Lets be honest here, 1 tin of tuna has about 35grams of protein in it, one protein shake of say 75 grams of whey has 75grams of protein... BUT... I bet my life that you will see more gains from the Tuna than the shake.
Try getting 250 grams of protein a day from food as opposed to 400 grams a day from shakes, you see better gains from the food - simple fact, well for me anyway, I've done it several times.
Shakes just go through you, there is no replacement for real food. 18 eggs a day, 4 tins of tuna a day (200gram tins), 3 chicken breasts a day and you are growing. All these shakes just go in one end and out the other in my opinion. All the advertising is hype and bullshit, I have stopped drinking shakes, period, I just get my protein from food and I am growing faster than when I spent $100 a week on whey. Only supplements I take are creatine and vitamins/minerals.
Pete