This study investigated the effects of rumen-protected methionine (RPM) and rumen-protected choline (RPC) on energy balance, postpartum lactation performance, antioxidant capacity and immune response in transition dairy cows. Forty-eight multiparous transition cows were matched and divided into four groups: control, 15 g/d RPC, 15 g/d RPM or 15 g/d RPC + 15 g/d RPM. Diet samples were collected daily before feeding, and blood samples were collected weekly from the jugular vein before morning feeding from 21 days prepartum to 21 days postpartum. Postpartum dry matter intake (DMI) was increased by both additives (P < 0.05), and energy balance values in supplemented cows were improved after parturition (P < 0.05). Both RPC and RPM decreased the plasma concentrations of non-esterified fatty acids (NEFA), β-hydroxybutyric acid (BHBA), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) (P < 0.05), but increased the plasma levels of glucose, very-low-density lipoprotein (VLDL) and apolipoprotein B100 (ApoB 100, P < 0.05). The supplements improved milk production (P < 0.05), and increased (P < 0.05) or tended to increase (0.05 < P < 0.10) the contents of milk fat and protein. The post-ruminal choline and methionine elevated the blood antioxidant status, as indicated by total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px) activity and the vitamin E concentration (P < 0.05), and reduced the plasma malondialdehyde (MDA) level (P < 0.05). Furthermore, RPM and RPC elevated the plasma interleukin 2 (IL-2) concentration and the CD4+/CD8+ T lymphocyte ratio in peripheral blood (P < 0.05). Alternatively, the levels of tumor necrosis factor-α (TNF-α) and IL-6 were decreased by RPM and RPC (P < 0.05). Overall, the regulatory responses of RPC and RPM were highly correlated with time and were more effective in the postpartum cows. The results demonstrated that dietary supplementation with RPC and RPM promoted energy balance by increasing postpartal DMI and regulating hepatic lipid metabolism, improved postpartum lactation performance and enhanced antioxidant capacity and immune function of transition dairy cows.

BackgroundIn rumen fermentation, fumaric acid (FA) could competitively utilize hydrogen with methanogenesis to enhance propionate production and suppress methane emission, but both effects were diet-dependent. This study aimed to explore the effects of FA supplementation on methanogenesis and rumen fermentation in goats fed diets varying in forage and concentrate particle size.MethodsFour rumen-cannulated goats were used in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments: low or high ratio of forage particle size: concentrate particle size (Fps:Cps), without or with FA supplementation (24 g/d). Fps:Cps was higher in the diet with chopped alfalfa hay plus ground corn than in that with ground alfalfa hay plus crushed corn.ResultsBoth increasing dietary Fps:Cps and FA supplementation shifted ruminal volatile fatty acid (VFA) patterns toward more propionate and less acetate in goats. An interaction between dietary Fps:Cps and FA supplementation was observed for the ratio of acetate to propionate (A:P), which was more predominant when FA was supplemented in the low-Fps:Cps diet. Methane production was reduced by FA, and the reduction was larger in the low-Fps:Cps diet (31.72%) than in the high-Fps:Cps diet (17.91%). Fumaric acid decreased ruminal total VFA concentration and increased ruminal pH. No difference was found in ruminal DM degradation of concentrate or alfalfa hay by dietary Fps:Cps or FA. Goats presented a lower ruminal methanogen abundance with FA supplementation and a higher B. fibrisolvens abundance with high dietary Fps:Cps.ConclusionsAdjusting dietary Fps:Cps is an alternative dietary model for studying diet-dependent effects without changing dietary chemical composition. Fumaric acid supplementation in the low-Fps:Cps diet showed greater responses in methane mitigation and propionate increase.

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Studies proved that addition of nitrate in rumen could lead to reduction of methane emission. The mechanism of this function was involved in the competition effect of nitrate on hydrogen consumption and the inhibitory effect of generated nitrite on methanogen proliferation. The present study investigated an alternative mechanism that denitrifying anaerobic methane oxidizing (DAMO) bacteria, DAMO archaea and anammox bacteria may co-exist in rumen, therefore, more methane can be oxidized when addition of nitrate. Ruminal batch culture model was used to test the effects of addition of 5 mM NaNO3, 4 mM NH4Cl, or both into the culture substrate on methane production, fermentation patterns, and population of methanogens, NC10 and anaerobic methanotrophic-2d (ANME-2d). Our results showed that NC10 in the ruminal culture was detected by polymerase chain reaction (PCR) when using NC10 special primer sets, and addition of nitrate reduced methane production and the relative proportions of methanogen, whereas increased the relative proportion of NC10. A combined addition of ammonia salt and nitrate did not show further inhibitory effect on methane production but accelerated nitrate removal. We did not detect DAMO archaea in ruminal culture by real-time PCR when using ANME-2d special primer sets. The present study may encourage researchers to pay more attention to methane oxidation performed by anaerobic methanotroph when studying the strategies of inhibiting ruminal methane emission.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-017-0377-2) contains supplementary material, which is available to authorized users.

Corn grain has a high starch content and is used as main energy source in ruminant diets. Compared with finely ground corn (FGC), steam-flaked corn (SFC) could improve the milk yield of lactating dairy cows and the growth performance of feedlot cattle, but the detailed mechanisms underlying those finding are unknown. The rumen microbiome breaks down feedstuffs into energy substrates for the host animals, and contributes to feed efficiency. Therefore, the current study was conducted to investigate the ruminal bacterial community changes of heifers fed differently processed corn (SFC or FGC) using 16S rRNA sequencing technologies, and to uncover the detailed mechanisms underlying the high performance of ruminants fed the SFC diet. The results revealed that different processing methods changed the rumen characteristics and impacted the composition of the rumen bacteria. The SFC diet resulted in an increased average daily gain in heifers, an increased rumen propionate concentration and a decreased rumen ammonia nitrogen concentration. The relative abundance of the phylum Firmicutes and Proteobacteria were tended to increase or significantly increased in the heifers fed SFC diet compared with FGC diet. In addition, the relative abundance of amylolytic bacteria of the genera Succinivibrio, Roseburia and Blautia were elevated, and the cellulolytic bacteria (Ruminococcaceae_UCG-014 and Ruminococcaceae_UCG-013) were decreased by the steam flaking method. Spearman correlation analysis between the ruminal bacteria and the microbial metabolites showed that the rumen propionate concentration was positively correlated with genera Succinivibrio and Blautia abundance, but negatively correlated with genera Ruminococcaceae_UCG-014 abundance. Evident patterns of efficient improvement in rumen propionate and changes in rumen microbes to further improve feed conversion were identified. This observation uncovers the potential mechanisms underlying the increased efficiency of the SFC processing method for enhancing ruminant performance.