Wind Influences Corrected Auto-calibrated Soil Evapo-Respiration Chamber (ASERC), Evaporation Measures

The importance of the soil evaporation concerns our main life supports source for agriculture or for climate changes predictions science. A simple to operate instrument, based on non-steady state (NSS) technique, made for soil evaporation measurement appears then suitable. However, because the NSS chamber technique is highly invasive, special care should be provided to correct the wind influence on the evaporation process. As the wind influence on the evaporation is depending on numerous and not real-time monitorable variables, in order to make the measurements easily corrigible on a bare soil with a unique variable – wind speed (Ws), whatever is the soil nature, soil texture, and others soil or air meteorological variables – a self-calibrating chamber with corresponding protocol called Auto-calibrated Soil Evapo-Respiration Chamber (ASERC) was developed. A simple protocol followed by this chamber allows to determine the soil evaporation wind susceptibility (Z) and to correct the measurements achieving 0.95 accuracy confidence. Some interesting finding on sandy and clayey soils evaporation measured during a laboratory calibration will also be reported.

Technical Note: Validation of the GreenFeed System for measuring enteric gas emissions from cattle

There are knowledge gaps in animal agriculture on how to best mitigate greenhouse gas emissions while maintaining animal productivity. One reason for these gaps is the uncertainties associated with methods used to derive emission rates. This study compared emission rates of methane (CH4) and carbon dioxide (CO2) measured by a commercially available GreenFeed (GF) system to those from 1) a mass flow controller (MFC) that released known quantities of gas over time (i.e., emission rate), and 2) a respiration chamber (RC). The GF and MFC differed by only 1% for CH4 (P = 0.726) and 3% for CO2 (P = 0.013). The difference between the GF and RC was 1% (P = 0.019) for CH4 and 1% for CO2 (P = 0.007). Further investigation revealed that the difference in emission rate for CO2 was due to a small systematic offset error indicating a correction factor could be applied. We conclude that the GF system accurately estimated enteric CH4 and CO2 emission rates of cattle over a short measurement period, but additional factors would need to be considered in determining the 24-h emission rate of an animal.

Genetic variance and covariance components for carbon dioxide production and postweaning traits in Angus cattle

This experiment investigated phenotypic and genetic relationships between carbon dioxide production, methane emission, feed intake, and postweaning traits in Angus cattle. Respiration chamber data on 1096 young bulls and heifers from 2 performance recording research herds of Angus cattle were analyzed to provide phenotypic and genetic parameters for carbon dioxide production rate (CPR; n = 425, mean 3,010 ± SD 589 g/d) and methane production rate (MPR; n = 1,096, mean 132.8 ± SD 25.2 g/d) and their relationships with dry matter intake (DMI; n = 1,096, mean 6.15 ± SD 1.33 kg/d), body weight (BW) and body composition traits. Heritability estimates were moderate to high for CPR (0.53 [SE 0.17]), MPR (0.31 [SE 0.07]), DMI (0.49 [SE 0.08]), yearling BW (0.46 [SE 0.08]), and scanned rib fat depth (0.42 [SE 0.07]). There was a strong phenotypic (0.83 [SE 0.02]) and genetic (0.75 [SE 0.10]) correlation between CPR and MPR. The correlations obtained for DMI with CPR and with MPR were high, both phenotypically (rp) and genetically (rg) (rp: 0.85 [SE 0.01] and 0.71 [SE 0.02]; rg (0.95 [SE 0.03] and 0.83 [SE 0.05], respectively). Yearling BW was strongly correlated phenotypically (rp ≥ 0.60) and genetically (rg > 0.80) with CPR, MPR, and DMI, whereas scanned rib fat was weakly correlated phenotypically (rp < 0.20) and genetically (rg ≤ 0.20) with CPR, MPR, and DMI. The strong correlation between both CPR and MPR with DMI confirms their potential use as proxies for DMI in situations where direct DMI recording is not possible such as on pasture.

Role of Endocannabinoids in Energy-Balance Regulation in Participants in the Postobese State—a PREVIEW Study

Context Endocannabinoids are suggested to play a role in energy balance regulation. Objective We aimed to investigate associations of endocannabinoid concentrations during the day with energy balance and adiposity and interactions with 2 diets differing in protein content in participants in the postobese phase with prediabetes. Design and Participants Participants (n = 38) were individually fed in energy balance with a medium protein (MP: 15:55:30% of energy from protein:carbohydrate:fat) or high-protein diet (HP: 25:45:30% energy from P:C:F) for 48 hours in a respiration chamber. Main Outcome Measures Associations between energy balance, energy expenditure, respiratory quotient, and endocannabinoid concentrations during the day were assessed. Results Plasma-concentrations of anandamide (AEA), oleoylethanolamide (OEA), palmitoyethanolamide (PEA), and pregnenolone (PREG) significantly decreased during the day. This decrease was inversely related to body mass index (AEA) or body fat (%) (PEA; OEA). The lowest RQ value, before lunch, was inversely associated with concentrations of AEA and PEA before lunch. Area under the curve (AUC) of concentrations of AEA, 2-AG, PEA, and OEA were positively related to body fat% (P < .05). The HP and MP groups showed no differences in concentrations of AEA, OEA, PEA, and PREG, but the AUC of 2-arachidonoylglycerol (2-AG) was significantly higher in the HP vs the MP group. Conclusions In energy balance, only the endocannabinoid 2-AG changed in relation to protein level of the diet, whereas the endocannabinoid AEA and endocannabinoid-related compounds OEA and PEA reflected the gradual energy intake matching energy expenditure during the day.