the whey protein α-LA plays a role. We report the characterization of African elephant α-LA. Homology modeling of the α-LA showed that it is structurally similar to crystal structures of other mammalian species, which in turn may be an indication that its functional properties, such as lactose synthesis, should not be impaired.

2'-fucosyllactose: an abundant, genetically determined soluble glycan present in human milk

Lactose is the preeminent soluble glycan in milk and a significant source of energy for most newborn mammals. Elongation of lactose with additional monosaccharides gives rise to a varied repertoire of free soluble glycans such as 2'-fucosyllactose (2'-FL), which is the most abundant oligosaccharide in human milk. In infants, 2'-FL is resistant to digestion and reaches the colon where it is partially fermented, behaving as soluble prebiotic fiber. Evidence also suggests that portions of small soluble milk glycans, including 2'-FL, are absorbed, thus raising the possibility of systemic biological effects. 2'-FL bears an epitope of the Secretor histo-blood group system; approximately 70-80% of all milk samples contain 2'-FL, since its synthesis depends on a fucosyltransferase that is not uniformly expressed. The fact that some infants are not exposed to 2'-FL has helped researchers to retrospectively probe for biological activities of this glycan. This review summarizes the attributes of 2'-FL in terms of its occurrence in mammalian phylogeny, its postulated biological activities, and its variability in human milk.

Analysis and role of oligosaccharides in milk

Milk is an important fluid in glycobiology because it contains a number of short carbohydrate chains either free or as glycoconjugates. These compounds as a class are the most abundant component and benefit the infant by developing and maintaining the infant's gut flora. New and emerging methods for oligosaccharide analysis have been developed to study milk. These methods allow for the rapid profiling of oligosaccharide mixtures with quantitation. With these tools, the role of oligosaccharide in milk is being understood. They further point to how oligosaccharide analysis can be performed, which until now has been very difficult and have lagged significantly those of other biopolymers.

Metabolism of vertebrate amino sugars with N-glycolyl groups: resistance of α2-8-linked N-glycolylneuraminic acid to enzymatic cleavage

The sialic acid (Sia) N-acetylneuraminic acid (Neu5Ac) and its hydroxylated derivative N-glycolylneuraminic acid (Neu5Gc) differ by one oxygen atom. CMP-Neu5Gc is synthesized from CMP-Neu5Ac, with Neu5Gc representing a highly variable fraction of total Sias in various tissues and among different species. The exception may be the brain, where Neu5Ac is abundant and Neu5Gc is reported to be rare. Here, we confirm this unusual pattern and its evolutionary conservation in additional samples from various species, concluding that brain Neu5Gc expression has been maintained at extremely low levels over hundreds of millions of years of vertebrate evolution. Most explanations for this pattern do not require maintaining neural Neu5Gc at such low levels. We hypothesized that resistance of α2-8-linked Neu5Gc to vertebrate sialidases is the detrimental effect requiring the relative absence of Neu5Gc from brain. This linkage is prominent in polysialic acid (polySia), a molecule with critical roles in vertebrate neural development. We show that Neu5Gc is incorporated into neural polySia and does not cause in vitro toxicity. Synthetic polymers of Neu5Ac and Neu5Gc showed that mammalian and bacterial sialidases are much less able to hydrolyze α2-8-linked Neu5Gc at the nonreducing terminus. Notably, this difference was not seen with acid-catalyzed hydrolysis of polySias. Molecular dynamics modeling indicates that differences in the three-dimensional conformation of terminal saccharides may partly explain reduced enzymatic activity. In keeping with this, polymers of N-propionylneuraminic acid are sensitive to sialidases. Resistance of Neu5Gc-containing polySia to sialidases provides a potential explanation for the rarity of Neu5Gc in the vertebrate brain.

Structural characterization of neutral and acidic oligosaccharides in the milks of strepsirrhine primates: greater galago, aye-aye, Coquerel's sifaka and mongoose lemur

The structures of milk oligosaccharides were characterized for four strepsirrhine primates to examine the extent to which they resemble milk oligosaccharides in other primates. Neutral and acidic oligosaccharides were isolated from milk of the greater galago (Galagidae: Otolemur crassicaudatus), aye-aye (Daubentoniidae: Daubentonia madagascariensis), Coquerel's sifaka (Indriidae: Propithecus coquereli) and mongoose lemur (Lemuridae: Eulemur mongoz), and their chemical structures were characterized by (1)H-NMR spectroscopy. The oligosaccharide patterns observed among strepsirrhines did not appear to correlate to phylogeny, sociality or pattern of infant care. Both type I and type II neutral oligosaccharides were found in the milk of the aye-aye, but type II predominate over type I. Only type II oligosaccharides were identified in other strepsirrhine milks. α3'-GL (isoglobotriose, Gal(α1-3)Gal(β1-4)Glc) was found in the milks of Coquerel's sifaka and mongoose lemur, which is the first report of this oligosaccharide in the milk of any primate species. 2'-FL (Fuc(α1-2)Gal(β1-4)Glc) was found in the milk of an aye-aye with an ill infant. Oligosaccharides containing the Lewis x epitope were found in aye-aye and mongoose lemur milk. Among acidic oligosaccharides, 3'-N-acetylneuraminyllactose (3'-SL-NAc, Neu5Ac(α2-3)Gal(β1-4)Glc) was found in all studied species, whereas 6'-N-acetylneuraminyllactose (6'-SL-NAc, Neu5Ac(α2-6)Gal(β1-4)Glc) was found in all species except greater galago. Greater galago milk also contained 3'-N-glycolylneuraminyllactose (3'-SL-NGc, Neu5Gc(α2-3)Gal(β1-4)Glc). The finding of a variety of neutral and acidic oligosaccharides in the milks of strepsirrhines, as previously reported for haplorhines, suggests that such constituents are ancient rather than derived features, and are as characteristic of primate lactation is the classic disaccharide, lactose.

Efforts to emulate human milk oligosaccharides

Research on human milk oligosaccharides (HMO) began with the characterisation of their chemical structures and is now focused on the elucidation of their biological roles. Previously, biological effects could only be investigated with fractions or structures isolated from breast milk; consequently, clinical observations were limited to comparisons between outcomes from breast-fed infants and their formula-fed counterparts. In some cases, it was inferred that the observed differences were caused by the presence of HMO in breast milk. Presently, analytical techniques allow for the fast analysis of milk samples, thus providing insights on the inherent variability of specimens. In addition, methods for the synthesis of HMO have provided single structures in sufficient quantities to perform clinical studies with oligosaccharide-supplemented formulae. Furthermore, studies have been conducted with non-mammalian oligosaccharides with the purpose of assessing the suitability of these structures to functionally emulate HMO. Taken together, these developments justify summarising current knowledge on HMO to further discussions on efforts to emulate human milk in regard to its oligosaccharide content. The present account summarises published data and intends to provide an historical context and to illustrate the state of the field.

Milk composition of three free-ranging African elephant ( Loxodonta africana africana ) cows during mid lactation

Data are presented that indicate the dynamic changes of nutrients in milk from three free ranging African elephant (Loxodonta africana africana) cows during lactation. At the respective collection times of 12, 14 and 18 months of lactation the nutrient content was 47.3, 52.0 and 68.6 g protein; 60.7, 87.4 and 170.8 g fat; 1.6, 2.1 0.5 g lactose and 20.9, 21.5 and 8.6 g oligosaccharides per kg milk. The protein fraction respectively consisted of 18.0, 31.7 and 45.9 g caseins/kg milk and of 29.3, 20.3 and 22.7 g whey proteins/kg milk. Electrophoresis and identification of protein bands showed that polymorphs of one whey protein may be present in elephant's milk similar to polymorphs of alpha-lactalbumin found in cow's milk. From the middle of the lactation time lactose was replaced by oligosaccharides as major carbohydrate, and the major compound of these was identified as isoglobotriose by 1H NMR spectroscopy. The lipid fraction contains a high content, of capric and lauric acids, approximately 70% of the total fatty acids, and low content of myristic, palmitic and oleic acids. During these lactation times the content of short chain fatty acids, capric and caprylic acids increased, while fatty acids lauric acid and longer decreased.

The composition of serval (Felis serval) milk during mid-lactation

Milk was obtained from three captive servals. The average nutrient content was 158.3+/-44.4 g protein; 152.6+/-62.3 g fat; and 68.7+/-31.4 g lactose per kg milk. The protein fraction respectively consisted of 117.7+/-44.8 g caseins per kg milk and of 40.6+/-6.7 g whey proteins per kg milk. Electrophoresis and identification of protein bands showed a similar migrating sequence of proteins as seen in cheetah and cat milk, with small differences in the beta-caseins. The lipid fraction contains 313.3+/-18.8 g saturated and 338.6+/-11.9 g mono unsaturated fatty acids per kg milk fat respectively. The high content of 292.4+/-24.9 g kg(-1) milk fat of polyunsaturated fatty acids is due to a high content in linolenic acid. No short chain fatty acids, but substantial levels of uneven carbon chain fatty acids were observed. In general, serval milk has a higher protein and fat content than that of the domestic cat and cheetah, and a lower content of unsaturated fatty acids than that of the domestic cat.