Apparent and standardised ileal digestibility coefficients of amino acids in wheat, soybean meal and rapeseed meal for broilers

The apparent (AID) and(SID) ileal amino acid digestibilities in wheat, soybean meal, and rapeseed meal were determined with Ross 308 broiler chicken (n = 64) using the slaughter technique with chromium mordanted straw as an indigestible marker. The recovery of endogenous amino acids at the distal ileum was determined with a protein-free diet and it was used to calculate the SID digestibilities of the studied feed ingredients. The mean amino acid AID and SID were higher in soybean meal and wheat than in rapeseed meal (p<0.05). The mean amino acid flow measured from the ileum was the highest in rapeseed meal, intermediate in soybean meal, and the lowest in wheat (p<0.05). The main amino acids in the basal endogenous secretion were aspartic and glutamic acid and the lowest ones present were methionine and histidine (p<0.05). The difference between amino acid AID and SID values varied among ingredients and was higher in wheat than in soybean meal and rapeseed meal (p<0.05).

Two-Step Derivatization of Amino Acids for Stable-Isotope Dilution GC–MS Analysis: Long-Term Stability of Methyl Ester-Pentafluoropropionic Derivatives in Toluene Extracts

Analysis of amino acids by gas chromatography-mass spectrometry (GC–MS) requires at least one derivatization step to enable solubility in GC–MS-compatible water-immiscible organic solvents such as toluene, to make them volatile to introduce into the gas chromatograph and thermally stable enough for separation in the GC column and introduction into the ion-source, and finally to increase their ionization by increasing their electronegativity using F-rich reagents. In this work we investigated the long-term stability of the methyl esters pentafluoropropionic (Me-PFP) derivatives of 21 urinary amino acids prepared by a two-step derivatization procedure and extraction by toluene. In situ prepared trideuteromethyl ester pentafluoropropionic derivatives were used as internal standards. GC–MS analysis (injection of 1 µL aliquots and quantification by selected-ion monitoring of specific mass fragments) was performed on days 1, 2, 8, and 15. Measured peak areas and calculated peak area ratios were used to evaluate the stability of the derivatives of endogenous amino acids and their internal standards, as well as the precision and the accuracy of the method. All analyses were performed under routine conditions. Me-PFP derivatives of endogenous amino acids and their stable-isotope labelled analogs were stable in toluene for 14 days. The peak area values of the derivatives of most amino acids and their internal standards were slightly higher on days 8 and 15 compared to days 1 and 2, yet the peak area ratio values of endogenous amino acids to their internal standards did not change. Our study indicates that Me-PFP derivatives of amino acids from human urine samples can easily be prepared, are stable at least for 14 days in the extraction solvent toluene, and allow for precise and accurate quantitative measurements by GC–MS using in situ prepared deuterium-labelled methyl ester as internal standard.

Molecular preservation in mammoth bone and variation based on burial environment

Biomolecules preserved in fossils are expanding our understanding of the biology and evolution of ancient animals. Molecular taphonomy seeks to understand how these biomolecules are preserved and how they can be interpreted. So far, few studies on molecular preservation have considered burial context to understand its impact on preservation or the potentially complementary information from multiple biomolecular classes. Here, we use mass spectrometry and other analytical techniques to detect the remains of proteins and lipids within intact fossil mammoth bones of different ages and varied depositional setting. By combining these approaches, we demonstrate that endogenous amino acids, amides and lipids can preserve well in fossil bone. Additionally, these techniques enable us to examine variation in preservation based on location within the bone, finding dense cortical bone better preserves biomolecules, both by slowing the rate of degradation and limiting the extent of exogenous contamination. Our dataset demonstrates that biomolecule loss begins early, is impacted by burial environment and temperature, and that both exogenous and endogenous molecular signals can be both present and informative in a single fossil.

Jerusalem Artichoke: Quality Response to Potassium Fertilization and Irrigation in Poland

The aim of this study was to determine the effects of soil potassium fertilization (150, 250 and 350 kg K2O ha−1) and irrigation on the tuber quality (content of ά-tocopherol, β-carotene, essential and endogenous amino acids) of three Jerusalem artichoke (Helianthus tuberosus L.) cultivars (Topstar, Violette de Rennes, Waldspindel). Jerusalem artichokes were grown during a field experiment in the Agricultural Experiment Station in Tomaszkowo (53°42′ N, 20°26′ E, north-eastern Poland). The content of ά-tocopherol and β-carotene was determined at 1.60–2.65 and 0.75–1.00 mg kg−1 DM, respectively, in all Jerusalem artichoke cultivars produced in north-eastern Poland. High rates of potassium fertilizer (250 and 350 kg K ha−1) increased the content of ά-tocopherol in tubers by 47% and 66% on average, respectively. The stimulatory effects of high potassium rates on the content of ά-tocopherol (2.5-fold increase) were observed only in response to irrigation. High rates of potassium fertilizer induced a particularly high increase (3.2-fold) in ά-tocopherol concentrations in Jerusalem artichokes cv. Waldspindel. Irrigation increased ά-tocopherol levels (by 40%) and decreased the concentrations of β-carotene (by 25%) and most essential and endogenous amino acids (isoleucine, leucine, lysine, phenylalanine, valine, alanine, glycine, histidine, serine, threonine). The Topstar cultivar accumulated the highest quantities of essential and endogenous amino acids. Leucine, methionine + cysteine were the limiting amino acids in Jerusalem artichoke tubers. The analyzed tubers were characterized by very high nutritional quality of dietary protein (Essential Amino-Acid Index, 66–78).