The positive relationship between fecal CP concentration and diet OM digestibility in cattle, which is based on increasing undigested microbial CP and decreasing fecal OM as OM digestibility increases, may be used as an indirect method for estimating diet OM digestibility from fecal CP concentration. Results of digestibility trials (445 individual observations) conducted at Hohenheim and Braunschweig, Germany, and at Gumpenstein, Austria, were used to study the relationship between CP concentration in feces (x, g/kg OM) and OM digestibility (y, %). The best fit was obtained with the curvilinear relationship y = ai -107.7e(-0.01515 x x), with a1 = 79.76 and a2 = 72.86 (R2 = 0.82; residual SD = 2.7; SE = 0.13), which takes into account the effects of location (i = 1 for Braunschweig and Hohenheim, and i = 2 for Gumpenstein). Dietary CP and crude fat concentration, and DMI had no effect on fecal CP content, whereas crude fiber content, proportion of concentrate in the diet, and forage type significantly affected CP concentration in feces; however, the magnitude of these effects was less than 2 percentage units, and the direction of the effect of proportion of concentrate in the diet was not uniform. The curvilinear relationship between fecal CP concentration (observed range, 100 to 300 g/kg of OM) and diet OM digestibility (observed range = 57 to 80%) may be used to estimate diet OM digestibility, particularly for field trials, as it requires no feed samples and does not physically restrict the animal.

Mo x C/CNT catalysts were prepared by carburization of an oxidic Mo precursor impregnated on multiwalled carbon nanotubes (CNTs). The effects of different carburization atmospheres, heating rates, and Mo loadings were tested. The catalysts were characterized by CO-TPD, XRD, N 2 physisorption, SEM, and TEM. The catalytic performance in the steam reforming of methanol (SRM) was used as a sensitive probe to indicate changes in the catalyst surface during catalytic action. Contrarily to the bulk Mo x C catalysts the heating rate during carburization has practically no effect on the catalysts. Instead, Mo loading and carburization atmosphere are the key factors for catalyst structure and performance. The Mo-based activity decreases at loadings >10 wt% at constant product selectivity. The CO 2 /CH 4 product ratio sensitively indicates changes in the catalyst properties at the loadings <20 wt%, where the activity is practically constant. Carburization in 20% CH 4 /H 2 yields 2 nm sized crystallites of cubic α-MoC. Carburization in pure H 2 and in He yields hexagonal β-Mo 2 C with a larger particle size. This phase change is documented in a different catalytic performance in terms of activity and CO 2 /CH 4 selectivity. Thus a multi-parameter toolbox for fine-tuning of catalyst properties is presented.[a]

The objective of the study was to determine the effect of nutrition level (NL, multiples of maintenance energy requirement) on the digestibility of nutrients for dairy cows regarding the energy supply of the animal. The digestion of nutrients and energy was investigated in two trials using lactating dairy cows. The NL varied from 2.7 to 5.0 using diets similar composition. In addition, sheep were given the same feed with a NL of 1.4. Digestibility of dry matter (DM) and all specific measures of dietary components declined significantly as NL increased. Digestibility of energy decreased by 4.1% for each increase in NL. The metabolizable energy, the ability to metabolize energy (metabolizable energy/gross energy), and the content of net energy for lactation (NE(L)) per kilogram of DM intake were calculated for NL from 1 to 6 on the basis of these relationships and as well as the gross energy, methane energy, and urine energy. Accordingly the NEL content declined by 0.11 MJ/kg of DM intake or 1.6% as the NL increased by one unit. It means that the NE(L) requirement above the maintenance requirement increased by 0.07 MJ of NE(L) per kilogram of fat-corrected milk, if the NL increased by one unit.

No abstract

No abstract