Postnatal differential expression of chemoreceptors of free fatty acids along the gastrointestinal tract of supplemental feeding v. grazing kid goats.

The gastrointestinal tract (GIT) of animals is capable of sensing various kinds of nutrients via G-protein coupled receptor-mediated signaling transduction pathways, and the process is known as 'gut nutrient chemosensing'. GPR40, GPR41, GPR43 and GPR119 are chemoreceptors for free fatty acids (FFAs) and lipid derivatives, but they are not well studied in small ruminants. The objective of this study is to determine the expression of GPR40, GPR41, GPR43 and GPR119 along the GIT of kid goats under supplemental feeding (S) v. grazing (G) during early development. In total, 44 kid goats (initial weight 1.35±0.12 kg) were slaughtered for sampling (rumen, abomasum, duodenum, jejunum, ileum, cecum, colon and rectum) between days 0 and 70. The expression of GPR41 and GPR43 were measured at both mRNA and protein levels, whereas GPR40 and GPR119 were assayed at protein level only. The effects of age and feeding system on their expression were variable depending upon GIT segments, chemoreceptors and expression level (mRNA or protein), and sometimes feeding system × age interactions (P0.05) on GPR43 expression; and there were no feeding system×age interactions (P>0.05) on GPR41 and GPR43 protein expression. The expression of GPR41 and GPR43 in rumen and abomasum linearly (P<0.01) increased with increasing age (from days 0 to 70). Meanwhile, age was the main factor affecting GPR40 expression throughout the GIT. These outcomes indicate that age and feeding system are the two factors affecting chemoreceptors for FFAs and lipid derivatives expression in the GIT of kids goats, and S enhanced the expression of chemoreceptors for FFAs, whereas G gave rise to greater expression of chemoreceptors for lipid derivatives. Our results suggest that enhanced expression of chemoreceptors for FFAs might be one of the benefits of early supplemental feeding offered to young ruminants during early development.

Dietary starch and rhubarb supplement increase ruminal dissolved hydrogen without altering rumen fermentation and methane emissions in goats.

Hydrogen is an important intermediate that is produced during carbohydrate fermentation to volatile fatty acid and utilized by methanogens to produce methane in the rumen. Ruminal volatile fatty acid and dissolved methane concentrations are more than 500 times greater than dissolved hydrogen concentration. Therefore, we hypothesized that dissolved hydrogen might have a higher sensitivity in response to dietary changes compared with volatile fatty acid and dissolved methane. Using goats, we investigated the effects of increasing dietary starch content (maize replaced with wheat bran) and supplementing with rhubarb rhizomes and roots on the relationships among dissolved hydrogen, dissolved methane and other fermentation end products. The study was conducted in a replicated 4×4 Latin square with a 2×2 factorial arrangement of four treatments: two starch levels (220 v. 320 g/kg dry matter (DM)), without and with rhubarb supplement (0% v. 2.8% of total mixed ration). Increased dietary starch and rhubarb supplementation did not alter volatile fatty acid concentrations or methane emissions in terms of g/day, g/g DM intake and g/g organic matter digested. However, goats fed the high-starch diet had greater dissolved hydrogen (P=0.005) and relative abundance of Selenomonas ruminantium (P<0.01), and lower (P=0.02) copy number of protozoa than those fed the low-starch diet. Rhubarb increased ruminal dissolved H2 (P=0.03) and total volatile fatty acid concentration (P<0.001), but decreased copies of bacteria (P=0.002). In conclusion, dissolved hydrogen appears to be more sensitive to dietary changes with starch content and rhubarb supplementation, when compared with volatile fatty acid concentrations and methane production.

Postnatal bacterial succession and functional establishment of hindgut in supplemental feeding and grazing goats.

The objectives of this study were 1) to investigate the age-related changes in functional achievement (establishment of fermentation capacity and enzyme activities) and bacterial succession (selected functional bacterial species) in the cecum and colon and 2) to assess the effect of feeding system (supplemental vs. grazing, Sup vs. G) on hindgut development in small ruminants. A total of 44 Liuyang black goat kids were randomly slaughtered at 0, 7, and 14 d of age (nonrumination period), 28 and 42 d of age (transition period), and 56 and 70 d of age (rumination period). Intestinal contents were sampled to determine VFA, activities of amylase, carboxymethylcellulase (CMCase), and xylanase, as well as abundances of total bacteria and selected functional bacterial species (genus Prevotella, cellulolytic and amylolytic bacteria) with quantitative PCR targeting the 16S rRNA subunit genes. Total VFA concentration (P < 0.01) and enzyme activities (P < 0.05) in hindgut contents were greater and total bacterial 16S rRNA gene copy numbers (P = 0.003) in the cecum were lower for Sup vs. G. Furthermore, irrespective of feeding system, hindgut total VFA concentrations and total bacterial 16S rRNA gene copy numbers increased with age (P < 0.01), with the greatest increase rate observed from 14 to 28 d. Amylase fluctuated with age, whereas CMCase and xylanase activities in Sup kids increased (P < 0.05) as age increased. The proportions of 16S rRNA copy numbers associated with the genus Prevotella and P. ruminicola increased (P < 0.05) with age, but those of cellulolytic bacteria and Ruminobacter amylophilus were detected only after 28 d of birth. The bacterial succession, fermentation capacity, and starch-degrading capacity in the hindgut of both groups were achieved at 1 mo, whereas fiber-degrading capacity in Sup kids was established at 2 mo of age; and supplemental feeding surpassed the grazing system in shaping hindgut development.

Inhibition of hepatitis B virus in vitro by antisense oligonucleotides.

A series of antisense phosphorothioate oligodeoxynucleotides against hepatitis B virus (HBV) were synthesized and evaluated for their antiviral effect in Hep-G2 cells transfected with HBV genome. The inhibitory effect of the tested antisense oligonucleotides was sequence-specific, dose-and time-dependent, and synergistic for certain combinations. In virus-inhibitory concentrations the oligonucleotides were harmless to 2.2.15 cells. The most effective antisense oligonucleotides were found directed against the HBV mRNA transcribed from the cap site of SP II promoter, the portion of polyadenylation signal and the initiation region of gene S, with an inhibition of the HBsAg and HBeAg production by 85-95% and 50- 60%, respectively. To our surprise, antisense oligonucleotides directed against three key sites of HBV X gene blocked the expression of HBsAg, HBeAg and HBxAg. This fact might be related to the trans-activation of HBV X protein. Using radioisotope labelling, we demonstrated that Lipofectin promoted the cellular uptake and antiviral effect of antisense oligomers in 2.2.15 cells. These results suggest a therapeutic potential of antisense oligonucleotides in the treatment of patients chronically infected with HBV.