Amino Acids In Milk Research Articles

Effect of high-concentrate diet on amino acid transporter expression and milk quality in Holstein dairy cows

In order to evaluate the effect of high-concentrate diet supplementation on milk protein content, six Holstein dairy cows were assigned into high-concentrate diet (HC) or low-concentrate diet (LC) groups (N = 3/group) for 50 days. With regard to milk protein, HC feeding significantly reduced the percentage of milk protein (P < 0.01), and milk protein yield also reduced. The milk somatic cell count numbers and N-acetyl-D-glucosaminidase activity was significantly higher (P < 0.01) in the HC group than in the LC group. A pre-column derivatization procedure of o-phthalaldehyde was used to analyze the milk amino acid profile, the contents of Asp, Gln, Ala, Ile, Leu, and Lys were significantly lower in milk (P < 0.05), but Arg and Phe were significantly higher (P < 0.05) in the HC group than in the LC group. The mRNA abundance for amino acid transporters SLC7A8, SLC7A10 (P < 0.05), SLC1A3 (P < 0.05), and SLC16A10 (P < 0.05) were decreased in the HC group. These data indicate that expression of amino acid transporters alters regulation of amino acid utilization and decreases milk quality in dairy cows.

Incorporation of endogenous urea nitrogen into amino acids of milk in goats fed diets with various protein levels

Incorporation of endogenous urea nitrogen into amino acids of milk in goats fed diets with various protein levels

Glutamine and glutamate (AminoGut) supplementation influences sow colostrum and mature milk composition

Glutamine and glutamate are the most abundant amino acids in milk and play important roles in neonatal development and growth. Glutamine and glutamate supplementation to both suckling and weanling piglets has beneficial effects on growth and health and we have previously demonstrated that such supplementation to the lactating sow can increase milk glutamine and glutamate content. This work was designed to determine if glutamine and glutamate (AminoGut) supplementation to lactating sows resulted in other changes in milk composition. Sows were provided with a conventional diet with or without 1.5% AminoGut from one week prior to parturition through the end of lactation (day 21). Compared with control pigs supplementation with AminoGut resulted in 60% higher fat content in colostrum, and although there was no significant difference in milk fat content between control and AminoGut supplemented pigs at day 7 of lactation, milk fat content was 33% higher in the AminoGut supplemented pigs at day 21 of lactation. On day 7 of lactation the somatic cell count (SSC) was approximately 55% higher in milk from the AminoGut supplemented pigs when compared with that from control pigs. In milk from control pigs the SSC dropped between days 7 and 21 of lactation but remained elevated in milk from AminoGut supplemented pigs throughout lactation. Milk protein, lactose and total milk solids were not influenced by AminoGut supplementation. Milk glutamine content was higher in AminoGut supplemented pigs throughout lactation. Thus supplementation with glutamine and glutamate to the sow resulted in major differences in glutamine and lipid content of the milk, both of which would be predicted to benefit the suckling piglet particularly at the time of abrupt weaning.

Účinek vybraných obilnin obsažených v krmné dávce na obsah aminokyselin v mléce

The aim of this study was to evaluate the possible effects of maize replacement in feeding rations on the amino acid content in cows´ milk. Cows were fed total mix ration based on the maize, clover silage and hay. There was a difference in the concentrate of the feeding ration. The first group (fed maize) was the control group, another two groups were experimental, one fed wheat and second fed triticale. During six weeks, totally 26 milk samples were taken from dairy cows of Czech Pied breed. Feed groups were preferably balanced in terms of milk yield, stage and number of lactations. The samples of feedstuffs as well as milk were modified for the analysis using acidic and oxidative hydrolyses. The analysis of amino acids content and composition of the sample hydrolysates was performed chromatographically by an AAA 400 analyzer, using Na-citrate buffers and ninhydrin detection. Total nitrogen content was determined according to Kjehldahl and the crude protein of the samples was determined by conversion from the nitrogen content multiplied by appropriate factor. The high content of crude protein in wheat did not influenced composition of milk from dairy cows fed this type of feedstuff. With respect to resulting amino acid content and composition of milk samples, none of the tested grains can be re­com­men­ded as a full-value maize replacement. Each feedstuff is an abundant source of several and ty­pi­cal amino acids in milk. However, triticale (cultivar Kitaro) seems to be acceptable replacement of maize owing to better crude protein efficiency, composition and health indicators of milk quality.

Variations in protein and fat contents and their fractions in milk from two species fed different forages

This study aimed at determining the variations in milk constituents which could be varied by feed and animal species. To achieve this goal, two groups of homoparity Baladi cows and Egyptian buffaloes (n = 20 per species) were used. Each group was divided into two subgroups (n = 10): subgroup I received legume forage (Egyptian clover) and subgroup II received grass forage (sorghum forage). All experimental animals were fed the diet consisting of concentrate, forage and rice straw as 50, 25 and 25% of dry matter intake respectively. Milk samples were taken for analysis. The trial lasted until the 3rd month of parturition. The main results indicated that lactating cattle fed legume forage significantly (p ≤ 0.01) had more content of casein nitrogen (513 mg/100 ml milk), lower content of glutamic acid (23.56 g/100 g milk protein) and more content of cis-9, trans-11 18:2 conjugated linoleic acid (CLA) (0.77 g/100 g milk fat) compared with 433, 26.67 and 0.53, respectively, for cattle fed grass forage. With regard to the species effect, results showed that buffalo milk appeared to contain significantly higher (p ≤ 0.01) contents of casein nitrogen, phenylalanine, glutamic and arachidonic acid compared with cow's milk. However, the latter was significantly (p ≤ 0.01) more in the cis-9, trans-11CLA (0.59 g/100 g milk fat) than that in buffalo milk (0.47 g/100 g milk fat). The results revealed that not only forage type played a critical role in determining the variations of milk nitrogen distribution, milk amino acids and fatty acids but also animal species had a significant effect on these parameters.

Free amino acid content in breast milk of adolescent and adult mothers in Ecuador

Because of increased incidence of teenage births and high prevalence of lactation in Latin America, we determined the patterning of free amino acids (FAAs) in breast milk of 65 primiparous Ecuadorian women of varying ages (14–27 years). An automatic amino acid analyzer quantified levels of FAAs in milk samples obtained at three lactation stages: colostrum, transition, and mature milk. Regardless of mother’s age, most FAAs increased with time postpartum, with taurine, glutamic acid, glutamine, and alanine being most abundant in all stages.

Evolution of the circadian profile of human milk amino acids during breastfeeding

Summary Human milk is a living fluid that changes with time, composition and volume. Circadian rhythms regulate a variety of biological processes in living organisms; and perhaps the most evident function is the sleep-wake cycle. The aim of the present study was to evaluate the circadian rhythm of breast milk amino acids and their evolution throughout the breastfeeding period. Human breast milk samples from 77 donors were collected every 3 hours over a 24-h period. The rhythmicity of the amino acids was determined by cosinor analysis. Colostrum samples showed no circadian rhythm in most amino acids except tryptophan. However, daily variations were observed in tryptophan and methionine at transitional phase, according to the newborn’s pattern of intake every 3 hours regardless of whether it is day or night. During the last stage (mature milk), when breast milk has fully stabilized, most amino acids showed a circadian rhythm. In conclusion, breast milk should be given to the baby at the same time of day it is expressed. Thus, the baby would be adjusting its circadian pattern in harmony with his environment (day/night), which is crucial for the proper functioning and synchronization of all systems in the human body.

Effect of distillers dried grains with solubles diet supplemented with rumen‐protected lysine and methionine on milk production and milk amino acids in the lactating cow

This study was to quantify the milk protein and amino acids (AA) in response to rumen‐protected lysine (Lys) and methionine (Met) supplementation in dairy cows fed distillers dried grains with solubles (DDGS) diet. Forty cows were divided into five dietary treatments: soybean meal diet (SM), DDGS diet and DDGS diets with 40 g/day Lys (DL), 20 g/ day Met dry matter (DM) and 20 g/ day Met plus 40 g/ day Lys (DLM), separately. Compared with SM, DL and DM groups, DLM group increased milk yield, 4% fat‐corrected milk, energy‐corrected milk yield and protein in milk. DDGS treatments increased total AA and the essential AA in milk. Results indicated that dietary DDGS increased intestinal supplies of Lys and Met.

GLUTAMINE, BUT NOT GLUTAMATE, CONCENTRATIONS CHANGE IN EQUINE MILK DURING LACTATION

Recently it has been realized that glutamine (gln) and glutamate (glu) are the most abundant amino acids in mammalian milk. The aim of this study was to determine the gln and glu concentration in blood and milk in Quarter‐Horse mares during lactation. Nineteen (19) mares were used and samples were collected: after 8 hours parturition, and every 30 days until weaning (180 days after birth). Data were analyzed by ANOVA and Tukey's test, with P&lt;0.05. Blood [glu] was 0.289±0.047 mol/mL at parturition day and when was 0.146+0.117 mol/ml at the end of the lactation, without significant changes (P&gt;;0.05). In contrast, blood [gln], which was 0.582+0.078mol/mL at parturition, decreased to 0.300±0.032mol/mL at weaning (~52%). In milk, [gln] was 0.738+0.113 mol/ml 8h after delivery, increase to 1.333±0.198 mol/ml at 3 months of lactation, and then decreased to 0.511±0.098 mol/mL at weaning. Also, [glu] changes significantly, with large concentration observed at 3rd month of lactation (0.862±0.085 mol/ml) and lowest at parturition (0.449±0.057 mol/ml). These changes in blood and milk gln content indicate major changes in glutamine but the site of synthesis, skeletal muscle or mammary gland remains to be determined.

Evaluation of Amino Acids in the Milk Preparations from Tiger Nut Rhizome and Its Mixed Varieties

The amino acid composition of yellow and brown tiger nut (Cyperus esculentus) milk preparations and their mixtures were studied. The mixed variety was prepared from mixing equal proportion of the two varieties. The milk preparation was obtained by blending and subsequent expression of the milk.. Protein analysis stated with the hydrolysis of the milk preparation with HCl for 23hrs and the resulting amino acids were quantified with amino acid analyzer (Technicom TSM-1). The % nitrogen for the yellow, Brown and the mixture are 3.72, 3.24 and 2.22 respectively. Arginine has the highest value of 15.87, 16.22 and 19.20 g/100g respectively conferring same order of amino acid basicity. Methionine and tyrosine are the lowest (0.60 and 0.63, 0.68 and 0.48, 0.49 and 0.48 g/100g protein) respectively. Tryptophan is not prominently associated with the myriad of essential amino acids of tiger nut milk. It was not detectable in any of the varieties. The overall result of the study showed that the tiger nut milk is a rich source of protein. It can also be consumed as a valuable substitute for conventional cow milk and other known milk sources. The milk prepared from mixed variety exhibited synergistic effect as it combined some beneficial amino acid that either of the two varieties lacks.

Large molecule protein feeding during the suckling period is required for the development of pancreatic digestive functions in rats

We examined if large molecule protein feeding during the suckling period is prerequisite for the proper development of pancreatic digestive functions. Most amino acids in breast milk exist as the constituent of large proteins and not as oligopeptides or free amino acids. Accumulating evidence indicates the nutritional importance of large protein feeding for suckling infants; however, evidence on the physiological significance remains small. We thus artificially reared rat pups on a standard rat formula with milk protein or a formula with milk protein hydrolysate from 7 to 21 days of age, and thereafter, fed a standard solid diet until 42 days of age. Pancreas weight and the stock of pancreatic digestive enzymes in the hydrolysate-fed rats were significantly lower than those in the protein-fed rats during and also after the suckling period. Plasma insulin, a stimulator of amylase synthesis, was also significantly low in the hydrolysate-fed rats compared with the protein-fed rats. At 28 days of age, we evaluated the pancreatic secretory ability in response to dietary protein and cholecystokinin (CCK) by means of pancreatic duct cannulation. Pancreatic secretion stimulated by dietary protein in the hydrolysate-fed rats was significantly weaker than that in the protein-fed rats. No significant difference was observed in the increasing rate of pancreatic enzyme secretion in response to CCK between the two groups. These results suggest that the presence of large proteins in breast milk is significant for the development of pancreatic digestive functions and the outcomes could remain even later on in life.

Rapid Determination of Free Amino Acids in Milk by Microchip Electrophoresis Coupled with Laser‐induced Fluorescence Detection

AbstractA simple and sensitive method for determination of free amino acids in milk by microchip electrophoresis (MCE) coupled with laser‐induced fluorescence (LIF) detection was developed. Seven kinds of standard amino acids were derivated with sulfoindocyanine succinimidyl ester (Cy5) and then perfectly measured by MCE‐LIF within 150 s. The parameters of MCE separation were carefully investigated to obtain the optimal conditions: 100 mmol·L−1 sodium borate solution (pH 10.0) as running buffer solution, 0.8 kV as injection voltage, 2.2 kV as separation voltage etc. The linear range of the detection of amino acids was from 0.01 µmol·L−1 to 1.0 µmol·L−1 and the detection limit was as low as about 1.0 nmol·L−1. This MCE‐LIF method was applied to the measurements of free amino acids in actual milk samples and satisfactory experimental results were achieved.

Intraoperative placement of transnasal small intestinal feeding tube during the surgery in 5 cases with high position intestinal obstruction and postoperative feeding

To explore the value of employing the small intestinal feeding tube in treating high position intestinal obstruction of newborn infant. Five newborn infants (3 males and 2 females; 1 premature infant and 4 fully-mature infants; 2 had membranous atresia of duodenum, 1 had annular pancreas, and 2 had proximal small intestine atresia; 1 infant had malrotation). The duodenal membrane-like atresia and the blind-end of small intestine were removed and intestinal anastomosis was performed, which was combined with intestinal malrotation removal. Before the intestinal anastomosis surgery, the anesthetist inserted via nose a 6Fr small intestinal ED tube, made by CREATE MEDIC CO LTD of Japan[ the State Food and Drug Administration-instrument (Im.) 2007-NO.2661620]. Twenty-four hours after surgery, abdominal X-ray plain film was taken and patients were fed with syrup; 48 hours later, formula milk was pumped or lactose-free milk amino acids were given by intravenous injection pump through the feeding tube. The amount of milk and fluids was gradually increased to normal amount according to the condition. In initial 3 days the intravenous nutrition was given and one week after operation, the infants were fed through mouth in addition to pumping milk through the tube and stopped infusion. Ten to 22 days after operation, the tube was removed and the infant patients were discharged. All the five infants showed that the feeding through the nutrition tube was accomplished and the time of venous nutrition was reduced and fistula operation was avoided. None of the infants on question was off the tube and no jaundice exacerbation was found and the liver function was also found normal. At the very beginning, the tube was occasionally blocked by milk vale in one infant and after 0.9% sodium chloride solution flushing patency restored. After that, the feeding tube was washed once with warm water after feeding. In one infant vomiting occurred due to enough oral milk. The photograph of upper gastrointestine did not show anastomomotic stricture or fistula, or intestinal obstruction. After pulling out the tube, the symptoms disappeared and then the patient was discharged. One child was found to have diarrhea with no lactose nutrition liquid and given compound lactic bacteria preparations for oral administration, the symptom disappeared. In the 5 cases, the shortest hospital stay was 10 days and the longest was 22 days, the average stay was 16 days. Three to 5 days after operation the weight restored to birth weight, the weight had increased, when discharged, to an average of 5.5 g (kg·d). The small intestinal feeding tube was very effective for the postoperative nutrition maintenance of high position intestinal obstruction in newborn infants.

Differences in the composition of total and whey proteins in goat and ewe milk and their changes throughout the lactation period

This study was conducted to evaluate changes in composition of whey proteins of Czech White Short-haired goat and East Friesian ewe milk and their comparison throughout lactation. Some differences in composition between ewe and goat milk were found. The results showed that the mean total protein (%), whey protein (g/100 g), and &amp;beta;-lactoglobulin (&amp;beta;-Lg, g/100 g) contents of goat milk were 2.75, 0.433, and 0.119 respectively and of ewe milk 6.36, 1.11, and 0.732 respectively. The contents of total protein as well as acid whey proteins in goat milk were nearly constant throughout the lactation period and fluctuated around the mean value while the contents of total protein as well as acid whey proteins in ovine milk were dependent on the period of lactation. The total protein content in ovine milk continuously increased during the lactation period. A higher content of ovine acid whey proteins was noticed at the beginning and in the final period of lactation. The average ratio of whey to total protein was 15.8  2.61% in goat milk and 17.4  2.68% in ewe milk and ranged from 13.0 to 20.4% in goat and from 14.0 to 20.8% in ewe milk. The total contents of two major whey proteins. &amp;alpha;-lactalbumin and &amp;beta;-lactoglobulin (&amp;alpha;-La + &amp;beta;-Lg = AG), averaged 87% of total whey protein, 92% in ovine milk. The main component of acid whey proteins in goat milk was &amp;alpha;-La while in ovine milk the main component of acid whey proteins was &amp;beta;-Lg, however, at the end of the lactation period the content of &amp;beta;-Lg for both kinds of milk increased steeply, and the &amp;beta;-Lg/&amp;alpha;-La ratio reached a maximum value of 1.94 in goat milk and of 9.74 in ewe milk. In addition, goat milk contains a similar amino acid profile to ewe milk but the amino acid pattern in whey proteins differs from that in milk. Total essential amino acids were approximately 40% of the total amino acids in goat and ewe milk as well as in goat and ewe whey. &amp;nbsp; &amp;nbsp;

Concentration of Free Amino Acids in Human Milk of Women with Gestational Diabetes Mellitus and Healthy Women

It is generally agreed that breastfeeding has a positive effect on the metabolic situation in diabetic mothers. However, negative long-term effects are described for breastfed offspring of diabetic women. It is unknown if the composition of free amino acids (FAAs) in breastmilk of women with gestational diabetes mellitus (GDM) differs from that in milk of healthy women. We studied the amount of FAAs in breastmilk of women with GDM and women with normal glucose tolerance (NGT). Human milk samples of 68 women (21 GDM and 47 NGT) were analyzed. Contents of FAAs in milk samples, obtained within the first 4 days after delivery (colostrum) and 6 weeks later (mature milk), were analyzed using high-performance liquid chromatography. Total amounts of FAAs in colostrum and in mature milk were compared between the groups. The impact of maternal age, body mass index (BMI), gestational age at birth, birth weight, and diagnosis of GDM on the total amount of FAAs was evaluated. Overall, the total amount of FAAs increased significantly from colostrum to mature milk in both groups (p<0.001). The total amount of FAAs did not significantly differ between GDM and NGT in colostrum and in mature milk (1,560 μmol/L vs. 1,730 μmol/L and 2,440 μmol/L vs. 2,723 μmol/L, respectively). No significant influence on the total amount of FAAs at both measurements of maternal age, BMI, gestational age at birth, birth weight, and diagnosis of GDM could be observed by regression analyses. The content of FAAs of human milk does not significantly differ between women with GDM and women with NGT.

Dietary supplementation with monosodium glutamate (MSG) is safe and improves growth performance in postweaning pigs

Glutamate is an abundant free and peptide‐bound amino acid in porcine milk to support growth and development of the piglet small intestine. However, after weaning, dietary intake of glutamate is markedly reduced due to low feed consumption. Piglets were weaned at 21 d of age to a corn‐ and soybean meal‐based diet supplemented with 0, 0.5, 1, 2, and 4% MSG (n=10/group). MSG was added to the diet at the expense of cornstarch. At 42 d of age, blood samples (10 mL) were obtained from the jugular vein of pigs at 1 and 4 h after feeding for hematological and clinical chemistry tests, and then pigs (n=6/group) were euthanized to obtain tissues for histopathological examinations. Feed intake did not differ among the 5 groups of pigs. Compared with the control, dietary supplementation with 2 and 4% MSG increased (P &lt; 0.05) weight gains of postweaning pigs by 10.2% and 15.5%, respectively. All variables in standard hematology and clinical chemistry tests did not differ among the 5 groups of pigs. Likewise, dietary supplementation with up to 4% MSG did not result in gross or microscopic lesions in any tissues examined, including brain, spinal cord, heart, lungs, spleen, liver, kidneys, adrenal gland, stomach, cecum, small intestine, large intestine, gonads, and bone marrow. We conclude that dietary MSG supplementation is safe and improves growth performance in postweaning pigs. (Supported by International Glutamate Technical Committee)

Glutamine and glutamate supplementation raise milk glutamine concentrations in lactating gilts

Glutamine is the most abundant amino acid in milk, and lactation is associated with increased glutamine utilization both for milk synthesis and as a fuel for the enlarged small intestine. A number of recent studies have indicated that lactation is accompanied by a mild catabolic state in which skeletal muscle proteins are degraded to provide amino acids that are used to synthesize additional glutamine. In this study we tested the hypothesis that supplemental L-glutamine or the commercially available glutamine supplement Aminogut (2.5% by weight mixed into daily feed) provided to gilts from 30 days prior to parturition until 21 days post-parturition would prevent a decrease in skeletal muscle glutamine while increasing the glutamine content of the milk. Muscle glutamine content decreased (P < 0.05) in control animals during lactation but this was prevented by supplementation with either L-glutamine or Aminogut. In this study, neither lactation nor supplementation had any effect on plasma glutamine or glutamate content. Free glutamine, and the total glutamine plus glutamate concentrations in milk from the control and the Aminogut group rose (P < 0.05) during the first 7 days of lactation, with milk concentrations in the L-glutamine supplemented group showing a similar trend (P = 0.053). Milk glutamate remained constant between day 7 and 21 of lactation in the control and L-glutamine supplemented groups, but by day 21 of lactation the free glutamine, glutamate, and glutamine plus glutamate concentrations in milk from Aminogut-treated gilts were higher than those of control gilts. Thus dietary glutamine supplementation can alleviate the fall in intramuscular glutamine content during lactation in gilts, and may alleviate some of the catabolic effects of lactation. Furthermore, the increased milk glutamine content in the supplemented gilts may provide optimum nutrition for piglet development.

Breastfeeding: More Than Just Good Nutrition

Breastfeeding: More Than Just Good Nutrition

Screening for Human Milk Amino Acids by HPLC-ESI-MS/MS

Amino acids have a determining effect on the nutritional status of the newborn, and their appropriate levels in breast milk are vital for this first stage of life. The amino acids tryptophan, arginine, glutamate, and taurine, for example, are suggested to have a positive effect on immune functions. The purpose of the present study was to develop a new method for the assay of amino acids in human milk by high-performance liquid chromatography–electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) after hydrolysis. Breast milk samples were collected from 77 healthy mothers living in the community of Extremadura (Spain) with less than 2 months of lactation. The samples were then stored at −80 °C. The HPLC-ESI-MS/MS technique proved to be a sensitive and efficient tool for the assay of amino acids in breast milk. The method could be used for the qualitative screening of 40 underivatized amino acids, and for the assay of 20. The resulting data will serve to improve commercial infant formula milks and bring them closer to the reference standard represented by human milk.

Lifestyle Modification to Promote Weight Loss in the Absence of Energy Restriction

Lifestyle Modification to Promote Weight Loss in the Absence of Energy Restriction