I’m going to agree with the others, it sure sounds like you have pullets, not older hens. Some pullets, especially production breeds, often lay through their first winter and continue until the next fall, when they molt and shut down laying. Nine to ten eggs out of ten production breed pullets is pretty good. Not all production breed pullets continue to lay through their first winter and not all “decorative” breeds stop, but there is a strong trend for this.
The days getting shorter in their second fall triggers a molt in practically any hen after their first winter unless you manipulate lights. Other things can cause a molt at other times of the year, but the main cause of a full molt and shutdown of egg production is the days getting shorter.
What you can probably expect with most of your production breed hens is that they will all molt next fall and most of them start back laying when the molt is finished, regardless of the length of the day. Most does not mean all, some likely will wait a bit on the longer days and maybe warmer weather to start laying after the molt. Each chicken is an individual regardless of breed. They don’t all do the exact same thing though there are breed trends.
I don’t know how severe your weather is going to be but it’s not that unusual for pullets or hens to reduce egg production in severe cold or hot weather. As an example, my current normal 9 to 10 a day might drop back to 6 or 7 when we hit single digits, but that’s a short change. It picks right back up when the weather breaks. I can have slowdowns in really hot weather too.
Some other things you can expect. Their laying rate follows a certain curve. They get to peak production fairly quickly after they start laying, but over time the rate of lay drops off a bit with steady production. That exact curve will vary per flock but don’t be surprised if your 9 to 10 a day drops next summer after they have been laying a year or so.
Egg quality can drop a bit too. The shells might get a little thinner, maybe more blood spots and meat spots, the whites might be more runny instead of firm, things like that. Their bodies just wear out after all that continuous production. The eggs are still safe to eat and all that, just don’t panic if you see a drop in quality.
With your brown egg layers, the egg shells typically get lighter the longer they lay. You may have already noticed that, the eggs are darkest when the pullet first starts to lay. I’ve had some hens gradually change from laying a fairly dark egg to an almost white egg just before the molt.
During the molt the hen recharges her body and stores up materials so when she starts back to laying the egg shells will again be dark and the egg quality should be great. The hens really need to recharge their system by molting at certain points. Some people that extend the lights find that they molt anyway.
This natural cycle is why some of us try to always have pullets every year, so we will get some eggs during the winter. It doesn’t always work, a couple of years back I went with no eggs for quite a spell because those pullets would just would not start laying like they normally do. This type of stuff doesn’t come with guarantees but there are some really strong trends.
Good luck and enjoy your eggs.
