The composition of the protosolar disk and the formation conditions for comets

Conditions in the protosolar nebula have left their mark in the composition of cometary volatiles, thought to be some of the most pristine material in the solar system. Cometary compositions represent the end point of processing that began in the parent molecular cloud core and continued through the collapse of that core to form the protosun and the solar nebula, and finally during the evolution of the solar nebula itself as the cometary bodies were accreting. Disentangling the effects of the various epochs on the final composition of a comet is complicated. But comets are not the only source of information about the solar nebula. Protostellar disks around young stars similar to the protosun provide a way of investigating the evolution of disks similar to the solar nebula while they are in the process of evolving to form their own solar systems. In this way we can learn about the physical and chemical conditions under which comets formed, and about the types of dynamical processing that shaped the solar system we see today. This paper summarizes some recent contributions to our understanding of both cometary volatiles and the composition, structure and evolution of protostellar disks.Comment: To appear in Space Science Reviews. The final publication is available at Springer via http://dx.doi.org/10.1007/s11214-015-0167-

Evaluation of the protein characteristics of four diverse grasses

Forage protein characteristics in four grasses were evaluated by the nylon bag method. All of the forages used (Bermudagrass hay, brome hay, forage sorghum hay, and prairie hay) were of relatively low quality, except the Bermudagrass, which was of average quality. The forages differed in the size of different protein fractions and in the rate and extent of protein degradation. Predicted extent of ruminal protein degradation (i.e., ruminal protein availability) was lowest for prairie hay, intermediate for Bermudagrass and forage sorghum hay, and highest for the brome hay

Effects of supplemental degradable intake protein on intake and digestibility of low-quality brome hay

The effects of increasing levels of degradable intake and digestion of low-quality brome hay were evaluated using 16 ruminally fistulated beef steers. Trends were evident for small, positive changes in total intake and digestion with increasing level of DIP supplementation. As a result, total digestible to feeding forage to provide .041, .082, and OM intake (TDOMI) increased with DIP supplementation but tended to plateau below the highest supplementation level