Shaoxun Tang

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.

Deriving fractional rate of degradation of logistic-exponential (LE) model to evaluate early in vitro fermentation.

Water-soluble components of feedstuffs are mainly utilized during the early phase of microbial fermentation, which could be deemed an important determinant of gas production behavior in vitro. Many studies proposed that the fractional rate of degradation (FRD) estimated by fitting gas production curves to mathematical models might be used to characterize the early incubation for in vitro systems. In this study, the mathematical concept of FRD was developed on the basis of the Logistic-Exponential (LE) model, with initial gas volume being zero (LE0). The FRD of the LE0 model exhibits a continuous increase from initial (FRD 0) toward final asymptotic value (FRD F) with longer incubation time. The relationships between the FRD and gas production at incubation times 2, 4, 6, 8, 12 and 24 h were compared for four models, in addition to LE0, Generalization of the Mitscherlich (GM), c th order Michaelis-Menten (MM) and Exponential with a discrete LAG (EXPLAG). A total of 94 in vitro gas curves from four subsets with a wide range of feedstuffs from different laboratories and incubation periods were used for model testing. Results indicated that compared with the GM, MM and EXPLAG models, the FRD of LE0 model consistently had stronger correlations with gas production across the four subsets, especially at incubation times 2, 4, 6, 8 and 12 h. Thus, the LE0 model was deemed to provide a better representation of the early fermentation rates. Furthermore, the FRD 0 also exhibited strong correlations (P < 0.05) with gas production at early incubation times 2, 4, 6 and 8 h across all four subsets. In summary, the FRD of LE0 model provides an alternative to quantify the rate of early stage incubation, and its initial value could be an important starting parameter of rate.

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.

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.

Protein or energy restriction during late gestation alters fetal growth and visceral organ mass: an evidence of intrauterine programming in goats.

The objective of this study was to examine the effects of maternal protein or energy restriction during late gestation on postnatal fetal growth and visceral organ mass of goats. Eighty pregnant goats with similar age (2.0 ± 0.3 yr) and body weight (BW, 20.0 ± 1.0 kg before pregnancy) were assigned to 3 dietary treatments during late gestation: control (CON), 40% protein restricted (PR) and 40% energy restricted (ER) diets until parturition, after which offspring received normal diets for nutritional recovery. Kids were killed and visceral tissues were harvested at birth and week 6. Maternal protein or energy restriction decreased (P < 0.05) birth weight, and the weights of thymus, heart, abomasums, small intestine. The length of fetus from PR and ER were all decreased (P < 0.05) compared with that from control. When expressed relative to BW, thymus and small intestine for PR and ER still remained less (P < 0.05) than that for control. After 6 weeks of nutritional recovery, there was no difference (P = 0.91) in BW among groups; the kids from nutritional restriction groups showed a greater (P < 0.05) growth rate compared with kids from CON. Moreover, liver (only in ER, P < 0.10) and kidney (only in ER, P < 0.05) were proportionally increased to BW at week 6. The results indicate that maternal protein or energy restriction programs the fetal growth in goats, particularly the proportional responses of fetal organs relative to BW, including thymus, small intestine, kidney and liver.

Effects of maternal protein or energy restriction during late gestation on antioxidant status of plasma and immune tissues in postnatal goats

Maternal malnutrition can have temporary or long-lasting effects on development and physiological function of offspring. Our objective was to investigate whether maternal protein or energy restriction in late gestation affects the antioxidant status of plasma, immune organs (thymus and spleen), and natural barrier organs (jejunum) in neonatal goats and whether the effects could be reversed after nutritional recovery. Forty-five pregnant goats (Liuyang Blacks) of similar age (2.0 ± 0.3 yr) and BW (22.2 ± 1.5 kg at d 90 of gestation) were assigned to 3 dietary treatments during late gestation: control (ME = 9.34 MJ/kg and CP = 12.5%, DM basis), 40% protein restricted (PR), and 40% energy restricted (ER) until parturition, after which offspring received the normal diet for nutritional recovery. Plasma and tissues of kids were sampled to determine antioxidant enzymes [superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), and catalase (CAT)] and gene expression of antioxidant enzymes (Cu/Zn-SOD [SOD1], CAT, and peroxiredoxin 2 [PRDX2]). Maternal protein or energy restriction decreased (P < 0.05) SOD activities in plasma, liver, thymus, and spleen and SOD1 expression in thymus, and maternal energy restriction also decreased (P < 0.05) plasma GSH-Px activity and expressions of SOD1 and CAT in liver at birth. After nutritional recovery of 6 wk, SOD activities in thymus (both in PR and ER) and spleen (only in PR) were greater (P < 0.05), but CAT activity of thymus (both in PR and ER) and CAT expression (only in ER) were less (P < 0.01) than those in control. After nutritional recovery of 22 wk, SOD1 and PRDX2 expression in thymus (both in PR and ER) and SOD1 expression in liver (only in ER) were greater (P < 0.05) whereas CAT expression in thymus (both in PR and ER) was less (P < 0.001) than in control. The current results indicate that maternal protein or energy restriction can decrease the antioxidant capacity of the neonatal kids and result in an imbalance of SOD and hydrogen peroxide-inactivating systems in thymus, even after 6 or 22 wk of nutritional recovery.