There are lots of factors involved here. I've used lots of different types of clovers in different fields. Each clover has a somewhat different peak time when it is most attractive. I don't find a significant difference in deer use between different clovers over the long run. Other factors like the alternate food sources, field location, hunting pressure, and such seem to play a much greater role than the variety of clover I use. It is easy to try something and then try something else and notice a big difference in deer use and then attribute it to the change. We tend to overlook all of the other factors that change from year to year and are different between field locations.
My observations are somewhat antidotal as well, but with a bit of supporting data. I've got over a dozen wireless cameras with solar panels running 24/7/365 for over 10 years. We analyze each picture for game and record it in a database along with our planting data. The database then has counts of deer by type and when the observations were made. We analyze this data, along with our harvest data and hunter logs, to use for trending analysis to see if our QDM management decisions are effective. While the only ag within 3 miles of us is pasture, we do have a wide variety of native competing foods due to our timber management including acorns in the fall.
I'm not saying that deer don't have a preference for certain crops over others. They do. What I am saying is that preference is not a first order factor in where they choose to feed. Deer, like most animals, have an algorithm going in their heads that balances food, security, and sex. The algorithm of life seems to be passing as much genetic material as far into the future as possible. If you die, you can't pass it on. If you are not healthy, you can't pass it on. If you are too passive when it comes to sex, you will pass little on. If you are too aggressive and take too many risks, you may pass more on in the short-run but die and pass less on in the long run. So, there is a constant algorithm that runs in the brain of a deer balancing food, security, and sex. Each deer has a different personality and different thresholds based on their genetic make-up and life experiences. (And the two interact in epigenetics). So, in many cases, when deer feel pressure, they will select a less attractive food source that they perceive as less risky. But, when food gets scarce and their health is at stake, they will take greater risks to get higher quality food. During short periods during the rut, bucks will often take great risks they otherwise would not take because if they don't breed does, others will, but the window is pretty short so their overall 12 month risk taking is pretty low compared to does that need to raise fawns. IF your fawns don't survive long enough to breed, then your genetic material stops with them.
There is some new research done with grasshoppers and spiders that illustrates this. They are studying the effect "fear" of predators has on prey species. I saw a PBS show where they are applying this to restoring large predators to some ecosystems in Africa. It is looking like predators have an even more important impact on controlling prey species than simply the prey that they kill. The "fear" of predators, changes the behavior and feeding patterns of prey species. It seems to keep each prey species feeding in their niche areas. By selecting less nourishing but safer foods, it reduces the birth rates for prey species. It also helps keep some plant species from being eliminated by overbrowsing when prey species diets begin to overlap.
Nature is amazing. All this shows the importance of hunting or the human as predator.
Sorry for the tangent, but understanding the big picture does help with our choices when it comes to deer management.
Thanks,
Jack