Although eugenol is widely used in dentistry, little is known about the molecular mechanisms responsible for its anesthetic properties. In addition to calcium channels, recently demonstrated by our group, there could be another molecular target for eugenol. Using a whole-cell patch-clamp technique, we investigated the effect of eugenol on voltage-gated sodium channel currents ( I_Na) in rat dental primary afferent neurons identified by retrograde labeling with a fluorescent dye in maxillary molars. Eugenol inhibited action potentials and I_Nain both capsaicin-sensitive and capsaicin-insensitive neurons. The pre-treatment with capsazepine, a competitive antagonist of transient receptor potential vanilloid 1 (TRPV1), failed to block the inhibitory effect of eugenol on I_Na, suggesting no involvement of TRPV1. Two types of I_Na, tetrodotoxin (TTX)-resistant and TTX-sensitive I_Na, were inhibited by eugenol. Our results demonstrated that eugenol inhibits I_Nain a TRPV1-independent manner. We suggest that I_Nainhibition by eugenol contributes to its analgesic effect.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

An experiment was conducted to identify the factors that cause reduced production of cows fed a diet with high content of corn distillers grains with solubles (DDGS). We hypothesized that the factors could be high sulfur (S) content in DDGS, which may directly (S toxicity) or indirectly (DCAD) cause reduced production. We also hypothesized that high PUFA in DDGS could be another major factor. In a randomized complete block design, 60 lactating cows (15 primiparous and 45 multiparous; average ± SD at the beginning of the trial: milk yield, 44.0 ± 6.9 kg/d; DIM, 123 ± 50; BW, 672 ± 82 kg) were blocked, and cows in each block were randomly assigned to 1 of the following treatments: SBM (4.7% fatty acids [FA], 0.22% S, and 178 mEq/kg DM of DCAD), a diet containing soybean meal as the main protein source; DG, with SBM replacing mainly soybean byproducts and supplemental fat with distillers grains at 30% dietary DM (4.7% FA, 0.44% S, and 42 mEq/kg DM of DCAD); SBM+S, SBM with sodium bisulfate for additional dietary S (4.8% FA, 0.37% S, and 198 mEq/kg DM of DCAD); SBM+CO, SBM with corn oil (4.7% FA, 0.23%, and 165 mEq/kg DM of DCAD); and DG+DCAD, DG with increased DCAD (4.7% FA, 0.40% S, and 330 mEq/kg DM of DCAD). Due to the limited number of tiestalls, blocks 1 to 6 started the experiment first as phase 1, and the rest of the blocks, as phase 2, started the experiment after phase 1. All cows were fed the SBM diet for 10 d as a covariate period followed by the experimental period for 35 d. Data were analyzed using PROC MIXED of SAS (Version 9.4, SAS Institute Inc.); block and phase were random effects; and treatments, repeated week, and interaction were fixed effects. We found an interaction of week by treatment for DMI. Although milk yield did not change, milk fat concentration tended to decrease (2.78% vs. 3.34%) for DG compared with SBM. Dry matter, OM, NDF, and CP digestibilities were lower when cows were fed the DG diet compared with SBM. Additionally, cows fed DG had lower blood concentrations of HCO₃^-, base excess, and total (t)CO₂ compared with SBM. The SBM+S diet did not affect production, nutrient digestibility, or blood parameters compared with SBM. The SBM+CO diet decreased milk fat concentration and yield compared with SBM. The DG+DCAD diet tended to increase milk fat yield and concentration (1.24 vs. 1.47 kg/d; 2.78% vs. 3.37%) and increased ECM (40.9 vs. 45.1 kg/d) compared with DG but did not improve nutrient digestibility. However, blood HCO₃^-, base excess, and tCO₂ were greater for DG+DCAD compared with DG. In conclusion, the indirect role of S^-, altering DCAD, along with the high PUFA content in DDGS, appear to be the factors causing reduced production responses to a high DDGS diet. Increasing DCAD to 300 mEq/kg DM in a high DDGS diet can be a feeding strategy to alleviate reduced production responses.

In three consecutive studies, we evaluated the effects of noni (Morinda citrifolia) meal on rumen fermentation and degradation characteristics, production performance, physiological parameters, and milk fatty acid profile in Holstein dairy cows. In in vitro (first study) and in situ (second study) experiments, rumen fluids from two fistulated Holstein dairy cows were used. The concentration of noni meal added was 0 (control), 1, 3, 5, or 7% of the basal diet (DM basis). In the in situ experiment, wheat bran was used as a control. Triplicated bags were incubated for 0, 4, 8, 12, 24, 48, 72, or 96 h. In an in vivo experiment (third study), 38 Holstein cows (145 ± 87 days DIM; 1.8 ± 0.9 parity; 35.4 ± 6.3 kg/day milk yield) were equally assigned to the control and treatment groups (19 cows each). Basal feed and noni meal pellets (1.5% of total feed DM basis) were fed to the treatment group. The control group was also fed the basal feed and pellets containing 0% noni meal. There were no significant differences in in vitro dry matter digestibility, pH, total gas production (TGP), CH4, NH₃-N, and volatile fatty acids (p > 0.05). In the in situ experiments, the crude protein (CP) rapidly soluble fraction ‘a’ (CP-a) was higher in noni meal than in wheat bran, and rumen degradable protein was also higher in noni meal than in wheat bran. In the in vivo experiments, when noni meal pellets were fed, there was no significant difference in milk yield and composition, but the triglyceride levels decreased (p < 0.05), the C18:1 fatty acid level increased (p < 0.05), and the C18:0 fatty acid level decreased (p < 0.05). Collectively, noni meal can be used as a feed ingredient up to 1.5% (total feed DM basis) in Holstein dairy cows and as feed supplementation to increase the C18:1 fatty acid level in milk.

Effects of isobutyrate and 2-methylbutyrate (IB-2MB) supplementation and its interaction with 2 levels of dietary RDP were investigated in a replicated 4 × 4 Latin square design with 2 × 2 factorial arrangement: 9% or 11% RDP (% of dietary DM) with or without IB-2MB supplementation (0.09% IB and 0.06% 2MB in dietary DM). The level of dietary RDP was mainly adjusted with soybean meal products, and the concentration of RUP was constant (6% of dietary DM) based on National Academies of Sciences, Engineering, and Medicine 2021 requirements. Eight ruminally cannulated Holstein cows in the second lactation (192 DIM ± 41.3 SD; milk yield, 42.6 kg/d ± 4.67 SD) were fed the treatment diets for 4 wk in each period. The triple marker system and reticular sampling technique were used to determine ruminal digestibility of nutrients and microbial protein synthesis. Total collection of feces and urine were collected for 3 d in the last week of each period. Data were analyzed using the PROC MIXED of SAS with treatment and period as fixed effects, and square and cow within square as random effects. The model for rumen fermentation data included time (repeated measure) and its interaction with RDP and IB-2MB as fixed effects (0, 3, 6 h after feeding). Milk yield and DMI were not affected by treatments. The high RDP treatments increased ruminal ammonia, plasma urea concentration, and increased urinary N and urea excretion compared with low RDP. Ruminal digestibility of NDF was lower (23.4% vs. 27.3%) for high RDP compared with low RDP. Milk fat yield was increased for IB-2MB when high RDP was supplied (1.20 kg/d vs. 1.43 kg/d) and was not affected under low RDP. The IB-2MB supplementation increased ruminal concentration of IB and did not affect 2MB concentration. An interaction between RDP and IB-2MB supplementation was observed in which milk fat yield and ECM were greater for IB-2MB supplementation under high RDP, whereas no difference was detected under low RDP. Similar interactions were observed for the concentrations of 18:1 trans-10 and UFA in milk fatty acids, which was decreased for IB-2MB supplementation under high RDP. The IB-2MB supplementation decreased ruminal true digestibility of nonammonia N and ruminal apparent digestibility of NDF and tended to decrease ruminal true digestibility of DM, and OM, although the efficiency of microbial protein synthesis (nonammonia bacterial N per unit of OM digested; efficiency of microbial protein synthesis [EMPS]) increased for IB-2MB supplementation. No effect of RDP levels, IB-2MB supplementation, or their interaction on total-tract DM, OM, NDF, N, and starch digestibility was observed. In conclusion, the IB-2MB supplementation increased milk fat yield only when RDP was sufficient and was likely due to changes in ruminal fatty acid metabolism. Although EMPS was increased, IB-2MB supplementation decreased ruminal apparent NDF digestibility in this experimental condition without affecting total-tract digestibility of NDF.

Objective: This in vitro study determined the combination effect of nitrate and lactate on nitrate reduction, rumen fermentation and methane production. We hypothesized that the combination decreases methane production and enhances nitrate reduction.Methods: An in vitro batch culture was conducted to determine the 2 main factors of nitrate and lactate in 2×2 factorial arrangement: a basal diet (CON), the basal diet supplemented with nitrate (2.2% in dietary dry matter [DM]; Nit), lactate (2.2%; Lact), or the combination of nitrate and lactate (Nit-Lact). Rumen fluids from lactating Holstein cows were obtained and mixed with McDougall’s buffer for the in vitro batch culture. Total gas production, methane production, pH, volatile fatty acid (VFA), NH3-N, NO3-N and NO2-N concentration, and DM digestibility were determined.Results: A trend of interaction between nitrate and lactate was observed for DM digestibility (p = 0.06), which occurred because DM digestibility tended to decrease for Nit compared with CON (42.2 vs. 45.3%) but did not for Nit-Lact. Nitrate decreased (p<0.05) methane (25.6 vs. 31.0 mL at 24 h) and total gas production (296 vs. 313 mL at 24 h). Total VFA production was not affected by treatments. However, nitrate increased the proportion of acetate (p<0.01) and decreased (p<0.01) proportions of propionate, butyrate and valerate at 24 h of incubation. However, lactate increased valerate at 24 h of incubation (p<0.01). The concentration of NO3-N for Nit-Lact was lower than that of Nit (41.2 vs. 51.0 mg/L; p<0.01) at 3 h of incubation.Conclusion: Nitrate decreased methane production. The combination of nitrate and lactate had beneficial effects on DM digestibility and nitrate reduction, compared with nitrate alone although no interaction between nitrate and lactate was shown for VFA production and methane production. Changes in the major VFA by nitrate indicated that nitrate acted as an alternative electron acceptor to decrease methane production.