Granting that Objectivism does not support the concept of "animal rights", a legal distinction, is there an argument to be made (in the application of Objectivist ethics) that animal welfare is a value to a rationally self interested man? Are pets a value? What about animals in the wild? Is there a different response for certain animals of negative value to humans, such as the house fly or mosquito? What about a harmful yet beautiful animal such as a shark?
Animal welfare is of value to a man inasmuch as the animal's welfare improves the man's life.
Eating diseased beef is not a value to a man, so making sure that the cows are healthy before they are slaughtered and packed for distribution and human consumption is valuable.
Pets are valuable because they feel good to hug and to take care of, and a good pet clearly appreciates being taken care of.
Animals in the wild are potential threats, nuisances, or sources of food. Capturing them, killing them, or eating them is sometimes of value to people.
Animals in the wild can also be fun to watch, so one might not want to kill them if they don't represent a threat or nuisance and you have other sources of food. Sharks might fall under this category, if you don't spend much time swimming in the water with them, but if your life involves a lot of swimming, you might wish to kill sharks.
Mosquitoes are a threat, so it's good to kill them.
Animal welfare as such, independent of human welfare which depends on it (or on its absence) has no value.
Any value of any animal life derives from the value of some human life.