0624191634cTerri, in the UK, was looking for some information about how we choose sires when we breed via artificial insemination:

Hi, Terri,
This is a great question. Deciding what genetics and cultural methods to bring into the herd — or just how the heck to get this cow bred so she’ll lactate — involves a lot of factors. There are a great many available sires filling straws out there, and it helps a lot if you can start by narrowing down the field. We can tell you how our decision-making is done, but in the end there is always some uncertainty.
First, breed. You’ve got that already, since you’re asking about Jerseys. We have almost universally used Jersey semen, too.
Then there are several factors that rank closely in importance. Grass genetics, for one — that’s all the resultant calf is going to get on our farm, so we select for a history of grass in the sire. Not that a grain-fed bull won’t sire calves that can do fine on grass, though — bovines are herbivores. But since we can select for a grass-fed bull, we do.
Longer teats in the bull’s mother and sisters. This is important, because we are going to hand-milk these girls, and there are few things more frustrating than trying to extract three gallons of milk from an udder just a few drops at a time.
High components in the milk of the bull’s mother and sisters. That should mean more fat and protein in our milk, too. Water we have already, from the house well; we don’t need watery milk.
‘Calving-ease’ genetics — in other words, the bull sires smaller calves. I’m not always there when Mama starts nesting, and I want her to be able to get that baby out without trouble.
Homozygous A2 betacasein is nice, if you can get it; A2A2 cows bring more in the home dairy cow market.
If we have a choice, we’ll select semen from a bull in an organic, non-medicated cultural practice, but as the language of regenerative agriculture is bought up by big business, terms lose their real meaning, so unless we can actually visit the farm, we can’t really know what the sire has or has not been exposed to. It’s a guessing game.
Then there is consanguinity! With the way semen has been shipped around the country in the past few decades, the bloodlines have gotten to be few and congested — that is, most of those bulls are related to one another, so even if I change bulls every year, pretty soon I’m breeding pretty close to the line. This is a serious problem in modern breeding — a narrowing of our genetic availability — and one we are taking steps to avoid on our farm.
Over the years we have used artificial insemination for most of our breeding, and I can’t actually say I have evidence one way or another for the success of our genetic choices! Mamas conceive, bear, and lactate pretty much the same whatever bull we use, of course. The one exception we can remember was the year we ordered special (all-grass, organic, Jersey, intensively grazed, A2A2) genetics from Nebraska. Twenty straws, plus shipping — it cost going on one thousand dollars, all told — and we only got two conceptions. Bad a.i. technique, or bad semen? We don’t know, but since then we order semen from Select Sires. They, at least, can absorb the loss if they accidentally send us inviable straws.

As for the progeny of our bulls, we’ve bred a lot of good family cows in the past fifteen years or so, and we’ve also seen a few short teats, double-os (two-hole) teats, and so on, to keep us humble.  By and large, we’ve been happy with the heifers our cows drop, and we feel confident about the overall upgrade of our line of stock.  Between the improvement of our pastures and forage, and the improvement of the genetics and expression of our livestock, we are milking better cows, with better outcomes, every year.  That’s success, for us.
All of that said, we believe that artificial insemination, and the genetic homogeneity it results in, is at best a poor second to bull-breeding. For the past two years we’ve kept a Dexter/Jersey cross bull to cover our cows, and this year’s crop of calves is lovely. As long as we have enough grass to spare for a bull, we hope to go on using one; if we ever have to down-size to our home farm (a scant seven or so acres of pasture set in another twenty of trees), things may change again.
We hope this helps!
Best of luck,
Shawn and Beth