Back while I was in grad school, Tyler Cowen presented a paper on animal welfare to the Buchanan House brown bag seminar in which he concluded (if I recall correctly) that, so long as animals are happier having been born than not, vegetarians are reducing animal welfare by inducing fewer of them to be born; he also argued that while there may be some cause to want more animals to move from the meat sector to the pet or zoo sectors, animals cannot readily bargain with owners to effect the transfer. Extensive discussion followed on whether animals' welfare ought to count per se or whether it only should count because people care about animals. I threw in that the reason that we ought to care about animal mistreatment isn't so much the violation of the animal's rights but rather that the kind of person who enjoys torturing animals probably also enjoys beating his children; Buchanan jumped in to agree.
The updated version of the paper uses a thinner reason for caring about animal welfare: it counts only inasmuch as people care about animals. In the thinner formulation, vegans may do good, but vegetarians do harm by inducing a shift in animals from the meat sector, where they're happier, to the dairy sector, where they're less happy.
Under either standard, what's gone on at Crafar Farms is repugnant. I grew up on a mixed farm with beef cattle. Calves would be born on February nights at 30 or 40 degrees below zero, and Dad would be out there, every night that a cow seemed likely to be dropping a calf, to make sure things went well. And if a calf was having problems in learning to drink, he or I would be out there a few times a day teaching the calf how to get on with it.
Baby calves are a joy. Here's a nice unicorn chaser for folks who hit the link through to Crafar Farms. I cannot understand how the farmers at Crafar could allow this to happen. I cannot understand how any human could stand by to watch this happen. But I suspect that they're very close kin, in terms of utility functions, to the Kahui whanau, who either murdered their twin boys or stood by and let it happen. Smithian sympathy fails: they couldn't step into the mind of the other and imagine the suffering they were causing, and I consequently can't step into theirs.
There's a dark side out there.