Zhiliang Tan

Effects of yeast culture and fibrolytic enzyme supplementation on in vitro fermentation characteristics of low-quality cereal straws

The effects of yeast culture and fibrolytic enzyme preparation (containing cellulase and xylanase) on in vitro fermentation characteristics of rice straw, wheat straw, maize stover, and maize stover silage were examined using an in vitro gas production technique. Four levels of yeast culture and fibrolytic enzyme supplements (0, 2.5, 5.0, and 7.5 g/kg of straw DM, respectively) were tested in a 4 x 4 factorial arrangement. Supplementation of yeast culture increased the cumulative gas production, theoretical maximum of gas production, rate of gas production, IVDMD, and in vitro OM disappearance (IVOMD), and decreased the lag time for each type of straw. Fibrolytic enzyme supplementation tended to increase cumulative gas production, theoretical maximum of gas production, and rate of gas production; prolonged lag time of gas production; and enhanced IVDMD and IVOMD for 4 types of cereal straws, with the significance of this effect being dependent on the level of supplemented enzymes. There were significant interactions between fibrolytic enzymes and yeast on all in vitro gas production parameters, IVDMD, and IVOMD of each type of straw. The outcome of this research indicated that the application of fibrolytic enzyme preparation and yeast culture could improve in vitro gas production fermentation of cereal straws.

Rumen development process in goats as affected by supplemental feeding v. grazing: age-related anatomic development, functional achievement and microbial colonisation.

The aim of the present study was to describe age-related changes in anatomic, functional and microbial variables during the rumen development process, as affected by the feeding system (supplemental feeding v. grazing), in goats. Goats were slaughtered at seven time points that were selected to reflect the non-rumination (0, 7 and 14 d), transition (28 and 42 d) and rumination (56 and 70 d) phases of rumen development. Total volatile fatty acid (TVFA) concentration (P= 0·002), liquid-associated bacterial and archaeal copy numbers (P< 0·01) were greater for supplemental feeding v. grazing, while rumen pH (P< 0·001), acetate molar proportion (P= 0·003) and solid-associated microbial copy numbers (P< 0·05) were less. Rumen papillae length (P= 0·097) and extracellular (P= 0·093) and total (P= 0·073) protease activity potentials in supplemented goats tended to be greater than those in grazing goats. Furthermore, from 0 to 70 d, irrespective of the feeding system, rumen weight, rumen wall thickness, rumen papillae length and area, TVFA concentration, xylanase, carboxymethylcellulase activity potentials, and microbial copy numbers increased (P< 0·01) with age, while the greatest amylase and protease activity potentials occurred at 28 d. Most anatomic and functional variables evolved progressively from 14 to 42 d, while microbial colonisation was fastest from birth to 28 d. These outcomes suggest that the supplemental feeding system is more effective in promoting rumen development than the grazing system; in addition, for both the feeding systems, microbial colonisation in the rumen is achieved at 1 month, functional achievement at 2 months, and anatomic development after 2 months.

Taxonomic Identification of Ruminal Epithelial Bacterial Diversity during Rumen Development in Goats.

ABSTRACT Understanding of the colonization process of epithelial bacteria attached to the rumen tissue during rumen development is very limited. Ruminal epithelial bacterial colonization is of great significance for the relationship between the microbiota and the host and can influence the early development and health of the host. MiSeq sequencing of 16S rRNA genes and quantitative real-time PCR (qPCR) were applied to characterize ruminal epithelial bacterial diversity during rumen development in this study. Seventeen goat kids were selected to reflect the no-rumination (0 and 7 days), transition (28 and 42 days), and rumination (70 days) phases of animal development. Alpha diversity indices (operational taxonomic unit [OTU] numbers, Chao estimate, and Shannon index) increased (P < 0.01) with age, and principal coordinate analysis (PCoA) revealed that the samples clustered together according to age group. Phylogenetic analysis revealed that Proteobacteria, Firmicutes, and Bacteroidetes were detected as the dominant phyla regardless of the age group, and the abundance of Proteobacteria declined quadratically with age (P < 0.001), while the abundances of Bacteroidetes (P = 0.088) and Firmicutes (P = 0.009) increased with age. At the genus level, Escherichia (80.79%) dominated at day zero, while Prevotella, Butyrivibrio, and Campylobacter surged (linearly; P < 0.01) in abundance at 42 and 70 days. qPCR showed that the total copy number of epithelial bacteria increased linearly (P = 0.013) with age. In addition, the abundances of the genera Butyrivibrio, Campylobacter, and Desulfobulbus were positively correlated with rumen weight, rumen papilla length, ruminal ammonia and total volatile fatty acid concentrations, and activities of carboxymethylcellulase (CMCase) and xylanase. Taking the data together, colonization by ruminal epithelial bacteria is age related (achieved at 2 months) and might participate in the anatomic and functional development of the rumen.

Variation in the nutritional characteristics of wheat straw

Abstract A number of agronomic, morphological and nutritive measurements were determined for three varieties of wheat from two types of soil in Northern China. The results were as follows: (1) higher neutral detergent fibre and lignin contents but lower crude protein and neutral detergent soluble contents were noted for the whole wheat straw plant during maturation; (2) the feed nutritive value of leaf blades (LB) is highest, then leaf sheath, and that of the stem (S) the lowest; however, as the stem constitutes more than 50% of the whole plant, the nutritive value of wheat straw is dependent on the nutritive quality of the stem; (3) from top to bottom of the plant, the nutritive value of wheat straw is from high to low; (4) the height of the plant and proportion of stem to whole plant are correlated negatively with the dry matter disappearance (DMD), but the thousand grain weight and the ratio leaf blade to leaf stem are correlated positively with DMD. It is possible, therefore, to predict the nutritive value of wheat straw on the basis of its agronomic, morphological and chemical features and their relationship with the DMD value.

Effect of Tea Catechins on Regulation of Antioxidant Enzyme Expression in H2O2-Induced Skeletal Muscle Cells of Goat in Vitro

Skeletal muscle cells (SMCs) of goats were stress induced with 1 mM H(2)O(2) in the absence or presence of 0.5, 5, and 50 μg/mL tea catechins (TCs) incubation. Cells were harvested at 48 h postincubation with TCs to investigate the effects of TCs on cell proliferation, cell membrane integrity, antioxidant enzyme activities, and antioxidant enzyme genes and protein expression levels. Results showed that H(2)O(2) induction inhibited cell proliferation with or without TC incubation; moreover, the inhibition effect was enhanced in the presence of TCs (P < 0.001). H(2)O(2)-induced stress increased the lactate dehydrogenase (LDH) activity in the absence or presence of TC incubation, but concentrations of TCs, less than 5 μg/mL, showed protective functions against LDH leakage than in other H(2)O(2)-induced treatments. The catalase (CAT) activity increased when SMCs were stress induced with H(2)O(2) in the absence or presence of TC incubation (P < 0.001). H(2)O(2)-induced stress decreased CuZn superoxide dismutase (CuZn-SOD) and glutathione peroxidase (GPx) activities, whereas this effect was prevented by incubation with TCs in a concentration-dependent manner. H(2)O(2)-induced stress with or without TC incubation had significant effects on mRNA and protein expression levels of CAT, CuZn-SOD, and GPx (P < 0.001). CAT and CuZn-SOD mRNA expression levels were increased by different concentrations of TC incubation, and this tendency was basically consistent with corresponding protein expression levels. The GPx mRNA expression level increased with a low concentration of TCs but decreased with concentrations greater than 5 μg/mL of TCs, whereas GPx protein expression in all TC-incubated groups was lower than in the control treatment. The current findings imply that TCs had an inhibitory effect on cell proliferation and enhanced damage to the cell membrane integrity, but TCs affected antioxidant status in SMCs by modulating antioxidant enzyme activities at mRNA and protein expression levels.

Morphological fractions, chemical composition and in vitro fermentation characteristics of maize stover of five genotypes.

Five morphological fractions (leaf blade, leaf sheath, stem, husk and cob) of stover of five maize genotypes, namely waxy, conventional, fodder, sweet and high-oil maize, respectively, were used to test the effects of genotype and morphological fractions on chemical composition and in vitro fermentation characteristics. The waxy maize had a higher (P < 0.05) stem but lower (P < 0.05) leaf blade proportion and fodder maize had a higher (P < 0.05) leaf blade but lower (P < 0.05) leaf sheath proportion than other genotypes, respectively. Maize genotype had a significant effect (P < 0.001) on the chemical composition of stover parts except for organic matter (OM) concentration. Chemical composition of stover parts was affected (P < 0.001) by morphological fractions. The interaction effects between genotype and morphological fraction on the fiber content of stover parts were significant. Over 0.40 and 0.50 of phosphorus (P) and crude protein (CP) of whole-plant maize stover were averagely contributed by leaf blade. Leaf blade, stem and cob contributed over 0.75 of OM, CP, P and fiber in the whole plant. There were significant effects of genotype and morphological fraction on both in vitro gas production parameters and in vitro organic matter disappearance of maize stovers. The genotype and morphological fraction of maize stover and their interaction had significant effects on NH3-N and total volatile fatty acid concentration and the molar proportion of volatile fatty acid in the supernatant after 72 h of incubation except for valeric acid. The present data indicated that the genotype and morphological fraction of maize resulted in variation in the nutritive value of maize stover.

In vitro evaluation on neutral detergent fiber and cellulose digestion by post-ruminal microorganisms in goats.

BACKGROUND Post-ruminal digestion of fiber has received much less attention than its ruminal digestion. Using in vitro incubation techniques, the present study explored whether variations in fiber digestion occurred in different segments of the post-ruminal tract and whether fiber structure could influence its digestibility. A split plot design was conducted with gut segments (jejunum, ileum, cecum and colon) as main plot and substrates (neutral detergent fiber (NDF) and cellulose (CEL)) as subplot. RESULTS With the same substrate, the final asymptotic gas volume (V(F)), gas production at t(i) (V(t(i)), digestibility, microbial crude protein (MCP), total bacteria number (TBN), total short-chain fatty acids (TSCFA) and xylanase in incocula from the cecum and colon exceeded (P < 0.01) those in incocula from the jejunum and ileum, while the NH3-N in the former was less (P < 0.01). For the same gut segment, the digestion of CEL was superior to NDF, as reflected in greater V(F), V(t(i)), maximum rate of gas production, digestibility, enzyme activities and SCFA but lower pH and NH3-N. CONCLUSION The current results imply that the intestinal contents from the cecum and colon have greater potential to digest fiber than those from the jejunum and ileum, and CEL is more easily digested in the post-ruminal tract than NDF.

Shifts in Rumen Fermentation and Microbiota Are Associated with Dissolved Ruminal Hydrogen Concentrations in Lactating Dairy Cows Fed Different Types of Carbohydrates

BACKGROUND Different carbohydrates ingested greatly influence rumen fermentation and microbiota and gaseous methane emissions. Dissolved hydrogen concentration is related to rumen fermentation and methane production. OBJECTIVES We tested the hypothesis that carbohydrates ingested greatly alter the rumen environment in dairy cows, and that dissolved hydrogen concentration is associated with these changes in rumen fermentation and microbiota. METHODS Twenty-eight lactating Chinese Holstein dairy cows [aged 4-5 y, body weight 480 ± 37 kg (mean ± SD)] were used in a randomized complete block design to investigate effects of 4 diets differing in forage content (45% compared with 35%) and source (rice straw compared with a mixture of rice straw and corn silage) on feed intake, rumen fermentation, and microbial populations. RESULTS Feed intake (10.7-12.6 kg/d) and fiber degradation (0.584-0.692) greatly differed (P ≤ 0.05) between cows fed the 4 diets, leading to large differences (P ≤ 0.05) in gaseous methane yield (27.2-37.3 g/kg organic matter digested), dissolved hydrogen (0.258-1.64 μmol/L), rumen fermentation products, and microbiota. Ruminal dissolved hydrogen was negatively correlated (r < -0.40; P < 0.05) with molar proportion of acetate, numbers of fungi, abundance of Fibrobacter succinogenes, and methane yield, but positively correlated (r > 0.40; P < 0.05) with molar proportions of propionate and n-butyrate, numbers of methanogens, and abundance of Selenomonas ruminantium and Prevotella spp. Ruminal dissolved hydrogen was positively correlated (r = 0.93; P < 0.001) with Gibbs free energy changes of reactions producing greater acetate and hydrogen, but not correlated with those reactions producing more propionate without hydrogen. CONCLUSIONS Changes in fermentation pathways from acetate toward propionate production and in microbiota from fibrolytic toward amylolytic species were closely associated with ruminal dissolved hydrogen in lactating dairy cows. An unresolved paradox was that greater dissolved hydrogen was associated with greater numbers of methanogens but with lower gaseous methane emissions.

In vitro evaluation of effects of gut region and fiber structure on the intestinal dominant bacterial diversity and functional bacterial species.

Understanding the intestinal bacteria in ruminants and their population kinetics is essential for their ecological function, as well as their interaction with the host. In this in vitro study, we aimed to determine whether gut region and fiber structure can influence bacterial diversity and functional bacterial population, together with the kinetics of functional bacterial species in the cecal inocula using PCR-DGGE and qPCR. A split plot design was conducted with gut regions (jejunum, ileum, cecum and colon) as main plot, and substrates (neutral detergent fiber (NDF) and cellulose (CEL)) as subplot. Incubation time and gut region affected dominant bacterial diversity. The numbers of total bacteria, cellulolytic bacteria, genus Prevotella and amylolytic bacteria in the hindgut inocula were greater (P < 0.05) than those in the small intestinal inocula. Fiber structure did not significantly influence the dominant bacterial diversity and the numbers of most examined functional bacterial species. The greatest increase rate of cellulolytic bacteria occurred earlier than amylolytic bacteria except for R. albus incubated with NDF. Changes in cellulolytic bacterial populations were not coordinative with alteration of fiber disappearance as well as CMCase and xylanase activities. All these suggest that the hindgut contents have greater potential to digest fiber than small intestinal contents, and cellulolytic bacteria are of significant value at the initial stage of fiber digestion among the fiber digestive microbes in the intestine.

Effects of different nonionic surfactants on in vitro fermentation characteristics of cereal straws

The effects of 3 nonionic surfactants (NIS), including alkyl polyglucoside (APG), sorbitan trioleate (Span85), and polyoxyethylene sorbitan monostearate (Tween80), on in vitro fermentation characteristics of maize stover, rice straw, and wheat straw were examined using an in vitro gas production technique. Four levels each of APG, Span85, and Tween80 [0, 0.02, 0.05, and 0.1% (vol/vol) of incubation solution] were tested in a 4 x 4 x 4 factorial arrangement. The NIS generally increased the in vitro maximal gas production (A), but decreased the lag time of cereal straws. The effects of NIS on the rate of gas production (B) were related to the surfactant type and fermented substrate. The NIS generally increased IVDMD and in vitro OM disappearance (IVOMD) of cereal straws, but responses were dose dependent. The NIS increased total VFA concentration of in vitro fermentation supernatant for maize stover and wheat straw, but decreased total VFA concentration for rice straw. The effects of NIS on the molar proportions of acetate, propionate, and butyrate were dependent on the dose and type of NIS and on fermented substrate. Several interactive effects were noted between or among 3 surfactants (APG, Span85, and Tween80) on in vitro gas production variables, IVD-MD, IVOMD, and VFA for each straw; the optimal combinations of 2 or 3 types of NIS were determined according to the responses of IVDMD and IVOMD to NIS addition. The results of this study suggest that NIS may improve in vitro fermentation of low quality roughages and have potential application as feed additives in ruminant production.