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Munoz C.,Agri Food and Biosciences Institute AFBI Agriculture Branch | Munoz C.,Institute Investigaciones Agropecuarias INIA Remehue | Yan T.,Agri Food and Biosciences Institute AFBI Agriculture Branch | Wills D.A.,Agri Food and Biosciences Institute AFBI Agriculture Branch | And 2 more authors.
Journal of Dairy Science

The objectives of the present study were to compare the sulfur hexafluoride (SF6) and respiration chamber techniques for measuring methane (CH4) emissions from dairy cows and to determine the proportion of CH4 that is released through the rectum. Data used were derived from 20 early lactation dairy cows in a 2 × 2 factorial design study for 4 periods with 6 wk/period. The 4 treatment diets consisted of grass silage and 2 levels of concentrate (30 and 60% dry matter basis), with or without yeast supplement. At the end of each period, CH4 emissions were measured simultaneously using the SF6 and respiration chamber techniques when cows were housed in chambers. The SF6 technique was also used when cows were housed in digestibility units (barn location) before and after respiratory chamber measurements (chamber location). The simultaneous measurements in chamber location revealed that CH4 emission estimates by the SF6 technique were similar to those by the respiration chamber technique in the first 3 periods, although the SF6 estimates were significantly higher in period 4. The regression of all data from the 4 periods demonstrated a linear relationship between the SF6 and respiration chamber measurements for total CH4 emissions (g/d, R2=0.69) and for CH4 emissions per unit of milk yield (g/kg, R2=0.88), and a quadratic relationship for CH4 emissions per unit of dry matter intake (g/kg, R2=0.64). The CH4 emissions from the rectum were calculated as the difference between CH4 estimates from the SF6 technique when cows were housed in respiratory chambers and barn locations, which was 3% of the total CH4 emissions from the mouth, nostrils, and rectum. The SF6 estimates in the chamber location accounted for all sources of emissions, whereas those in the barn location, like that in grazing conditions, did not include CH4 emission from the rectum. Therefore, the SF6 measurements for grazing cattle should be adjusted for CH4 emissions from the rectum (3% of total). We conclude that the SF6 technique is reasonably accurate for estimating CH4 emissions. © 2012 American Dairy Science Association. Source

Munoz E.,Andres Bello University | Munoz E.,University of the Frontier | Navia R.,University of the Frontier | Zaror C.,University of Concepcion | Alfaro M.,Institute Investigaciones Agropecuarias INIA Remehue
Journal of Soil Science and Plant Nutrition

The objective of this work was to quantify the country’s NH3 emissions from livestock production. This calculation was based on the mass flow of total ammoniacal nitrogen (TAN). The analysis was performed for all 15 geographical regions in Chile. The definition of livestock subcategories was based on data from the Chilean Agriculture and Forestry Census as well as technical reports published by the Chilean National Statistics Institute. Significant differences were observed among the sources of livestock emissions in Chile’s regions, and there was high variability depending on the degree of livestock confinement. In 2013, the total calculated emissions were 69.1 kt NH3/year (± 31.1). The O’Higgins Region had the highest NH3 emissions in Chile, representing 45% of the total. In terms of livestock production, 45% of the emissions were generated by pigs, 22% by poultry, 16% by cattle, 11% by equines and 4% by sheep. Emissions from the TAN that was available during manure and slurry management and the degree of animal confinement were the primary sources of uncertainty. This uncertainty could be greatly reduced by developing regional emission factors and by including the degree of animal confinement in Chile’s national statistics such as the Agriculture, Livestock and Forestry Census. © 2016, Sociedad Chilena de la Ciencia del Suelo. All rights reserved. Source

Escobar-Bahamondes P.,Agriculture and Agri Food Canada | Escobar-Bahamondes P.,University of Alberta | Escobar-Bahamondes P.,Institute Investigaciones Agropecuarias INIA Remehue | Oba M.,University of Alberta | Beauchemin K.A.,Agriculture and Agri Food Canada

The study determined the performance of equations to predict enteric methane (CH4) from beef cattle fed forage- and grain-based diets. Many equations are available to predict CH4 from beef cattle and the predictions vary substantially among equations. The aims were to (1) construct a database of CH4 emissions for beef cattle from published literature, and (2) identify the most precise and accurate extant CH4 prediction models for beef cattle fed diets varying in forage content. The database was comprised of treatment means of CH4 production from in vivo beef studies published from 2000 to 2015. Criteria to include data in the database were as follows: animal description, intakes, diet composition and CH4 production. In all, 54 published equations that predict CH4 production from diet composition were evaluated. Precision and accuracy of the equations were evaluated using the concordance correlation coefficient (r c), root mean square prediction error (RMSPE), model efficiency and analysis of errors. Equations were ranked using a combined index of the various statistical assessments based on principal component analysis. The final database contained 53 studies and 207 treatment means that were divided into two data sets: diets containing ⩾400 g/kg dry matter (DM) forage (n=116) and diets containing ⩽200 g/kg DM forage (n=42). Diets containing between ⩽400 and ⩾200 g/kg DM forage were not included in the analysis because of their limited numbers (n=6). Outliers, treatment means where feed was fed restrictively and diets with CH4 mitigation additives were omitted (n=43). Using the high-forage dataset the best-fit equations were the International Panel on Climate Change Tier 2 method, 3 equations for steers that considered gross energy intake (GEI) and body weight and an equation that considered dry matter intake and starch:neutral detergent fiber with r c ranging from 0.60 to 0.73 and RMSPE from 35.6 to 45.9 g/day. For the high-grain diets, the 5 best-fit equations considered intakes of metabolisable energy, cellulose, hemicellulose and fat, or for steers GEI and body weight, with r c ranging from 0.35 to 0.52 and RMSPE from 47.4 to 62.9 g/day. Ranking of extant CH4 prediction equations for their accuracy and precision differed with forage content of the diet. When used for cattle fed high-grain diets, extant CH4 prediction models were generally imprecise and lacked accuracy. © The Animal Consortium and Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada 2016 Source

Cardenas L.M.,Rothamsted Research | Hatch D.J.,Rothamsted Research | Scholefield D.,Rothamsted Research | Jhurreea D.,Rothamsted Research | And 6 more authors.
Soil Science and Plant Nutrition

A proportion of the nitrogen (N) applied to grasslands as organic or inorganic fertilizers can be lost to water courses as nitrate and to the atmosphere as nitrous and nitric oxides. Volcanic soils from Chile are not generally prone to leaching, possibly due to net immobilization of nitrate and/or ammonium, and/or due to inhibition of nitrification by either chemical or physical processes. In laboratory studies we found large mineralization potentials in soils from three different Chilean soils after 17 weeks of incubation, totalling 215 and 254 mg kg-1 dry soil for two Andisols and 127 mg kg-1 dry soil in an Ultisol. Nitrification occurred after a short period, and was lowest in the Ultisol. In addition, microbial analysis showed nitrifiers to be present in all three soils. Adsorption of ammonium was two-fold stronger than for nitrate, ranging from 29 to 180 kg N ha-1. The highest potential for N adsorption in the 0-60 cm soil profile was with the Ultisol (398 kg N ha-1), but was similar in both Andisols (193 and 172 kg N ha-1, respectively). The combination of ammonium retention together with delayed nitrification could account for the low leaching rates in these soils. © 2013 Copyright Rothamsted Research Ltd. Source

Sandana P.,Institute Investigaciones Agropecuarias INIA Remehue | Kalazich J.,Institute Investigaciones Agropecuarias INIA Remehue
Field Crops Research

The aim of this study was to evaluate the sensitivity of eco-physiological determinants of tuber yield in different potato genotypes (Solanum tuberosum L.) in response to phosphorus (P) availability. Two field experiments (Experiments 1 and 2) were carried out in southern Chile. In each experiment treatments were a factorial combination of (i) twenty-two genotypes of potatoes and (ii) two P fertilization rates (0 and 130kgPha-1, -P and +P, respectively). Tuber yields were affected (P<0.05) by the P rate, genotypes and the P rate×genotype interaction. Depending on the genotype, yield reduction ranged between 20 and 66%. Across experiments, tuber yield responses were highly related (R2=0.93, P<0.01) to total biomass and not to harvest index. The harvest index was only affected (P<0.05) by the genotype. In both experiments, radiation intercepted was affected by the P rate, genotype and the P rate×genotype interaction, while radiation use efficiency was only affected by the genotype as well as by P rate×genotype interaction in Experiment 2. Total biomass was better related (P<0.01) to radiation intercepted than to radiation use efficiency. Therefore, changes in tuber yield were related (P<0.001) to the changes in intercepted radiation in response to P deficiency. In addition, the results showed that yield, biomass and radiation intercepted responses to P fertilizer varied with genotype. The present study demonstrated in a broad range of genotypes that radiation interception is more important than radiation use efficiency in determining potato yield under P deficiency. Based on genotypic variability in yield response and sensitivity of radiation intercepted to P deficiency, there is potential for improving P use efficiency in potato production systems through breeding and crop management programs. © 2015 Elsevier B.V. Source

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