Only if you regard all animals as equal in moral value. Is an aphid equal in moral value to a human being? Are you just counting numbers of discrete organisms?
The animals killed in huge quantities are only marginally sentient at best, some may even be non-sentient.
I don't usually take anything smaller than a grain of rice very seriously, their brains just aren't likely to have enough neurons to support much meaningful sentience. This goes for larger animals with
very small brains/nerve clusters too, like worms (some seem non-sentient, some marginally so).
Fruit flies, for example, are about 2.5 millimeters long (like half the length of a grain of rice or less), and have only around a quarter million neurons (most likely devoted to sight, smell/taste, and flight, and
quick response time).
We could debate whether fruit flies are sentient ( they probably are, but only
barely:
https://www.ncbi.nlm.nih.gov/pubmed/21392558 ), but the important point is that we can't use binary reasoning here to decide that they either have no value, or value equal to a cow or human.
Portia spiders are an outlier in small arthropods, at around the length of a grain of rice, they are almost certainly sentient (and have demonstrable learning behaviors to back it up).
This is a very incomplete list, and a crude approximation anyway, but it may help you:
https://en.wikipedia.org/wiki/List_of_animals_by_number_of_neurons
Note that a rat has about a thousand times the neurons of small insects, and a cow probably closer to ten million times.
It's important to understand, though, that the whole is worth more than the sum of the parts, and where intelligence is concerned the growth with neurons is more exponential than linear. Something with twice the brain power is not necessarily just twice as sentient.
The Portia spiders have around twice the neurons of a fruit fly, but their intelligence is profoundly greater since more of those neurons are devoted to intelligence and deliberative problem solving vs. sensation and quick movement.
The same way, a cow is not necessarily only worth some tens of thousands of pest insects, like the value of a human life probably isn't worth only 300,000 fruit flies.
Very small animals outside certain spiders and some hymenoptera are unlikely to be meaningfully sentient.
Cows are very sentient, and so are the millions of humans affected by climate change.
These are conservative longer term estimates, but the death toll is already mounting from heat related deaths and malnutrition due to breakdown in agriculture from changing weather patterns (as well as disease and other factors):
http://www.who.int/mediacentre/factsheets/fs266/en/
Aside from that, cows are not benign to other animals either. They will stomp on and eat insects, mice, and even birds and raid ground bird nests like other opportunistic 'herbivores' in the wild. Don't assume that they are dainty little angels living harmless lives out there on the pasture.
