Modern farming practices are definitely spreading the bird flu in the cows.
For the cows, for some unknown reason the bird flu virus is spreading from the respiratory tract to lots of different organs without killing them. For most animals spreading to other organs makes the virus fatal. In the case of the cows, it doesn't kill them and makes it all the way to the milk in the udder. Apparently cows didn't get influenza type A before this outbreak. Its not definitely known how the virus went from birds to cows and its still not completely understood what all the avenues are being used to go from cow to cow.
Unsanitary conditions are the most likely source once the virus gets into a herd. The milking machines are spreading it from cow to cow and the cow's milk infects the feeding calves. The milking machine is not cleaned between each milking. Contaminants in the food sources such as infected animal droppings, dead animals, nasal secretions and saliva will also pass it around. One of the food sources is the open field with grass or feed spread in it which is impossible to keep clean. Piles of hay or grains, common food troughs, are all sources of infection. Not much can be done about the situation using the current practices.
Cows can also get bird flu by eating infected meat, such as dead animals or even live ones. Cows like other herbivores do eat meat occasionally, including live birds. There are many instances of cows eating a chicken now and then. If a cow needs extra minerals or vitamins it can eat dead animals it finds in the field to satisfy those cravings. Cows will also eat anything that might just be in the feed or hay that is alive or dead such as rodents, lizards, insects, birds.
People are at a very low risk of getting the bird flu, though farm workers can get it, such as being splashed by infected milk. Several different anti viral drugs are effective against the bird flu. Once the virus gets in one farm, it can eventually be found in neighboring farms but the method of transmission between farms is unknown. It could be a single type of source that infects each farm individually. Farmers trading or buying cows to add to their herds can definitely spread the virus. It could also be the vehicles transporting the cows or other equipment between farms. People are at a very low risk of getting the bird flu, though farm workers can get it, such as being splashed by infected milk. Several different anti viral drugs are effective against the bird flu.
Once the milk is pasteurized the virus is dead and can't infect anything. There is a health craze, for a small percentage of the population, of drinking unpasteurized milk. Its probably not a good practice to continue or take up the practice. It looks like some, maybe many, of the cows get the virus but show no symptoms and there is a 90 percent recovery rate for known sick cows. It's like shades of covid, with sporadic testing, unsanitary milking machines, and unregulated quarantines.
The milk producing cows that get symptoms can produce milk that is thickened and icky looking to say it as nice as possible. If you drink milk you probably don't want to read this, the milk goes from the cows, through the milking machines, and then into big tanks. When cows have mixed diets, including whatever they pick up in the field, the quality of the milk can vary from day to day anyway, and it all gets blended together. Once cows are identified as producing bad milk, they are removed from the milking process.
So far, the unlimited killing of cows has not been practiced although some cows have been killed. Farmers can get some limited financial help for improving sanitary conditions and the handling of sick cows. The US government and 2 dozen educational institutions and commercial drug companies are seriously working on a bird flu vaccine for cows. Because influenza is considered to be dangerous and the research is a security risk, there is a lot of red tape and paperwork for working with the influenza type A virus which can hamper progress.
The US government has hired Moderna to make a mRNA bird flu vaccine for cows. There are several bird flu vaccines for people.
phys.org
