Coenzyme Q10 in maternal plasma and milk throughout early lactation

In contrast to other lipophilic antioxidants Coenzyme Q10 originates from food intake as well as from endogenous synthesis. The CoQ10 concentration and lipid content of maternal milk and maternal plasma was investigated during early lactation. Breast milk was obtained from 23 women: A: colostrums (24-48 hours postpartum), B: transitional milk (day 7 pp), C: mature milk (day 14 pp). At the same time capillary blood specimens were collected. Milk and plasma were stored at -84 degrees C until CoQ10 was analysed after hexane extraction by HPLC. The lipid content was determined by PAP-analysis of cholesterol. The plasma content of CoQ10 was the highest soon after delivery (A: 1.29, B:1.20, C:1.07 pmol/microl; Wilcoxon p < 0.05 A vs. C and B vs. C). This tendency was still evident after lipid-adjustment (A:209, B:180, C:175 micromol CoQ10/mol cholesterol; Wilcoxon p < 0.01 A vs. B and C). The level of CoQ10 in milk showed a gradual decline during early lactation (A:0.80, B:0.57, C:0.44 pmol/microl; Wilcoxon p < 0.02 A vs. B and C). After lipid-adjustment this tendency became even more evident (A: 137, B:86, C:67 micromol CoQ10/mol cholesterol; Wilcoxon p < 0.002 A vs. B and C, p < 0.05 B vs. C). The content of CoQ10 in plasma and milk showed a correlation with early milk (Spearman p < 0.005) but not with mature milk. Although lipid content is low the colostrums is a rich source for the lipophilic antioxidant CoQ10.     

大熊猫乳汁中富含游离精氨酸

采用高效液相色谱法测定了8只圈养大熊猫20个乳样中游离氨基酸的含量。结果显示:大熊猫初乳和常乳中均含有丰富的游离精氨酸,并且是含量最高的游离氨基酸;泌乳2-10d的大熊猫初乳中总游离氨基酸含量约为82mg/100ml,其中游离精氨酸平均含量达61mg/100ml,常乳中游离精氨酸含量约为54mg/100ml,均明显高于人、牛和藏绵羊乳;游离精氨酸在大熊猫干乳期乳腺分泌物中含量显著下降。推测乳中高水平的游离精氨酸在大熊猫幼仔生长发育中可能发挥重要作用[动物学报52(2):309-315,2006]。     

Human and bovine lactoferrins in the milk of recombinant human lactoferrin-transgenic dairy cows during lactation

Seven Friesian human lactoferrin (hLf)-transgenic primiparous dairy cows expressing recombinant hLf (rhLf) in their milk were included in the study. After calving, concentrations of rhLf and bovine LF (bLf) in the milk, somatic cell count and milk yield were determined. The concentration of rhLf was found to be constant, about 2.9 mg/mL, throughout the early lactation period of 3 months. The concentration of bLf in colostrum was higher after calving, but decreased rapidly during the first days of lactation. The mean concentration of bLf was 0.15 mg/mL, but concentrations varied between cows from 0.07 mg/mL to 0.26 mg/mL. Based on that, it may be possible to improve the non-specific host defence mechanism in the mammary gland of dairy cows by enhancing the content of rhLf in the milk.     

Selenium, zinc, and copper concentrations in the blood and milk of lactating women

The aim of the study was to determine Se, Zn, and Cu concentrations in blood plasma and milk of lactating women from central Poland who were in different stages of lactation and to investigate the relationship between the content of trace elements in mothers’ blood and concentrations of microelements in their milk. Se and Zn concentrations in blood plasma of mothers were the lowest and Cu was the highest on the first 4 d of lactation (colostrum, n=43) and were found to be 34.9±11.8 μg/L, 0.51±0.13 mg/L, and 1.70±0.55 mg/L, respectively. The highest plasma level of Se and Zn and the lowest content of Cu could be observed between d 10 and 30 of lactation (mature milk, n=41), and were found to be 54.3±14.6 μg/L for Se (p<0.001), 0.76±0.20 mg/L for Zn (p<0.001), and 1.03±0.30 mg/L (p<0.001) for Cu. The results of Se, Zn, and Cu determination in breast milk samples demonstrate a pattern of decline in their concentration with advancing stages of lactation. We found out that Se, Zn, and Cu concentrations were the highest in colostrum (n=43) and amounted to 24.8±10.1 μg/L, 8.2±2.8 mg/L, and 0.45±0.11 mg/L, respectively. The content of all determined microelements declined significantly during the time of lactation. Statistically significant linear correlation was found between concentrations of Zn in blood plasma and milk in the first stage of lactation. Weak but statistically significant linear correlations were also found between plasma Se content in plasma and in transitional and mature milk of breast-feeding women.     

Concentration of lactoferrin and transferrin throughout lactation in cow's colostrum and milk

The evolution of the concentration of lactoferrin and transferrin was studied in cow's colostrum and milk throughout lactation. The highest concentrations of both proteins were found in the first milking (0.83 mg/ml for lactoferrin and 1.07 mg/ml for transferrin), decreasing sharply during the first days of lactation (colostral period). Thereafter, the concentrations of these proteins decreased slowly, reaching their definitive values during the third week post-partum (0.09 mg/ml for lactoferrin and 0.02 mg/ml for transferrin). The ratio transferrin/albumin in colostrum (first milking), mature milk, milk from mastitic cows and serum was determined, and found to be four times greater in colostrum than in mature or mastitic milk, suggesting a specific transport of transferrin from blood to milk.     

Longitudinal study of the dietary selenium intake of exclusively breast-fed infants during early lactation in Korea and Japan.

213 samples of human breast milk were collected from 51 healthy Korean women. Selenium content of the samples was determined by atomic absorption spectrometry with hydride generation. The selenium content of Korean milk decreased with increase of days after birth: The arithmetic mean of selenium content was higher in colostrum (< 4 days) 34 micrograms/kg (SD +/- 11, n = 44) than in transitional milk 21 micrograms/kg (SD +/- 8, n = 78) or in mature milk (> 10 days) 13 micrograms/kg (SD +/- 6, n = 91). The daily dietary selenium intake of 0-1 month aged Korean infants fed on breast milk is estimated to be around 10 micrograms per day (3 micrograms/kg body weight) regardless of days postpartum, resulting from the calculation of our selenium data and daily milk intake during early lactation. The same result on selenium intake for Japanese newborns, as well as Korean infants, is also estimated to be around 10 micrograms per day (3 micrograms/kg body weight) regardless of days postpartum.     

Synthesis and evolution of concentration of beta-lactoglobulin and alpha-lactalbumin from cow and sheep colostrum and milk throughout early lactation

Synthesis of beta-lactoglobulin and alpha-lactalbumin by explants of ovine mammary gland and evolution of concentration of these proteins in cow and sheep colostrum and milk throughout early lactation have been studied. The evolution of both proteins was similar in cow and sheep species. The highest concentration was found in the first milking (19 and 2 mg/ml for beta-lactoglobulin and alpha-lactalbumin, respectively). Then, levels of beta-lactoglobulin decreased sharply and those of alpha-lactalbumin slowly during the first days of lactation, reaching stable values during the second week postpartum (4 and 1.5 mg/ml). The concentration ratio beta-lactoglobulin/alpha-lactalbumin was four times greater in colostrum than in mature milk. On the other hand, synthesis of these proteins represented about 25-30% of the synthesized total soluble proteins. The synthesis ratio beta-lactoglobulin/alpha-lactalbumin in explants obtained at 12 and 30 hours postpartum was found to be 3.5 and 1.7. These results indicate that the synthesis and secretion of beta-lactoglobulin are comparatively greater than those of alpha-lactalbumin during colostral period, suggesting that beta-lactoglobulin could have some specific function during this period.     

Changes of beta-casomorphin content in human milk during lactation

Milk is the best, complete food important for the development and nourishment of a neonate. Except for nutrients, milk contains biologically active opioid peptides derived from beta-casein, named beta-casomorphins (BCMs), which can exert effects in the gastrointestinal tract as well as in the whole body of neonates. The content of beta-casomorphins in human milk during maturation phases has not been studied so far. The aim of this study was to determine the content of beta-casomorphin-5 and -7 in human milk in different phases of lactation. A significantly higher concentration of both beta-casomorphins was found in colostrum than in mature milk. The concentration of beta-casomorphin in milk collected in the second month of lactation was similar to the level obtained in the fourth month of lactation. The content of beta-casomorphins in human milk was observed with the period of lactation. The level of opioid peptides may depend on the function of these peptides in neonate's body and may be associated with the maturation process.     

Cholesterol in human semen

1. The cholesterol content of human seminal plasma has been estimated in 200 samples. The mean concentration is 46.8mg./100ml. (s.e.m.+/-1.1, range 15-88). The free cholesterol corresponds to about 40% of the total. 2. Cholesterol in human semen is secreted almost entirely from the prostate gland.     

The mammary gland of the echidna, Tachyglossus aculeatus' with observations on the incubation of the egg and on the newly-hatched young

During the non-breeding season the lobules of the mammary glands consist of solid cords of cells which may occasionally be embedded in a pad of fat tissue.
During the breeding season some mammary glands can exhibit a tubular grade of organization and can even secrete milk without the intervention of pregnancy. Apparently the stimulus of pregnancy and incubation of an egg in the pouch is generally, but not invariably necessary for development of an alveolar grade of organization. The ducts leading from the lobules to the skin of the areola undergo hypertrophy during the course of lactation.
The present work shows that the gestation period is at least 16 days long but evidence in the literature shows it may be as long as 27 days. The incubation period of an egg in the pouch was found to be of the order of 10–10·5 days.
A newly-hatched echidna weighed 378 mg and was 1·47 cm long; it exhibited an egg tooth and the remains of foetal membranes attached to the abdomen. The newly-hatched had well-developed olfactory organs including sensory cells in the olfactory epithelium. The alimentary tract exhibited a degree of differentiation consistent with the notion that it could digest milk.
The fatty acid composition of the triglyceride fraction of a sample of milk taken just after hatching differed from that of mature milk in that the ratio of the concentration of oleic acid to palmitic acid in the early milk was about unity whereas it was 3·7 in mature milk. A high level of arachidonic acid may be a characteristic of the milk at hatching.
Iron was present in a concentration of 8·3 μg/ml in the early milk, and of 43·0 μ/mlg/ml in a sample of mature milk. The regression of the mammary glands from the alveolar to the solid-cord state is described.
Two corpora lutea of pregnancy, taken about 11 and 19 days after egg laying, were degenerate.     

Gangliosides in bovine milk. Changes in content and distribution of individual ganglioside levels during lactation.

Bovine milk undergoes changes in its ganglioside contents during the different stages of lactation. These contents are higher in colostrum (7.5 mg of lipid-bound NeuAc/kg) than in transitional (2.3 mg) or mature (1.4 mg) milk. The sialic acid content of milk follows a similar profile to that of gangliosides with the highest content during the first few days post partum followed by a gradual decrease towards the end of the period studied. When the individual distribution of gangliosides was examined throughout the course of lactation, several changes were also found. GD3 is the major ganglioside (about 60-70%) found; its content decreases from the first to the fifth day, increasing towards the end of the period considered. GM3, GD3 and GT3, sialyllactosylceramide-containing gangliosides account for 80-90% of the total lipid-bound NeuAc content. The most striking change in the ganglioside pattern was the gradual increase in G3.     

Mammary Specific Transgenic Over-expression of Insulin-like Growth Factor-I (IGF-I) Increases Pig Milk IGF-I and IGF Binding Proteins,with no Effect on Milk Composition or Yield

IGF-I regulates lactation by stimulating mammary mitogenesis, inhibiting apoptosis, and partially mediating the effects of growth hormone on lactogenesis. Herein, lactation performance during first and second parity was assessed in transgenic swine (TG) that over-expressed human IGF-I in milk under the control of the bovine α-lactalbumin promoter, regulatory regions and signal peptide coding sequence. Milk samples were collected throughout lactation (farrowing to d24) from TG sows and non-transgenic littermates (CON) and IGF-I, IGF-II, and IGFBP determined. Colostral (<24 h postpartum) IGF-I content was 26-fold greater (p < 0.001) in TG sows (949 ± 107 μg/L; range 228–1600 μg/L) than CON (36 ± 17.8 μg/L) and was 50- to 90-fold greater (p < 0.001) in mature milk (d2-24 postpartum). There was no effect of parity on milk IGF-I content. Milk IGF-II concentration was unaffected by IGF-I over-expression. Low molecular weight IGFBP (IGFBP-2 and -5) in the milk of TG sows were higher (p = 0.02) than CON in the early postpartum period, but did not differ in mature milk. Milk yield, determined by weigh-suckle-weigh, was similar in TG and CON as was litter weight gain. Milk nutrient composition was not significantly affected by IGF over-expression. Thus, mammary specific transgenic over-expression of IGF-I significantly increased milk IGF-I and IGFBP content, but did not impact lactation performance in swine.     

Leptin treatment during lactation increases transfer of iodine through the milk

We have previously shown that protein restriction during lactation is associated with changes in iodine secretion into the milk and that a pup's serum leptin concentration was increased at the end of lactation. So, here we evaluate whether leptin treatment during lactation affects iodine transfer through the milk to the pups. Lactating rats were divided into two groups: the leptin (Lep) group, single injected with recombinant rat leptin (8 microg/100g of body weight, daily for 3 consecutive days), and the control (C) group that received the same volume of saline. We studied iodine transfer to the pups through the milk on Days 4, 12 and 21 of lactation. In those days, the dams were separated from their pups for 4 h. Then, the mothers received an injection of 131I (2.22x10(4) Bq ip) and the pups were allowed to nurse for 2 h. The animals were sacrificed 2 h later. Leptin, total serum T3 and total serum T4 concentrations were higher (P<.05) in pups of Lep mothers only on Day 4, suggesting a higher transfer of leptin through the milk at this period, probably with a direct stimulatory effect on thyroid hormone secretion. In other periods, however, even without a detectable increase in a pup's serum leptin concentration, maternal leptin administration increased the pup's thyroid iodine uptake (Day 12, 39%; Day 21, 34%), probably caused by a higher transfer of iodine through the milk, since they had a higher gastric content of 131I on Days 12 (31%) and 21 (128%).     

Ribonucleic acids of human milk

The milk feeding is the most essential process laying the foundation of human health at the postnatal development. However little is known about nucleic acids secreted into mother's milk during lactation. In order to investigate the composition and abundance of human milk NA we adapted the conventional isolation method to achieve high yield of total nucleic acids from milk samples. Concentration of total NA in milk samples of different donors varies from 20 to 68 mkg/ml at early stages of lactation. The average concentration tends to fall down to the end of lactation. The chain length of the major forms of NA varies from mononucleotides up to approximately 100 bases. Compositions of milk oligonucleotides are similar in samples of different donors. Major milk oligonucleotides are formed of RNA. Human milk contains the set of long-chain oligonucleotides with a developed secondary structure. Sequences of some oligo-RNAs correspond to the 3'-part of 5.8 S human ribosomal RNA and to the 3'-parts of tRNAVal and tRNATyr Primary structures of some others oligo-RNAs were related to fragments of human 18S and 28S rRNAs.     

Leptin in bovine colostrum and milk.

We studied leptin content in bovine colostrum, milk and plasma during the first month of lactation, and investigated relationships between selected milk components and milk leptin in five multiparous dairy cows. Colostrum/milk yield and composition were measured on days 0, 10, 20, and 30 of lactation. Leptin was assayed using a multi-species leptin RIA kit. Leptin concentration was 56 % lower in mature milk (day 10) than colostrum (13.90 vs. 6.14 microg/l; p < 0.001), but remained steady over the twenty days afterwards. Daily secretion of leptin into mature milk was 28 % lower than into colostrum (173.2 microg/d vs. 220.0 microg/d; p = 0.09) notwithstanding an 80 % increase in production. Colostrum and milk leptin levels correlated with fat (0.90; p < 0.001) and choline phospholipid (0.76; p < 0.05). Plasma and milk leptin decreased during the first month, but remained higher in milk, and highest in colostrum. Thus, leptin is present in large quantities in colostrum, less so and more variably in untreated milk, and is likely to be decreased in skimmed milk. These findings have implications for the use of untreated milk and colostrum-based (functional) food products.     

Southern elephant seals: IgM concentration in milk of cows and serum of their pups

Serum and milk Immunoglobulin M (IgM) concentrations in 11 mother-pup pairs were measured in southern elephant seals (Mirounga leonina) throughout lactation during 2 breeding seasons at King George Island. Samples were obtained sequentially throughout the suckling period (approximately 23 days). The IgM concentration was measured by single radial immunodiffusion on agarose plates. Milk IgM concentrations showed significant differences throughout lactation, with the highest concentrations on the 1st day (x=989.7 mg/dL skimmed milk; SD=433.2) followed by a sharp fall during the next 3–6 days of the suckling period. The ratio of milk IgM/serum IgM concentrations from mothers ranged from 0.21 to 21.92, with highest values in the 1st day of lactation (x=8.25, SD=5.4) and a decrease in concentration as lactation progressed. This was due to the fact that, throughout lactation, milk IgM concentrations fell while serum IgM values showed an increasing trend. Pups showed the lowest serum IgM values in the 1st day of the suckling period (x=13.0 mg/dL, SD=4.3) with an increasing trend as lactation progressed. Despite the high IgM concentrations of milk at day 1 of lactation, by 1 week of age pups had serum IgM concentrations only slightly greater than at birth. This suggests that much of this Ig was newly formed and little or no milk IgM was absorbed during the 1st week. Possibly, the function of ingested IgM is to provide local immunity in the pup's gut, during the first few days of postnatal life. Accepted: 26 March 2000     

Qualitative and quantitative changes in milk fat during lactation in the tammar wallaby (Macropus eugenii)

There are major quantitative and qualitative changes in the milk lipids during lactation in the tammar wallaby, Macropus eugenii. The crude lipid content of the milk is relatively low during the first 10 weeks of lactation; between 10 and 26 weeks post partum the lipid content increases gradually but after that it increases rapidly. The triglyceride fraction of the lipid at early stages of lactation contains a large amount of palmitic acid and relatively little oleic acid whereas mature milk exhibits little palmitic and much oleic acid. In the early stages of lactation fat represents 15% of the total solids and carbohydrate 55%; around 26-30 weeks post partum the carbohydrate moiety falls sharply to a level less than 2% of the solids while lipids increase to c. 60% of the solids. These changes coincide with increases in milk solids, emergence of the young from the pouch, ingestion of herbage, and fermentation of cellulose in the stomach.     

Ribonucleic Acids of Human Milk

The milk feeding is the most essential process laying the foundation of human health at the postnatal development. However little is known about nucleic acids secreted into mother's milk during lactation. In order to investigate the composition and abundance of human milk NA we adapted the conventional isolation method to achieve high yield of total nucleic acids from milk samples. Concentration of total NA in milk samples of different donors varies from 20 to 68 mkg/ml at early stages of lactation. The average concentration tends to fall down to the end of lactation. The chain length of the major forms of NA varies from mononucleotides up to approximately 100 bases. Compositions of milk oligonucleotides are similar in samples of different donors. Major milk oligonucleotides are formed of RNA. Human milk contains the set of long‐chain oligonucleotides with a developed secondary structure. Sequences of some oligo‐RNAs correspond to the 3′‐part of 5.8 S human ribosomal RNA and to the 3′‐parts of tRNAVal and tRNATyr Primary structures of some others oligo‐RNAs were related to fragments of human 18S and 28S rRNAs.     

Using post-grazing sward height to impose dietary restrictions of varying duration in early lactation: its effects on spring-calving dairy cow production

The objective of this study was to investigate the immediate and carryover effects of imposing two post-grazing sward heights (PGSH) for varying duration during early lactation on sward characteristics and dairy cow production. The experiment was a randomised block design with a 2×2 factorial arrangement of treatments. A total of 80 spring-calving (mean calving date – 6 February) dairy cows were randomly assigned, pre-calving, to one of the two (n=40) PGSH treatments – S (2.7 cm) and M (3.5 cm) – from 13 February to 18 March, 2012 (P1). For the subsequent 5-week period (P2: 19 March to 22 April, 2012), half the animals from each P1 treatment remained on their treatment, whereas the other half of the animals switched to the opposing treatment. Following P2, all cows were managed similarly for the remainder of the lactation (P3: 23 April to 4 November, 2012) to measure the carryover effect. Milk production, BW and body condition score were measured weekly, and grass dry matter intake (GDMI) was measured on four occasions – approximately weeks 5, 10, 15 and 20 of lactation. Sward utilisation (above 2.7 cm; P1 and P2) was significantly improved by reducing the PGSH from 3.5 (0.83) to 2.7 cm (0.96). There was no effect of PGSH on cumulative annual grass dry matter (DM) production (15.3 t DM/ha). Grazing to 2.7 cm reduced GDMI by 1.7 and 0.8 kg DM/cow in P1 and P2, respectively, when compared with 3.5 cm (13.3 and 14.0 kg/cow per day, respectively). Cows grazing to 2.7 cm for both P1 and P2 (SS) tended to have reduced cumulative 10-week milk yield (−105 kg) and milk solids yield (−9 kg) when compared with cows grazing to 3.5 cm for both periods (MM; 1608 and 128 kg/cow, respectively). Treatments that alternated PGSH at the end of P1, SM and MS had intermediate results. There was no interaction between P1 and P2 treatments. There was also no carryover effect of early lactation grazing regime on milk and milk solids production in P3, given the reduction in early lactation milk yield. The results indicate that the diet of dairy cows should not be restricted by imposing a severe PGSH for all of the first 10 weeks of lactation, cows should graze to 3.5 cm for at least 5 of these weeks.     

Choline and Choline Metabolite Patterns and Associations in Blood and Milk during Lactation in Dairy Cows

Milk and dairy products are an important source of choline, a nutrient essential for human health. Infant formula derived from bovine milk contains a number of metabolic forms of choline, all contribute to the growth and development of the newborn. At present, little is known about the factors that influence the concentrations of choline metabolites in milk. The objectives of this study were to characterize and then evaluate associations for choline and its metabolites in blood and milk through the first 37 weeks of lactation in the dairy cow. Milk and blood samples from twelve Holstein cows were collected in early, mid and late lactation and analyzed for acetylcholine, free choline, betaine, glycerophosphocholine, lysophosphatidylcholine, phosphatidylcholine, phosphocholine and sphingomyelin using hydrophilic interaction liquid chromatography-tandem mass spectrometry, and quantified using stable isotope-labeled internal standards. Total choline concentration in plasma, which was almost entirely phosphatidylcholine, increased 10-times from early to late lactation (1305 to 13,535 µmol/L). In milk, phosphocholine was the main metabolite in early lactation (492 µmol/L), which is a similar concentration to that found in human milk, however, phosphocholine concentration decreased exponentially through lactation to 43 µmol/L in late lactation. In contrast, phosphatidylcholine was the main metabolite in mid and late lactation (188 µmol/L and 659 µmol/L, respectively), with the increase through lactation positively correlated with phosphatidylcholine in plasma (R ² = 0.78). Unlike previously reported with human milk we found no correlation between plasma free choline concentration and milk choline metabolites. The changes in pattern of phosphocholine and phosphatidylcholine in milk through lactation observed in the bovine suggests that it is possible to manufacture infant formula that more closely matches these metabolites profile in human milk.