Greenhouse gas emission from the activities of all productive sectors is currently a topic of foremost importance. The major contributors in the livestock sector are ruminants, especially dairy cows. This study aimed to evaluate and compare 21 equations for predicting enteric methane emissions (EME) developed on the basis of milk traits and fatty acid profiles, which were selected from 46 retrieved through a literature review. We compiled a reference database of the detailed fatty acid profiles, determined by GC, of 992 lactating cows from 85 herds under 4 different dairy management systems. The cows were classified according to DIM, parity order, and dairy system. This database was the basis on which we estimated EME using the selected equations. The EME traits estimated were methane yield (20.63 ± 2.26 g/kg DMI, 7 equations), methane intensity (16.05 ± 2.76 g/kg of corrected milk, 4 equations), and daily methane production (385.4 ± 68.2 g/d, 10 equations). Methane production was also indirectly calculated by multiplying the daily corrected milk yield by the methane intensity (416.6 ± 134.7 g/d, 4 equations). We also tested for the effects of DIM, parity, and dairy system (as a correction factor) on the estimates. In general, we observed little consistency among the EME estimates obtained from the different equations, with exception of those obtained from meta-analyses of a range of data from different research centers. We found all the EME predictions to be highly affected by the sources of variation included in the statistical model: DIM significantly affected the results of 19 of the 21 equations, and parity order influenced the results of 13. Different patterns were observed for different equations with only some of them in accordance with expectations based on the cow's physiology. Finally, the best predictions of daily methane production were obtained when a measure of milk yield was included in the equation or when the estimate was indirectly calculated from daily milk yield and methane intensity.

Milk from cows grazing on alpine pastures has higher quality than milk from indoor-fed cows, likely due to diet-driven differences in rumen microbiota. We assessed the effects of supplementing alpine herbs—each varying in its content of fiber, protein, and polyphenol—on rumen microbiota via in vitro fermentation, comparing these to a grass hay control using metagenomic sequencing. Fermentations with alpine herbs compared to grass hay control had higher content of fibrolytic Prevotella and lower abundances of Butyrivibrio, Ruminococcaceae, Anaerovibrio, Succiniclasticum, and Desulfovibrio. Fermentations with high starch content (Alchemilla vulgaris, Gallium odoratum and Sanguisorba officinalis) had low, microbial diversity, while fermentations with high content of structural fibre (Sisymbrium officinale, Tanacetum vulgare, and Cicerbita alpina) had high microbial diversity. C. alpina, Sa. officinalis, and T. vulgare fermentations that had high lignin content showed a higher abundance of Bacteroidetes and a lower abundance of Firmicutes. Fermentations with high protein content (G. odoratum and T. vulgare) induced higher abundance of fibrolytic Lachnospiraceae. Sa. officinalis and A. vulgaris fermentations with high content of polyphenols were associated with increased abundances of Streptococcus and family RF-16 and lower abundances of family BS11 and Desulfovibrio. Fermentations with C. alpina and Si. Officinale induced higher abundance of fibrolytic Fibrobacter succinogenes. The beta diversity between fermentations corresponded to differences in the contents of protein, lignin, and polyphenols in the plant material. In conclusion, different herbs can promote the abundance of various fibrinolytic bacteria and change the microbial diversity, which has potential to increase the feed efficiency and the robustness of microbiota and reduce methane production.

Iodoform has been shown to be an enteric methane-reducing agent. This study aimed to investigate if iodoform differentially affected maize (MS) and clover grass silage (GS). These substrates were used in four 22 h in vitro gas production fermentations with and without 0.032 mg/g of dry matter substrate of 0.064% iodoform in zeolite (IZ). The results of organic matter degradation (dOM, g/g), volatile fatty acids (VFAs, mMol/L), partitioning factor (PF, mg/mL), total gas production (TGP, mL/g OM), and periodic hydrogen and methane yield (mL/g OM) were evaluated. The interaction between substrate and IZ for dOM was significant with significantly less in GS. The interaction between substrate and additive was continuously significant for TGP. The additive in GS numerically decreased the TGP, but significantly increased TGP in MS. The interaction between substrate and additive was sporadically significant with methane, increasing the yield when IZ was added to MS, but a consistent, non-significant, decrease in yield was found when IZ was added to GS. Total VFA production and propionate content increased in both substrates with the addition of IZ, but only significantly in GS. Iodoform significantly decreased the efficiency of microbial conversion (PF) in both substates. Differential effects of iodoform on GS and MS were evident. More research is needed to determine the modes of action of iodoform.

Introduction: This research aimed to evaluate the impact of ruminant digestion on viability and germination pattern of the seeds of 9 weed species (A. theophrasti, A. myosuroides, A. retroflexus, A. sterilis, C. album, D. stramonium, E. crus-galli, L. multiflorum and S. halepense).Methods: One hundred seeds of each species were included in nylon bags and exposed to in vitro procedures simulating the rumen fermentation according to an experimental design that considered: 9 weed species, 3 incubation times in the artificial rumen (12, 24 and 48 h), 2 diets (lactating cows, and heifers), 4 replications, plus 4 additional replicas per species with seeds not subjected to the in vitro digestion as a control. This design was repeated two times (2 batches), involving a total of 504 replicas. Results were expressed in relative terms, using the data from the untreated seeds as a scaling factor. Data were analyzed, by species, with a model that considered diet and incubation time, and their interaction as fixed factors, and the batch as a random effect.Results and conclusions: Incubation time evidenced the greatest impact on seed germination and viability (6 species), where diet (4 species) and Incubation time x diet interaction (3 species) had lower impact. Compared to the control, A. theophrasti germination increased to 150% after 12 h but dropped to ~20% after 48 h under the lactating cows’ diet. Germination of A. myosuroides remained stable initially but fell to ~60% after 48 h, while A. sterilis showed consistently low germination, further declining with digestion. Germination of C. album rose to ~130% after 48 h, and the one of E. crus-galli to ~140%. For D. stramonium, germination decreased to ~20%, with heifers’ diet causing greater losses. No significant effects were noted for L. multiflorum, S. halepense, or A. retroflexus. Viability losses were significant for A. theophrasti and A. myosuroides under the lactating cows’ diet and for D. stramonium under the heifers’ diet. Possible variation causes were evidenced in the thickness and the fibrous content (NDF, ADF, ADL) of the seed coats, correlated with the rumen microbial activity.