Effect of residual methane emission on physiological characteristics and carcass performance in Japanese Black cattle.

This study investigated the physiological characteristics and carcass performance associated with residual methane emissions (RME), and the effects of bull differences on CH4-related traits in Japanese Black cattle. Enteric methane (CH4) emissions from 156 Japanese Black cattle (111 heifers and 45 steers) were measured during early fattening using the sniffer method. Various physiological parameters were investigated to clarify the physiological traits between the high, middle, and low RME groups. CH4-related traits were examined to determine whether bull differences affected progeny CH4 emissions. Ruminal butyrate and NH3 concentrations were significantly higher in the high-RME group than in the low-RME group, whereas the propionate content was significantly higher in the low-RME group. Blood urea nitrogen, ß-hydroxybutyric acid, and insulin concentrations were significantly higher, and blood amino acids were lower in the high-RME group than in the other groups. No significant differences were observed in the carcass traits and beef fat composition between RME groups. CH4-related traits were significantly different among bull herds. Our results show that CH4-related traits are heritable, wherein bull differences affect progeny CH4 production capability, and that the above-mentioned rumen fermentations and blood metabolites could be used to evaluate enteric methanogenesis in Japanese Black cattle.

Variation among individual beef cattle in methane-to-carbon dioxide ratio measured under on-farm conditions using the sniffer method.

This study proposed a method for measuring the methane (CH4 )/carbon dioxide (CO2 ) ratio from individual beef cattle under on-farm conditions and estimated the variance components of the CH4 /CO2 ratio. Gas measurements were conducted using 166 Japanese Black cattle group-housed in pens equipped with individual feed bins. The gas containing the animal's breath was measured individually after concentrate feeding by covering the feed bin with a sheet with sampling inlets. Measurements were performed six times (three consecutive days, twice daily) per individual. Most of the sampled gas contained more than 1000 ppm of the mean background-corrected CO2 , suggesting that the method proposed in this study successfully collected sufficient breath concentration to accurately measure the CH4 /CO2 ratio. The between-animal variance accounted for 31.7% of the total variance in the CH4 /CO2 ratio. The results showed that the gas collection method proposed in this study could be a useful tool for measuring the CH4 /CO2 ratio under on-farm conditions. The variance component obtained from this study will help to establish protocols for generating data for genetic evaluation and performing dietary experiments with sufficient statistical power.

Effects of fermentative quality of corn silage on lactation, blood metabolites, and rumen fermentation in dairy cows.

We investigated the effect of fermentation quality of corn silage on dry matter intake (DMI), milk yield, ruminal fermentation, methane (CH4 ) emissions, and plasma metabolites in lactating cows. Six lactating Holstein cows were used in a 2 × 2 crossover design with two dietary treatments containing high quality corn silage with lower pH (high group) or low quality corn silage with higher pH (low group). The cows were fed partial mixed ration (PMR containing 50%DM of each corn silage) ad libitum plus 0.7 kg/day of concentrates at milking. The DMI of cows in the low group (24.8 kg/day) tended to be lower (p < 0.10) than that in the high group (26.8 kg/day). The dietary treatment did not affect milk yield or milk fat, protein, or lactose concentrations. The ruminal acetic acid proportion of the low group was significantly higher (p < 0.05) than that of the high group. The CH4 emission per DMI of the low group tended to be higher (p < 0.10) than that of the high group. The plasma concentration of the total cholesterol (TCHO) and the activity of aspartate aminotransferase and alanine aminotransferase of the low group were significantly higher than those of the high group.

Prediction of methane emissions from fattening cattle using the methane-to-carbon dioxide ratio.

This study aimed to develop a prediction equation for methane (CH4 ) emissions from fattening cattle based on the CH4 /carbon dioxide (CO2 ) ratio and validate the predictive ability of the developed equation. The prediction equation was developed using the CH4 /CO2 ratio combined with oxygen consumption and respiratory quotient estimations that were theoretically calculated from the relation between gas emissions and energy metabolism. To validate the prediction equation, gas measurements in the headboxes were conducted using eight Japanese Black steers. The predictive ability of the developed equation was compared with that of two previously reported equations. As a result, the developed and reported equations had significant (P < 0.01) linear relationships between the observed and predicted CH4 emissions. Notably, only the developed equation had a significant (P < 0.01) linear relationship between the observed and predicted CH4 emissions when expressed per unit of dry matter intake. The results suggest that the developed prediction equation has a higher predictive ability than previously reported equations, particularly in evaluating the efficiency of CH4 emissions. Although further validation is required, the equation developed in this study can be a valuable tool for on-farm estimations of individual CH4 emissions from fattening cattle.

The influence of breath concentration in the gas sample on the accuracy of methane to carbon dioxide ratio using the sniffer method in dairy cows.

The purpose of this study was to investigate the carbon dioxide (CO2 ) concentration in the sampled gas to avoid low concentration of breath while measuring the methane (CH4 )/CO2 ratio using the sniffer method. This study also assessed the effect of selective elimination by applying the threshold of CO2 concentration to the CH4 /CO2 ratio. The gas measurement in the automatic milking system was conducted with 26 multiparous Holstein cows using an electric fan to manipulate the CO2 concentration in the sampled gas. Four different thresholds of the background-corrected CO2 concentrations (0, 0.025, 0.05, and 0.1%) were applied to every 1-s value of the individual gas measurement. Subsequently, three different upper limits of the proportion of eliminated values (none, 0.5, and 0.33) were applied to the individual records per milking. The results showed that the sampled gas must contain more than 0.1% of the corrected CO2 concentration to enable accurate calculation of the CH4 /CO2 ratio. It is recommended that at least half of the values in the data be larger than the threshold of the corrected CO2 concentration for unbiased measurement of the CH4 /CO2 ratio.

Prediction of enteric methane emissions from lactating cows using methane to carbon dioxide ratio in the breath.

The aim of this study was to develop prediction equations for methane (CH4 ) emissions from lactating cows using the CH4 /carbon dioxide (CO2 ) ratio in the breath measured in the automatic milking system (AMS) and to evaluate the predicted values and factors affecting the CH4 /CO2 ratio. The model development was conducted using a dataset determined in respiration chambers or head boxes (n = 121). Then, gas measurements in the AMS as well as in the head box were carried out with six lactating cows fed one of three different levels of neutral detergent fiber (NDF) content, following a 3 × 3 Latin square experimental design. The obtained equation that is suitable for practical use on farms to predict CH4 was CH4 (L/day) = -507 + 0.536 live weight (kg) + 8.76 energy-corrected milk (kg/day) + 5,029 CH4 /CO2 (adjusted R2 = 0.83; root mean square error = 40.8 L/day). Results showed that the predicted values correlated positively with the observed values, the determined CH4 /CO2 ratio increased with increasing dietary NDF content, and the detected eructation rate was in the normal range. On the other hand, the CH4 /CO2 ratio was affected by the time interval between measurement and last eating before the measurement.

Effects of use of conventional and sexed semen on the conception rate in heifers: A comparison study.

Conception rate with the use of sexed semen is lower than that with the use of conventional semen, posing a major problem in the dairy industry. The aim of this study was to understand the risk factors that affect the conception rate after artificial insemination (AI) with conventional and sexed semen using field data. The records of the first insemination in Holstein heifers with conventional (n = 41,857) and sexed semen (n = 45,465) in Hokkaido, Japan were analyzed. The mean conception rate after AI from 2012 to 2016 was 56.9% with conventional semen and 47.3% with sexed semen. A multivariable logistic regression model including the effects of year, heifer age, time of the year, semen type, service sire, and their interactions was used to evaluate the interaction effect of heifer age and time of the year by semen type on the conception rate. In the analysis using heifer age, we found that heifers inseminated with sexed semen were approximately 21 days younger than those inseminated with conventional semen. Interestingly, in early, warmer months (Jun, Jul, and Aug), the conception rate after AI with sexed semen significantly decreased compared with that after AI with conventional semen (P < 0.01). Our results showed that more careful implementation of AI is required for a stable conception using sexed semen, particularly during warmer months.

Radiofrequency hydrogen ion source with permanent magnets providing axial magnetic field.

Uniform axial magnetic field of about 70 G is applied to a radiofrequency (rf) hydrogen ion source by arrays of permanent magnets. The plasma density and electron temperature downstream of the source and near the magnetic filter are compared with those in the previously described ion source, where the axial field has been applied by two solenoids. The source is operated at ∼350 kHz and above 10 kW rf power with a field-effect-transistor-based invertor power supply in 1.5 Pa hydrogen. The results show that the plasma density of ∼10(19) m(-3) near the source exit and ∼10(18) m(-3) near the magnetic filter can be obtained, which are higher than those with the solenoids.

Five cases of aconite poisoning: toxicokinetics of aconitines.

Aconite poisoning was examined in five patients (four males and one female) aged 49 to 78 years old. The electrocardiogram findings were as follows: ventricular tachycardia and ventricular fibrillation in case 1, premature ventricular contraction and accelerated idioventricular rhythm in case 2, AIVR in case 3, and nonsustained ventricular tachycardia in cases 4 and 5. The patient in case 1 was given percutaneous cardiopulmonary support because of unstable hemodynamics, whereas the other patients were treated with fluid replacement and antiarrhythmic agents. The main aconitine alkaloid in each patient had a half-life that ranged from 5.8 to 15.4 h over the five cases, and other detected alkaloids had half-lives similar to the half-life of the main alkaloid in each case. The half-life of the main alkaloid in case 1 was about twice as long as the half-lives in the other cases, and high values for the area under the blood concentration-time curve and the mean residence time were only observed in case 1. These results suggest that alkaloid toxicokinetics parameters may reflect the severity of toxic symptoms in aconite poisoning.