Milorganite is a fertilizer. There is anecdotal evidence that suggests it repels some wildlife when used as a top dressing. However, some wildlife/animals can be attracted to the odor. We have no research.
When you have deer in the area, it is recommended to plant deer resistant plants and protect the plants that deer like to feed on with fencing or repellents. If you cannot protect your plants with fencing/netting, then you may have to rely on repellents. They will have to be reapplied as they wear away in the elements. It also helps to rotate the repellents as deer can get used to them. Follow all label directions.
Also, See our publication on Deer Resistant Ornamentals. Keep in mind that deer may browse on any new plantings until mature. So you may want to initially protect them with repellents or deer netting.