Animal Industry Report

Extension Number

ASL R3044



Summary and Implications

With increased availability of fractionated (de-oiled) coproducts, supplementing excess dietary CP is likely when utilizing these high protein and energy coproducts as an energy source. At this time, the effects of these excessive CP diets on beef cow reproduction have not been extensively studied. In addition, the effects consuming excess dietary CP from feedstuffs that differ in rumen degradability with low quality forage on plasma amino acid concentrations of cows have not been extensively characterized. As part of a larger study analyzing the effects of diets containing 150% of metabolizable protein (MP) requirements from a moderately high (corn gluten meal) or low (soybean meal) rumen undegradable protein (RUP) fraction on ovarian function around the time of ovulation, blood samples were taken near ovulation to evaluate the effects of excess MP on circulating plasma amino acid (AA) concentrations. We observed that cows supplemented with excess CP from sources differing in rumen degradability had similar total circulating AA profiles; however, the relative proportions of each AA were different based on protein source. Based on these data, supplementing excess dietary MP from sources differing in degradability differentially affects circulating plasma AA profiles. However, the mechanisms by which these different AA profiles will alter biological, and specifically, reproductive processes are unknown at this time.

Copyright Holder

Iowa State University