So here's the thing..
Have a sow,twice I've gotten 7 pups. What's the chances she will have bigger litter numbers? Also is it one of those things where if the gilt didn't come from a big litter then she too will have a small litter? And how much of a roll in litter numbers does the boar play?
The problem of small litters is kind of a hard one when you only have one sow. Generally if you have a few sows and they all throw small litters the problem is your boar. With just 1 of each it is hard to know who is having the issue but i would guess it is the boar.
Typically unless you have landrace pigs you do not want more then 12 piglets in a litter as mom sow only has 12 teats. If all 12 teats do not work then you need to look at a smaller litter, our duroc sow has two non-functioning teats so we wounldnt want more then 10 piglets per litter with her. You can have more piglets then teats of course but more often then not the "extras" die and your entire litter will be more prone to being runty because of reduced calories. They may not appear runty at first but if compared to a smaller size litter of piglets they will be smaller at birth and at wean on average.
The number of piglets in the litter the gilt comes from does play a part which depends on the genetics the sow had. This can be completely mis-leading though as the sow's genetics may say she is capable of having 12-18 piglets per litter but if the boar doesnt do his job she may only produce 8 making the breeder think her genetics are only ment to produce smaller litters. So if you got a gilt from the 8 piglet litter her genetics would be for large litters but you wouldnt know that if you only went off the size of litter she came from.
Conversely the sow could have genetics for large litters and the boar could have genetics for small litters, so which the gilt would have is a roll of the dice even if she came from a small litter, she could end up being a large or small litter producer.
The boar plays a very large role in the litter size. Small litters could be due to a imature boar, an inexperienced boar, a boar with low mobility sperm, etc.
Most farmers have several gilts/sows and pu the boar to all of them and see the results that is how you figure out if the boar is good or not. We recently sent our new boar to freezer camp for not producing. The boar had 3 heats to breed 5 gilts and after 3 heats for each of them we ended up with one gilt pregnant with 4 piglets. That is a pretty good indication of the boar having an issue. Out of 15 heats total he only got one pregnant.
The other option is to AI the gilt with proven boar semen but unless you have practice doing AI on pigs a small litter or no litter could still be human error. Luckily AI'ing pigs is quite easy and if we AI twice in a row and both litters come out small we generally assume it is the gilt and replace her.
Out of curiosity...any reason your calling them pups?
