Oxygen and Carbon Dioxide Rhythms Are Circadian Clock Controlled and Differentially Directed by Behavioral Signals

This is the author accepted manuscript. The final version is available from Elsevier (Cell Press).Daily rhythms in animal physiology are driven by endogenous circadian clocks in part through rest-activity and feeding-fasting cycles. Here, we examined principles that govern daily respiration. We monitored oxygen consumption and carbon dioxide release, as well as tissue oxygenation in freely moving animals to specifically dissect the role of circadian clocks and feeding time on daily respiration. We found that daily rhythms in oxygen and carbon dioxide are clock controlled and that time-restricted feeding restores their rhythmicity in clock-deficient mice. Remarkably, day-time feeding dissociated oxygen rhythms from carbon dioxide oscillations, whereby oxygen followed activity, and carbon dioxide was shifted and aligned with food intake. In addition, changes in carbon dioxide levels altered clock gene expression and phase shifted the clock. Collectively, our findings indicate that oxygen and carbon dioxide rhythms are clock controlled and feeding regulated and support a potential role for carbon dioxide in phase resetting peripheral clocks upon feeding.British Heart FoundationEuropean Research CouncilEuropean Union, Seventh Framework Program, Marie Curie Action

Preliminary results on methane emission by nelore cattle in Brazil grazing Brachiaria brizantha cv. Marandu.

Methane emissions by Nelore cattle grazing Brachiaria brizantha were monitored during winter (August) and spring (December) seasons. Sixteen Nelore steers with live weight (LW) varying from 206 to 525 kg, 196 to 538kg during winter and spring, respectively. Methane emissions were measured with the sulfur hexafluoride (SF6) technique. Mean methane emissions were 102.3 and 136.5 g/animal/day and 0.343 and 0.420 g/kg LW/day in winter and spring, respectively. The mean emissions showed 39.7 and 35.3 g/kgDDMI for winter and spring seasons, respectively. For both seasons a high associative effect was observed of CH4 emissions and live weight (r=0.78 and r= 0.97, respectively) and DDMI (r= 0.73 and r=0.96, respectively). Relative methane emissions (g/kgLW) were inversely correlated with LW (r=-0.75 and -0.87 for winter and wet seasons, respectively). Variations in observed methane production among seasons were related to forage quality that affects digestibility and consumption

Tannin-based product in feedlot diet as a strategy to reduce enteric methane emissions of Nellore cattle finished under tropical conditions.

Abstract: A total of 120 Nellore bulls, [initial body weight (BW) = 307 ± 11.6 kg and 12 mo of age] were allocated into 12 collective pens (10 bulls per pen) in a commercial feedlot to evaluate the effects of a specific blend of tannin and saponins on enteric methane (CH4) emissions. The study was a completely randomized design, in which pens were considered the experimental units (N = 6 pens per treatment) and were randomly allocated into one of two treatments: 1) Control (CON), a basal diet with monensin supplementation (25 mg/kg dry matter [DM]; Rumensin, Elanco Animal Health, Greenfield, IN, USA), or 2) Control + a specific blend of tannin and saponins (TAN; 7 g/kg DM; composed of quebracho and chestnut tannin extracts along with carriers from cereals rich in saponins; SilvaFeed BX, Silvateam, San Michele Mondovi, CN, Italy). After the adaptation period (20 d), the experiment was divided into two phases: growing phase (21 to 53 d; total of 33 d) and fattening phase (54 to 139 d; total of 86 d). Enteric methane emissions were estimated using the sulfur hexafluoride (SF6) tracer gas technique. Interactions between treatment and period (growing vs. fattening) were detected for daily CH4 emissions, in which animals fed TAN reduced CH4 emissions by 17.3% during the fattening period compared to bulls fed CON (P = 0.05). In addition, bulls fed TAN had lower CH4 emissions expressed by dry matter intake (DMI) during the fattening period compared to bulls fed CON (P = 0.06). The findings presented herein indicate that a specific blend of tannin and saponins can be used as a strategy to reduce enteric CH4 emissions and its intensity of Nellore bulls finished in feedlot systems under tropical conditions