I did a little searching, seems that this started as a poster at a meeting, FWIW.
Southeast Deer Study Group 56
POSTER SESSION ABSTRACTS
PERENNIAL FOOD PLOTS: SHOULD YOU MOW OR LET THEM GROW?
Authors: Bonner L. Powell, Lindsey M. Phillips, Craig HarperUniversity of Tennessee, Department of Forestry, Wildlife, and Fisheries
Abstract: Mowing perennial food plots regularly through the growing season is commonly recommended to increase nutritional quality and attractiveness for white-tailed deer. We collected biomass (lbs/ac), nutritional (percent crude protein [CP], phosphorus [P], and calcium [Ca]), and digestibility (percent acid detergent fiber [ADF]) data on alfalfa (2018, 2019) and red clover (2018, 2019) to determine effects of mowing. On average, mowing reduced biomass of alfalfa by 23% and red clover by 30%. Mowing did not increase the nutritional quality of the two forages, though CP and P were slightly greater numerically 1 – 3 weeks after the first mowing event in young plant material. Mowing had no effect on ADF or Ca among the forages. Nutritional quality of young plant material of both forages, mowed or not mowed, approached or exceeded the maximum requirement of a doe with twin fawns. Our data suggest mowing red clover and alfalfa food plots throughout the growing season provides little, if any, benefit with regard to nutritional quality or digestibility for deer. We recommend mowing perennial forages once in late summer and perhaps as necessary during the growing season to reduce weed competition, but presence of some naturally occurring forbs complement planted forages by providing additional nutrition and structure that can make the plot more attractive to deer.
In regards to "forbs", I noticed that the deer have been absolutely pounding the lambsquarter lately, nothing but stems left.