Effects of diet fermentability and supplementation of 2-hydroxy-4-(methylthio)-butanoic acid and isoacids on milk fat depression: 2. Ruminal fermentation, fatty acid, and bacterial community structure

Abstract

The experiment was conducted to understand ruminal effects of diet modification during moderate milk fat depression (MFD) and ruminal effects of 2-hydroxy-4-(methylthio)-butanoic acid (HMTBa) and isoacids on alleviating MFD. Five ruminally cannulated cows were used in a 5 × 5 Latin square design with the following 5 dietary treatments (dry matter basis): a high-forage and low-starch control diet with 1.5% safflower oil (HF-C); a low-forage and high-starch control diet with 1.5% safflower oil (LF-C); the LF-C diet supplemented with HMTBa (0.11%; 28 g/d; LF-HMTBa); the LF-C diet supplemented with isoacids [(IA) 0.24%; 60 g/d; LF-IA]; and the LF-C diet supplemented with HMTBa and IA (LF-COMB). The experiment consisted of 5 periods with 21 d per period (14-d diet adaptation and 7-d sampling). Ruminal samples were collected to determine fermentation characteristics (0, 1, 3, and 6 h after feeding), long-chain fatty acid (FA) profile (6 h after feeding), and bacterial community structure by analyzing 16S gene amplicon sequences (3 h after feeding). Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC) in a Latin square design. Preplanned comparisons between HF-C and LF-C were conducted, and the main effects of HM-TBa and IA and their interaction within the LF diets were examined. The LF-C diet decreased ruminal pH and the ratio of acetate to propionate, with no major changes detected in ruminal FA profile compared with HF-C. The α-diversity for LF-C was lower compared with HF-C, and β-diversity also differed between LF-C and HF-C. The relative abundance of bacterial phyla and genera associated indirectly with fiber degradation was influenced by LF-C versus HF-C. As the main ef-fect of HMTBa within the LF diets, HMTBa increased the ratio of acetate to propionate and butyrate molar proportion. Ruminal saturated FA were increased and unsaturated FA concentration were decreased by HMT-Ba, with minimal changes detected in ruminal bacterial diversity and community. As the main effect of IA, IA supplementation increased ruminal concentration of all branched-chain volatile FA and valerate and increased the percentage of trans-10 C18 isomers in total FA. In addition, α-diversity and the number of functional features were increased for IA. Changes in the abundances of bacterial phyla and genera were minimal for IA. Interactions between HMTBa and IA were observed for ruminal variables and some bacterial taxa abundances. In conclusion, increasing diet fermentability (LF-C vs. HF-C) influenced rumen fermentation and bacterial community structure without major changes in FA profile. Supplementation of HMTBa increased biohydrogenation capacity, and supplemental IA increased bacterial diversity, possibly alleviating MFD. The combination of HMTBa and IA had no associative effects in the rumen and need further studies to understand the interactive mechanism.

Conditions stimulating neutral detergent fiber degradation by dosing branched-chain volatile fatty acids. III: Relation with solid passage rate and pH on prokaryotic fatty acid profile and community in continuous culture

“…The average ASV that were observed (n = 1,308) or derived by the Chao 1 nonparametric statistic (n = 1,392) indicate a robust prokaryotic community. Although we noted no change in our study resulting from dosing BCVFA, when BCVFA were fed to lactating dairy cattle, the number of ASV and most indices of α-diversity increased (Lee et al, 2021). Our β-diversity results (Figure 1) support the major shifts in relative ASV abundance associated with pH, and the period effect reflects the important role of differing inocula sources.…”

“…Following thawing, DNA was extracted and purified (Wenner et al, 2020) before sequencing of the 16S rRNA gene. Computational procedures were as described by Lee et al (2021). Briefly, the Illumina MiSeq 2 × 300 pairedend protocol was used, followed by filtering, annotation, and cluster analysis using amplicon sequencing variants (ASV) clustered at 99% similarity.…”

“…Briefly, the Illumina MiSeq 2 × 300 pairedend protocol was used, followed by filtering, annotation, and cluster analysis using amplicon sequencing variants (ASV) clustered at 99% similarity. The α and β diversity indices were derived as described by Lee et al (2021) except for Bray-Curtis dissimilarity (Wenner et al, 2020).…”

Effects of Dietary Supplementation With Clostridium butyricum on Growth Performance, Apparent Digestibility, Blood Metabolites, Ruminal Fermentation and Bacterial Communities of Fattening Goats

“…Numerous studies have also shown that C. butyricum can regulate the relative abundance of intestinal flora, consolidate intestinal barrier function and accelerate metabolism, to improve bodily health and immunity ( 12 , 15 , 16 ). In addition, its metabolite butyrate and other substances are also widely used in animal production to improve the performance of livestock and poultry, including improving the rumen fermentation of ruminants, and regulating rumen flora ( 17 , 18 ). High-concentrate diets in production can provide higher energy in the short term for increasing ruminant growth rates.…”

Effect of zinc source (zinc sulfate or zinc hydroxychloride) on relative abundance of fecal Treponema spp. in lactating dairy cows

“…Amplicon libraries were pooled and sequenced (2 × 300 bp paired-end sequencing) using the MiSeq platform (Illumina Inc.). Quality control (denoising, merging, removal of chimeras) was applied through QIIME2 (version 2019.10; Bolyen et al, 2019), similarly to Lee et al (2021). The final quantity of quality amplicon sequencing variants (ASV) used in this analysis numbered 3,855,702 and were clustered into taxonomy based on 99% similarity using the Silva 16S reference database (NR 132 version; Quast et al, 2013).…”