My wife discovered that the mead we are brewing smells a bit off, and a book we have on the topic suggest we may not have applied enough micronutrient. Any suggestions on getting more in? We have brewed for only a week and this is our first batch if that helps.
The most common nutrients for mead making, DAP and Fermaid-K or -O, come in powder form. Adding a tsp of each to a 5-gallon batch of mead and mixing well is all it takes. If you see the nutrient doesn't dissolve well you can pre mix it with a little clean water (1/4cup) before adding it in. A normal nutrient regimen is to add small amounts of nutrients (with mixing) on day 1, 3, and 5. Then let it ferment along on its own. Occasional mixing at day 10 or 13 will help to degas the mead. Degassing the mead prevents dissolved CO2 from slowing the yeast. (Similar issue to the dude that left the comment about open vs. closed fermentation)
As a counterpoint, I've done mead batches with zero nutrients, and batches with different levels of nutrients, with success each time. So far I've only used diammonium phosphate (DAP) and Wyeast yeast nutrient in the primary. I've never done additional mixing, and I've never added nutrients partway through the primary, and only recently have I ever added more nutrients to the secondary (see other post). I start with what I start with, and I let the primary fermentation go until it's done and then some -- generally about a month at least. The key is giving it time to do its thing.
Yes, sometimes things smell a little funny, as yeast with less nutrient than they like might produce some temporary off-notes in the nose. A sulfury eggy smell is one such common odor. However, after 30-odd batches, I've always found that these will age out, so long as you're patient. And the thing about mead is, the longer it ages, the better it gets. :)
In one extreme instance of bad smells (my first ever usage of Lalvin K1V-1116 yeast, and my first-ever Italian plum melomel with the plums in the primary), the smell was so sudden and so pervasive that my wife thought we had a gas leak in the house and she called the gas company. Their engineer didn't find any methane leaks, but he did recognize the issue. Even after such a funky start, the end product was blissfully divine.
If you do decide to add nutrients partway through the primary, mix it in well. One important caveat I've heard about is that you might get a fizz-up: if the early mead is carbonated enough, adding nutrients may cause that carbonation to come out, so make sure you have enough headroom between the top of the liquid and the top of your container -- or you might wind up with a Mentos + Coca Cola kind of situation, and a huge sticky mess to clean up. 😳