I continue supporting my thesis with the third and the fourth attribute mentioned by Piazza.

Furthermore, for the survival of the human species, it is also not necessary at all to eat meat. Quite the contrary. Kastner et al (2012) describe clearly that the world could feed more human beings if, instead of feeding wheat and corn to animals, we ate it ourselves. This can also be supported by the figures from Alexander et al (2016), according to which 25kg of feed are necessary to produce one kg of beef. The fourth and final attribute concerns the question of whether it could be seen as ‘nice’ to eat meat: possibly if we treated animals naturally and, as Rolston (1989) demands, ‘not above a baseline of pain’ and ‘basic to animal and human ecology’[1]. But as we produce and sell meat, it has become a product on a worldwide market. Such a production is submitted to global market laws ruled by industrial and political interests, and supply and demand. This means, the way meat will be produced will always be optimized for this business, which rarely serves the wellbeing of the product, the animal.
^{1 Rolston III, Holmes (1989): "Treating Animals Naturally?" in: Between the Species: Vol. 5: Iss. 3, Article 4. DOI: https://doi.org/10.15368/bts.1989v5n3.2}

Again, there is no rule without exception. I can leave the gap commas out if the sentence is perfectly clear without them. Have a look at the examples.
No. 1 is the full sentence with all repeated words and listing commas. It’s a bit clumsy.
No. 2 is the example with listing commas and gapping commas for the words left-out. In this sentence, the second listing comma is only put to avoid misreading. It feels a bit orvermarked with commas.
No 3. is the example with the reduced gapping commas. The sentence is fully clear without them. The second listing comma is only put to avoid misreading. This looks better.

1 Brazil is proud of being the biggest exporter of beef, the American continent is proud of being the biggest exporter of chicken, and China is proud of being the biggest exporter of fish.
2 Brazil is proud of being the biggest exporter of beef, the American continent, of chicken, and China, of fish.
3 Brazil is proud of being the biggest exporter of beef, the American continent of chicken, and China of fish.