The objective of this study was to examine changes in potential forage value of honey mesquite (Prosopis glandulosa) throughout the year. During 2012, samples were obtained at approximately 2 week intervals from April to December in south-central New Mexico. Crude protein content of leaves decreased (P < 0.05) during the year from 25.4 to 10.8%, while acid detergent fiber (ADF) and neutral detergent fiber (NDF) increased (P < 0.05) from 14.8% to 33.9% and 22.4% to 47.0%, respectively. Changes in these nutrients displayed cubic relationships over time with large changes in the spring and autumn and minimal changes in the summer. Crude protein content of pods decreased (P < 0.05) over time from 21.0% to 10.9%, but we did not detect any phenological changes in ADF (range of 19.0 to 34.1%) and NDF levels (range of 27.7 to 49.0%). A sample of mesquite flowers collected in May 2013 was evaluated for nutritive content. Mesquite flowers appear to be high quality forage with a crude protein content of 24.0% and ADF and NDF levels of 16.7 and 31.5%, respectively. We used in vitro gas production as an indicator of secondary compound impacts on forage value. Mesquite samples were mixed with dormant grass (Sporobolus spp.) in a 30:70 ratio. Rumen fluid was obtained from 4 cannulated cows fed beardless wheat hay. Rate of gas production was measured at 4 hour intervals for 48 hours. Rate of gas production of mesquite leaves varied (P < 0.05) among spring and autumn samples with greater initial rates in autumn samples. No phenological changes in rate of gas production were detected (P > 0.10) for mesquite pods. Honey mesquite has the potential to provide livestock forage with relatively high nutritive values from spring through autumn if animals can contend with any associated secondary compounds.
Oral presentation and poster titles, abstracts, and authors from the Society for Range Management (SRM) Annual Meetings and Tradeshows, from 2013 forward.