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BACKGROUND: The objective of this study was to determine the effects of forage conservation method and condensed tannins (CT) in conserved forage on rumen fermentation. Purple prairie clover (PPC; Dalea purpurea Vent.) containing 84.5 g kg−1 dry matter (DM) of CT was harvested at full flower and preserved as freeze‐dried green chop (F), hay (H) or silage (S). Batch culture incubations were conducted using conserved forages as a substrate and treatments were arranged as 3 × 2 factorial design of forage type (F, H and S) with or without polyethylene glycol (PEG). PEG was used to isolate the effects of CT on fermentation. Incubation was repeated twice with quadruplicate vials for each treatment in each incubation. 15N‐labelled ammonium sulfate was used as microbial N marker and headspace gas was sampled to determine methane production. RESULTS: Concentrations of neutral detergent fiber (NDF) and acid detergent fiber were lower (P < 0.01) in F than in H or S. Ensiling decreased (P < 0.001) total phenolics and extractable CT, but had no effect on total CT, whereas none of these phenolic fractions were altered in H. Hay and silage had lower (P < 0.01) true DM disappearance (TDMD) and NDF disappearance (NDFD) than F. Inclusion of PEG did not affect TDMD or NDFD after 8, 24 or 72 h of incubation. Productions of total gas, methane and total volatile fatty acid and the rate of gas production (c) were also similar, but ammonia was higher (P < 0.05) and microbial N was lower (P < 0.05) with than without PEG after 72 h of incubation. After 72 h, a lower (P < 0.001) proportion of acetate but higher (P < 0.05) proportion of propionate was noted with S, resulting in a lower (P < 0.001) acetate:propionate ratio as compared to F or H after 8 h of incubation. CONCLUSION: Condensed tannins in PPC decreased protein degradation in vitro, but had minimal effects on overall rumen fermentation, and conservation of PPC as hay or silage had little effect on the efficacy of CT in modulating rumen fermentation. © 2020 Her Majesty the Queen in Right of Canada. Journal of The Science of Food and Agriculture © 2020 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The present study assessed the effect of purple prairie clover (PPC) and PPC condensed tannins (CT) on the fecal microbiota of lambs using high-throughput 16S rRNA gene pyrosequencing. A total of 18 individual lambs were randomly divided into three groups and fed either green chop alfalfa (Alf), a 40:60 (DM basis; Mix) mixture of Alf and PPC, or Mix supplemented with polyethylene glycol (Mix-P) for 18 days. Fecal samples were collected on days 13 through 18 using digital rectal retrieval. The DNA of fecal samples was extracted and the microbial 16S rRNA gene amplicons were sequenced using 454 pyrosequencing. Regardless of diet, the bacterial community was dominated by Firmicutes and Bacteroidetes with many sequences unclassified at the genus level. Forage type and CT had no effect on the fecal microbial composition at the phylum level or on α-diversity. Compared to the Alf diet, the Mix diet reduced the relative abundance of Akkermansia ( P = 0.03) and Asteroleplasma ( P = 0.05). Fecal microbial populations in Alf and Mix-P clustered separately from each other when assessed using unweighted UniFrac ( P < 0.05). These results indicate that PPC CT up to 36 g/kg DM in the diet had no major effect on fecal microbial flora at the phyla level and exerted only minor effects on the genera composition of fecal microbiota in lambs. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of purple prairie clover (PPC, Dalea purpurea Vent.) hay and its condensed tannins (CT) on feed intake, growth performance, wool growth, nutrient digestibility, blood metabolites and rumen fermentation in lambs fed diets containing PPC and alfalfa hay. Alfalfa and PPC were harvested at similar growth stage, sun-cured to <12% moisture, and stored in a shed for 120 d. Thirty six individually fed lambs were randomly allocated into three groups and fed total mixed ration containing 40% (dry matter (DM) basis) of a pelleted barley grain based concentrate and 60% of alfalfa hay (AH), or 60% PPC hay (PH) or PH supplemented with polyethylene glycol (PH-p) for 77 d. Lambs were fed once daily and weighed bi-weekly. Faeces samples were collected in the 5th wk for 5 d to determine nutrients digestibility using acid insoluble ash as a marker. Lambs were slaughtered at the end of experiment to evaluate the carcass characteristics. Wool yield and quality were measured using a 10 cm dye band applied on d 0 and harvested on d 75. Blood samples were collected to analyze serum metabolites and antioxidant enzymes, and rumen fluid was sampled to analyze rumen fermentation products. Lambs fed PH had lower (P < 0.01) DM intake than AH or PH-p. Growth performance, wool growth parameters and carcass characteristics did not differ among diets. Lambs fed PH-p had greater (P < 0.05–0.001) DM, organic matter (OM), crude protein (CP), neutral detergent fibre (aNDF) and acid detergent fibre (ADF) digestibility than those fed AH, and greater (P < 0.05–0.001) CP, aNDF and ADF digestibility than those fed PH diet. Lambs fed PH exhibited greater apparent total tract digestibility of DM (P < 0.05) and OM (P < 0.05) and tended (P = 0.059) to have greater CP digestibility compared to those fed AH. Lambs consuming PH diet had lower (P < 0.05) blood urea nitrogen and creatinine than AH and lower (P < 0.05) blood glucose and urea than PH-p, but greater (P < 0.01) total antioxidant capacity and catalase activity than AH diet. Lambs fed PPC CT had lower (P < 0.05) concentrations of ammonia, total VFA, propionate, iso -butyrate, iso -valerate and protozoa. It was concluded that PPC hay had greater nutritive value to alfalfa hay owing to its greater DM, OM and protein digestibility, but did not improve lamb growth. [ABSTRACT FROM AUTHOR]