Z. Csapó-Kiss

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.

Hydrolysis of proteins performed at high temperatures and for short times with reduced racemization, in order to determine the enantiomers of d- and l-amino acids

Abstract Racemization of free amino acids is considerably lower those bound in peptide. In the same experimental conditions, the rate of racemization of free amino acids is only 20%–80% that of peptide-bound amino acids. When using traditional protein hydrolysis, the racemization was 1.2–1.6 times as high as that obtained at high temperatures (160–180 °C), under conditions ensuring total hydrolysis of the protein. This lower degree of racemization may be explained by the fact that, at high temperatures, the protein hydrolyses more rapidly into free amino acids and the racemization of free amino acids is considerably lower than those bound in polypeptides. When hydrolysis is conducted at lower temperatures for longer times, the amino acids bound in the peptide chain are exposed for a longer time to the effects racemization. As a result, we may say that any factor that speeds up hydrolysis will lower the degree of racemization. Racemization was higher for proteins in milk powder than for pure proteins. This may be explained as a result of catalysis of the racemization by the heavy metals present. After 48 h at 110 °C and in the presence of 4 M barium hydroxide, all amino acids (whether free or bound in peptide) were totally racemized. Therefore, the racemization of tryptophan cannot be determined using barium hydroxide promoted protein hydrolysis. High temperature hydrolysis (at 160 °C for 45–60 min, at 170 °C for 30–45 min and 180 °C for 30 min) is recommended for those who would like to hydrolyse the protein for short times and determine the degree of racemization occurring in the polypeptide chain, but do not wish to use enzyme hydrolysis.

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.

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.

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.

Rapid Method for the Determination of Diaminopimelic Acid Using Ion Exchange Column Chromatography

Abstract A new method for determinating diaminopimelic acid (DAPA) from rumen fluid was developed. The concentration of DAPA is used as an indicator for the estimation of protein content of bacterial origin. Due to the performic acid oxidation preceding hydrolysis of proteins, the neighbouring amino acids do not interfere in the determination of DAPA. As a result, even trace concentrations of DAPA may be accurately determined. Since, following the performic acid oxidation the sample does not contain methionine, the buffers developed for rapid determination of methionine may be used to advantage. As a result of this, DAPA may be determined by ion exchange coilumn chromatography in ca. 18 minutes. Following the development of the analytical method, it was applied to the determination of DAPA in the rumen fluid and the bacterial proteins prepared from the rumen fluid of cattle, goats and sheep. Based on the results, a method for evaluation of protein content of bacterial origin, based on the DAPA content, wa...