Could it be something I'm doing or could the chickens just be slowing down?
Not really either one. Before they were domesticated chickens developed instincts to lay eggs and raise chicks during the good weather months, stop laying and use the nutrition that as going into making eggs to replace worn out feathers in the fall, and not lay eggs and raise chicks until the days warmed up in the spring. The signal to stop laying eggs and molt is the days getting shorter. The signal to start laying in the spring is the days getting longer. From your post I assume you are in the Northern Hemisphere, yet another example of where putting your general location in your profile so it is always available might be helpful.
When we domesticated them thousands of years ago we started breeding them for certain traits. Some were bred to lay more, some were bred more for meat, and some more to be decorative. Today we tend to feed them well all year around, house them to protect them from the weather, maybe add lights or heat, and so forth. They still retain those basic life-cycle instincts but with breeding and how we manage them they don't always follow that cycle as closely.
Some pullets now do what yours did, skip the molt their first fall and continue to lay even without extending lights. A lot of that is due to breeding. Some people manipulate lights so they don't know when the days are getting shorter. Some hens even go broody in the middle of winter because the way they are managed, they don't know it is the middle of winter. From what you have posted it sounds like yours are going through this natural cycle and are currently molting. When they finish they should start up laying again.
Hens go through another natural cycle when it comes to laying. They tend to lay really well their first laying season. Those bred to be productive layers lay a lot, decorative and meat birds not so much. But all of them should lay as well as they ever will. After their first adult molt (which yours are now going through) they come back laying really well again, the eggs should even be a bit larger. But after their second adult molt (next fall for you) production drops. Ho much depends on the individual chicken. In the commercial egg laying flocks using the hybrids specially bred for egg laying, a large flock averages about a 15% to 20% drop. You only have four hens so averages won't mean much. Some individual hen's laying won't drop much at all, others will really drop. So I don't know what will happen to yours. After each adult molt after that production drops even more.
You have Production Reds. These are not the commercial hybrid egg layers that
@Egghead_Jr is talking about. Commercial hybrids are small in body so more of what they eat can go to egg production instead of having to maintain a larger body so they have an excellent feed to egg conversion rate. Production Reds are were developed from dual purpose chickens. I've read different things on what breeds were used to develop them, some say Rhode Island Reds and New Hampshire, other sources say Leghorns were also used with these two breeds. The result is that you get a larger chicken that still lays really well but are not prone to the medical issues the commercial hybrids have. They are going to act pretty close to what dual purpose hens would, not those specialty egg laying hybrids.
The commercial egg laying hybrids have relatively small bodies for the size of egg they lay. Their eggs are a decent size usually grade A large. Their internal egg making factory is specialized in egg making and is fairly sensitive. I compare it to the Cornish X meat birds who are bred to convert feed to meat. Their bodies are fairly sensitive too, if you don't manage how you feed them they will break down. The commercial egg laying flocks are typically fed a 16% protein diet. That is the efficient feed for production. They lay a lot of nice sized eggs at that protein level. If they are fed a higher protein level the eggs get bigger and that delicate internal egg making factory is strained even further. They are more prone to prolapse, internal laying, and becoming egg bound than dual purpose to start with but like the Cornish X feeding them too well can just make it worse.
Since yours are dual purpose a lot of this doesn't apply to you, I'm trying to explain why not.
When are chickens normally slaughtered for meat?
I assume you are talking about older hens, that's pretty obvious. We all set up different management schemes depending on our goals and conditions. Your flock is only four hens, that can affect your decision. Some people replace the entire flock at specific ages, maybe after one, two, or three laying seasons. I have more chickens so I replace half the hens every year. Say I have eight hens. During the summer I have four that have been through one adult molt, four that were pullets the last year with most skipping the molt their first fall, and four that are young pullets getting ready to lay. When they older ones start to molt I remove the four oldest and keep four pullets and four going through their first adult molt. Others use a one third scheme instead of half each year.
We are all different, this is something you'll have to work out yourself. Hopefully there is enough information in these different posts to help you with that. Jut be flexible, very few things work out exactly as planned.
You can eat any chicken regardless of age or sex. But their age affects how you can cook them. That's worth an entire different thread there are so many different options and requirements. People have been eating old roosters and hens for thousands of years. Hunters don't know how old fowl they bring home is. How you cook them can be important, they can be delicious or they can be inedible.
Good luck!
