Zhixiong He

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.

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.

Effects of energy and protein restriction, followed by nutritional recovery on morphological development of the gastrointestinal tract of weaned kids.

Effects of energy, protein, or both energy and protein restriction on gastrointestinal morphological development were investigated in 60 Liuyang Black kids, which were sourced from local farms and weaned at 28 d of age. Weaned kids were randomly assigned to receive 1 of 4 dietary treatments (15 kids per treatment), which consisted of adequate nutrient supply (CON), energy restriction (ER), protein restriction (PR), or energy and protein restriction (EPR). The entire experiment included adaptation period (0 to 6 d), nutritional restriction period (7 to 48 d), and recovery period (49 to 111 d). Three kids from each group were killed at d 48 and 111, and the rumen, duodenum, jejunum, and ileum were harvested. On d 48 (end of nutritional restriction), lengths of the duodenum (P = 0.005), jejunum (P = 0.003), and ileum (P = 0.003), and weights of the rumen (P = 0.004), duodenum (P = 0.006), jejunum (P = 0.006), and ileum (P = 0.004) of kids in ER, PR, and EPR were less than those of kids in CON. Compared with CON, PR decreased papillae width (P = 0.03) and surface area (P = 0.05) of the rumen epithelium, villus surface area (P = 0.05), and N concentration (P = 0.02) of the jejunum mucosa on d 48. Compared with CON, EPR decreased papillae height (P = 0.001), width (P = 0.001), and surface area (P = 0.003), N concentration (P = 0.01), and the ratio of N to DNA (P = 0.03) of the rumen epithelium. Compared with CON, EPR also decreased villus height (P = 0.01), width (P = 0.006), and surface area (P = 0.006), N concentration (P < 0.001), and the ratio of N to DNA (P < 0.001) of the jejunum mucosa on d 48. On d 111 (end of nutritional recovery), lengths of the duodenum (P = 0.001), jejunum (P = 0.001), and ileum (P = 0.001), weights of the rumen (P < 0.001), duodenum (P = 0.001), jejunum (P < 0.001), and ileum (P < 0.001) of kids in ER, PR, and EPR were still less than those of kids in CON; N concentrations of rumen epithelium of kids in PR (P = 0.01) and EPR (P = 0.001), and the ratio of N to DNA of jejunum mucosa of kids in EPR (P < 0.001) were greater than those of kids in CON. Results indicate that nutritional restriction of 6 wk can retard gastrointestinal morphological development for kids weaned at 28 d of age and retarded development remains evident, even after nutritional recovery of 9 wk.

A mathematical model to describe the diurnal pattern of enteric methane emissions from non-lactating dairy cows post-feeding

Enteric methane emission is not only a source of energy loss in ruminants, but also a potent contributor to greenhouse gas production. To identify the nature and timing of interventions to reduce methane emissions requires knowledge of temporal kinetics of methane emissions during animal husbandry. Accordingly, a mathematical model was developed to investigate the pattern of enteric methane emissions after feeding in dairy cows. The model facilitated estimation of total enteric methane emissions (V, g) produced by the residual substrate (V1, g) and newly ingested feed (V2, g). The model was fitted to the 10 h methane emission patterns after morning feeding of 16 non-lactating dairy cows with various body weights (BW), and the obtained parameters were used to predict the kinetics of 24 h methane emission for each animal. The rate of methane emission (g/h) reached a maximum within 1 to 2 h after feeding, followed by a gradual post-prandial decline to a basal value before the next feeding. The model satisfactorily fitted curves for each cow according to the criterion of goodness-of-fit, and provided biological descriptions for fluctuations in methane emissions based on basal V1 and feeding V2 in response to the changes in BW and dry matter intake (DMI) of different dairy cows. The basal V1 and feeding V2 are probably maintained by slow- and readily-degradable substrates, respectively. The former contributed at least 0.6 of methane production. In summary, the model provides a means to separate basal V1 and feeding V2 within V, and can be used to predict 24 h emission from a single feeding period.

Cloning, Phylogenetic Analysis, and Distribution of Free Fatty Acid Receptor GPR120 Expression along the Gastrointestinal Tract of Housing versus Grazing Kid Goats

G-protein-coupled receptor 120 (GPR120) is reported as a long-chain fatty acid (LCFA) receptor that elicits free fatty acid (FFA) regulation on metabolism homeostasis. The study aimed to clone the gpr120 gene of goats (g-GPR120) and subsequently investigate phylogenetic analysis and tissue distribution throughout the digestive tracts of kid goats, as well as the effect of housing versus grazing (H vs G) feeding systems on GPR120 expression. Partial coding sequence (CDS) of g-GPR120 was cloned and submitted to NCBI (accession no. KU161270 ). Phylogenetic analysis revealed that g-GPR120 shared higher homology in both mRNA and amino acid sequences for ruminants than nonruminants. Immunochemistry, real-time PCR, and Western blot analysis showed that g-GPR120 was expressed throughout the digestive tracts of goats. The expression of g-GPR120 was affected by feeding system and age, with greater expression of g-GPR120 in the G group. It was concluded that the g-GPR120-mediated LCFA chemosensing mechanism is widely present in the tongue and gastrointestinal tract of goats and that its expression can be affected by feeding system and age.

Unchanged interleukin 6 level of protein and energy restricted goats during late gestation: the role of elevated blood nitric oxide.

Twelve pregnant goats were assigned to three dietary treatments during late gestation, namely control (C: metabolizable energy, 5.75 MJ/kg; crude protein, 12.6% and dry matter basis), 40% protein restricted (PR) and 40% energy restricted (ER), to examine the effects of nutrient restriction on the immune status of pregnant goats. Plasma was sampled on day 90, 125 and 145 from pregnant goats to determine cytokine production (interleukin 2 (IL2), IL6) and tumor necrosis factor α (TNFα)). Peripheral blood mononuclear cells were obtained on day 145 and activated by lipopolysaccharide to determine cytokine production, and then exposed (PR and ER) to sodium nitroprusside (SNP), a nitric oxide (NO) donor, or control to NG-nitro-l-arginine methyl ester hydrochloride (l-NAME), an NO synthase inhibitor to explore the role of NO in regulating cytokine production. Plasma IL2, IL6 and TNFα were not altered during gestation, but NO was increased (P<0.05) at gestation day 145 for PR and ER. In vitro, compared with control, NO was lower for PR and ER (P<0.001), but IL6 was higher for PR (P<0.001) and ER (P=0.11). The addition of SNP decreased IL6 (P<0.001, PR; P=0.12, ER) in the malnourished group, and l-NAME increased (P<0.001) IL6 in control compared to those treatments without SNP or l-NAME. The results indicate that plasma NO acted as a regulator of cytokine function exhibiting negative feedback to maintain steady plasma IL6 concentration in PR or ER goats during late gestation.

Effects of Momordica charantia Saponins on In vitro Ruminal Fermentation and Microbial Population

This study was conducted to investigate the effects of Momordica charantia saponin (MCS) on ruminal fermentation of maize stover and abundance of selected microbial populations in vitro. Five levels of MCS supplements (0, 0.01, 0.06, 0.30, 0.60 mg/mL) were tested. The pH, NH3-N, and volatile fatty acid were measured at 6, 24, 48 h of in vitro mixed incubation fluids, whilst the selected microbial populations were determined at 6 and 24 h. The high dose of MCS increased the initial fractional rate of degradation at t-value = 0 (FRD0) and the fractional rate of gas production (k), but decreased the theoretical maximum of gas production (VF) and the half-life (t0.5) compared with the control. The NH3-N concentration reached the lowest concentration with 0.01 mg MCS/mL at 6 h. The MSC inclusion increased (p<0.001) the molar proportion of butyrate, isovalerate at 24 h and 48 h, and the molar proportion of acetate at 24 h, but then decreased (p<0.05) them at 48 h. The molar proportion of valerate was increased (p<0.05) at 24 h. The acetate to propionate ratio (A/P; linear, p<0.01) was increased at 24 h, but reached the least value at the level of 0.30 mg/mL MCS. The MCS inclusion decreased (p<0.05) the molar proportion of propionate at 24 h and then increased it at 48 h. The concentration of total volatile fatty acid was decreased (p<0.001) at 24 h, but reached the greatest concentration at the level of 0.01 mg/mL and the least concentration at the level of 0.60 mg/mL. The relative abundance of Ruminococcus albus was increased at 6 h and 24 h, and the relative abundance of Fibrobacter succinogenes was the lowest (p<0.05) at 0.60 mg/mL at 6 h and 24 h. The relative abundance of Butyrivibrio fibrisolvens and fungus reached the greatest value (p<0.05) at low doses of MCS inclusion and the least value (p<0.05) at 0.60 mg/mL at 24 h. The present results demonstrates that a high level of MCS quickly inhibits in vitro fermentation of maize stover, while MCS at low doses has the ability to modulate the ruminal fermentation pattern by regulating the number of functional rumen microbes including cellulolytic bacteria and fungi populations, and may have potential as a feed additive applied in the diets of ruminants.

Comparison of two live Bacillus species as feed additives for improving in vitro fermentation of cereal straws.

This study was performed in a 2 × 4 factorial arrangement to explore and compare the effects of inclusion of two live Bacillus additives (B. licheniformis and B. subtilis) at four doses (0, 0.25 × 10(7), 0.50 × 10(7) and 0.75 × 10(7) colony-forming units (cfu)) on in vitro gas production kinetics, fiber degradation, methane production and ruminal fermentation characteristics of maize stover and rice straw by mixed rumen microorganisms in dairy cows. The pH, concentrations of ammonia nitrogen (NH3-N) and isovalerate were increased (P < 0.05), while the methane (CH4) production, ratio of acetate to propionate, and total volatile fatty acids (TVFA) concentration were decreased (P < 0.05) by the supplementation of B. licheniformis compared with that of B. subtilis. Adding B. licheniformis and B. subtilis raised (P < 0.05) or numerically raised the maximum gas production, while decreasing (P < 0.05) or numerically lowering pH and concentrations of most volatile fatty acids. The addition of B. licheniformis increased (P < 0.05) the NH3-N concentration but reduced CH4 production and ratio of acetate to propionate (P < 0.05), while the NH3 -N concentration was decreased (P < 0.05), and the CH4 production and ratio of acetate to propionate were increased by that of B. subtilis compared to the control. Results obtained in this research suggest that B. licheniformis would be preferred as a live Bacillus additive in comparison with B. subtilis, and its optimal dose should be 0.25 × 10(7) cfu/500 mg substrates.

Effects of dietary cellulase and xylanase addition on digestion, rumen fermentation and methane emission in growing goats.

The objective of this study was to evaluate the effectiveness of supplementation of cellulase and xylanase to diets of growing goats to improve nutrient digestibility, utilisation of energy and mitigation of enteric methane emissions. The experiment was conducted in a 5 × 5 Latin square design using five goats with permanent rumen fistulae and five treatments consisted of two levels of cellulase crossed over with two levels of xylanase plus unsupplemented Control. The cellulase (243 U/g) derived from Neocallimastix patriciarum was added at 0.8 and 1.6 g/kg dry matter intake (DMI) and the xylanase (31,457 U/ml) derived from Aspergillus oryzae was fed at 1.4 and 2.2 ml/kg DMI. There were no differences in apparent digestibility of organic matter, neutral detergent fibre, acid detergent fibre and rumen fermentation parameters (i.e. ammonia-nitrogen [N], volatile fatty acids) among all treatments. Dietary cellulase and xylanase addition did not influence energy and N utilisation. But compared to xylanase addition at the higher dose, at the low xylanase dose the retained N, the availability of retained N and digested N were increased (p < 0.01). Moreover, enzyme addition did not affect the enteric methane emission and community diversity of ruminal methanogens. The present results indicated that previous in vitro findings were not confirmed in ruminant trials.