Itoko Nonaka

Effects of selenium supplementation on plasma progesterone concentrations in pregnant heifers

It is known that selenium (Se) has various functions in animals. Many investigations on the biochemical and physiological effects of Se have been previously reported; however, the detailed function of Se in reproduction is not yet clear. We proposed the possibility that Se plays a notable role in progesterone production. The aim of this study was to clarify the effects of Se supplementation on progesterone levels of pregnant Holstein heifers. Eight Holstein heifers (-Se) were fed basal diet (containing 0.022 ppm of Se) throughout the experiment. While a 0.3 ppm diet of Se (sodium selenite) was fed to another seven animals (+Se) with basal diet. Blood sampling was carried out every week. Plasma Se concentrations were higher in Se-supplemented cows compared with controls (-Se) (P < 0.01) throughout the experiment. Se supplementation increased plasma progesterone in the 29-39 weeks of pregnancy from 4.98 ± 0.64 to 6.86 ± 0.49 ng/mL on average (P < 0.05). The present findings suggest that Se contributes to maintaining the function of the corpus luteum and/or placenta in the latter period of pregnancy.

Effects of serum deprivation on myofibrillar proteolysis in chick myotube cultures.

We examined the effects of serum deprivation on myofibrillar proteolysis in chick myotubes. Myotubes were incubated with serum-free medium for 24 hours. Nτ-methylhistidine release, as an index of myofibrillar proteolysis, as well as protease activities such as calpain, proteasome, and cathepsins (B+L and D) activities were increased by serum deprivation. These results indicate that serum deprivation induces calpain, proteaosme, and cathepsins activities, resulting in an increase in myofibrillar proteolysis in chick myotubes.

An improved dry ash procedure for the detection of titanium dioxide in cattle feces.

We improved the dry ash procedure for detecting titanium dioxide (TiO2 ) in cattle feces containing chromium oxide [corrected] (Cr(2)O(3) ). First, the effect of amount of sodium sulfate (Na2 SO4 ) on the recovery of TiO2 from cattle feces that contained Cr2 O3 was evaluated. Average recovery of TiO2 at the 2.5 g Na2 SO4 level was significantly higher (P < 0.0001) than that at 0.75 g Na2 SO4 . Second, the effect of Cr2 O3 concentration on the recovery of TiO2 of cattle feces by using two levels of Na2 SO4 addition was examined. The recovery of TiO2 decreased with the increase in the amount of Cr2 O3 at the 0.75 g Na2 SO4 level but was consistently high at 2.5 g Na2 SO4 . Third, the recovery of Cr2 O3 from cattle feces was checked. The recoveries of TiO2 and Cr2 O3 were high enough at the 2.5 g Na2 SO4 level. Fourth, the improved dry ash procedure (5 mL of concentrated H2 SO4 and 2.5 g of Na2 SO4 were used for sample digestion) was compared to the wet ash procedure. Average recovery of TiO2 by the improved dry ash procedure was significantly higher (P = 0.0077) than that by the wet ash procedure. Thus, the improved dry ash procedure can be used for TiO2 analysis in cattle feces containing Cr2 O3 .