J. Csapó

Protein, fats, vitamin and mineral concentrations in porcine colostrum and milk from parturition to 60 days

Abstract The concentrations of protein, protein fractions, amino acids, total solids, fat, fatty acids, fat soluble vitamins (A, D3, E, K3), vitamin C, macro- and micro-elements and biological value of colostrum and milk of 10 Danish Large White, 10 Danish Duroc and 10 Norwegian Landrace sows were determined. The total protein content of the first colostrum (16.65%) was approximately three times the level in milk at the end of lactation (5.83%). All protein fractions decreased during lactation, with the exception of casein, which reached its maximum between 24–72 h of lactation with a value of 3.4−3.6%, and non-protein nitrogen, which increased from the beginning (0.41%) to the end of lactation (0.47%). Significant differences were observed between the free amino acid content of colostrum and milk. Colostrum contained less acidic and hydroxy, and more basic amino acids than milk. The concentrations of amino acids in colostrum and milk, similar to the change in total protein, decreased during lactation. However, when amino acid concentrations were expressed as g AA 100 g−1 protein, most of the essential amino acids (threonine, cystine, valine) decreased, while the non-essential glutamic acid and proline increased. This explains why the biological value of colostral protein was approximately 11% higher during the first 5 days of lactation (118–129) than that of milk protein on the 10–60th days of lactation. The first colostrum contained 24.03% total solids and 5.32% fat; these increased to 27 and 13.1%, respectively, at 48–72 h, but decreased afterwards to 18.7 and 6.5%, respectively, at the end of lactation. The fat of sows milk contained only very low concentrations (in fact just above the limit of identification) of saturated fatty acids with 4–12 C. Sows milk contained significantly more unsaturated fatty acids than cows milk; particularly large differences were found in the case of linolenic acid. Sows milk contained more ash (0.843%), calcium (1965 mg kg−1), phosphorus (1510 mg kg−1), zinc (6.49 mg kg−1), iron (2.44 mg kg−1) and copper (1.34 mg kg−1), and less potassium (748 mg kg−1), sodium (387 mg kg−1) and magnesium (111 mg kg−1) than cows milk, while there were no differences between the two species in manganese content. Potassium, sodium, iron and copper contents decreased, while the concentrations of calcium and phosphorus increased during lactation. The concentrations of vitamins A, D3, E, K3 and C in colostrum were 1.61, 0.015, 3.69, 0.092 and 68.4 mg kg−1 respectively, and with the exception of vitamin K3, were 1.5−2.0 times the levels in late lactation milk (0.92, 0.009, 2.53, 0.089 and 45.3 mg kg−1). These concentrations of vitamins in sows milk were 2–3 times those in cows milk. There were no significant differences among breeds or interaction between breeds and sampling dates relative to the composition of colostrum and milk samples.

Composition of mares' colostrum and milk. Fat content, fatty acid composition and vitamin content

Changes in the fat content, fatty acid composition and vitamin contents of mares colostrum and milk during the flrst 45 days of lactation were studied. Milk samples (300{800 ml) from 29 lactat- ing mares, were collected daily at the beginning of the lactation and weekly from 5 to 45 days postpartum. Colostrum and early milk samples were obtained by hand, without oxytocin administration, while the foal nursed. Later milk samples were from mixed milk of the totally-milked udder. Each sample was analysed for total solids, fat content, fatty acid

Composition of mares' colostrum and milk. Protein content, amino acid composition and contents of macro- and micro-elements

Changes in the protein content, protein fractions and amino acid composition of mares colostrum and milk, and biological value of milk protein during the flrst 45 days of lactation were studied. Milk samples (averaging 300{800 cm 3 ) from 29 lactating mares were collected daily at the beginning of the lactation and weekly from the 5 th to 45 th days post-partum. Colostrum samples were obtained by hand milking without oxytocin administration, while the foals nursed and milk samples

Composition of colostrum from goats, ewes and cows producing twins

Abstract Colostra from 11 single- and 7 twin-lambing Hungarian merino ewes, 6 single- and 4 twin-dropping Hungarian white goats and 32 single- and 32 twin-calving Hungaro-Friesian and Holstein-Friesian cows were analysed for dry matter, total protein, true protein, whey protein, true whey protein, immunoglobulin-G, casein, amino acid composition, biological value, micro- and macro elements and non-protein nitrogen content as a function of time post-partum. The first milked colostrum of the twin-producing animals contained significantly more dry matter, total protein, true protein, whey protein, true whey protein and immunoglobulin-G than that of mothers with single progeny. For cows, the biological value of protein was higher in colostrum samples from twin-bearing cows than in those from single-bearing cows. The NPN content was higher in the colostrum from cows producing a single calf. There were no differences in casein content or contents of macro- and micro-elements for any of the three species. Twenty-four hours after parturition, no differences in composition of collostrum were found. Furthermore, the sex of progeny of twin-calving cows had no influence on the composition of colostrum.

USE OF AMINO ACIDS AND THEIR RACEMISATION FOR AGE DETERMINATION IN ARCHAEOMETRY

Abstract After reviewing previous attempts to use the extent of amino acid racemisation (AAR) for the determination of the age of archaeological samples containing proteins, the authors describe their own approach. Following an optimised protein hydrolysis with low racemisation the d - and l -amino acid content in fossil bone samples of known age (radiocarbon method) was determined by HPLC after precolumn derivatisation. Based on the obtained half-lives of racemisation and plotting the d / l ratio as a function of time for various amino acids, calibration curves are obtained which can be used for the age determination of fossil bone samples in the range of 2000–500 000 years. Another method is presented for the determination of age of textiles in the range of 100–1800 years. This method is based on the determination by an amino acid analyser of the age-dependent alteration of amino acid composition of proteins. Cystine, methionine and tyrosine content decreases, while cysteic acid content increases with age. Prediction equations were developed as linear regressions of the age of wool based on cysteic acid, cystine and tyrosine contents.

The influence of manufacture on the free D-amino acid content of Cheddar cheese.

Summary.The changes in the concentration and those of composition of alanine, aspartic acid and glutamic acid enantiomers were investigated during manufacture of Cheddar cheese. The amount of D-alanine increased continuously during ripening following the liberation of L-alanine originated from the proteolysis of milk proteins. There was slightly more D-aspartic and D-glutamic acid in the dry matter of curd after pressing than before pressurization. The D-amino acid content and the ratio of the D-enantiomers related to the total amount of free amino acids differed significantly among cheeses produced with different single-strain starters. The D-amino acid composition changed during manufacture, but the influence of the strain selection was not significant on the D-amino acid pattern.

Age determination based on amino acid racemization: a new possibility

SummaryA method has been developed to determine the age of fossil bone samples based on amino acid racemization (AAR). Approximately one hundred fossil bone samples of known age from Hungary were collected and analysed for D- and L-amino acids. As the racemization of amino acids is affected by temperature, pH, metal content of the soil, and time passed since death, these factors were eliminated by comparing the estimated age to age determined by the radiocarbon method. Determining the D- and L-amino acid contents in samples of known age, determining the half life of racemization and plotting the D/L ratio as a function of time, calibration curves were obtained. These curves can be used for the age estimation of samples after determining their D- and L-amino acid content. The D/L ratio for 2 to 3 amino acids was determined for each sample and the mean value of estimated ages based on calibration curves was considered to estimate age of the fossil samples.

The influence of extrusion on loss and racemization of amino acids

Summary.The influence of the operation conditions (temperature and residence time) of a thermic treatment on the total amount (free and protein-bound) of amino acid enantiomers of dry fullfat soya was investigated. Total amino acid content was determined using conventional ion-exchange amino acid analysis of total hydrolysates and chiral amino acid analysis was performed by HPLC after precolumn derivatization with o-phthaldialdehyde and 1-thio-β-D-glucose tetraacetate. Contrary to corn that was investigated previously, notable racemization was detected even at lower temperatures. At 140 °C the ratio of the D-enantiomer was 0.87% for glutamic acid, 2.81% for serine, and 1.92% for phenylalanine; at 220 °C the ratios of the D-enantiomer of the above amino acids were 1.43, 4.61, and 4.68%, respectively. The concentration of several L-amino acids decreased. At 220 °C there was 10% less L-glutamic acid, 17% less L-serine, 5% less L-phenylalanine, 6.6% less L-aspartic, acid and 21% less L-lysine than in the control; their loss can be assigned to different degrees of L – D conversion. While nearly complete transformation of L-phenylalanine can be attributed to racemization, the main cause of the loss of L-lysine is not racemization. The treatments in the same order of magnitude resulted in the formation of more D-amino acids and greater extent of racemization of amino acids in fullfat soya than that of maize.

Quantitative determination of protein of bacterial origin

Abstract Several methods have been developed for the determination of the proportion of nitrogen-containing substances of microbial origin in the digestive tracts of cattle. These include assays that use nucleic acids and adenosine triphosphate as indicators, radioisotopes 35 S, 15 N, 32 P and 33 P incorporated into bacterial protein and phospholipids, duodenal amino acid composition with amino-ethylphosphonic acid, diaminopimelic acid and d -alanine ( d -Ala) contents as indicators. On the basis of the data in the literature on d -amino acid content of milk and milk products the authors came to the conclusion that d -glutamic acid ( d -Glu) and d -aspartic acid ( d -Asp) can be considered as markers for proteins of bacterial origin. To demonstrate this, experiments have been carried out and some of the results are reported here.

Mercaptoethanesulphonic acid as a protecting and hydrolysing agent for the determination of the amino acid composition of proteins using an elevated temperature for protein hydrolysis

Abstract Mercaptoethanesulphonic acid (MES-OH) (3 M) was used for the hydrolysis of different samples (pure proteins, free typtophan and milk powder with a high sugar content). Different temperatures (160, 170 and 180°C) and time periods (15–90 min) were compared under standard conditions to minimize side-reactions in order to obtain the best recovery of the amino acids (especially tryptophan and methionine). The materials used for testing the hydrolysis methods were bovine ribonuclease, lysozyme, cytochrome c , free tryptophan and mares milk powder. Hydrolysis at high temperature was successfully applied for the amino acid analysis of milk powder with high contents of carbohydrate and pure proteins. In some instances, such as in tryptophan and methionine determination at 160–170°C for 15–30 min, the results were better than those obtained by the original MES-OH method. A disadvantage of the MES-OH hydrolysis method is that it reduces cystine to cysteine, which co-elutes with proline from the ion-exchange column used to separate the released amino acids and it may interfere with the determination of proline in high-cystine proteins.