Husbandry can improve agriculture instead of taking away from it
Some animals recapture wasted greenhouse light
Hydroculture crops like rice and seaweed are grown in water. While a lot of your light will be absorbed by the plants, a lot of it will also go into the water around your plants giving you the ability to grow an entire second ecosystem using the same space. The area around your rice in a healthy rice paddy for example will grow algae. This algae becomes food for various other organisms that will include various fish and arthropods which are both sources of meat that you basically get for free when growing water crops.
Other animals recapture waste from the actual plants you grow
While claims about cows needing 6-7kg of feed per 1kg of meat may be true, it is also very deceptive when you consider that you can get away with growing 0kg of specialized feed plants per 1kg of meat. When you grow edible plants like fruits or grains, only a small % of what you grow is fit for human consumption. The rest of the plant is still full of nutrients that you just wasted a lot of energy growing, but can not eat... however, other animals may be able to eat these parts of the plants. While animals like cows, goats, and sheep are grossly inefficient sources of meat in terms of how much food they eat to how much they produce, they can digest and live off of the biproducts of human agriculture. On Earth, we often grow specialized feed crops so we can produce more and fattier meat than we could off of just crop waste, but this is not necessary. If you assume your colonists only eat red meat a few times a month, then you can simply sustain a smaller herd completely off of agricultural waste.
These animals can also produce additional products like wool, gelatin, leather, tallow, etc. which your colonists would be able to use for things that plant matter may not necessarily be ideal for.
Some animals help you grow more plants
The issue of pollinating your plants is tricky when you leave it humans, but if you bring honey bees into the mix, then you have a perfect system that not only pollinates your plants for you, but also gives you that sweet sweet honey as a reward for your total lack of effort. Plants spend energy making nectar whether we use it or not; so, not only do bees produce an additional food source, they do it by recapturing another one of those wasted parts of the plant.
Also, non-editable plant parts often take a very long time to decompose. Thrown into a compost pile, plant matter can take anywhere from 3 months to several years to decompose enough to become a proper fertilizer. In this time, they release all of the same CO2 and Methane emissions that cows get criticized so much for, they just do it more slowly. This means for every kg of plant matter you have growing somewhere in your habitat, you have an equal mass of plant matter decomposing, waiting to be reintroduced to your agricultural system. However, by pushing your wasted plant matter through an animal's digestive system, you will have a pile of fertilizer within 1-3 days. This means you spend much less time waiting on nutrients to be recaptured to be put back into your agriculture; so, the space you would be wasting on giant composting chambers can instead contribute to space used for animal pens.