Even in the 3rd world the primary source of calories is GRAIN, which should be obvious as these are the cheapest calories in any country or market. 3rd world diets are meat and protein poor, but this dose not make them vegetable rich, the calorie deficit is generally filled with more cheap grain not vegetables, this is why people are generally so malnourished and unhealthy in the 3rd world their diet is even worse then western diet.
As automation and robotics are increasingly incorporated into agricultural production here on Earth, could some of these technologies be useful for Mars?
For lab grown meat, it requires a very rich nutrient solution just to survive, currently it is a very inefficient method to produce food. It would be better to feed the colonists the broth used to grow the meat rather than the meat itself.
If you read Jared Diamond's Gun Germs and Steel, you will see that advances in human civilization is associated with more efficient ways to grow food and exploit natural resources in general. The typical way to exploit plant resources that were not directly edible by people was through domesticated animals. The first food animals we will have will eat resources not directly edible by people, such as metabolism products (think tillapia in aquaponics) or leftover stalks from the plants. Is it worth it to create a nutrient broth for artificial meat or to grow the animal and slaughter it? What is the infrastructure that required for the one or the other option and what is its other utility? Being an agronomist I am more in favor of growing the entire animal, because that was what I was taught in class. What I am comfortable with is not necessarily what is the best solution in our case. In any case our answer will be depended on the technological advances as we get closer to mounting the colonization mission.