Estimating Rumen Undegradable Protein in

An in situ trial was conducted to compare estimates of rumen undegradable protein (UIP) using a single incubation time point and rates of degradation. Four forage samples (three legumes and one grass) were incubated in situ for their mean retention time estimated from in vitro dry matter disappearance plus a 10-hour lag time as well as for a time point equal to 75% of the total mean retention time (mean retention time plus lag). The UIP values obtained from the fractional rates of degradation and passage were more highly correlated with those estimated from 75% of the total mean retention time (R2 = 0.99) than those estimated from the total mean retention time (R2 = 0. 62). The UIP of birdsfoot trefoil was higher than that in the other forages

Sex Determination:Why So Many Ways of Doing It?

Sexual reproduction is an ancient feature of life on earth, and the familiar X and Y chromosomes in humans and other model species have led to the impression that sex determination mechanisms are old and conserved. In fact, males and females are determined by diverse mechanisms that evolve rapidly in many taxa. Yet this diversity in primary sex-determining signals is coupled with conserved molecular pathways that trigger male or female development. Conflicting selection on different parts of the genome and on the two sexes may drive many of these transitions, but few systems with rapid turnover of sex determination mechanisms have been rigorously studied. Here we survey our current understanding of how and why sex determination evolves in animals and plants and identify important gaps in our knowledge that present exciting research opportunities to characterize the evolutionary forces and molecular pathways underlying the evolution of sex determination

Undegradable Intake Protein Supplementation of Compensating, Grazing Steers

A trial was conducted to evaluate the effect of previous winter gain on response to undegradable intake protein (UIP) supplementation during the summer grazing period. Steers wintered at the FAST rate of gain had a greater response to UIP supplementation than steers with SLOW rate of gain. Maximum response for FAST cattle occurred at 150 g/d of supplemental UIP, while SLOW cattle showed no response through 150 g/d. Forage DM intake was similar for FAST and SLOW cattle, therefore SLOW cattle consumed more as a percentage of body weight. Increased gains from UIP supplementation were not maintained during the finishing phase

Forage Quality and Animal Performance of Steers Grazing Smooth Bromegrass/Legume Pastures

A trial was conducted to evaluate effects of interseeding legumes into smooth bromegrass pastures on animal performance and forage quality. Animal gains on legume/bromegrass treatments were higher than bromegrass alone. Laboratory analysis of diet samples collected from ruminally fistulated steers indicated no difference in the undegradable intake protein content of pastures. Legume/bromegrass treatments had higher IVDMD than the control. Therefore, the increases in gain are attributed to increased energy of legume/bromegrass diets and not undegradable protein content