High N fertilizer application to irrigated wheat in Northern Mexico for conventionally tilled and permanent raised beds: Effects on N balance and short term N dynamics

Nitrogen (N) surpluses from fertilizer application can cause major environmental harm including pollution of surface water, groundwater, and air. To assess such negative externalities, N balances are a complex but useful tool to predict surpluses and to measure effects of nutrient optimization strategies in agriculture. The Yaqui Valley in north‐western Mexico is representative for thousands of square kilometres of intensive, irrigated wheat production under arid conditions worldwide and has been targeted for conservation agriculture in recent years. For these cropping systems, detailed N balances are scarce and often incomplete. To help fill this knowledge gap, data from a long‐term experiment were collected in 2013/14 on a Vertisol to examine the impact of three tillage‐straw management practices (CTB: conventionally tilled beds; PB‐straw: permanent raised beds with residue retention; PB‐burn: permanent raised beds with residue burning) on N dynamics. Tillage had significant effects on soil NO₃‐N, NH₄‐N, and total N contents across the cropping period. Soil total N content was at all sampling depths lowest in CTB. Soil NO₃‐N in the 0–90 cm profile was highest in PB‐burn over the cropping period and ranged from 77 kg ha^?1 in the bed before pre‐planting fertilizer application up to 269 kg ha^?1 in the furrow after the second fertilizer application. Annual simple N balances were +59 kg N ha^?1 in CTB, +39 kg N ha^–1 in PB‐straw, and +46 kg N ha^?1 in PB‐burn. Residual mineral soil N was significantly affected by tillage‐straw management and lowest for PB‐straw (+205 kg N ha^?1) and highest for CTB, and for PB‐burn (+283 kg N ha^?1 each) in the 0–90 cm soil profile. Soil NO₃‐N moved out of the effective wheat root zone, as indicated by the high residual NO₃‐N content at 30–90 cm depth, which is an important pathway of N leaching. Quantifiable N losses through leaching and volatilization averaged 100 kg N ha^?1. Our findings suggest that there is potential for substantial reductions in N inputs in all tillage‐straw systems to decrease N losses and to reduce mineral residual soil N, but care should be taken to avoid reducing grain protein content, which in PB straw was already below the quality standard. A knowledge transfer of the European “N_min” concept is advisable in this region to regulate N fertilizer over‐application.     

Pre-implantation exogenous progesterone and pregnancy in sheep. Ⅱ. Effects on fetalplacental development and nutrient transporters in late pregnancy

Background: Administration of progesterone(P4) to ewes during the first 9 to 12 days of pregnancy accelerates blastocyst development by day 12 of pregnancy, likely due to P4-induced up-regulation of key genes in uterine epithelia responsible for secretion and transport of components of histotroph into the uterine lumen. This study determined if acceleration of blastocyst development induced by exogenous P4 during the pre-implantation period affects fetal-placental development on day 125 of pregnancy. Suffolk ewes(n = 35) were mated to fertile rams and assigned randomly to receive daily intramuscular injections of either corn oil vehicle(CO, n = 18) or 25 mg progesterone in CO(P4, n = 17) for the first 8 days of pregnancy. All ewes were hysterectomized on day 125 of pregnancy and: 1) fetal and placental weights and measurements were recorded; 2) endometrial and placental tissues were analyzed for the expression of candidate mRNAs involved in nutrient transport and arginine metabolism; and 3) maternal plasma, fetal plasma, allantoic fluid, and amniotic fluid were analyzed for amino acids,agmatine, polyamines, glucose, and fructose.Results: Treatment of ewes with exogenous P4 did not alter fetal or placental growth, but increased amounts of aspartate and arginine in allantoic fluid and amniotic fluid, respectively. Ewes that received exogenous P4 had greater expression of mRNAs for SLC7 A1, SLC7 A2, SLC2 A1, AGMAT, and ODC1 in endometria, as well as SLC1 A4, SLC2 A5, SLC2 A8 and ODC1 in placentomes. In addition, AZIN2 protein was immunolocalized to uterine luminal and glandular epithelia in P4-treated ewes, whereas AZIN2 localized only to uterine luminal epithelia in CO-treated ewes.Conclusions: This study revealed that exogenous P4 administered in early pregnancy influenced expression of selected genes for nutrient transporters and the expression of a protein involved in polyamine synthesis on day 125 of pregnancy, suggesting a ‘programming' effect of P4 on gene expression that affected the composition of nutrients in fetal-placental fluids.     

Assessment of the qualitative variation in bacterial microflora among compartments of the intestinal tract of dogs by use of a molecular fingerprinting technique

OBJECTIVE: To evaluate the qualitative variation in bacterial microflora among compartments of the intestinal tract of dogs by use of a molecular fingerprinting technique. ANIMALS: 14 dogs (similarly housed and fed identical diets). PROCEDURE: Samples of intestinal contents were collected from the duodenum, jejunum, ileum, colon, and rectum of each dog. Bacterial DNA was extracted from the samples, and the variable V6 to V8 region of 16S ribosomal DNA (gene coding for 16S ribosomal RNA) was amplified by use of universal bacterial primers; polymerase chain reaction amplicons were separated via denaturing gradient gel electrophoresis (DGGE). Similarity indices of DGGE banding patterns were used to assess variation in the bacterial microflora among different compartments of the intestine within and among dogs. Bacterial diversity was assessed by calculating the Simpson diversity index, the Shannon-Weaver diversity index, and evenness. RESULTS: DGGE profiles indicated marked differences in bacterial composition of intestinal compartments among dogs (range of similarity, 25.6% to 36.6%) and considerable variation among compartments within individual dogs (range of similarity, 36.7% to 579%). Similarities between neighboring intestinal compartments were significantly greater than those between non-neighboring compartments. Diversity indices for the colon and rectum were significantly higher than those of the duodenum, jejunum, and ileum. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that the different intestinal compartments of individual dogs appear to host different bacterial populations, and these compartmental populations vary among dogs. In dogs, fecal sample analysis may not yield accurate information regarding the composition of bacterial populations in compartments of the gastrointestinal tract.     

Effect of presence or absence of antibiotics and use of modified single layer centrifugation on bacteria in pony stallion semen

Bacteria contaminate semen during collection and handling. The objective of this study was to identify the bacteria in pony stallion semen, the effects of antibiotics included in commercial semen extenders (lincomycin and spectinomycin) and the effect of modified single layer centrifugation (MSLC), on bacterial load. Ejaculates from six pony stallions, 3 ejaculates per animal, were extended in EquiPlus extender either with or without antibiotics. Aliquots were processed by MSLC to form four treatment groups: control and MSLC with antibiotics (CA and SA, respectively) and control and MSLC without antibiotics (CW and SW, respectively). Bacteriological examinations were carried out within 2 hr. Thirty‐one species of bacteria were isolated from one or more ejaculates, with Corynebacterium spp. being the most frequently detected. Corynebacterium spp. were present in all ejaculates. The MSLC resulted in a significantly lower total bacterial count than controls (CA vs. SA, p < 0.001; CW vs. SW, p < 0.0001).     

Identification of organic acids in wine that stimulate mechanisms of gastric acid secretion

Wine may cause stomach irritation due to its stimulatory effect on gastric acid secretion, although the mechanisms by which wine or components thereof activate pathways of gastric acid secretion are poorly understood. Gastric pH was measured with a noninvasive intragastric probe, demonstrating that administration of 125 mL of white or red wine to healthy volunteers stimulated gastric acid secretion more potently than the administration of equivalent amounts of ethanol. Between both beverages, red wine showed a clear trend for being more active in stimulating gastric acid secretion than white wine (p = 0.054). Quantification of the intracellular proton concentration in human gastric tumor cells (HGT-1), a well-established indicator of proton secretion and, in turn, stomach acid formation in vivo, confirmed the stronger effect of red wine as compared to white wine. RT-qPCR experiments on cells exposed to red wine also revealed a more pronounced effect than white wine on the fold change expression of genes associated with gastric acid secretion. Of the quantitatively abundant organic acids in wine, malic acid and succinic acid most actively stimulated proton secretion in vitro. However, addition of ethanol to individual organic acids attenuated the secretory effect of tartaric acid, but not that of the other organic acids. It was concluded that malic acid for white wine and succinic acid for red wine are key organic acids that contribute to gastric acid stimulation.     

Phosphorus forms and enzymatic hydrolyzability of organic phosphorus in soils after 30 years of organic and conventional farming

Lower P‐input levels in organic than conventional farming can decrease soil total and available P, which can potentially be resupplied from soil organic P. We studied the effect of 30 y of conventional and organic farming on soil P forms, focussing especially on organic P. Soil samples (0–20 cm) were taken in a field experiment with a nonfertilized control, two organic systems receiving P inputs as animal manure, and two conventional systems receiving only mineral P or mineral P and manure. Soils were analyzed for total, inorganic, organic, and microbial P, by sequential P fractionation and by enzyme additions to alkaline soil extracts. Samples taken prior to starting the experiment were also analyzed. Average annual P balances ranged from –20 to +5 kg ha^–1. For systems with a negative balance, labile and moderately labile inorganic P fractions decreased, while organic and stable inorganic P fractions were hardly affected. Similar quantities and proportions of organic P extracted with NaOH‐EDTA were hydrolyzed in all soils after addition of an acid phosphatase, a nuclease, and a phytase, and enzyme‐stable organic P was also similar among soils. Thus, neither sequential fractionation nor enzyme addition to alkaline soil extracts showed an effect of the type of applied P (manure vs. mineral) on organic P, suggesting that organic P from manure has largely been mineralized. Thus far, we have no indication that the greater microbial activity of the organic systems resulted in a use of stable P forms.     

Genetic analyses of the radiographic appearance of the distal sesamoid bones in Hanoverian Warmblood horses

OBJECTIVE: To evaluate whether additive genetic correlations existed between certain aspects of the radiographic appearance of the distal sesamoid (navicular) bones (RNB) or between RNB and other types of radiographic changes in the limbs of Hanoverian Warmblood horses. ANIMALS: 5,157 horses. PROCEDURES: Quasi-linear and binary traits were defined by the appearance of canales sesamoidales (CSs) and the structure and contour of the forelimb navicular bones (NBs). Prevalences of osseous fragments in the metacarphophalangeal and metatarsophalangeal (fetlock) and tarsocrural joints and deforming arthropathy in tarsal joints were analyzed as binary traits. Genetic parameters were estimated by use of multivariate linear models. RESULTS: Heritability estimates for the RNB traits ranged from 0.10 to 0.34. Additive genetic correlations among those traits were usually close to unity. Extensive radiographic changes in the NBs, including changes in CSs and alterations in structure and contour, had correlations with less distinct radiographic changes. Negative additive genetic correlations were observed between small numbers of short and conical CSs in the central portion of the distal border of the NB and osseous fragments and arthropathy, and between most types of radiographic findings in the NBs and osseous fragments in tarsal joints. CONCLUSIONS AND CLINICAL RELEVANCE: The genetic bases for different types of RNB were not identical. The detection of correlations between normal RNB and findings of short and conical CSs versus deformed CSs and structural and contour changes warrants further study. Genetically justified distinction between physiologic and pathologic NB changes will increase the efficiency of selecting against NBs with radiographically apparent alterations.     

Identification of bitter off-taste compounds in the stored cold pressed linseed oil

Whereas freshly pressed linseed oil provides a delicate nutty flavor, a lingering bitter off-taste is developing upon storage at room temperature. Using a sensory guided fractionation approach, the key bitter compound was identified in stored linseed oil, and its structure was determined as the methionine sulfoxide-containing, cyclic octapeptide cyclo(PLFIM OLVF) by means of FTIR, LC-MS, NMR spectroscopy, and amino acid analysis. Although this peptide is known in the literature as cyclolinopeptide E, the bitter taste activity of this compound has not previously been described. Sensory evaluation revealed a recognition threshold concentration of 12.3 micromol/L water.