Background: Dietary energy source and level in lactation diets can profoundly affect milk yield and composition.Such dietary effects on lactation performance are underpinned by alteration of the rumen microbiota, of w...Background: Dietary energy source and level in lactation diets can profoundly affect milk yield and composition.Such dietary effects on lactation performance are underpinned by alteration of the rumen microbiota, of which bacteria, archaea, fungi, and protozoa may vary differently. However, few studies have examined all the four groups of rumen microbes. This study investigated the effect of both the level and source of dietary energy on rumen bacteria, archaea, fungi, and protozoa in the rumen of lactating dairy cows. A 2 × 2 factorial design resulted in four dietary treatments: low and high dietary energy levels(LE: 1.52–1.53;and HE: 1.71–1.72 Mcal/kg dry matter) and two dietary energy sources(GC: finely ground corn;and SFC: steam-flaked corn). We used a replicated 4 × 4 Latin square design using eight primiparous Chinese Holstein cows with each period lasting for 21 d. The rumen microbiota was analyzed using metataxonomics based on kingdom-specific phylogenetic markers [16 S r RNA gene for bacteria and archaea, 18 S r RNA gene for protozoa, and internally transcribed spacer 1(ITS1) for fungi] followed with subsequent functional prediction using PICRUSt2.Results: The GC resulted in a higher prokaryotic(bacterial and archaeal) species richness and Faith's phylogenetic diversity than SFC. For the eukaryotic(fungi and protozoa) microbiota, the LE diets led to significantly higher values of the above measurements than the HE diets. Among the major classified taxa, 23 genera across all the kingdoms differed in relative abundance between the two dietary energy levels, while only six genera(none being protozoal)were differentially abundant between the two energy sources. Based on prokaryotic amplicon sequence variants(ASVs) from all the samples, overall functional profiles predicted using PICRUSt2 differed significantly between LE and HE but not between the two energy sources. Fish Taco analysis identified Ruminococcus and Coprococcus as the taxa potentially contributing to the enriched KEGG pathways for biosynthesis of amino acids and to the metabolisms of pyruvate, glycerophospholipid, and nicotinate and nicotinamide in the rumen of HE-fed cows. The co-occurrence networks were also affected by the dietary treatments, especially the LE and GC diets, resulting in distinct co-occurrence networks. Several microbial genera appeared to be strongly correlated with one or more lactation traits.Conclusions: Dietary energy level affected the overall rumen multi-kingdom microbiota while little difference was noted between ground corn and steam-flaked corn. Some genera were also affected differently by the four dietary treatments, including genera that had been shown to be correlated with lactation performance or feed efficiency.The co-occurrence patterns among the genera exclusively found for each dietary treatment may suggest possible metabolic interactions specifically affected by the dietary treatment. Some of the major taxa were positively correlated to milk properties and may potentially serve as biomarkers of one or more lactation traits.展开更多
Background:Heat stress(HS)affects the ruminal microbiota and decreases the lactation performance of dairy cows.Because HS decreases feed intake,the results of previous studies were confounded by the effect of HS on fe...Background:Heat stress(HS)affects the ruminal microbiota and decreases the lactation performance of dairy cows.Because HS decreases feed intake,the results of previous studies were confounded by the effect of HS on feed intake.This study examined the direct effect of HS on the ruminal microbiota using lactating Holstein cows that were pair-fed and housed in environmental chambers in a 2×2 crossover design.The cows were pair-fed the same amount of identical total mixed ration to eliminate the effect of feed or feed intake.The composition and structure of the microbiota of prokaryotes,fungi,and protozoa were analyzed using metataxonomics and compared between two thermal conditions:pair-fed thermoneutrality(PFTN,thermal humidity index:65.5)and HS(87.2 for daytime and 81.8 for nighttime).Results:The HS conditions altered the structure of the prokaryotic microbiota and the protozoal microbiota,but not the fungal microbiota.Heat stress significantly increased the relative abundance of Bacteroidetes(primarily Gram-negative bacteria)while decreasing that of Firmicutes(primarily Gram-positive bacteria)and the Firmicutes-toBacteroidetes ratio.Some genera were exclusively found in the heat-stressed cows and thermal control cows.Some co-occurrence and mutual exclusion between some genera were also found exclusively for each thermal condition.Heat stress did not significantly affect the overall functional features predicted using the 16S rRNA gene sequences and ITS1 sequences,but some enzyme-coding genes altered their relative abundance in response to HS.Conclusions:Overall,HS affected the prokaryotes,fungi,and protozoa of the ruminal microbiota in lactating Holstein cows to a different extent,but the effect on the structure of ruminal microbiota and functional profiles was limited when not confounded by the effect on feed intake.However,some genera and co-occurrence were exclusively found in the rumen of heat-stressed cows.These effects should be attributed to the direct effect of heat stress on the host metabolism,physiology,and behavior.Some of the“heat-stress resistant”microbes may be useful as potential probiotics for cows under heat stress.展开更多
基金partially funded by grants from the National Key Research and Development Program of China (2018YFD0501600)the Scientific Research Project for Major Achievements of The Agricultural Science and Technology Innovation Program (ASTIP)(No. CAAS-ZDXT2019004+3 种基金CAASXTCX2016011–01ASTIP-IAS07)Beijing Dairy Industry Innovation Team(BAIC06–2019)the USDA National Institute of Food and Agriculture(award number:2019–67030-29003)。
文摘Background: Dietary energy source and level in lactation diets can profoundly affect milk yield and composition.Such dietary effects on lactation performance are underpinned by alteration of the rumen microbiota, of which bacteria, archaea, fungi, and protozoa may vary differently. However, few studies have examined all the four groups of rumen microbes. This study investigated the effect of both the level and source of dietary energy on rumen bacteria, archaea, fungi, and protozoa in the rumen of lactating dairy cows. A 2 × 2 factorial design resulted in four dietary treatments: low and high dietary energy levels(LE: 1.52–1.53;and HE: 1.71–1.72 Mcal/kg dry matter) and two dietary energy sources(GC: finely ground corn;and SFC: steam-flaked corn). We used a replicated 4 × 4 Latin square design using eight primiparous Chinese Holstein cows with each period lasting for 21 d. The rumen microbiota was analyzed using metataxonomics based on kingdom-specific phylogenetic markers [16 S r RNA gene for bacteria and archaea, 18 S r RNA gene for protozoa, and internally transcribed spacer 1(ITS1) for fungi] followed with subsequent functional prediction using PICRUSt2.Results: The GC resulted in a higher prokaryotic(bacterial and archaeal) species richness and Faith's phylogenetic diversity than SFC. For the eukaryotic(fungi and protozoa) microbiota, the LE diets led to significantly higher values of the above measurements than the HE diets. Among the major classified taxa, 23 genera across all the kingdoms differed in relative abundance between the two dietary energy levels, while only six genera(none being protozoal)were differentially abundant between the two energy sources. Based on prokaryotic amplicon sequence variants(ASVs) from all the samples, overall functional profiles predicted using PICRUSt2 differed significantly between LE and HE but not between the two energy sources. Fish Taco analysis identified Ruminococcus and Coprococcus as the taxa potentially contributing to the enriched KEGG pathways for biosynthesis of amino acids and to the metabolisms of pyruvate, glycerophospholipid, and nicotinate and nicotinamide in the rumen of HE-fed cows. The co-occurrence networks were also affected by the dietary treatments, especially the LE and GC diets, resulting in distinct co-occurrence networks. Several microbial genera appeared to be strongly correlated with one or more lactation traits.Conclusions: Dietary energy level affected the overall rumen multi-kingdom microbiota while little difference was noted between ground corn and steam-flaked corn. Some genera were also affected differently by the four dietary treatments, including genera that had been shown to be correlated with lactation performance or feed efficiency.The co-occurrence patterns among the genera exclusively found for each dietary treatment may suggest possible metabolic interactions specifically affected by the dietary treatment. Some of the major taxa were positively correlated to milk properties and may potentially serve as biomarkers of one or more lactation traits.
基金funded by the National Natural Science Foundation of China(award number:31872383)the Scientific Research Project for Major Achievements of The Agricultural Science and Technology Innovation Program(award number:ASTIP-IAS07-1)the Beijing Dairy Industry Innovation Team(Award number:BAIC06-2021).
文摘Background:Heat stress(HS)affects the ruminal microbiota and decreases the lactation performance of dairy cows.Because HS decreases feed intake,the results of previous studies were confounded by the effect of HS on feed intake.This study examined the direct effect of HS on the ruminal microbiota using lactating Holstein cows that were pair-fed and housed in environmental chambers in a 2×2 crossover design.The cows were pair-fed the same amount of identical total mixed ration to eliminate the effect of feed or feed intake.The composition and structure of the microbiota of prokaryotes,fungi,and protozoa were analyzed using metataxonomics and compared between two thermal conditions:pair-fed thermoneutrality(PFTN,thermal humidity index:65.5)and HS(87.2 for daytime and 81.8 for nighttime).Results:The HS conditions altered the structure of the prokaryotic microbiota and the protozoal microbiota,but not the fungal microbiota.Heat stress significantly increased the relative abundance of Bacteroidetes(primarily Gram-negative bacteria)while decreasing that of Firmicutes(primarily Gram-positive bacteria)and the Firmicutes-toBacteroidetes ratio.Some genera were exclusively found in the heat-stressed cows and thermal control cows.Some co-occurrence and mutual exclusion between some genera were also found exclusively for each thermal condition.Heat stress did not significantly affect the overall functional features predicted using the 16S rRNA gene sequences and ITS1 sequences,but some enzyme-coding genes altered their relative abundance in response to HS.Conclusions:Overall,HS affected the prokaryotes,fungi,and protozoa of the ruminal microbiota in lactating Holstein cows to a different extent,but the effect on the structure of ruminal microbiota and functional profiles was limited when not confounded by the effect on feed intake.However,some genera and co-occurrence were exclusively found in the rumen of heat-stressed cows.These effects should be attributed to the direct effect of heat stress on the host metabolism,physiology,and behavior.Some of the“heat-stress resistant”microbes may be useful as potential probiotics for cows under heat stress.
