PubMed Health⌕ Search

Biomedical subjects

W E Potts

Publications and source records attributed to W E Potts.

8 recordsLinked to original sources
PubMed1994

Effects of alfalfa and orchardgrass on digestion by dairy cows.

The effects of alfalfa and orchardgrass diets of similar NDF content on ruminal digestion and digesta kinetics as measured using radiolabeled herbage were evaluated in Holstein cows. Two dry and two lactating cows, fitted with ruminal and duodenal cannulas, were fed 12 times daily at restricted and ad libitum intakes, respectively, in a crossover design. Diets were 65:35 and 55:45 hay: concentrate in DM for alfalfa and orchardgrass, respectively, with approximately 19% CP and 42% NDF. The DMI by lactating cows was greater for the alfalfa diet than for the orchardgrass diet. Ruminal and apparent total tract digestibilities of NDF and ADF were less for cows consuming the alfalfa diet than for those on the orchardgrass diet. Particle size of ruminal digesta, based on specific activity from a ruminal pulse-dose of 14C-labeled alfalfa or orchardgrass, did not decrease consistently with time and was greater than fecal particle size, suggesting selective retention of large digesta particles before passage. Ruminal and total tract fractional passage rates of indigestible NDF, based on 14C-labeled forage, did not differ as a result of forage or lactation stage, but NDF gut fill was greater in lactating than in dry cows, indicating that changes in gut fill were related more to differences in intake than to passage rate.

Animal Feed↗
PubMed1991

A reevaluation of the Fe(II), Ca(II), Zn(II), and proton formation constants of 4,7-diphenyl-1,10-phenanthrolinedisulfonate.

The compound 4,7-diphenyl-1,10-phenanthrolinedisulfonic acid (BPDS) has been found to be very useful in studying Fe uptake by plants, because it forms a large charged complex that is not absorbed. The quantity of BPDS bound to metals in hydroponic solutions can be estimated from calculations using formation constants of BPDS complexes. These formation constants were used in an earlier experiment to predict the availability of Cu to corn plants. In the experiment, bioassays indicated that Cu was not as phytoavailable in the BPDS-added solutions as predicted by chemical equilibrium calculations. To determine sources of error in this prediction, metal and proton BPDS formation constants were reevaluated at 25 degrees C and 0.10M ionic strength. The CaBPDS formation constant was determined by direct measurement of CaBPDS3 formation and was shown to be approximately 1.0; a value much less than that reported before. Formation constants for the HBPDS, H(BPDS)2, and H(BPDS)3 beta 1, beta 2, and beta 3 complexes were, respectively, 5.05 +/- 0.044, 7.44 +/- 0.019, and 9.33 +/- 0.28. The BPDS sulfonic acid group pKs were less than 1.0, not 2.8 as has been reported. The FeBPDS3 complex determined by ligand competition with EDTA (ethylenediaminetetraacetate) was 20.24 +/- 0.08. Copper and Zn constants were determined using the method of corresponding solutions. The CuBPDS, CuBPDS2, and CuBPDS3 beta 1, beta 2, and beta 3 constants were, respectively, 9.76 +/- 0.08, 15.9, and 20.9. The ZnBPDS, ZnBPDS2, and ZnBPDS3 beta 1, beta 2, and beta 3 constants were, respectively, 6.43 +/- 0.07, 10.7 +/- 5.4, and 17.3 +/- 0.8. Results indicated that BPDS affinity to metals was similar to that of its parent compound, phenanthroline, and that errors in published formation constants caused erroneous predictions of Cu phytoavailability used in an earlier experiment.

Calcium↗