Mineral salt intake effects on faecal-N concentration and the volume and composition of beef cattle urine

The effect of mineral salts on water ingestion and urine volume in cattle has been extensively studied. However, recently, this effect has been investigated as a potential mitigator of environmental aspects related to the nitrogen (N) cycle, such as nitrate (NO₃^?) lixiviation, ammonia (NH₃) volatilisation, and nitrous oxide (N₂O) emissions. The effect of mineral salts, particularly sodium chloride (NaCl), on urine-N concentration, urine volume, the proportion of N compounds in the urine, and faecal-N concentration has not yet been explored in field conditions with respect to environmental aspects of beef cattle production. The present study investigated the effect of dietary mineral salt rates on these parameters. A Latin square (5?×?5) experimental design was utilised with five concentrations of mineral salts in the diet: 0.0, 2.0, 4.0, 6.0, and 8.0 g based on dry matter (DM) ingestion (g/kg DM). The nitrogen concentration in the urine and urine volume increased linearly. The total N excreted (g/day) via urine did not vary with increasing mineral salt concentrations. When evaluated, the N compounds of urine (urea-N, allantoin-N, and hippuric acid-N) also reacted to the increased mineral salt concentrations, while creatinine-N did not. Urea-N, allantoin-N, and hippuric acid-N linearly increased their proportions in total N-urine. The N concentration in faeces was not affected by mineral salt concentrations. The urine volume, concentration of N, and proportion of N compounds in the urine affected N₂O emissions and NH₃ volatilisation. Therefore, mineral salt utilisation may be an option for mitigating N pollution from beef cattle, especially for grasslands in tropical countries.

     

Factors Affecting Air Pycnometer Performance For its Use in the Composting Process

Air filled porosity (AFP) is a crucial factor in composting to guarantee aerobic conditions inside the composting matrix. Among the different methods proposed to measure AFP in composting processes, air pycnometry is defined as the most adequate. There is a lack of a standard methodology for air pycnometry utilization for AFP determination in heterogeneous samples as those from composting materials. Air pycnometers currently used for this purpose are custom made instruments operating under different conditions (sample volume, initial pressure, etc.). All factors affecting air pycnometry accuracy in the composting process are related to the proper maintenance and handling of the air pycnometer and the composting sample. In this study, AFP measurements have been performed in more than 50 samples of a wide range of composting materials using two different custom made pycnometers, one of them coupled to a composting reactor allowing in situ AFP measurement. While temperature variation during AFP measurement has been discarded as an error source, the determination of the sample volume has been found to be a significant factor affecting the air filled porosity calculation. Regarding the initial pressure to use, a compromise between accuracy and practicality has to be established for each pycnometer design as AFP values obtained with diverse initial pressures (from 200 to 500 kPa gauge pressure) were found to present no statistical differences. An initial pressure in the range of 300-500 kPa (gauge pressure) is recommended. In conclusion, there is a need for a standard methodology for AFP determination or prediction at industrial scale. A complete procedure for air filled porosity determination by air pycnometry is also presented in this work.     

Canine coronavirus induces apoptosis in cultured cells

Canine coronavirus (CCoV) is widespread in dogs in several countries and causes mild enteric illness evolving to severe enteritis in young pups. In in vitro cultures canine coronaviruses generally induce extensive cell death, however nature of the events leading to cell death remains largely unknown. We analysed the induction of cytopathic effect by CCoV in a canine fibrosarcoma cell line (A-72) in order to characterize the apoptotic effect in homologous cell system. Following CCoV infection A-72 cell line, which is permissive to CCoV, showed reduced growth rate, as detected by MTT assay, a standard colorimetric assay for measuring cellular proliferation, and underwent to apoptotic death. Starting from 24h after CCoV infection, cells morphology appeared dramatically changed, with cells rounding and detachment from culture surface. Morphologic and biochemical features of apoptosis, such as blebbing of the plasma membrane, translocation of phosphatidilserine to cell surface and annexin V positive staining, nuclear fragmentation, apoptotic bodies formation and DNA laddering, were detected in CCoV-infected cells. Propidium iodide staining of infected culture indicated the appearance of hypodiploid DNA peak corresponding to apoptotic cell population. Commonly to other animal coronavirus infection caspase-3 is likely to contribute to the execution phase of apoptosis induced by CCoV in A-72 cells since we found activation of enzymatic activity as well as procaspase-3 activating cleavage. Apoptotic death of infected cells is detrimental as it causes cell and tissue destruction as well as inflammatory responses. Therefore in the case of CCoV associated gastroenteritis, apoptosis of epithelial mucosa cells may be responsible for pathology induced by CCoV infection.     

Evaluation of antioxidant capacity of cereal brans

Several oat brans (crunchy oat bran, oat bran alone, and oat breakfast cereal) and wheat brans (wheat bran alone, wheat bran powder, wheat bran with malt flavor, bran breakfast cereal, tablet of bran, and tablet of bran with cellulose) used as dietary fiber supplements by consumers were evaluated as alternative antioxidant sources (i) in the normal human consumer, preventing disease and promoting health, and (ii) in food processing, preserving oxidative alterations. Products containing wheat bran exhibited higher peroxyl radical scavenging effectiveness than those with oat bran. Wheat bran powder was the best hydroxyl radical (OH*) scavenger. In terms of hydrogen peroxide (H2O2) scavenging, wheat bran alone was the most effective, while crunchy oat bran, oat bran alone, and oat breakfast cereal did not scavenge H2O2. The shelf life of fats (obtained by the Rancimat method for butter) increased most in the presence of crunchy oat bran. When the antioxidant activity during 28 days of storage was measured by the linoleic acid assay, all of the oat and wheat bran samples analyzed showed very good antioxidant activities. The Trolox equivalent antioxidant capacity (TEAC) assay was used to provide a ranking order of antioxidant activity. The wheat bran results for TEAC (6 min), in decreasing order, were wheat bran powder > wheat bran with malt flavor > or = wheat bran alone > or = bran breakfast cereal > tablet of bran > tablet of bran with cellulose. The products made with oat bran showed lower TEAC values. In general, avenanthramide showed a higher antioxidant level than each of the following typical cereal components: ferulic acid, gentisic acid, p-hydroxybenzoic acid, protocatechuic acid, syringic acid, vanillic acid, vanillin, and phytic acid.     

Ingestive behavior of supplemented Nellore heifers grazing palisadegrass pastures managed with different sward heights

Three sward heights (15, 25 and 35 cm) and three supplement types (energy, energy‐protein, and a mineral mix supplement) were evaluated in a 3 × 3 factorial arrangement distributed in a completely randomized design to study changes in forage search patterns in Nellore heifers in a continuous grazing system. Pasture data were collected using two replicates (paddocks) per treatment over four periods during the rainy season. The behavior assessments were made in the first and fourth grazing seasons. It was hypothesized that supplements and pasture management would modify ingestive behavior, considering that animals would require less time grazing if they had energy requirements met through higher digestibility of better managed paddocks, or use of supplements high in energy. Total and green forage masses along with green : dead material ratio were greater in treatments managed with higher sward heights. Sward managed with 35 cm height resulted in lower leaf : stem ratio compared with 15 cm sward height treatments. The animals on the 15 cm pastures spent more time grazing overall and during each meal, but there were no differences observed in meal numbers in comparison to 35 cm treatments. Heifers fed protein and/or energy supplements spent less time grazing in the early afternoon, but overall grazing time was the same for all animals.     

Canopy characteristics and tillering dynamics of Marandu palisade grass pastures in the rainy–dry transition season

The objective of this study was to evaluate the effect of pasture management during the rainy–dry transition season in Jaboticabal, Brazil, on the structural and tillering characteristics of Marandu palisade grass. The treatments were as follows: 15 cm sward height in the rainy season and ungrazed in the rainy–dry transition season (15/0); 25 cm sward height during the rainy season and fixed stocking rate of 2·5 AU ha^?1 during the rainy–dry transition season (25/2·5); and 35 cm sward height in the rainy season and fixed stocking rate of 2·5 AU ha^?1 in the rainy–dry transition season (35/2·5). There were more herbage mass, stem and dead herbage mass in treatments 25/2·5 and 35/2·5 than 15/0. Tiller appearance rate was greater in treatment 15/0 and tiller mortality rate was higher in treatment 35/2·5 compared to treatment 15/0. Tiller population stability index was 1 in treatment 15/0 and lower in treatment 35/2·5. Although treatment 15/0 showed favourable structural and tillering characteristics, it also has the lowest herbage mass. Treatment 25/2·5 can be regarded as an adequate management strategy for Marandu palisade grass, since it has similar herbage mass and better tillering characteristics than treatment 35/2·5.     

Investigation of soil surface organic and inorganic carbon contents in a low-intensity farming system using laboratory visible and near-infrared spectroscopy

ABSTRACT

In some regions of Italy, low-intensity farming systems, together with variable climate conditions, have lowered soil organic carbon (SOC) content and soil quality attributes. This work aims to investigate on some aspects of (1) total organic carbon (TOC) prediction using Vis-NIR reflectance spectroscopy in combination with partial least squares regression (PLSR); (2) the most appropriate pre-processing techniques of Vis-NIR absorbance spectra; (3) the composition of organic carbon using variable importance of prediction (VIP). The study area was an olive grove, located at Montecorvino Rovella (Salerno, southwestern Italy), characterized by a calcaric soil (Leptic Calcisols) and (Luvic Phaeozem), with a low content of TOC (mean 2.03 g kg^?1), caused by a low-intensity farming. Results of univariate PLSR analyses showed a good agreement between measured and predicted values both for TOC (R²: 0.66) and total carbonate content (R²: 0.93), when pH, electrical conductivity (EC) and absorbance spectra were used as predictors. The best results were obtained using as pre-treatments of the spectral data: 1) standard normal variate (SNV); 2) Savitzky-Golay algorithm; 3) first derivative. Variable Importance for Prediction (VIP) statistics showed to be a good tool to gain insights in TOC composition also when its content is low and influenced by carbonate.     

Areal identification of groundwater nitrate contamination sources in periurban areas

Background, Aims and Scope  The purpose of this study is to verify a method for groundwater contamination risk assessment in urban and periurban areas using Geographic Information Systems (GIS). The method is based on agricultural hazard evaluation. In urban and periurban areas, the problem of dealing with NO₃ concentrations mainly entails identifying nitrate sources from the excessive use of fertilizers, or leaks from the sewage network and old septic systems. Residential areas coexisting with farming, and high and increasing nitrate concentrations, were identified in a densely inhabited area (>2 million inhabitants in about 1,000 km²) with an alluvial aquifer, located in southern Italy. Methods  First of all, comparison between the Contamination Vulnerability Map and the distribution of NO₃ concentrations highlights anomalous areas with low or moderate vulnerability in spite of the diffuse nitrate contamination of the aquifer. Assuming the agricultural origin of the nitrates, the hazard is calculated using the ANHI (Agricultural Nitrate Hazard Index), a parametric index which assesses the potential hazard of nitrate contamination originating from agriculture on a regional scale (Padovani and Trevisan 2002). The ANHI integrates two categories of parameters: the hazard factors (HF), which represent all farming activities that cause, or might cause, an impact on soil quality in terms of nitrate (use of fertilizers, application of livestock and poultry manure, food industry wastewater and urban sludge), and the control factors (CF) which adapt the hazard factors to the characteristics of the site (geographical location, climatic conditions and agronomic practices). Organization, processing and mapping are performed using a Geographical Information System (GIS: ILWIS 3.3 and ARCGIS 9.1). Results  The ANHI Map is obtained by multiplying the hazard factors (HF) and the control factors (CF), and dividing the resulting values into 6 classes. Finally, the Potential risk Map (R) is obtained by coupling the potential hazard of nitrate pollution (ANHI) and the aquifer Contamination Vulnerability Map. Discussion  By using spatial statistics, the Potential Agricultural Nitrate Contamination Risk Map and the Nitrate content of the aquifer correlation can be correlated. Where areas with low correlation in the Land Use Map are in the ‘urban areas and artificial land’ class, the source of the groundwater nitrate is not necessarily related to intensive farming and livestock. Conclusions  The Potential Agricultural Nitrate Contamination Risk Map in urban and periurban environments indicates the relationship between the high nitrate values and land use, giving useful information about the source of nitrate in groundwater. Recommendations and Perspectives  Based on this study, we formulate a hypothesis on the source of groundwater nitrate which should be verified on several case studies using nitrogen isotope techniques.     

Management intensity affects density fractions of soil organic matter from grazed bahiagrass swards

Soil fertility and agricultural systems sustainability depend upon soil organic matter (SOM). The effects of pasture management intensity on SOM are not well understood. The objectives of this study were to determine the effect of management intensity of ‘Pensacola’ bahiagrass (Paspalum notatum Flügge) pastures on the light density fraction of SOM (LD-SOM), the fraction that responds most readily to changes in pasture management practices. Pastures were grazed from 2001-2004 at four management intensities, defined as the combination of stocking method, N fertilization, and stocking rate (SR). Treatments were continuously stocked (CS) Low (40 kg N ha⁻¹ yr⁻¹ and SR of 1.4 animal units ha⁻¹ (AU=500 kg live weight)); CS Moderate (120 kg N and SR of 2.8 AU); CS High (360 kg N and SR of 4.2 AU); and rotationally stocked with a 7-d grazing period and 21-d resting period (360 kg N and SR of 4.2 AU). Composite soil samples (0-8 cm) from each pasture were collected in 2004. Management intensity did not affect C and N concentration in the bulk soil, but it did impact C and N concentrations of size fractions of LD-SOM. In particles from 250 to 2000 μm, both C and N concentration were greater with increasing management intensity. In particles<53 μm, however, the lowest management intensity presented the greatest soil C and N concentrations. Increasing C and N in slow turn over SOM fractions with increased management intensity may result in greater C sequestration and potential soil fertility, but the increased likelihood of negative environmental impact and the questionable sustainability of high N fertilizer rates must also be considered.