Predicting CO production of lactating dairy cows from animal, dietary, and production traits using an international dataset.

Automated measurements of the ratio of concentrations of methane and carbon dioxide, [CH]:[CO], in breath from individual animals (the so-called "sniffer technique") and estimated CO production can be used to estimate CH production, provided that CO production can be reliably calculated. This would allow CH production from individual cows to be estimated in large cohorts of cows, whereby ranking of cows according to their CH production might become possible and their values could be used for breeding of low CH-emitting animals. Estimates of CO production are typically based on predictions of heat production, which can be calculated from body weight (BW), energy-corrected milk yield, and days of pregnancy.

Effects of replacement of barley with oats on milk fatty acid composition in dairy cows fed grass silage-based diets.

This study consists of milk fatty acid (FA) data collected during 2 in vivo experiments. For this study, 8 cows from each experiment were included in a replicated 4 × 4 Latin square design. At the start of experiment 1 (Exp1) cows were at (mean ± standard deviation) 87 ± 34.

Prediction of nitrogen excretion from data on dairy cows fed a wide range of diets compiled in an intercontinental database: A meta-analysis.

Manure nitrogen (N) from cattle contributes to nitrous oxide and ammonia emissions and nitrate leaching. Measurement of manure N outputs on dairy farms is laborious, expensive, and impractical at large scales; therefore, models are needed to predict N excreted in urine and feces. Building robust prediction models requires extensive data from animals under different management systems worldwide.

Effects of ruminal protozoa on methane emissions in ruminants-A meta-analysis.

The effects of different ruminal protozoa (RP) on CH emissions from ruminants were evaluated in a meta-analysis, using 64 publications reporting data from 79 in vivo experiments. Experiments included in the database reported CH emissions (g/d) and total RP (TRP, log cells/mL) from the same group of animals. The relationship between CH emissions and RP (TRP, entodiniomorphids, and isotrichids), and TRP-, entodiniomorphid-, and isotrichid-based CH emission prediction models, were evaluated as mixed models with experiment as a random effect and weighted by the reciprocal of the standard error of the mean and centered around one.